Seep Manual

for finite element seepage analysis

Version 5

USER’S GUIDE GEO-SLOPE

OFFICE

Software License The software described in this manual is furnished under a license agreement. The software may be used or copied only in accordance with the terms of the agreement.

Software Support Support for the software is furnished under the terms of a support agreement.

Copyright Information contained within this User's Guide is copyrighted and all rights are reserved by GEO-SLOPE International Ltd. The GEO-SLOPE Office software is a proprietary product and trade secret of GEOSLOPE. The User’s Guide may be reproduced or copied in whole or in part by the software licensee for use with running the software. The User’s Guide may not be reproduced or copied in any form or by any means for the purpose of selling the copies.

Disclaimer of Warranty GEO-SLOPE reserves the right to make periodic modifications of this product without obligation to notify any person of such revision. GEO-SLOPE does not guarantee, warrant, or make any representation regarding the use of, or the results of, the programs in terms of correctness, accuracy, reliability, currentness, or otherwise; the user is expected to make the final evaluation in the context of his (her) own problems.

Trademarks WindowsTM is a registered trademark of Microsoft Corporation.

Copyright © 1991-2001 by GEO-SLOPE International Ltd. Calgary, Alberta, Canada ALL RIGHTS RESERVED Printed in Canada

SEEP/W Table of Contents Chapter 1 Technical Overview................................................... 11 Introduction.................................................................................................................. 11 About the Documentation ....................................................................................... 11 Applications ................................................................................................................. 11 Unconfined Flow ..................................................................................................... 12 Precipitation Infiltration............................................................................................ 12 Pond Infiltration ....................................................................................................... 13 Excess Pore-Water Pressure.................................................................................. 14 Transient Seepage.................................................................................................. 14 Features and Capabilities ........................................................................................... 15 User Interface.......................................................................................................... 15 Seepage Analysis ................................................................................................... 25 Using SEEP/W.............................................................................................................. 28 Defining Problems................................................................................................... 28 Solving Problems .................................................................................................... 30 Contouring and Graphing Results........................................................................... 30 Formulation .................................................................................................................. 31 Product Integration ..................................................................................................... 33 Product Support .......................................................................................................... 33

Chapter 2 Installing GEO-SLOPE Office ................................... 35 Basic Windows Skills .................................................................................................. 35 Managing Data Files ............................................................................................... 35 Windows Fundamentals.......................................................................................... 35 Basic GEO-SLOPE Office Skills ................................................................................. 36 Starting and Quitting GEO-SLOPE Office Applications .......................................... 36 Dialog Boxes in GEO-SLOPE Office Applications .................................................. 36 Using Online Help ................................................................................................... 38 Installing GEO-SLOPE Office ..................................................................................... 38 Running Setup from the CD-ROM .......................................................................... 38 Managing GEO-SLOPE Office License Files.......................................................... 39

2 SEEP/W Managing Network Licenses....................................................................................42 Files Installed by Setup............................................................................................45 Viewing GEO-SLOPE Office Manuals .....................................................................46

Chapter 3 SEEP/W Tutorial........................................................ 49 An Example Problem................................................................................................... 49 Defining the Problem .................................................................................................. 49 Set the Working Area ...............................................................................................50 Set the Scale............................................................................................................50 Set the Grid Spacing ................................................................................................51 Save the Problem.....................................................................................................52 Sketch the Problem..................................................................................................53 Identify the Problem .................................................................................................55 Specify the Analysis Type........................................................................................56 Specify the Analysis Control ....................................................................................57 Define a Hydraulic Conductivity Function ................................................................58 Define Material Properties .......................................................................................60 Generate Finite Elements ........................................................................................61 Set View Preferences ..............................................................................................64 Specify Node Boundary Conditions .........................................................................65 Draw Flux Sections ..................................................................................................67 Sketch Axes .............................................................................................................68 Verify the Problem ...................................................................................................70 Finish DEFINE .........................................................................................................71 Solving the Problem.................................................................................................... 71 Start Solving.............................................................................................................72 Finish SOLVE...........................................................................................................73 Viewing the Results..................................................................................................... 73 Draw the Velocity Vectors........................................................................................76 Draw the Contour Values .........................................................................................77 Draw the Flux Value.................................................................................................78 Draw Flow Paths ......................................................................................................79 Zoom In and Out ......................................................................................................80 Print the Drawing......................................................................................................81 Display Node and Element Information ...................................................................81 Plot a Graph of the Results......................................................................................83

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Chapter 4 DEFINE Reference..................................................... 85 Introduction.................................................................................................................. 85 Toolbars........................................................................................................................ 85 Standard Toolbar .................................................................................................... 86 Mode Toolbar .......................................................................................................... 87 View Preferences Toolbar....................................................................................... 89 Grid Toolbar ............................................................................................................ 89 Zoom Toolbar .......................................................................................................... 90 The File Menu............................................................................................................... 91 File New .................................................................................................................. 91 File Open................................................................................................................. 92 File Import: Data File............................................................................................... 94 File Import: Picture .................................................................................................. 95 File Export ............................................................................................................... 97 File Save As ............................................................................................................ 98 File Print .................................................................................................................. 99 File Print Selected ................................................................................................. 101 File Save Default Settings..................................................................................... 102 The Edit Menu ............................................................................................................ 103 Edit Undo .............................................................................................................. 103 Edit Redo .............................................................................................................. 103 Edit Copy All.......................................................................................................... 103 Copy Selection ...................................................................................................... 104 The Set Menu ............................................................................................................. 104 Set Page ............................................................................................................... 104 Set Scale ............................................................................................................... 106 Set Grid ................................................................................................................. 108 Set Zoom............................................................................................................... 109 Set Axes ................................................................................................................ 110 The View Menu........................................................................................................... 111 View Node Information.......................................................................................... 112 View Element Information ..................................................................................... 113 View Edge Information .......................................................................................... 115 View Node Boundary Conditions .......................................................................... 116 View Edge Boundary Conditions .......................................................................... 117 View Preferences .................................................................................................. 119 View Toolbars ....................................................................................................... 122 View Redraw ......................................................................................................... 124 The KeyIn Menu ......................................................................................................... 124 KeyIn Analysis Settings......................................................................................... 124

4 SEEP/W KeyIn Material Properties.......................................................................................132 KeyIn Functions Conductivity.................................................................................135 KeyIn Functions Vol. Water Content......................................................................146 KeyIn Functions Grain Size ...................................................................................149 KeyIn Functions Boundary.....................................................................................158 KeyIn Functions Modifier .......................................................................................161 KeyIn Nodes...........................................................................................................162 KeyIn Elements ......................................................................................................163 KeyIn Flux Sections ...............................................................................................165 KeyIn Initial Water Table........................................................................................166 KeyIn Generate Plan View.....................................................................................167 The Draw Menu .......................................................................................................... 168 Draw Nodes ...........................................................................................................169 Draw Single Elements............................................................................................169 Draw Multiple Elements .........................................................................................171 Draw Infinite Elements ...........................................................................................174 Draw Boundary Conditions ....................................................................................176 Draw Element Properties .......................................................................................179 Draw Flux Sections ................................................................................................179 Draw Initial Water Table.........................................................................................180 The Sketch Menu ....................................................................................................... 182 Sketch Lines...........................................................................................................182 Sketch Circles ........................................................................................................182 Sketch Arcs ............................................................................................................183 Sketch Text ............................................................................................................184 Sketch Axes ...........................................................................................................187 The Modify Menu ....................................................................................................... 188 Modify Objects .......................................................................................................188 The Tools Menu ......................................................................................................... 196 Tools Verify/Sort.....................................................................................................196 Tools SOLVE .........................................................................................................199 Tools CONTOUR ...................................................................................................199 Tools Options .........................................................................................................199 The Help Menu ........................................................................................................... 200

Chapter 5 SOLVE Reference ................................................... 201 Introduction................................................................................................................ 201 The File Menu............................................................................................................. 201 File Open Data File ................................................................................................202

GEO-SLOPE Office 5 The Help Menu ........................................................................................................... 202 Running SOLVE ......................................................................................................... 203 Stop-Restart ............................................................................................................... 205 Halt Iteration............................................................................................................... 206 Graph .......................................................................................................................... 207 Viewing the Graph................................................................................................. 207 Changing the Graph Display ................................................................................. 208 Files Created .............................................................................................................. 210 Head File ............................................................................................................... 211 Velocity File ........................................................................................................... 212 Material Properties File ......................................................................................... 213 Flux File................................................................................................................. 214 Convergence File .................................................................................................. 215 Initial Condition Files ............................................................................................. 215

Chapter 6 CONTOUR Reference.............................................. 219 Introduction................................................................................................................ 219 Toolbars...................................................................................................................... 219 Mode Toolbar ........................................................................................................ 221 View Preferences Toolbar..................................................................................... 222 The File Menu............................................................................................................. 223 File Open............................................................................................................... 224 The Edit Menu ............................................................................................................ 227 The Set Menu ............................................................................................................. 227 The View Menu........................................................................................................... 227 View Time Increments........................................................................................... 228 View Element Regions .......................................................................................... 229 View Node Information.......................................................................................... 230 View Element Information ..................................................................................... 231 View Preferences .................................................................................................. 233 View Toolbars ....................................................................................................... 236 The Draw Menu .......................................................................................................... 237 Draw Contours ...................................................................................................... 237 Draw Contour Labels ............................................................................................ 241 Draw Vectors......................................................................................................... 242

6 SEEP/W Draw Flux Labels ...................................................................................................243 Draw Flow Paths ....................................................................................................243 Draw Graph............................................................................................................244 The Sketch Menu ....................................................................................................... 250 The Modify Menu ....................................................................................................... 251 The Help Menu ........................................................................................................... 251

Chapter 7 Modelling Guidelines.............................................. 253 Introduction................................................................................................................ 253 Modelling Progression ...........................................................................................253 Units .......................................................................................................................253 Mesh Design ..........................................................................................................254 Relevant Materials .................................................................................................258 Basic Solution Requirements.................................................................................260 Incremental Time Sequences ................................................................................260 Conductivity Function Requirements .....................................................................261 Initial Conditions.....................................................................................................262 Adaptive Time Stepping.........................................................................................266 Boundary Conditions ................................................................................................ 269 Upstream Vertical Boundary ..................................................................................269 Downstream Vertical Boundary .............................................................................270 Fluctuating Reservoir .............................................................................................271 Nonzero Flux Boundary .........................................................................................272 Internal Boundary Conditions.................................................................................273 Ground Surface Flux ..............................................................................................273 Boundary Reviews .................................................................................................... 275 Boundary Reviews for Potential Seepage Faces ..................................................275 Handling Convergence Difficulties.......................................................................... 276 The Problem with Steep Functions ........................................................................276 Using Convergence Parameters............................................................................277 Selecting Convergence Parameters ......................................................................278 Acceptable Convergence.......................................................................................278 Effect of the Volumetric Water Content Function...................................................281 Unnatural Boundary Conditions .............................................................................281 Transmissivity and Storativity ................................................................................. 281 Transmissivity and Storativity..........................................................................281

GEO-SLOPE Office 7 Axisymmetric Analysis ............................................................................................. 282 Plan View Analysis .................................................................................................... 283 Element Addition and Removal................................................................................ 284 The Use of Infinite Elements .................................................................................... 284 The Implications of Infinite Elements .................................................................... 284 The Pole Position .................................................................................................. 285 Infinite Flux Boundaries......................................................................................... 286 Flow Paths.................................................................................................................. 286 Flow Lines .................................................................................................................. 287

Chapter 8 Theory...................................................................... 289 Introduction................................................................................................................ 289 Volumetric Water Content Functions .................................................................... 289 Hydraulic Conductivity Functions .......................................................................... 291 Flow Law ............................................................................................................... 292 Governing Equations............................................................................................. 293 Coordinate Systems.............................................................................................. 295 Interpolating Functions.......................................................................................... 297 Field Variable Model ............................................................................................. 299 Interpolation Function Derivatives......................................................................... 299 Finite Element Equations ...................................................................................... 303 Time Integration .................................................................................................... 306 Numerical Integration ............................................................................................ 306 Hydraulic Conductivity Matrix................................................................................ 310 Mass Matrix ........................................................................................................... 311 Flux Boundary ....................................................................................................... 313 Assembly of Global Equations and Equation Solver ............................................ 315 Iteration Scheme ................................................................................................... 316 Gradients and Velocities ....................................................................................... 317 Flow Quantities ..................................................................................................... 318 Material Functions ..................................................................................................... 321 Weighted Splines .................................................................................................. 321 Best-Fit Splines ..................................................................................................... 322 Infinite Elements ........................................................................................................ 324 Mapping Functions................................................................................................ 325 Pole Definition ....................................................................................................... 327

8 SEEP/W Density-Dependent Flow........................................................................................... 328

Chapter 9 Verification .............................................................. 331 Introduction................................................................................................................ 331 Dam Foundation Cutoff..........................................................................................331 Unconfined Dam Seepage.....................................................................................333 Slope Infiltration .....................................................................................................336 Radial Flow to a Well .............................................................................................340 Consolidation Analysis ...........................................................................................343 Reservoir Clay Liner ..............................................................................................345 Reservoir Filling Analysis .......................................................................................348 Rapid Drawdown Analysis .....................................................................................352

Appendix A Unsaturated Hydraulic Conductivity .................. 355 Introduction................................................................................................................ 355 Direct Measurement of the Hydraulic Conductivity Function .................................355 Hydraulic Conductivity Predictive Methods - Introduction .....................................355 Hydraulic Conductivity Predictive Method (Fredlund et al, 1994)..........................356 Hydraulic Conductivity Predictive Method (Green and Corey, 1971) ....................358 Hydraulic Conductivity Predictive Method (van Genuchten, 1980) .......................359 Direct Measurement of Water Content Function ...................................................360 Volumetric Water Content Predictive Methods - Introduction ................................361 Volumetric Water Content Predictive Methods (Arya and Paris, 1981).................362 Volumetric Water Content Predictive Methods (MK - Modified Kovacs Method) ..363 Volumetric Water Content Predictive Methods (Fredlund and Xing, 1994) ...........366 Volumetric Water Content Predictive Methods (van Genuchten, 1980) ................367 Example Material Property Functions ....................................................................367 Uniform Fine Sand #1 - Function #1 ......................................................................369 Uniform Fine Sand #2 - Function #2 ......................................................................371 Sandy Loam - Function #3.....................................................................................374 Very Fine Sand - Function #4 ................................................................................375 Sandy Silt (Coarse Tailings) - Function #5 ............................................................377 Silty Sand - Function #6.........................................................................................380 Well-Graded #1 - Function #7................................................................................381 Well-Graded #2 - Function #8................................................................................384 Silt #2 - Function #9 ...............................................................................................386 Glacial Till (Uncompacted) - Function #10.............................................................388 Glacial Till (Compacted) - Function #11 ................................................................390 Silt Loam - Function #12 ........................................................................................392 Sandy Silty Clay - Function #13.............................................................................394 Silty Clay (Fine Tailings) - Function #14 ................................................................396 Uniform Silt - Function #15 ....................................................................................398

GEO-SLOPE Office 9 Clay Silt - Function #16 ......................................................................................... 400 Well-Graded #3 (high clay) - Function #17 ........................................................... 402 Uniform Sand - Function #18 ................................................................................ 404 Sand - Function #19.............................................................................................. 406 Fine Sand - Function #20...................................................................................... 407 Silt - Function #21 ................................................................................................. 409 Silt (Tailings) - Function #22 ................................................................................. 411 Sandy Clayey Silt - Function #23.......................................................................... 413 Clayey Silt - Function #24 ..................................................................................... 415

Appendix B DEFINE Data File Description ............................. 419 Introduction................................................................................................................ 419 File Keyword .............................................................................................................. 419 FILEINFO Keyword ............................................................................................... 419 TITLE Keyword ..................................................................................................... 419 ANALYSIS Keyword.............................................................................................. 420 CONVERGE Keyword........................................................................................... 421 TIME Keyword....................................................................................................... 422 MATERIAL Keyword ............................................................................................. 424 KFUNCTION Keyword .......................................................................................... 424 SFUNCTION Keyword .......................................................................................... 426 BFUNCTION Keyword .......................................................................................... 427 MFUNCTION Keyword.......................................................................................... 429 NODE Keyword..................................................................................................... 430 ELEMENT Keyword .............................................................................................. 432 POLE Keyword...................................................................................................... 434 FLUX Keyword ...................................................................................................... 435 DENSITY Keyword................................................................................................ 436 WATERTABLE Keyword....................................................................................... 436 qBOUNDARY Keyword......................................................................................... 437 MATLCOLOR Keyword......................................................................................... 438

10 SEEP/W

Chapter 1 Technical Overview Introduction SEEP/W is a finite element software product that can be used to model the movement and pore-water pressure distribution within porous materials such as soil and rock. Its comprehensive formulation makes it possible to analyze both simple and highly complex seepage problems. SEEP/W has application in the analysis and design for geotechnical, civil, hydrogeological, and mining engineering projects. SEEP/W is a 32-bit, graphical software product that operates under Microsoft Windows 95 and up. The common "look and feel" of Windows applications makes it easy to learn how to use SEEP/W, especially if you are already familiar with the Windows environment.

About the Documentation The documentation is divided into nine chapters and two appendices. The first chapter provides a technical overview of the product including its features and capabilities, how the product is used, and its formulation. Chapter 2 provides information on installing the software, including installation of the network version. The third chapter provides a step-by-step tutorial where a specific problem is defined, the solution computed, and the results viewed. Chapters 4, 5, and 6 contain detailed reference material for the DEFINE, SOLVE and CONTOUR programs. Chapter 7 gives guidelines for modelling many varied situations and is useful for finding practical solutions to modelling problems. Chapter 8 contains the formulation details including the governing equation and its finite element implementation. In Chapter 9, model verification examples are presented to illustrate the correct numerical solution to problems for which an analytical solution exists. Appendix A contains a library of grain-size, volumetric water content and hydraulic conductivity functions for a wide range of soils. It also provides a summary of several common methods that can be used to estimate the volumetric water content and hydraulic conductivity functions. Appendix B documents the details of the data file format generated by the DEFINE program. The documentation in its entirety is available in the online help system and on the distribution CD-ROM as Adobe Portable Document Format, (.PDF), files. You can use these files to print some or all of the documentation to meet your own requirements. If you do not have Adobe Acrobat viewer, you can install the software from the GEO-SLOPE Office CD-ROM.

Applications SEEP/W is a general seepage analysis program that models both saturated and unsaturated flow. The ability to model unsaturated flow allows SEEP/W to handle a wider range of real problems than many other seepage software products. The inclusion of unsaturated flow in groundwater modelling is important for obtaining physically realistic analysis results. In soils, the hydraulic conductivity and the water content, or water stored, changes as a function of pore-water pressure. SEEP/W models these relationships as continuous functions. Most other seepage analysis software packages do not take these relationships into account. Instead they use the physically unrealistic assumption that these functions are step-functions. For example, at pore-water pressures of zero and greater, (i.e. below the water table), there is a saturated conductivity value; at pore-water pressures less than zero, (i.e. above the water table), the hydraulic conductivity is zero. The use of such unrealistic step functions to model soil hydraulic conductivity and water content can lead to erroneous analysis results. This section gives a few examples of the many kinds of problems that can be modelled using SEEP/W. Highlighted here are problems that require an analysis of flow in both the saturated and unsaturated zone

12 SEEP/W to obtain realistic results and for which models capable of modelling saturated flow only, do not suffice.

Unconfined Flow SEEP/W can readily handle unconfined flow problems because it is formulated to compute both saturated and unsaturated flow. With SEEP/W you discretize your entire flow domain into a finite element mesh. After achieving a converged solution, the zero-water pressure contour within the mesh is the phreatic surface, as illustrated in Figure 1.1. The phreatic surface is not a flow boundary, but simply a line of zero pore-water pressure. Not only does this simplify the analyses of unconfined flow, but it includes the flow in the capillary zone above the phreatic surface, which is a real and significant component of the total flow. This portion of the flow is illustrated by the flow vectors above the phreatic surface in Figure 1.1. Figure 1.1 Unconfined Flow Through an Earth Dam

Precipitation Infiltration Inclusion of unsaturated flow in the analysis allows you to analyze a wide range of infiltration problems such as the infiltration of precipitation. In these cases, a physically realistic analysis must adequately compute flow through the unsaturated zone as the infiltrating precipitation migrates downward. Figure 1.2 illustrates a typical case of precipitation infiltration. A less permeable layer in the ground has some profound effects. It creates a perched water table and causes some flow to exit near the top of the slope and some vertical flow throughout the less permeable layer into the underlying slope, ultimately exiting below the slope toe. The shaded areas in the figure are saturated zones while the non-shaded areas are unsaturated zones with negative pore-water pressures. This type of analysis can only be performed by including unsaturated flow in the analysis.

GEO-SLOPE Office 5 13 Figure 1.2 Precipitation Infiltration Resulting in Perched, Inverted and Mounded Water Tables

Pond Infiltration Infiltration of water from surface ponds is another type of infiltration analysis. In these cases the pond water continually enters the ground. However, for certain soil conditions, the soil may not completely saturate the soil below the pond as water flows downward from the pond to the natural water table. Again, computations which include the unsaturated flow are required for the analysis to be physically realistic. Figure 1.3 illustrates a case where leakage from a pond causes mounding of the natural water table. SEEP/W allows you to model the water table mounding and answer questions such as determining the impact that clay liners can have on the mounding. Figure 1.3 Pond Infiltration Resulting in Inverted and Mounded Water Table

14 SEEP/W

Excess Pore-Water Pressure SEEP/W can also be used to model the dissipation of excess pore-water pressure. A typical case is the dissipation of pore-water pressure in an embankment after drawdown of a reservoir. Consider the case in Figure 1.4. A steady-state condition may have been reached after some time and then the reservoir is suddenly emptied. SEEP/W’s saturated/unsaturated formulation makes it possible to analyze the dissipation of the excess pore-water pressure. Note the flow out of the embankment in Figure 1.4. The capability of modelling the dissipation of excess pore-water pressure also makes it possible to perform consolidation analyses. This is discussed later in this chapter in the section entitled Product Integration. Figure 1.4 Dissipation of Excess Pore-Water Pressure in an Earth Dam After Reservoir Drawdown

Transient Seepage Another large class of problems that can be analyzed using SEEP/W is transient seepage. SEEP/W can account for the drainage of water from soil pores, or water filling soil pores, and the changes in hydraulic conductivity that occur in a transient seepage flow system. Examples of transient analyses are illustrated in Figures 1.5 and 1.6. Figure 1.5 shows the migration of the wetting front through and earth dam after reservoir filling while Figure 1.6 shows the changing position of the phreatic surface after reservoir drawdown. Figure 1.5 Transient Wetting Front Migration Through an Earth Dam After Reservoir Filling

GEO-SLOPE Office 5 15 Figure 1.6 Movement of Phreatic Surface in an Earth Dam After Reservoir Drawdown

The SEEP/W capability of accommodating both saturated and unsaturated flow makes it a very powerful tool for analyzing almost any kind of seepage problem you may encounter.

Features and Capabilities User Interface Problem Definition CAD is an acronym for Computer Aided Drafting. GEO-SLOPE has implemented CAD-like functionality in SEEP/W using the Microsoft Windows graphical user interface. This means that defining your problem on the computer is just like drawing it on paper; the screen becomes your "page" and the mouse becomes your "pen." Once your page size and engineering scale have been specified, the cursor position is displayed on the screen in engineering coordinates. As you move the mouse, the cursor position is updated. You can then "draw" your problem on the screen by moving and clicking the mouse. The following are some of the model definition interface features: ·

Display axes, snap to a grid, and zoom. To facilitate drawing, x and y axes may be placed on the drawing for reference. Using the mouse, axes may be selected, then moved, resized or deleted. For placing the mouse on precise coordinates, a background grid may be specified. Using a "snap" option, the mouse coordinates will be set to exact grid coordinates when the mouse cursor nears a grid point. To view a smaller portion of the drawing, it is possible to zoom in by using the mouse to drag a rectangle around the area of interest. Zooming out to a larger scale is also possible.

·

Sketch graphics, text and import picture. Graphics and text features are provided to aid in defining models and to enhance the output of results. Graphics such as lines, circles and arcs, are useful for sketching the problem domain before defining a finite element mesh. Text is useful for annotating the drawing to show information such as material names and properties among other things. A dynamic text feature automatically updates the project information text on the drawing whenever the project information is changed. This ensures that the project information shown on the drawing always matches the project settings used in the model. The import picture feature is useful for displaying graphics from other applications in your drawing. For example, a cross-section drawing could be imported from a drafting application for use as a background graphic while defining the problem domain. This feature can also be used to display things like photographs or a company logo on the drawing. Pictures are imported as a Windows metafile (WMF), an enhanced metafile (EMF), or a Windows bitmap (BMP). Using the mouse, individual or groups of graphics and text objects may be selected, then moved, resized or deleted.

16 SEEP/W

·

Graphical finite element mesh generation and editing. After the problem has been sketched, the problem domain must be discretized into a finite element mesh. To facilitate this, quadrilateral and/or triangular regions are drawn in the problem domain. Inside each region, any number of finite elements can automatically be generated. Individual or groups of nodes and elements may be moved or deleted using the mouse to select and drag these objects. The figure below shows how a quadrilateral region is interactively meshed with quadrilateral elements.

·

Graphical application of soil types and boundary conditions. Each element in the mesh must be associated with a soil type. This can be accomplished using the mouse to select individual or groups of elements to which a soil type will be assigned. Boundary conditions can also be assigned to nodes and edges using the mouse. The figure below shows the application of a fixed 0.3 m total head boundary condition being applied to node 10.

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·

Graphical and keyboard editing of functions. SEEP/W makes extensive use of functions. For example, boundary conditions can be a function of time, and hydraulic conductivity is a function of pore-water pressure. All these functions can be edited graphically using the mouse and exact numerical values can be input using the keyboard. The figure below shows a point on a conductivity function being moved using the mouse.

18 SEEP/W

·

Graphical flux section definition. It is often of interest to compute seepage fluxes across some section of the problem domain. Multiple flux sections can be drawn through the problem domain using the mouse.

·

Graphical initial water table definition. For transient analyses, initial conditions are required. The fastest way to specify initial conditions is to draw the water table across the problem domain, which can be done using the mouse.

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Computing Results After defining the problem, the solution is computed. Non-linear analyses require an iterative procedure which must converge to a solution. To check on the convergence progress, it is possible to graph the convergence in real-time. The figure below shows the Residual Vs Iteration graph produced during the solution of a challenging seepage problem requiring more than 100 iterations to reach a satisfactory solution.

Alternatively, you may also like to view the convergence of a solving problem by selecting a K Vs Suction plot, In this plot the estimated K used in the computation (red dots) is compared with the specified K function (blue squares) of all soils. A converged solution can be assumed when the red dots line up with the blue squares.

20 SEEP/W

Viewing Results After your problem has been defined and the solution computed, you can interactively view the results graphically. The following features allow you to quickly isolate the information you need from the vast amount of computed data: ·

View computed values at nodes and in element Gauss regions. You can view the computed parameter values in a window as you click on each node or element Gauss region. The following dialog boxes show the information which can be viewed at nodes and in element Gauss regions, respectively.

·

Graph computed values. You can also select a group of nodes and produce an x-y graph of any parameters versus space or time. The following figure shows the total head as a function of time at some nodes of interest.

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·

Contour computed values. All computed parameters such as head, pressure, gradient, velocity, and conductivity, can be contoured. Contour value labels can be displayed by clicking on the contour. The variation in the contoured parameter can be gradationally shaded from a high to a low color intensity. The figure below shows labeled contours of total head and velocity vectors.

·

View velocity vectors. Velocity vectors provide a graphical representation of the flow direction, the size of each vector indicating the relative rate of flow.

22 SEEP/W

·

View water table movement. Transient conditions can be displayed by plotting the changing position of the water table as a function of time. The following figure shows the migration of the phreatic surface through an earth dam as a function of time. The labels on the lines indicate the time step number.

·

View flux quantities. Flux quantities can be displayed by clicking on the flux section. The figure below shows a flux section located beneath a concrete gravity dam and the computed flow rate below the dam in units of ft3/hr.

·

View flow paths. Groundwater flow paths can be displayed by clicking at any point within the problem domain. The figure below shows the flow paths for water infiltrating the ground surface at the top of the slope. Also shown on the figure are boundary conditions, contours of total head, material colors, velocity vectors and the water table, (blue line).

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·

Export computed data and graphics. To prepare reports, slide presentations, or add further enhancements to the graphics, SEEP/W has support for exporting data and graphics to other applications. Computed data can be exported to other applications, such as spreadsheets, using ASCII text or using the Windows clipboard. The mouse can be used to select the nodes for which export data is required. The Windows enhanced metafile format, (EMF), and the Windows metafile format, (WMF), are supported for exporting graphics. For converting a WMF or EMF file to other file formats such as DXF, third party file format conversion programs can be used.

Other Interface Features In addition to the features listed for model definition, computation and viewing of results, the user interface has many other features commonly found in Windows applications. These are: ·

Context sensitive help. All user interface items such as menu items, toolbars and dialog boxes provide context sensitive help. For example when a dialog box is displayed, hitting the F1 key will display a help topic related to that dialog box.

·

On-line documentation. The on-line documentation contains the entire manual in the form of a Windows help file. This provides fast access to technical information and facilitates searching the manual for specific information. Each chapter of the on-line documentation is also available on the distribution CD-ROM as Microsoft Word documents that you can view or print.

24 SEEP/W

·

Toolbar shortcuts for all menu commands. Toolbars contain buttons that provide a shortcut for all menu commands. The dockability of the toolbars mean that they can be repositioned and hidden according to your preferences.

·

Extensive control on view preferences. View preference control allows you to display different types of objects on the drawing at the same time. Examples of these objects include nodes, elements, boundary conditions, material colors, flux sections, water table, sketch objects, text, and axes. All object types are displayed by default; however, you can turn off object types that you do not wish to view. This command also can be used to change the default font used for the problem, as well as the font size used for node and element numbers and for the axes.

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·

Designed for Windows NT, Windows 95 and up Because SEEP/W was designed for Windows NT, Windows 95 and up, it has the common look and feel of other applications built for these operating systems. For example, SEEP/W supports file names longer than eight characters, a most-recently-used file list for fast opening of recently used files, and common dialog boxes for common operations such as opening, saving and printing files.

In summary, the user interface features in SEEP/W work together to make the software both easy to learn, and easy to use.

Seepage Analysis Analysis Types SEEP/W can model both saturated and unsaturated flow, a feature that greatly broadens the range of problems that can be analyzed. In addition to traditional steady-state saturated flow analysis, the saturated/unsaturated formulation of SEEP/W makes it possible to analyze seepage as a function of time and to consider such processes as the infiltration of precipitation. The transient feature allows you to analyze such problems as the migration of a wetting front and the dissipation of excess pore-water pressure. The following lists the analysis types possible with SEEP/W: ·

Modelling of saturated and unsaturated flow systems. SEEP/W is rigorously formulated with hydraulic conductivity and water content as a function of porewater pressure, thus giving a seamless transition from the saturated to the unsaturated zone in the

26 SEEP/W model. Saturated flow is simply a special case of this formulation, and as such, SEEP/W can model groundwater flow in confined systems. ·

Steady-state and transient analyses. Many seepage problems can be adequately modelled using steady-state groundwater flow. In other cases, transient groundwater flow is required. SEEP/W can compute steady state or transient groundwater flow.

·

Two-dimensional plane or axisymmetric geometry. The two-dimensional plane geometry is useful for modelling seepage in two-dimensions, such as a vertical cross-sectional plane or a plan view of the system. Axisymmetric geometry is useful for situations where there is symmetry about a vertical axis, such as near a single vertical well.

Boundary Conditions ·

Multiple boundary condition types. Multiple boundary condition types are implemented to support virtually all seepage modelling scenarios. In SEEP/W, total head, nodal seepage flux and area seepage flux may be specified.

·

Transient boundary conditions. A boundary condition function may be associated with each boundary condition. This feature us useful for specifying boundary conditions that vary with time. In addition, transient boundary conditions may be cycled, allowing specification of transient boundary conditions that repeat themselves with some frequency.

·

Review boundaries. For certain types of seepage problems, the boundary conditions are a function of the flow process. An example of this is when groundwater leaves the flow system on a seepage face, such as exiting from a slope. Below the point where the phreatic surface intersects the slope, groundwater will exit the seepage face. Above this point, the soil may be wet, but water will not exit because the pore-water pressures are negative with respect to atmospheric pressure. In these cases, the types of boundary conditions, (specified head or zero flux), to be applied to the seepage face must be solved for using an iterative procedure similar to that required to solve the nonlinear finite element equations. Using the review boundary feature, it is possible for SEEP/W to automatically determine the correct boundary conditions on the seepage face boundary.

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Head as a function of volume. For problems where groundwater is recharged from and discharging to a reservoir with fluctuating levels, the head boundary condition at the reservoir is a function of the reservoir level. To facilitate the application of boundary conditions in these cases, SEEP/W allows head boundary conditions to be a function of the volume of groundwater flow into or out of the system through the group of nodes along the reservoir boundary.

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Pressure boundaries. Pressure head boundary condition can be specified to model boundaries with known water pressure. SEEP/W converts the pressure head to required total head automatically. A zero pressure boundary condition sets the total head equal to the node elevation. This facilitates defining a free surface along a set of nodes.

GEO-SLOPE Office 5 27

Soil Properties ·

Hydraulic conductivity and volumetric water content as a function of pore-water pressure. In saturated/unsaturated flow systems, hydraulic conductivity and volumetric water content, (storage), are a function of pore-water pressure. The pore-water pressure dependent soil properties of hydraulic conductivity and volumetric water content are supported. More detailed information regarding the formulation of SEEP/W is presented later in this chapter.

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Anisotropic and heterogeneous soil properties. Anisotropy refers to the directional dependence of material properties. SEEP/W supports anisotropic hydraulic conductivity. Heterogeneity refers to the spatial dependence of material properties. For example, a system with different soil strata is a heterogeneous system. SEEP/W also supports heterogeneous hydraulic properties such as hydraulic conductivity and storage.

Finite Element Implementation ·

Isoparametric quadrilateral and triangular finite elements. Isoparameteric quadrilateral and triangular finite elements are implemented and each may have various numbers of optional secondary nodes to provide higher order interpolation of nodal values within the element.

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Infinite elements. Infinite elements can be used at the boundaries of the problem domain that are for practical purposes unbounded. An example of an unbounded problem is radial flow to a well. Without infinite elements, many regular elements have to be used in the problem domain until the influence of the problem domain boundary becomes negligible. Using infinite elements allows the problem domain size to be decreased.

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Staged addition and removal of elements. Any element can be considered to be nonexistent by assigning the conductivity function number a value of zero. This feature makes it possible to simulate the construction of embankments and excavations.

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32-bit processing. 32-bit processing allows full utilization of the CPU in current personal computers. Compared to 16-bit processing, 32-bit processing can result in a computational speed increase by a factor of two to three times, depending on problem size, number of iterations and number of time steps.

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No specific limits on problem size. SEEP/W has been implemented using dynamic memory allocation, so there is no specific limits on problem size in terms of number of nodes, element or material types. Therefore the maximum size of the problem is a function of the amount of available computer memory.

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Unlimited number of time steps for transient analyses. In cases where small time steps are required, such as for contaminant transport analyses, the number of time steps to be computed can be large. For this reason, SEEP/W has no limitations on the number of time steps.

28 SEEP/W

·

Stopping and restarting of computations. Stopping and restarting the main computations is useful for problems that take a significant amount of time to complete. With this feature it is possible to restart a previous analysis from some intermediate time step or to recover from computer mishaps without having to restart the computations from the very beginning.

Using SEEP/W SEEP/W includes three executable programs; DEFINE, for defining the model, SOLVE for computing the results, and CONTOUR for viewing the results. This section provides an overview of how to use these programs to perform seepage analyses.

Defining Problems The DEFINE program enables problems to be defined by drawing the problem on the screen, in much the same way that drawings are created using Computer Aided Drafting, (CAD), software packages. To define a problem you begin by setting up the drawing space. This is done by setting a page size, a scale, and the origin of the coordinate system on the page. Default values are available for all of these settings. To orient yourself while drawing, coordinate axes and a grid of coordinate points may be displayed. Once the drawing space is specified, you can begin to draw your problem on the page using sketch graphics such as lines, circles and arcs. You can additionally import background graphics to perform the same function. Having a sketch or picture of the problem domain helps when generating finite elements across the domain because the elements can be interactively generated and deleted while the background graphics remain displayed. After defining the drawing space and displaying the problem domain, you then must specify material properties, discretize the problem domain into finite elements, and apply boundary conditions to define the finite element model. Figure 1.7 shows the DEFINE window after defining the drawing space and displaying the problem domain. Also shown are the drawing commands available on the Draw menu. These commands allow you to generate finite elements, apply boundary conditions, associate finite elements with material properties, set up flux sections, and specify an initial water table. All these tasks can be performed by drawing with the mouse. Material property values are keyed into dialog boxes using commands available under the KeyIn menu. Figure 1.7 also shows a few of the user interface features designed to make the software easier to use. Toolbars contain button shortcuts for commonly used menu commands. DEFINE has five toolbars, each for different groups of commands. A status bar, located at the bottom of the window shows the type of analysis being performed, (in this case 2-Dimensional), and the mouse position in engineering coordinates. Figure 1.8 shows the end result of defining the finite element model. The problem domain has been discretized into finite elements, material properties have been assigned to elements and boundary conditions have been applied. Saving the problem creates a DEFINE data file to be read in by the SOLVE program. After this is complete, the problem is ready to be solved.

GEO-SLOPE Office 5 29 Figure 1.7 Problem Domain Displayed in DEFINE Window

Figure 1.8 Fully Defined Finite Element Model

30 SEEP/W

Solving Problems Once a data file is created with DEFINE, the problem is solved using the SOLVE program. Figure 1.9 shows the main window of the SOLVE program with a DEFINE data file opened. Pressing the Start button begins the computations. Information is displayed in the large list box area during the computations. At any time the computations can be stopped or the iteration can be halted to be restarted later. In addition, a graph of the iteration convergence can be displayed by pressing the Graph button. Figure 1.9 SOLVE Main Window

Contouring and Graphing Results CONTOUR can graphically display the analysis results computed by SOLVE. The results may be presented as contours, graphs, tables of values, velocity vectors, flow paths, flux values, and a series of phreatic surface lines in the case of a transient analysis. The CONTOUR program has the same CAD-like features as DEFINE and operates in a similar fashion. Data review is accomplished using commands on the View and Draw menus, shown in Figures 1.10 and 1.11, respectively. The View menu contains commands oriented towards selecting time increments and element regions to view, and viewing numerical node and element information. The Draw menu contains commands oriented towards presenting the results graphically. All computed data parameters can be contoured and graphed in space or time. Contour labels can be added by clicking on a contour at the position where a label is desired. Other data visualization includes velocity vectors, flow paths and flux quantities on flux sections. In addition to data visualization, the drawing can be enhanced and labelled with sketch graphics and text. Objects can be selected with the mouse and then moved, resized or deleted.

GEO-SLOPE Office 5 31 Figure 1.10 View Menu in CONTOUR

Figure 1.11 Draw Menu in CONTOUR

Formulation SEEP/W is formulated to analyze both saturated and unsaturated flow. Flow in unsaturated soil follows Darcy's Law in a similar manner to flow in saturated soil. The flow is proportional to the hydraulic gradient and the hydraulic conductivity (coefficient of permeability). The major difference between saturated and unsaturated flow is that in a saturated soil, the hydraulic conductivity is insensitive to the pore-water pressure, while in an unsaturated soil, the hydraulic conductivity varies greatly with changes in pore-water pressure. Figure 1.12 presents the form of the relationship between hydraulic conductivity and pore-water pressure. This relationship is known as a conductivity function. For saturated-unsaturated analysis, the conductivity function must be defined for each soil type. Figure 1.12 A Typical Hydraulic Conductivity Function

The variation of hydraulic conductivity with pore-water pressure makes the finite element equations

32 SEEP/W nonlinear, and an iterative process is consequently required to solve the equations. Hydraulic head (porewater pressure plus elevation) is the primary unknown computed. Since the hydraulic conductivity is related to hydraulic head, the appropriate hydraulic conductivity is dependent on the computed results. During transient processes, the amount of water entering an elemental volume of soil may be larger than the amount of water exiting the volume, or vice versa. This results in a certain amount of water either being retained or released during a particular time increment. The ability of the soil to store water must be defined by a soil-water characteristic curve, such as the one illustrated in Figure 1.13. For steady-state analyses, the amount of water entering and leaving an elemental soil volume is the same; therefore, the soil-water characteristic function is not required. Figure 1.13 A Typical Soil-Water Characteristic Curve

SEEP/W is formulated for both triangular and quadrilateral elements. The simplest elements are threenoded triangular and four-noded quadrilateral elements. Higher-order elements can also be used by defining secondary nodes at the midpoints of the element sides. Triangular elements can have up to three secondary nodes, while quadrilateral elements can have up to four secondary nodes. Any combination of secondary nodes can be used; for example, it is possible to use five , six , seven , and eight noded quadrilateral elements. SEEP/W uses Gaussian numerical integration to formulate the element characteristic matrices. The integration involves sampling the element characteristics at selected points and summing the sampled values. As a result, it is possible to use a different material property at each sampled point with the result that the material properties, such as the hydraulic conductivity, can vary throughout the element. For triangular elements, it is possible to sample the element properties at one or three points and for quadrilateral elements at four or nine points. SEEP/W is also formulated to handle transient boundary conditions and to modify boundary conditions in response to computed results. The filling and draining of a reservoir is a typical example of a transient boundary condition. The exit point of the phreatic surface on free surface seepage faces can be computed by SEEP/W. The boundary conditions are modified at the end of each iteration until there is no excess pressure head on the seepage face.

GEO-SLOPE Office 5 33 SEEP/W dynamically dimensions all vectors and arrays as required for each particular problem. This powerful feature provides for flexibility in the allowable number of nodes and elements contained in a problem and in the node number difference (bandwidth) within an element.

Product Integration GEO-SLOPE provides the following suite of geotechnical and geo-environmental engineering software products: ·

SLOPE/W for slope stability

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SEEP/W for seepage

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CTRAN/W for contaminant transport

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SIGMA/W for stress and deformation

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TEMP/W for geothermal analysis

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QUAKE/W for dynamic earthquake analysis

SEEP/W is integrated with SLOPE/W, SIGMA/W, QUAKE/W and CTRAN/W. The integration of this geotechnical software allows you to use results from one product as input for another product. Examples of the integration between products are listed below. ·

A finite-element mesh developed in SEEP/W for a seepage analysis can be imported into SIGMA/W for a stress/deformation analysis or into CTRAN/W for a contaminant transport analysis.

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The SEEP/W computed head distribution can be used in SLOPE/W slope stability analyses, which is particularly powerful in the case of transient processes. Using the SEEP/W results for each time increment in a SLOPE/W stability analysis makes it possible to determine the factor of safety as a function of time.

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SEEP/W and SIGMA/W can be used together to perform fully-coupled consolidation analyses. To perform the consolidation analysis, SEEP/W’s SOLVE program solves for continuity and SIGMA/W’s SOLVE program solves for equilibrium, simultaneously at each time step.

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SEEP/W and QUAKE/W can be used together to analysis the dissipation of the excess pore-water pressure generated from QUAKE/W dynamic earthquake analysis.

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SEEP/W together with CTRAN/W can be used to perform contaminant transport analyses, including coupled density-dependent analyses. For density-independent analyses, SEEP/W is used to compute the seepage flow velocities first, then CTRAN/W uses the computed velocities in the computations of contaminant transport. For density-dependent analyses, the seepage flow and the contaminant transport are coupled. For these analyses, SEEP/W’s and CTRAN/W’s SOLVE programs simultaneously compute seepage flow velocity and contaminant concentration at each time step.

Product Support You may contact GEO SLOPE in Calgary to obtain additional information about the software. GEO SLOPE’s product support includes assistance with resolving problems related to the installation and operation of the software. Note that the product support does not include assistance with modelling and engineering problems. GEO SLOPE updates the software periodically. For information about the latest versions and available updates, visit our World Wide Web site.

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http://www.geo-slope.com If you have questions or require additional information about the software, please contact GEO SLOPE using any of the following methods: E-Mail: [email protected] Phone: 403-269-2002 Fax: 403-266-4851 Mail or Courier: GEO-SLOPE International Ltd. Suite 1400, Ford Tower 633 - 6th Avenue S.W. Calgary, Alberta, Canada T2P 2Y5 GEO SLOPE’s normal business hours are Monday to Friday, 8 a.m. to 5 p.m., Mountain time.

Chapter 2 Installing GEO-SLOPE Office Basic Windows Skills Managing Data Files Opening Data Files in GEO-SLOPE Office applications Knowing how to locate files and folders in Windows is essential to learning how to use GEO-SLOPE Office. When you install GEO-SLOPE Office, a variety of example data files are also installed that illustrate the use of the software. You can find these examples in the Examples folder, located within the folder that you selected for installing GEO-SLOPE Office. You should create a different folder for saving your own data files; this will keep your own problems separate from the example problems included with GEO-SLOPE Office. Windows Explorer will help you to manage and locate GEO-SLOPE Office data files. When you have found a data file in Explorer that you wish to open, you can right-click on the file name in Explorer and Open it; this will launch the GEO-SLOPE Office DEFINE module and display the problem definition. Alternatively, you can open DEFINE from the Windows Start menu and then choose the File Open command to open the data file.

Viewing Data Files All input data and result data can be displayed directly in the various GEO-SLOPE Office applications. However, in some circumstances, you may also wish to view the contents of the data files themselves. GEO-SLOPE Office saves all data files in ASCII text format, allowing you to view the files with any text editor. However, GEO-SLOPE Office allows you to compress all of your data files for a problem into one "ZIP" file, a PK-ZIP compatible data file.. You can open both compressed and uncompressed data files in each GEO-SLOPE Office application. If you wish to view the contents of the compressed data files, you can use a PK-ZIP compatible Windows program like WinZip. WinZip will display a list of the uncompressed data files contained in the ZIP file; you can then extract the specific files that you wish to view. Once the data files are uncompressed, you can use a program that views text files (like Windows Notepad) to view the contents of each data file. The DEFINE data file format is described in an appendix.

Windows Fundamentals To install and use GEO-SLOPE Office, you must first install Microsoft Windows and be familiar with its operation. The Microsoft Windows documentation will help you in learning how to use Windows. Since the GEO-SLOPE Office documentation does not fully cover the Windows operating instructions, you may need to use both the Windows and the GEO-SLOPE Office documentation while you are getting started. All commands in GEO-SLOPE Office applications are accessed from the menu bar or from toolbars. To choose a menu command with the mouse, click on the menu name, and then click on the name of the command in the drop-down menu. A short description of the command is displayed in the status bar as you move the mouse over the menu item. To choose a menu command from the keyboard, press ALT to select the menu bar, and use the arrow keys to move to the command; press ENTER to choose the command. Alternatively, press ALT, and then press the underlined letter of the menu name. When the drop-down menu is displayed, press the letter of the command. To choose a toolbar command, click on the desired toolbar button. If you hold the cursor above the

36 SEEP/W toolbar button for a few seconds, the command name is displayed in a small "tool-tip" window. Commands are named according to the menu titles. For example, the File Open command is so named because it is accessed by selecting the File menu from the menu bar and then choosing Open from the File menu. Some drop-down menu commands contain a triangle on the right side. This means that there is a cascading menu with additional commands. An example of this type of command is the KeyIn Functions command found in DEFINE. Many commands use dialog boxes to obtain additional information from you. Dialog boxes contain various options, each asking for a different piece of information. To move to a dialog option using the mouse, click on the option. To move to the next option in the sequence using the keyboard, press TAB. Press SHIFT+TAB to move to the previous option. Command buttons are options in dialog boxes that initiate an immediate action. For example, a button labelled OK accepts the information supplied by the dialog box, while a button labelled Cancel cancels the command. To choose a button with the mouse, click on the button. To choose a button from the keyboard, select the button by moving to it with the TAB key. A dark border appears around the currently selected, or default, button. Press ENTER to choose this button. The Cancel button can be chosen from the keyboard by pressing ESC.

Basic GEO-SLOPE Office Skills Starting and Quitting GEO-SLOPE Office Applications Each GEO-SLOPE Office application can be started by launching the DEFINE module. You can then start SOLVE and CONTOUR as necessary from within the DEFINE module. Ø

To start any GEO-SLOPE Office application: 1. Click the Start button open the Start menu. 2. In the Programs folder, select the GEO-SLOPE Office folder to display a list of installed GEOSLOPE Office applications. 3. Click on the appropriate application folder and then select the DEFINE icon to start DEFINE.

Ø

To quit any GEO-SLOPE Office application: 1. Choose File Exit from the DEFINE menu or click on the Close button in the top-right corner of the DEFINE window. 2. If you are prompted to save any changes, you can choose to do so before DEFINE exits. DEFINE will then close. If you have launched SOLVE or CONTOUR from DEFINE, these modules will also close. For more details on running applications in Windows, refer to your Windows documentation.

Dialog Boxes in GEO-SLOPE Office Applications GEO-SLOPE Office uses many types of dialog boxes for entering and editing your model data. One commonly-used type of dialog box handles lists of numeric data. An example of this type of dialog box, illustrated below, is used for entering and modifying a list of finite element nodes.

GEO-SLOPE Office 5 37 A Dialog Box for Entering and Modifying Nodes

New nodes are entered by typing the coordinates in the edit boxes and copying to the list box. Nodes are edited by copying data from the list box to the edit boxes and making changes. Copy Copies values from the edit boxes to the list box. Delete Deletes the line of data that is highlighted in the list box. Delete All Deletes all lines of data in the list box. OK Saves the changes you have made to the values in the list box. Cancel Ignores all entries and changes made to the dialog box and returns you to the previous state of the program. Ø

To enter a new node in the list box: 1. Type the node number and its coordinates in the edit boxes. 2. Select Copy. The new node is copied into the list box.

Ø

To change the data relating to an existing node: 1. In the list box, click on the node to change. The line in the list box is highlighted, and the node number and its coordinates are automatically copied to the edit boxes. 2. Make the necessary changes in the edit boxes. 3. Select Copy. The node is copied into the list box, replacing the node that has a node number matching the value contained in the # edit box.

Ø

To delete a node from the list box: 1. In the list box, click on the node to delete.

38 SEEP/W

2. Select Delete. The node is removed from the list box. Dialog boxes of this type may have other controls, such as a View button. See the appropriate command reference section for details on each specific dialog box.

Using Online Help The GEO-SLOPE Office Online Help system provides you with a powerful means of accessing the documentation for each GEO-SLOPE Office product. It gives you several different ways to answer your questions: ·

Browse the Contents Tab to see a hierarchical display of all Help Topics.

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Browse the Index Tab to view an alphabetical index of Help Topics.

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Select the Search Tab to search for all Help Topics that contain a specific word or phrase.

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Display the Help Topic for the dialog box or command that you are currently using.

You can access Online Help from DEFINE, SOLVE, or CONTOUR in the following different ways: ·

Choose Help Topics from the Help menu or press the F1 key. A Help Topics dialog box is displayed containing the Contents, Index and Search tabs.

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Move the mouse over a menu item (such that the menu command is highlighted) and press the F1 key. The help topic corresponding to the selected menu command is displayed.

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Press down on a toolbar button and press the F1 key. The help topic corresponding to the selected toolbar button is displayed.

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While you are in a interactive mode, such as Sketch Text, press the F1 key. The help topic corresponding to the mode is displayed (e.g., the Sketch Text help topic).

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While you are in a dialog box, press the F1 key or press the question mark button in the top-right corner of the dialog box. The help topic corresponding to the dialog box is displayed.

Installing GEO-SLOPE Office Running Setup from the CD-ROM GEO-SLOPE Office is distributed to you on a CD-ROM. The CD-ROM contains a setup program that installs each GEO-SLOPE Office application on your computer. Ø

To install GEO-SLOPE Office: 1. Insert the distribution CD-ROM into your CD-ROM drive.

GEO-SLOPE Office 5 39 The Setup program is automatically loaded when the CD-ROM is inserted into the drive. Alternatively, from the Start Menu, you can select run and type d:\autorun in the dialog box (where d: is your CDROM drive), and then select OK to start the Setup program. 2. Click on the View Installation Instructions option if you wish to display or print the setup instructions. 3. Click on Install GEO-SLOPE Office to install the software. The GEO-SLOPE Office Setup program begins execution. 4. Follow the instructions given by the Setup program to install the software. By default, Setup will install each GEO-SLOPE Office application. Setup will also install all GEOSLOPE Office license files that are distributed to you on the CD-ROM. Any applications that you have not purchased licenses for can still be run as Evaluation Software. The Evaluation Software is a feature-complete version of each product that you are free to copy and distribute; you can use it to examine, test and assess all features of the software. The only limitation of the Evaluation Software is that you cannot save data files. Therefore, you cannot analyze your own specific problems. When you purchase a license for an application you've already installed, the license can be e-mailed to you. Once it is placed in your Licenses folder, you can use the software to analyze your own specific problems. See the Managing GEO-SLOPE Office License Files section for more information on installing new licenses.

Managing GEO-SLOPE Office License Files GEO-SLOPE Office Version 5 supports GLOBEtrotter's FLEXlm Flexible License Management System. Operation of the license management system depends on a license file and a hardware device. The hardware device, to which the license file is linked using the unique ID of the device, is known as the "Hostid". GEO-SLOPE Office Software supports two types of Hostid's: a "FLEXid" hardware key that attaches to your computer, or the address of an ethernet card installed on your computer. Once a license is issued for a specific Hostid, the license can only be used with the same FLEXid key or on the computer having the same ethernet address. GEO-SLOPE Office licenses are of two main types. ·

A "Standalone License", which only allows the software to run on a specific computer.

·

A "Network License", which allows the software to be run from anywhere on the network.

Each GEO-SLOPE Office application is installed with a Standalone "evaluation license" by default. If the CD-ROM was shipped to you after you purchased a Standalone License, then the full-featured license file is installed during the software setup; no further action is necessary.

Purchasing Licenses You can contact GEO-SLOPE to purchase new licenses for the GEO-SLOPE Office software. First, you must decide whether you would like a Standalone License or a Network License. Second, you must select the type of Hostid to use with your license file. You can choose either a hardware key attached to your computer or the ethernet address of a computer on your network. If you select the ethernet address option as your Hostid, you will need to determine your ethernet Hostid, as described below, and include it with your purchase order. GEO-SLOPE will then e-mail the license file(s) as soon as your purchase order is processed.

40 SEEP/W If you select the FLEXid hardware key as your Hostid, you do not need to send any Hostid information to GEO-SLOPE. Your FLEXid dongle will be sent to you, together with the license file, once your purchase order is processed. Please contact GEO-SLOPE if you have any questions about purchasing licenses.

Finding your Ethernet Address The following steps describe how to determine a computer's ethernet address (for use as the Hostid): If you have installed GEO-SLOPE Office, you may get your ethernet address by running the "FLEXlm License Utility". 1. Log on to the computer that will be used as the Hostid. 2. If you wish to run the command line version of the license utility, open a command window, change to the GEO-SLOPE\Utilities folder and run the following command: lmutil lmhostid -ether You can then copy the returned ethernet address as the Hostid. 3. If you wish to run the graphical version of the license utility, click on the Start button and select Programs, GEO-SLOPE Office, Utilities, FLEXlm License Utility. You can then click on the System Settings tab and copy the displayed ethernet address. To copy the address to the Windows clipboard, highlight the address and select CTRL-C. You can then paste the address into an e-mail message using CTRL-V and send it to GEO-SLOPE. If you have not installed GEO-SLOPE Office and you are using Windows NT, 2000, or XP, you can obtain your ethernet address as follows: 1. Select Run from the Start menu, type cmd, and press Enter. A command window is displayed. 2. In the command window, type the following command: ipconfig /all Under the heading "Ethernet adapter Local Area Connection", your ethernet Card address is located where it says "Physical Address". If you have not installed GEO-SLOPE Office and you are using Windows 9x or ME, you can obtain your ethernet address as follows: 1. Select Run from the Start menu, type winipcfg, and press Enter. The "IP Configuration" window appears. 2. Select your ethernet card from the drop-down list box. Look for the field labeled "Adapter Address". It will have a 12 character code that looks something like: "00-05-9A-A0-60-94". It should not begin with a "44-45" or "44-44". This is your ethernet address.

GEO-SLOPE Office 5 41

Installing a Standalone License file Once you have received a new license file for a GEO-SLOPE Office application, you can install the license file on your computer. If you have received a Network license, please refer to the topic titled "Managing Network Licenses" for instructions on installing the license. To install a Standalone license file on your computer: 1. If you purchased a license with a FLEXid key as the Hostid, attach it to your computer's USB or parallel port as appropriate. 2. From the Windows Start Menu, select Programs, GEO-SLOPE Office 5, Utilities and click on "License Setup Utility". The following window is displayed:

3. Select the "Use License Files Only" option. 4. Click on the "Get New License File" button and select the license file name from the dialog box that appears. NOTE: If you received an error message at this point, it is very likely that the FLEXid key is not attached or the software is being installed on a computer with the wrong ethernet address. 5. If you have purchased a license for the complete GEO-SLOPE Office suite, select the "Use GEOSLOPE Office Package License" option. Otherwise, make sure that the "Use Individual Product Licenses" option is selected in order to use the individual product licenses (e.g. SEEP/W, SLOPE/W, etc.) that you have purchased.

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6. Click Done. You are now ready to run the GEO-SLOPE Office application. Choose Help About to view the application's license information.

Managing Network Licenses Network Licenses for GEO-SLOPE Office applications make it possible for you to use the software on any computer on your network. It also allows a group of people to use the software simultaneously. For example, if you purchased a 5-user Network license for SLOPE/W, up to 5 people on the network can use SLOPE/W concurrently. A FLEXlm License Server Program must be run on a designated computer on the network; this computer is referred to here as the license server computer. The License Server Program monitors the number of users running Office software concurrently and ascertains that properly licensed software is being used. If the license file is issued for a FLEXid key, then the correct FLEXid key should be attached to the license server computer. If you chose to use the ethernet address of a particular computer as the Hostid, the license server program should be run on that computer. For Network licenses to work properly, the following requirements should be met: ·

Network Software installed on the License Server Computer.

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Correct FLEXid key attached to the License Server Computer if the Network licenses require a FLEXid key.

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License Server Program should be running.

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Client computers should be set to use the licenses available at the License Server Computer using the GEO-SLOPE License Utility.

Requirements for running Network Licenses GEO-SLOPE Office Programs communicate with the License Server through TCP/IP network protocol. Therefore, your network must support the TCP/IP protocol. If you are using Novell Netware you must be using a recent version that supports TCP/IP. However, the License Server and the GEO-SLOPE Office application should both be run on the Windows operating system.

Choosing the License Server Computer The License Server Computer can be any Windows workstation on the network and not necessarily a Network Server. You should select a stable system as the License Server Computer; in other words, you shouldn't pick a system that is frequently rebooted or shut down for one reason or another. GEO-SLOPE software supports only a single License Server on a network. Therefore, the GEO-SLOPE License Server should not be running on multiple computers in the Network.

Installing the Network License Software To install the network license software: 1. On the License Server computer that you have selected, insert the GEO-SLOPE Office CD-ROM. The Setup program is automatically loaded when the CD-ROM is inserted into the drive. Alternatively, from the Start Menu, you can select run and type d:\autorun in the dialog box (where d: is your CDROM drive), and then select OK to start the Setup program. 2. Choose "Install Network License Utilities" to install the software required for managing Network

GEO-SLOPE Office 5 43

licenses. The Network License Utilities setup program begins execution. 3. Follow the instructions given by the Setup program to install the software. You can use all of the default options. It is unnecessary to install the GEO-SLOPE Office client software on the License Server Computer.

Running the License Server as a Windows Service You can run the license server as a Windows Service so that the License Server starts at boot up and runs in the background. To setup the Windows Service: 1. Go to Start, Program Files, GEO-SLOPE Office 5, Network Utilities and click on "FLEXlm License Utility". This will bring up the License Utility (LMTOOLS) Window. 2. On the "Service/License File" tab, select the "Configuration using Services" option. 3. Select the "Configure Services" tab and type in a name for the FLEXlm Service (e.g. GEO-SLOPE License Service). 4. Type in the path to the lmgrd.exe file (e.g. C:\Program Files\GEO-SLOPE\FLEXlm Network Utilities\lmgrd.exe). 5. Type in the path to the license file. (If you need to run multiple license files as a Service, create an empty folder, and copy only the required license files to this folder; type in the folder name including the path.) 6. Type in a file name for the debug log including the path. 7. Select the "Use Services" checkbox. 8. Select the "Start Server at Power Up" option. 9. Click on the Save Service button. 10. Go to Control Panel (e.g. Start, Settings, Control Panel in Windows NT). Double click on Services to launch the Services dialog box. You will see the Service Name you typed in LMTOOLS. Click on it and click on the Start button. Alternatively, you can reboot to start the Service. Your License Server Service is now running. You can remove a License Service by clicking on the Remove Service button.

44 SEEP/W

To install or remove the License Server Service manually, rather than using the above method: 1. Run the installs.exe program provided with the Network utilities to install the service. From a command line, run: installs path_to_lmgrd where path_to_lmgrd is the full path to lmgrd.exe (e.g., "C:\Program Files\GEO-SLOPE\Network License Utilities\lmgrd.exe"). After installs.exe is run successfully, the License Server is installed as a Windows Service and will be started automatically each time your system is booted. 2. To remove the service from the registered service list, run: installs remove

Running the License Server on the command line The License Server can also be run in the command line mode (also known as the debug mode). The disadvantage of running the License Server this way is that it will occupy a total of three command line windows on the desktop. Also, it may be difficult to start and stop the License Server. To run and stop the License Server on the command line: 1. Open a command line window and navigate to the GEO-SLOPE\Network License Utilities folder. 2. Run the License Server by typing the following: lmgrd -c license_file_path where license_file_path is the license file name, including the file path. If multiple license files need to be run, separate them using semicolons (";"). This will bring up two additional command windows; these windows should not be directly shut down before shutting down the License Server Program.

GEO-SLOPE Office 5 45

2. Shut down the License Server by typing the following: lmutil lmdown -c license_file_path

Setting up the Client Computers Once the License Server is setup, the client computers running GEO-SLOPE Office need to point to the correct license server. To specify the location of the License Server on each client computer: 1. Go to Start, Program Files, GEO-SLOPE Office 5, Utilities and click on "License Setup Utility". This will bring up the GEO-SLOPE License Utility. 2. Select the Use License Server option. 3. Click on the Add/Change button. This will bring the License Server Setup dialog box. Type the license server computer name and click OK 4. Now select the appropriate "Type of License File to use for GEO-SLOPE Office" option, depending on whether you purchased individual product licenses (e.g. SEEP/W, SLOPE/W, etc.) or the GEOSLOPE Office Package license. 5. Click Done.

The client computers are now ready to use the GEO-SLOPE Office Network license.

Files Installed by Setup The table describes the files installed by GEO-SLOPE Office Setup and specifies the default directories where they are installed.

46 SEEP/W GEO-SLOPE Office Files and Installation Directories GEO-SLOPE Office File

Description

Slope1.exe, Seep1.exe, etc.

GEO-SLOPE Office DEFINE

Slope2.exe, Seep2.exe, etc.

GEO-SLOPE Office SOLVE

Slope3.exe, Seep3.exe, etc.

GEO-SLOPE Office CONTOUR

Slphlp.chm, Sephlp.chm, etc.

GEO-SLOPE Office Online Help

Slpcust.dat, Sepcust.dat, etc.

GEO-SLOPE Office Information Files

GSI0132.DLL

GEO-SLOPE Office DLL

NSLMS324.DLL

GEO-SLOPE Office DLL

GSW32.EXE

Graphics Server program

GSWAG32.DLL

Graphics Server DLL

GSWDLL32.DLL

Graphics Server DLL

SYSEQN2.DLL

GEO-SLOPE Office DLL

Example Files

GEO-SLOPE Office example problems

Manual Files

User’s Guide PDF documents

GSIEVAL.LIC

Evaluation Software License

LICUTIL.EXE

GEO-SLOPE License Management Utility

LMTOOLS.EXE

Globetrotter License Utility Tool

README.TXT

Readme File

ORDER.TXT

Order Form

SERVICES.TXT

Software License Ageeement

Viewing GEO-SLOPE Office Manuals The GEO-SLOPE Office Online Help system provides you with a powerful, interactive means of accessing the GEO-SLOPE Office documentation from within the software. The documentation in its entirety is available in the online help system and on the distribution CD-ROM as Adobe Portable Document Format (.PDF), files. You can use these files to print some or all of the documentation to meet your own requirements. If you do not have Adobe Acrobat viewer, you can install the software from the GEO-SLOPE Office CD-ROM. Ø

To install the Adobe Acrobat Reader: 1. Run the main Setup program from the distribution CD-ROM. 2. Click on Install Adobe Acrobat Reader in the Setup window. The Adobe Acrobat Reader Setup program begins execution. 3. Follow the instructions given by the Adobe Acrobat Reader Setup program.

Ø

To view and print the GEO-SLOPE Office manual: 1. Start Adobe Acrobat Reader.

GEO-SLOPE Office 5 47

2. Choose File Open and load the GEO-SLOPE Office manual that you wish to print. 3. Choose File Print to print the file from Adobe Acrobat Reader. The above procedure can be used to print the manual for any other GEO-SLOPE Office software product.

Chapter 3 SEEP/W Tutorial An Example Problem This chapter introduces you to SEEP/W by presenting the step-by-step procedures involved in analyzing a simple seepage problem. By executing each step in the sequence presented, you will be able to define a problem, solve the problem, and view the result. By completing this exercise, you can quickly obtain an overall understanding of the features and operations of SEEP/W. Figure 3.1 presents a schematic diagram of a seepage problem. The objective is to examine the porewater pressure conditions in the foundation beneath a water retention structure and to estimate the seepage losses through the foundation. Figure 3.1 A Sample Seepage Problem

Defining the Problem The SEEP/W DEFINE function is used to define a problem. Ø

To start DEFINE: ·

Select DEFINE from the Start Programs menu under SEEP/W. -- or --

·

Double-click the DEFINE icon in the SEEP/W Group window. When the DEFINE window appears, click the Maximize button in the upper-right corner of the DEFINE window so that the DEFINE window will cover the entire screen. This maximizes the workspace for defining the problem.

NOTE: It is assumed that you are readily familiar with the fundamentals of the Windows environment. If you are not, then you will first need to learn how to navigate within the Windows environment before learning how to use SEEP/W. The SEEP/W User’s Guide does not provide instructions on the fundamentals of using Windows. You will have to get this information from other documentation.

50 SEEP/W

Set the Working Area The working area is the size of the space available for defining the problem. The working area may be smaller, equal to or greater than the printer page. If the working area is larger than the printer page, the problem will be printed on multiple pages when it is displayed at 100% or greater. The working area should be set so that you can work at a convenient scale. For this example, a suitable working area is 260 mm wide and 200 mm high. Ø

To set the working area size: 1. Choose Page from the Set menu. The Set Page dialog box appears.

The Printer Page group box displays the name of the printer selected and the printing space available on one printer page. This information is presented to help you define a working area that will print properly. 2. Select mm in the Page Units group box. 3. Type 260 in the Working Area Width edit box. Press the TAB key to move to the next edit box. 4. Type 200 in the Height edit box. 5. Select OK.

Set the Scale The geometry of the problem is defined in meters. As shown in Figure 3.1, the problem is 15 m wide and about 10 m high. The lower-left corner of the problem will be drawn at (3,3). The extents need to be larger than the size of the problem to allow for a margin around the drawing. Let us estimate the extents in the x-direction from 0 to 20 m and from 0 to 15 m in the y direction. Once the extents of the problem have been set, DEFINE computes an approximate scale. The scale can then be adjusted to an even value. The maximum x and y extents will then be automatically adjusted to reflect the scale you have selected. Ø

To set the scale: 1. Choose Scale from the Set menu. The following dialog box appears:

GEO-SLOPE Office 5 51

2. Select Meters in the Engineering Units group box. 3. Type the following values in the Problem Extents edit boxes: Minimum: x: 0 Minimum: y: 0 Maximum: x: 20 Maximum: y: 15 The Horz. 1: scale will change to 76.923 and the Vert. 1: scale to 75. We do not want to work at such an odd scale. An even scale of 1:80 in both directions appears acceptable for this problem. 4. Type 80 in the Horz. 1: edit box, and type 80 in the Vert. 1: edit box. The Maximum x will change to 20.8 and the Maximum y will change to 16. This means that at a scale of 1:80, the allowable problem extents are from zero to 20.8 m in the x direction and from zero to 16 m in the y direction for the previously selected working area 260 mm wide and 200 mm high. 5. Select OK. Since the problem is defined in terms of meters and kN, the unit weight of water must be 9.807 kN/m3, which is the default value when the engineering dimensions are defined in meters.

Set the Grid Spacing A background grid of points is required to assist in drawing the problem. These points can be "snapped to" when creating the problem geometry in order to create nodes and elements with exact coordinates. A suitable grid spacing in this example is 1 meter. Ø

To set and display the grid: 1. Choose Grid from the Set menu. The Set Grid dialog box will appear.

52 SEEP/W

2. Type 1 in the Grid Spacing X: edit box. 3. Type 1 in the Y: edit box. The actual grid spacing on the screen will be a distance of 12.5 mm between each grid point. This value is displayed in the Actual Grid Spacing group box. 4. Check the Display Grid check box. 5. Check the Snap to Grid check box. 6. Select OK. The grid is displayed in the DEFINE window. As you move the cursor in the window, the coordinates of the nearest grid point (in engineering units) are displayed in the status bar.

Save the Problem The problem definition data must be saved in a file. This allows the SOLVE and CONTOUR functions to obtain the problem definition for solving the problem and viewing the results. The data may be saved at any time during a problem definition session. It is good practice to save the data frequently. Ø

To save the data to a file: 1. Choose Save from the File menu. The following dialog box will appear.

GEO-SLOPE Office 5 53

2. Type a file name in the File Name edit box. For example, type LEARN. 3. Select Save. The data will be saved to the file LEARN.SEP. Once it is saved, the file name is displayed in the DEFINE window title bar. The file name may include a drive name and directory path. If you do not include a path, the file will be saved in the directory name displayed in the Save In box.. The file name extension must be SEP. SEEP/W will add the extension to the file name if it is not specified. The next time you choose File Save, the file will be saved without first bringing up the Save File As dialog box. This is because a file name is already specified. It is often useful when modifying a file to save it under a different name. This preserves the previous contents of the file. Ø

To save data to a file with a different name: 1. Choose File Save As. The same dialog box appears. 2. Type the new file name. If the file name you type already exists, you will be asked whether you wish to replace the file which already exists. If you select No, you must retype the file name. If you select Yes, the previous copy of the file will be lost.

Sketch the Problem In developing a finite element mesh, it is convenient to first prepare a sketch of the problem dimensions. This sketch is a useful guide for drawing the finite element mesh and defining the boundary conditions. Ø

To sketch the foundation of the problem: 1. In the Zoom toolbar, click on the Zoom Page button with the left mouse button. The entire working area is displayed in the DEFINE window. 2. Choose Lines from the Sketch menu. The cursor will change from an arrow to a cross-hair, and the

54 SEEP/W

status bar will indicate that "Sketch Lines" is the current operating mode. 3. Using the mouse, move the cursor near position (3,3), as indicated in the status bar at the bottom of the window, and click the left mouse button. The cursor snaps to the grid point at (3,3). As you move the mouse, a line is drawn from (3,3) to the new cursor position. The cursor position (in engineering units) is always displayed in the status bar. It is updated as you move the cursor with the mouse. 4. Move the cursor near (18,3) and click the left mouse button. The cursor snaps to (18,3) and a line is drawn from (3,3) to (18,3). 5. Move the cursor near (18,9) and click the left mouse button. A line is drawn from (18,3) to (18,9). 6. Move the cursor near (3,9) and click the left mouse button. A line is drawn from (18,9) to (3,9). 7. Move the cursor near (3,3) and click the left mouse button. A line is drawn from (3,9) to (3,3). 8. Click the right mouse button to finish sketching a line. The cursor will change from a cross-hair back to an arrow; you are then back in Work Mode. 9. In the Zoom Toolbar, click on the Zoom Objects button with the left mouse button. The drawing is enlarged so that the lines you just sketched fill the DEFINE window. After you have completed the above steps, your screen should look like the following:

NOTE: If you sketch a line in the wrong position, use the Modify Objects command to move it. For more information about this command, see Modify Objects in Chapter 4. You should now know how to sketch a line. After scrolling the drawing down a bit, sketch the dam in the same way you sketched the foundation: 1. Choose Sketch Lines. 2. Position the cursor and click the left mouse button at (13,9), (10,13), (9,13), and (9,9). 3. Click the right mouse button to finish sketching the dam.

GEO-SLOPE Office 5 55 Sketch the cutoff in the same way: 1. Choose Sketch Lines. 2. Position the cursor and click the left mouse button at (10,9), (10,6), (11,6), and (11,9). 3. Click the right mouse button to finish sketching the cutoff. Sketch the reservoir line in the same way: 1. Choose Sketch Lines. 2. Position the cursor and click the left mouse button at (3,12) and (9,12). 3. Click the right mouse button to finish sketching the reservoir line. You may sketch a water level symbol on the reservoir line if you wish. To do so, you must first turn off the grid by clicking on the Snap to Grid button in the Grid toolbar. Click on the Snap to Grid button once more to turn the background grid on again. You can also turn off the grid by selecting Grid from the Set menu and un-ckecking the Snap to Grid option. After you have completed the above steps, your screen should look like the following:

Identify the Problem Ø

To name and identify the problem: 1. Choose Analysis Settings from the KeyIn menu. The following dialog box appears.

56 SEEP/W

2. Type in any appropriate text in the Title edit box and the Comments edit box. 3. Select OK. This information will be written to all data input and output files.

Specify the Analysis Type This problem is a steady-state analysis. Ø

To specify this information: 1. Choose Analysis Settings from the KeyIn menu and select the Type property sheet tab. The following dialog box will appear:

GEO-SLOPE Office 5 57

2. Use the default values in the dialog box. §

The Steady-State button should be selected as the Problem Type.

3. Select OK.

Specify the Analysis Control This problem is a two-dimensional analysis. Ø

To specify this information: 1. Choose Analysis Settings from the KeyIn menu and select the Control property sheet tab. The following dialog box will appear:

58 SEEP/W

2. Use the default values in the dialog box. §

The 2-Dimensional button should be selected as the Control Type.

3. Select OK.

Define a Hydraulic Conductivity Function The foundation material has a hydraulic conductivity equal to 1 x 10-5 m/sec, and it is independent of the pore-water pressure level. Since the hydraulic conductivity must be defined as a function, the constant hydraulic conductivity can be defined by a two-point horizontal function. Ø

To define a conductivity function: 1. Choose Functions from the KeyIn menu. The Functions cascading menu will appear. 2. Choose Conductivity from the Functions cascading menu. The following dialog box will appear:

3. Type 1 in the Function Number edit box and select Edit. The following dialog box will appear to let you enter the data points in Function 1:

GEO-SLOPE Office 5 59

4. Type 1 in the # edit box, 0 in the Pressure edit box, and 1e-5 in the Conductivity edit box. 5. Select Copy. The values you typed in the edit boxes will be copied into the list box, creating the first function point. 6. Type 2 in the # edit box, 100 in the Pressure edit box, and 1e-5 in the Conductivity edit box. 7. Select Copy to create the second function point. 8. Select View to display a graph of the conductivity function.

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The graph window contains tools for moving points, adding more points, copying the graph to the Windows clipboard, and printing the graph. For more information about these tools, see KeyIn Functions Conductivity in Chapter 4. 9. Click on the X in the upper-right corner of the graph window. This closes the graph window. 10. Type an appropriate name for the function in the Description edit box. The function name is helpful when later choosing a function to edit or import. 11. Select OK in the KeyIn Edit Conductivity Functions dialog box from Step 3. This saves the points in Function 1. 12. Select Done in the KeyIn Conductivity Functions dialog box from Step 2. There are many more features of the KeyIn Functions Conductivity command that are not discussed in this section. See the KeyIn Functions Conductivity command in Chapter 4 for details on these features.

Define Material Properties For each material type, you must specify: ·

a material number unique to the material

·

a hydraulic conductivity function (kx)

·

a volumetric water content function, if the problem is a transient analysis

GEO-SLOPE Office 5 61

·

the ratio of the ky to kx hydraulic conductivities

·

the direction of the kx hydraulic conductivity

For this example, only one material type is used. The properties of Material 1 are:

Ø

·

Conductivity Function 1

·

no volumetric water content function

·

hydraulic conductivity ratio is 1.0

·

angle of the major hydraulic conductivity is 0.

To define the properties of Material 1: 1. Choose Material Properties from the KeyIn menu. The following dialog box appears:

2. Type 1 in the # edit box to indicate that you are defining Material 1. 3. Click the down arrow beside the K-Fn # edit box. A drop-down list appears, containing the numbers of all defined conductivity functions. Select 1 from the list. By default, the W.C. Fn # is zero, the K-Ratio is 1.0, and the K-Direction is 0.0. Leave these values unchanged, since these are the values you will use for this material. 4. Select Copy. The values contained in the edit boxes will be copied into the list box, creating the material. 5. Select OK to save the material properties.

Generate Finite Elements For this problem, it is adequate to use four-noded quadrilateral elements in the geometry. All elements have the properties of Material 1. Elements will be generated in three regions. Ø

To generate finite elements in the first region of the problem: 1. Choose Multiple Elements from the Draw menu. The cursor will change from an arrow to a cross-

62 SEEP/W

hair and the status bar will indicate that "Draw Multiple Elements" is the current mode. 2. Click the left mouse button near (3,3). SEEP/W snaps to the grid and creates a node (Node 1) at this position. As you move the mouse, a line is drawn from the node to the new cursor position. 3. Move the cursor near (10,3) and click the left mouse button. SEEP/W snaps to the grid, creates a node (Node 2) at this position, and draws a line from Node 1 to Node 2. As you move the mouse, a line is drawn from Node 2 to the new cursor position. 4. Move the cursor near (10,9) and click. 5. Move the cursor near (3,9) and click. The following dialog box appears:

6. In the Draw Multiple Elements dialog box, enter or select the following: §

The Element Type should be the Quadrilateral (4 nodes) option. Leave the Secondary Nodes check box unchecked.

§

The Element Distribution group box should have 7 Elements with a Size Ratio of 1 for Side 1 and 6 Elements with a Size Ratio of 1 for Side 2. This will generate 42 elements.

§

The Material Type should be Material 1.

§

The Quad. Integration Order should be 4.

§

The Element Thickness should be 1. This value is appropriate for a two-dimensional analysis such as this problem.

7. Click the Apply button. Forty-two elements each 1 m x 1 m will be drawn. You can alter the # of Elements for Side 1 and Side 2 and click Apply again if you do not get the correct 42 elements the first time. 8. Select OK to accept the mesh generation when you are satisfied that the mesh is correct.. The node and element numbers are sorted and the problem is redrawn in the DEFINE window. The elements appear as a light yellow color to indicate that they have Material Type 1. Choose Preferences from the View menu and uncheck the Material Colors check box if you do not want the elements to be shaded.

GEO-SLOPE Office 5 63 After you have completed the above steps, your screen should look like the following:

The above procedure will now be repeated to generate elements in the remaining two regions. Ø

To generate elements in the second region: 1. Choose Multiple Elements from the Draw menu. 3. Move the cursor and click near (11,3), (18,3), (18,9), and (11,9). 2. When the Draw Multiple Elements dialog box appears, select OK to accept the defaults. This will generate elements with the same properties as the elements previously generated.

Ø

To generate elements in the last region: 1. Choose Multiple Elements from the Draw menu. 2. Move the cursor and click near (10,3), (11,3), (11,6), and (10,6). 3. In the Draw Multiple Elements dialog box, enter or select the following: §

The Element Type should be the Quadrilateral (4 nodes) option. Leave the Secondary Nodes check box unchecked.

§

The Element Distribution group box should have 1 Element with a Size Ratio of 1 for Side 1 and 3 Elements with a Size Ratio of 1 for Side 2.

§

The Material Type should be Material 1.

§

The Quad. Integration Order should be 4.

§

The Element Thickness should be 1.

4. Click Apply to generate the elements. 5. Select OK to accept the mesh generation. Three elements are generated, and all node and element

64 SEEP/W

numbers are re-sorted. After you have completed the above steps, your screen should look like the following:

NOTE: Nodes can also be drawn individually with the Draw Nodes command. See Chapter 4 for details on the Draw Nodes command.

Set View Preferences When defining a problem, the default values are automatically selected in the View Preferences dialog box. Ø

To set the view preferences for the drawing: 1. Choose Preferences from the View menu. The Preferences group box can be used to check or un-check any of the options in the Items to View group box. The Font size and type can be set for nodes, elements and axes using the Font Size group box options. Checking the Convert All Sketch Text Fonts option and selecting a font will convert all of the sketch text to the corresponding font.

GEO-SLOPE Office 5 65

2. Accept the defaults and Select OK. NOTE: You can also select and unselect the View Preferences by clicking on the icons in the View Preferences toolbar. You can learn about each of the icons by placing the cursor over the icon. A tool tip will appear for a few seconds and a description is displayed on the status bar at the bottom of the window.

Specify Node Boundary Conditions Boundary conditions may be specified as total head (H), total nodal flow or flux (Q), or flow per unit length along the side of an element (q). The boundary conditions for this problem are:

Ø

·

Total head is 12 m at the base of the reservoir.

·

Total head is 9 m at the ground surface downstream of the dam.

·

Total flux is zero across the left and right vertical boundaries, across the bottom of the finite element mesh, and along the base of the dam.

·

Flux is zero along the cutoff wall.

To specify the node boundary conditions: 1. Choose Boundary Conditions from the Draw menu. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Draw Boundary Conditions" is the current mode. The following dialog box appears:

66 SEEP/W

2. To specify the total head at the base of the reservoir, type 12 in the Action edit box. 3. Use the remaining default values in the dialog box. §

H should be selected as the Boundary Type.

§

Boundary Fn. # and Mod. Fn. # should be 0.

§

(none) should be selected as the method to Review By.

4. Click the left mouse button near Node 7. The cursor snaps to Node 7 and the node symbol is changed to a red circle, indicating the node is a head boundary. 5. The remaining reservoir boundary nodes will be defined by dragging a rectangle around a group of nodes. Move the cursor above and to the left of Node 14. Hold the left mouse button down, but do not release it. Now move the mouse to the right, and a rectangle appears. "Drag" the mouse until the rectangle encompasses Node 14, Node 21, Node 28, Node 35, Node 42, and Node 49. Now release the left mouse button, and all of these nodes are redrawn as red circles. Node boundary conditions can therefore be defined both by clicking on each node individually or by dragging a rectangle around a group of nodes. Another way of specifying boundary nodes is to hold down the SHIFT key and select nodes along any straight line. See the Draw Boundary Conditions command reference in Chapter 4 for more information. 6. To specify the total head at the ground surface downstream of the dam, type 9 in the Action edit box. 7. Use the remaining default values in the dialog box. §

H should be selected as the Boundary Type.

§

Boundary Fn. # should be 0.

§

(none) should be selected as the method to Review By.

8. Use the procedure described in Step 5 to drag a rectangle around Nodes 77, 84, 91, 98, 105, and 112. You may need to move the dialog box if it overlaps these nodes. All of these nodes are redrawn as red circles, indicating each node is a head boundary. 9. To specify a total flux of zero for the remaining boundary conditions, type 0 in the Action edit box. 10. Select Q as the Boundary Type. 11. Use the remaining default values in the dialog box. §

Boundary Fn. # should be 0.

GEO-SLOPE Office 5 67 §

(none) should be selected as the method to Review By.

12. Drag a rectangle around all the nodes along the left vertical boundary of the mesh except for Node 7. All of these nodes are redrawn as blue triangles. The triangle symbol indicates the node is a flux boundary, while the color blue indicates total flux (Q). 13. Drag a rectangle around all the nodes along the bottom boundary of the mesh. 14. Drag a rectangle around all the nodes along the right vertical boundary except for Node 112. 15. Drag a rectangle around all the nodes along the perimeter of the cutoff wall, and click on Node 70. 16. Click the right mouse button (or select Done) to finish defining the node boundary conditions. After you have completed defining the boundary conditions, your screen should look like the following:

If you wish to experiment with zooming your drawing, you may select any of the zoom buttons from the Zoom toolbar. For more information about zooming, see Zoom Toolbar in Chapter 4.

Draw Flux Sections A flux section is desired for this problem to compute the total seepage flow through the foundation of the dam. Ø

To define a flux section: 1. Turn off the grid by choosing Set Grid and un-checking the Snap to Grid option or by clicking on the Snap Grid button on the Grid toolbar. (The flux section you draw will not be snapped to a grid point). 2. Display flux sections on the drawing by choosing View Preferences and checking the Flux Sections check box. 3. Choose Flux Sections from the Draw menu. The following dialog box appears:

68 SEEP/W

4. Use the default value in the Section Number box. It should be set to 1. 5. Select OK. The cursor will change from an arrow to a cross-hair and the status bar will indicate that "Draw Flux Sections" is the current operating mode. 6. Using the mouse, move the cursor near position (10.5, 2.5), directly below the cutoff wall and below the bottom boundary of the mesh. Click the left mouse button. As you move the mouse, a dashed black line is drawn from (10.5, 2.5) to the new cursor position. 7. Move the cursor near (10.5, 6.5), just above the base of the cutoff wall, and click the left mouse button. A blue dashed line is drawn, indicating a flux section along this area. 8. Click the right mouse button to finish defining this flux section.

Sketch Axes Sketching an axis on the drawing facilitates viewing the drawing and interpreting the drawing after it is printed. Ø

To sketch an axis: 1. Turn on the background grid by choosing Set Grid and checking the Snap to Grid option or by clicking on the Snap Grid button on the Grid toolbar. This will re-display the background grid and allow you to define an evenly-spaced region for the axis.

GEO-SLOPE Office 5 69 2. Click on the Zoom Page button in the Zoom toolbar. (If the Zoom toolbar is not displayed, choose View Toolbars and click on the Zoom check box). The entire working area is displayed in the DEFINE window. 3. Choose Axes from the Sketch menu. The following dialog box appears:

4. Check the Left Axis, Bottom Axis, and Axis Numbers check boxes in the Display group box. The Top Axis and Right Axis check boxes should be unchecked. This will cause an X-axis to be sketched along the bottom side of the specified region and a Y axis to be sketched along the left side of the specified region. 5. Type an appropriate title for the bottom X-axis in the Bottom X edit box. 6. Type an appropriate title for the left Y-axis in the Left Y edit box. 7. Select OK. The cursor will change from an arrow to a cross-hair, and "Sketch Axes" will be added to the status bar, indicating the mode in which you are operating. 8. Move the cursor near position (2,2). Hold the left mouse button down, but do not release it. As you move the mouse, a rectangle appears. 9. "Drag" the mouse near (18,14), and release the left mouse button. An axis is generated within the region.

70 SEEP/W After you click on the Zoom Objects button in the Zoom toolbar, your screen should look like the following:

The View Preferences command allows you to change the font and the size of the axis numbers. For more information about this command, see View Preferences in Chapter 4. The number of increments along each axis is calculated by SEEP/W when the axis is generated. Choose the Set Axes command if you wish to override these values.

Verify the Problem The problem definition should now be verified by SEEP/W to ensure that the data has been defined correctly. To solve the finite element equations, it is also important that the node numbers are sorted in a horizontal or vertical direction and that they form a complete sequence starting with Number 1. Keeping the node number difference in each element as low as possible helps to minimize the memory requirements of the SOLVE function. Although SEEP/W sorts the node and element numbers each time that multiple elements are generated, the mesh is not sorted when single elements are drawn using Draw Single Elements or when nodes and elements are added using the KeyIn Nodes and KeyIn Elements commands. Ø

To verify the validity of the data and sort the node and element numbers: 1. Choose Verify/Sort from the Tools menu. The following dialog box appears:

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2. Press the Verify/Sort button in the dialog box. SEEP/W sorts the node and element numbers and deletes any duplicate nodes (nodes that have the same coordinates). Since the node and element data has not been changed since we generated multiple elements, none of the node and element numbers will change. SEEP/W also performs a number of checks on the node and element data, including filling any missing node numbers. Messages appear in the dialog list box stating which sorting or verification step is being performed. Error messages will also appear in the list box if necessary. The following messages appear in the dialog box:

Finish DEFINE The problem definition is now complete. Choose File Save to save the LEARN.SEP data file to disk.

Solving the Problem The second part of an analysis is to use the SEEP/W SOLVE function to compute the total hydraulic head at each node, the flow velocity within each element, and the total flux across specified sections. To start SOLVE and automatically load the LEARN.SEP data file, click on the SOLVE button in the Standard toolbar.

72 SEEP/W The SOLVE window appears. SOLVE automatically opens the LEARN.SEP data file and displays the data file name in the SOLVE window.

Alternatively, you can start SOLVE by clicking the SOLVE icon in the SEEP/W Group folder and opening LEARN.SEP with the File Open Data File command. It is simpler, however, to start SOLVE from the DEFINE Standard toolbar when you wish to analyze a problem you have just defined. For more information about opening data files, see File Open Data File in Chapter 5.

Start Solving To start solving the problem, click on the Start button in the SOLVE window. A green dot appears between the Start and Stop buttons; the dot flashes while the computations are in progress.

GEO-SLOPE Office 5 73 Information about the computations is displayed in a list box in the SOLVE window while the problem is being solved.

In this example, the Step # is 0, since it is a steady-state analysis. Two iterations are required to achieve a solution. Recall that the hydraulic conductivity was defined as a constant 1x10 5 m/sec. This makes the finite element equations linear; consequently, the computed heads are the same for the two iterations. The Vector Norm is the norm of the pressure head vector. For a detailed description of this parameter, see Running SOLVE in Chapter 5. The computations come to a halt when the percentage change in the Vector Norm from one elevation to the next is less than the specified percentage tolerance. You can halt the computations manually by clicking the Stop button.

Finish SOLVE You have now finished solving the problem. Click the Minimize button in the top-right corner of the SOLVE window to reduce the window to an icon or choose the File Exit command to exit from SOLVE.

Viewing the Results The SEEP/W CONTOUR function allows you to view the results of the problem analysis graphically by: ·

Generating contour plots

·

Displaying velocity vectors that represent the flow direction

·

Displaying the computed flux across each specified section

74 SEEP/W

·

Clicking on individual nodes and elements to display numerical information

·

Plotting graphs of the computed results

To start CONTOUR and automatically load the LEARN.SEP data file, click on the CONTOUR button in the Standard toolbar (if DEFINE still has the LEARN problem open). This is the same way in which SOLVE was launched previously.

The CONTOUR window appears. CONTOUR automatically opens the LEARN.SEP data file:

Alternatively, you can start CONTOUR by clicking the CONTOUR icon in the SEEP/W Group folder and opening LEARN.SEP with the File Open command. It is simpler, however, to start CONTOUR from the DEFINE Standard toolbar when you wish to view the results of a problem that has already been analyzed. For more information about opening files in CONTOUR, see File Open in Chapter 6. The drawing displayed in the CONTOUR window will be drawn according to the View Preference options selected at the time you exited from the DEFINE function. You can view different parts of the drawing by choosing Preferences from the View menu or choosing items on the View Preference toolbar. Since the nodes and elements do not need to be displayed, choose View Preferences and uncheck the Nodes and Elements check boxes, and select OK. Alternatively, uncheck these items on the View Preferences toolbar. NOTE: You can select and unselect the View Preferences by clicking on the icons in the View Preferences toolbar. You can learn about each of the icons by placing the cursor over the icon. A tool tip will appear for a few seconds and a description is displayed on the status bar at the bottom of the window.

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Draw Contours Ø

To draw contours of the results: 1. Select Contours from the Draw menu. The following dialog box appears:

By default, Total Head is the parameter that will be contoured, and default contour values are displayed in the edit boxes. If you wish to change these values, select a different parameter from the Contour Parameter drop-down list box or type new contour values in the edit boxes. The range of the total head data is from 9 to 12, as displayed in the Data Range group box. 2. Click on Apply to generate and view the contours. 3. Select OK to accept the results. SEEP/W produces the following contour plot:

76 SEEP/W

Each contour interval is shaded a different color. You can alter the shading with the Contour Shading controls in the Draw Contours dialog box. You can try various Methods, and Start and End Colors to see the effect. After each new selection, click Apply to see what you get. Finally, click on Cancel to return to the default shading you created earlier.

Draw the Velocity Vectors Ø

To change the length at which the velocity vectors are displayed: 1. Choose Vectors from the Draw menu. The following dialog box appears:

2. Select mm as the units. 3. Type 15 in the Length edit box. The longest vector drawn will be 15 mm. 4. Select OK. SEEP/W will redraw the velocity vectors to make them longer:

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SEEP/W draws a vector in each element, with the end point of the vector at the center point of the element. The vector represents the average velocity within the element. The element with the highest velocity has a vector length of 15 mm. All other vector lengths are directly proportional to this length as a ratio of the average velocity to the maximum velocity. Sometimes it is more useful to talk about the vectors at a certain magnification. You can, for example, type 200000 in the Magnification dialog box. The maximum vector length then is 14.102. So you can either set the maximum length or the magnification.

Draw the Contour Values Ø

To label the contours on the drawing: 1. Since the velocity vectors do not need to be displayed anymore, click on the View Vectors icon in the View Preferences toolbar. 2. Choose Contour Labels from the Draw menu. The cursor changes from an arrow to a cross-hair, and "Draw Contour Labels" is displayed on the status bar to indicate the current mode. 3. Move the cursor to a convenient point on a contour, and click the left mouse button. The contour value appears on the contour. If you wish to remove the contour label, simply re-click on the label, and the label disappears. Click again, and the label will re-appear. 4. Repeat Step 3 for as many contours as you wish. 5. Click the right mouse button to finish labelling contours.

78 SEEP/W After you have completed the above steps, your screen should look similar to the following:

NOTE: The View Preferences command allows you to change the font and the size of the contour values.

Draw the Flux Value Ø

To draw the flux value on the drawing: 1. Choose Flux Label from the Draw menu. The cursor changes from an arrow to a cross-hair, and "Draw Flux Labels" appears on the status bar to indicate the current mode. 2. Move the cursor to a convenient point on the flux section, and click the left mouse button. The value of the total flux across the section appears on the section. If you wish to remove the flux label, simply re-click on the label, and the label disappears. If you wish to place the label elsewhere on the section, click again on a different part of the flux section. 3. Click the right mouse button to finish labelling flux sections.

GEO-SLOPE Office 5 79 After you have completed the above steps, your screen should look similar to the following:

Draw Flow Paths You can draw a path that a drop of water would travel from the reservoir to the exit point on the ground surface downstream of the dam. Ø

To Draw Flow Paths 1. Choose Flow Paths from the Draw menu. The cursor changes from an arrow to a cross-hair, and "Draw Flow Paths" appears on the status bar ti indicate the current mode. 2. Move the cursor to a point somewhere in the middle of the flow region and click the left mouse button. A flow path is projected in both directions to the boundary. 3. Move the cursor and click at each point you want to draw a flow path. Sometimes the paths will encounter a zone with little or no flow and SEEP/W will not be able to complete the path. You will see a warning message if this occurs. 4. Click the right mouse button to finish drawing flow paths

80 SEEP/W The following shows some typical flow paths.

NOTE: Flow paths drawn by SEEP/W are NOT flow lines or stream lines as in a traditional flow net. They are simply a graphical representation of a path that a drop of water would follow from the entrance to exit point.

Zoom In and Out Any part of the drawing can be magnified or reduced with the Zoom tools. In this example problem, the flux value may be fairly small to read. This can be overcome by enlarging this part of the drawing. Ø

To enlarge parts of a drawing: 1. Ensure that the Zoom toolbar is displayed. If the Zoom toolbar is not displayed, choose View Toolbars and click on the Zoom check box. 2. In the Zoom toolbar, click on the Zoom In button with the left mouse button. The cursor changes to a magnifying glass with a plus sign and the Zoom In button appears pushed-in to indicate that you are in a Zooming In mode. 3. The zoom region is defined by dragging a rectangle around the region. Move the cursor above and to the left of the flux section. Push the left mouse button down, but do not release it. Now move the mouse to the right, and a rectangle appears. "Drag" the mouse until the rectangle encompasses the flux section. 4. Release the left mouse button. The selected region is enlarged so that it fills the entire window. The Zoom In button returns to its normal state. The edit box in the Zoom toolbar shows the percentage the drawing is reduced or magnified.

Ø

To display the drawing at its previous size: ·

In the Zoom toolbar, click on the Zoom Out button with the left mouse button.

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The drawing is displayed at the previous size.

Print the Drawing Ø

To print the CONTOUR drawing: 1. Ensure that the entire drawing is displayed in the window before printing. To display the entire drawing in the window click on the Zoom Objects button in the Zoom toolbar. (If the Zoom toolbar is not displayed, choose View Toolbars and click on the Zoom check box). 2. Click on the Print button in the . The following dialog box appears:

3. Select OK to print the drawing on the default printer at the currently displayed size. For more information on printing, see the File Print command in Chapter 4.

Display Node and Element Information The View Node Information and View Element Information commands allow you to check the exact computed values at any node or Gauss region by clicking on the node or Gauss region. Ø

To view the computed results at any node: 1. Choose Node Information from the View menu. The nodes are displayed on the drawing, and the following dialog box appears:

82 SEEP/W

2. Click on any node to see the results computed at the node. For example, click on the node at the top-left corner of the mesh. The node is selected on the drawing, and the following information is displayed in the dialog box:

3. To see all the information that was computed at the node, scroll through the list box. 4. Repeat Steps 2 to 3 for all nodes at which you want to see the computed results. Select the Copy button if you wish to copy the information to the Windows Clipboard for importing into other applications, or select the Print button if you wish to print the information. 5. Select Done when you are finished displaying information at the nodes. The parameters that SEEP/W computes at the nodes are total head, pressure, and pressure head. The remaining parameters, such as conductivity and velocity, are computed at the Gauss regions and projected to the nodes by CONTOUR for display purposes. Ø

To see results at Gauss regions: 1. Choose Element Information from the View menu. The View Element Information dialog box is displayed. 2. Click within any element Gauss region to see the results computed at the element Gauss point. For example, click inside the element Gauss region at the top-left corner of the mesh. The element Gauss region is selected on the drawing, and the following information is displayed in the dialog box:

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3. To see all the information that was computed at the element Gauss region, scroll through the list box. 4. Repeat Steps 2 to 3 for all elements at which you want to see the computed results. Select the Copy button if you wish to copy the information to the Windows Clipboard for importing into other applications, or select the Print button if you wish to print the information. 5. Select Done when you are finished displaying the element Gauss region information.

Plot a Graph of the Results A powerful feature of CONTOUR is the ability to generate x-y plots of the computed results. For instance, in the example problem that you have just analyzed, you may wish to plot a graph of the computed pressure head along the base of the dam versus the nodal x-coordinates. This will help you to verify that the cutoff underneath the dam is indeed lowering the uplift pressure on the dam itself. Ø

To plot the graph: 1. Choose Graph from the Draw menu. The following dialog box appears:

2. In the Graph Type group box, select Pressure Head from the first drop-down list box, and select XCoordinate from the second drop-down list box. Moving the mouse pointer outside of the dialog box will change the pointer to a large black pointer indicating you are in a selection mode. This is used to select the nodes from which to generate the graph, 3. If the snap-to-grid is currently displayed, turn it off by clicking on the Snap Grid button in the Grid toolbar. 4. Move the cursor near the node at the top-left corner of the mesh. Hold down the left mouse button

84 SEEP/W and drag a rectangle over all the nodes along the top of the mesh. The selected nodes are shown in reverse video with a black square around the node. 5. Click on the Graph button in the Draw Graph dialog box. The following graph will be displayed.

The pressure on the base of the dam drops from 2.73 m to 0.44 m across the cutoff. You can look at the numerical values at each node with the View Node Information command. 6. Select File Print from the Graph window menu if you wish to print the graph on the default printer. Select Edit Copy from the Graph window menu if you wish to copy the graph to the Windows Clipboard for importing into other applications. 7. Select File Close in the Graph Window or click on the X in the upper-right hand corner of the Graph Window to close the window. 8. Select Done from the Draw Graph dialog box to finish with the graphing. See the Draw Graph command reference in Chapter 6 for a complete discussion of the CONTOUR graphing capabilities, since there are other features of the command that have not been discussed in this section. You have reached the end of this introductory learning session. You have learned sufficient concepts to give you a general understanding of the operation and capability of SEEP/W. Not all of the powerful features of SEEP/W have been used in this learning session, nor have all of the technical details been discussed about the features that have been used. Details about each command are given in the chapters that follow.

Chapter 4 DEFINE Reference Introduction The first step in a seepage analysis is to define the problem. SEEP/W DEFINE is an interactive and graphical function for accomplishing the definition part of an analysis. This chapter describes the purpose, operation, and action of each SEEP/W DEFINE command. The DEFINE commands are accessible by making selections from both the DEFINE menus and toolbars. The toolbars contain icons which invoke many of the commands available in the menus. The menus available and the function of each are as follows: ·

File Opens and saves files and prints the drawing. For more information about this command, see The File Menu in this chapter.

·

Edit Undo and Redo last or previous actions and copies the drawing to the Clipboard. For more information about this command, see The Edit Menu in this chapter.

·

Set Sets page, scale, grid, zoom and axes settings. For more information about this command, see The Set Menu in this chapter.

·

View Controls viewing options and displays node and element information. For more information about this command, see The View Menu in this chapter.

·

KeyIn Allows for typing in problem data. For more information about this command, see The KeyIn Menu in this chapter.

·

Draw Defines problem data by drawing. For more information about this command, see The Draw Menu in this chapter.

·

Sketch Defines graphic objects to label, enhance, and clarify the problem definition. For more information about this command, see The Sketch Menu in this chapter.

·

Modify Allows graphic and text objects to be moved or deleted and text objects or pictures to be modified. For more information about this command, see The Modify Menu in this chapter.

·

Tools Allows verification of problem data and gives quick access to running SOLVE and CONTOUR. For more information about this command, see The Tools Menu in this chapter.

·

Help Displays the online help system and information about SEEP/W. For more information about this command, see The Help Menu in this chapter.

In the remainder of this chapter, the commands in the toolbars and in each of these menus are presented and described.

Toolbars Toolbars are small windows that contain buttons and controls to help perform common tasks quickly. Pressing a toolbar button is usually a shortcut for a command accessible from the menu; therefore, less time and effort is required to invoke a command from a toolbar than from a menu. You can choose to display or hide toolbars. To toggle the display of a toolbar, use the View Toolbars command, or put the cursor on a displayed toolbar and click the right mouse button. For more information on the View Toolbars command, see View Toolbars in this chapter.

86 SEEP/W Toolbars are movable and dockable and may be reshaped. Movable means you can move a toolbar by dragging it with the mouse to any location on the display. Dockable means you can "dock" a toolbar at various locations on the display such as below the menu bar, or on the sides or bottom of the main window. You can reshape a toolbar by dragging the corner of the toolbar with the mouse. As this is done, the toolbar outline changes to reflect its new shape. The best way to get a feel for moving, docking and reshaping toolbars is to try these things yourself using the mouse. In DEFINE, five toolbars are available for performing various tasks: Standard Toolbar Contains buttons for file operations, printing, copying, redrawing and accessing other SEEP/W programs. For more information about this toolbar, see Standard Toolbar in this chapter. Mode Toolbar Contains buttons for entering different operating modes which are used to display and edit graphic and text object data. For more information about this toolbar, see Mode Toolbar in this chapter. View Preferences Toolbar Contains buttons for toggling various display preferences. For more information about this toolbar, see View Preferences Toolbar in this chapter. Grid Toolbar Contains controls for specifying the display of a drawing grid. For more information about this toolbar, see Grid Toolbar in this chapter. Zoom Toolbar Contains controls for zooming in and out of the drawing. For more information about this toolbar, see Zoom Toolbar in this chapter.

Standard Toolbar The Standard toolbar, shown in Figure 4.1, contains commands for initializing new problems, opening previously saved problems, saving a current problem, verifying and sorting nodes and elements, printing the current problem, copying the current problem to the Windows clipboard, redrawing the display, and starting the SOLVE and CONTOUR programs. Figure 4.1 The Standard Toolbar

The toolbar buttons are: New Problem Use the New Problem button to clear any existing problem definition data and reset DEFINE back to the user-defined default settings. This places DEFINE in the same state as when it was first invoked. This button is not the same as the File New command--for information about the File New command, see File New in this chapter. Open Use the Open button as a shortcut for the File Open command. For information about this command, see File Open in this chapter.

GEO-SLOPE Office 5 87 Save Use the Save button as a shortcut for the File Save command. For information about this command, see The File Menu in this chapter. Verify/Sort Use the Verify/Sort button as a shortcut for the Tools Verify/Sort command. For more information about this command, see Tools Verify/Sort in this chapter. Print Use the Print button as a shortcut for the File Print command. For more information about this command, see File Print in this chapter. Print Selection Use the Print Selection button to print a selected area of the drawing. For more information, see Print Selection Button below. Copy All Use the Copy All button as a shortcut for the Edit Copy All command. For information about this command, see Edit Copy All in this chapter. Copy Selection Use the Copy Selection button to copy a selected area of the drawing to the Windows Clipboard. For more information, see Copy Selection Button below. Redraw Use the Redraw button as shortcut for the View Redraw command. For information about this command, see View Redraw in this chapter. SOLVE Use the SOLVE button as a shortcut for the Tools SOLVE command. For information about this command, see Tools SOLVE in this chapter. CONTOUR Use the CONTOUR button as a shortcut for the Tools CONTOUR command. For information about this command, see Tools CONTOUR in this chapter.

Mode Toolbar The Mode toolbar, shown in Figure 4.2, contains buttons that put DEFINE into "modes" used to accomplish specific tasks such as viewing node and element information, drawing nodes and elements, drawing boundary conditions, setting element properties, drawing flux sections, drawing an initial water table, drawing sketch objects and text, and modifying objects and pictures. Figure 4.2 The Mode Toolbar

The toolbar buttons are:

88 SEEP/W Default Mode Use the Default Mode button to exit any current mode and return to the default mode. View Node Information Use the View Node Information button as a shortcut for the View Node Information command. For information about this command, see View Node Information in this chapter. View Element Information Use the View Element Information button as a shortcut for the View Element Information command. For information about this command, see View Element Information in this chapter. View Edge Information Use the View Edge Information button as a shortcut for the View Edge Information command. For information about this command, see View Edge Information in this chapter. Draw Nodes Use the Draw Nodes button as a shortcut for the Draw Nodes command. For more information about this command, see Draw Nodes in this chapter. Draw Single Elements Use the Draw Single Elements button as a shortcut for the Draw Single Elements command. For more information about this command, see Draw Single Elements in this chapter. Draw Multiple Elements Use the Draw Multiple Elements button as a shortcut for the Draw Multiple Elements button. For more information about this command, see Draw Multiple Elements in this chapter. Draw Infinite Elements Use the Draw Infinite Elements button as a shortcut for the Draw Infinite Elements command. For more information about this command, see Draw Infinite Elements in this chapter. Draw Boundary Conditions Use the Draw Boundary Conditions button as a shortcut for the Draw Boundary Conditions command. For more information about this command, see Draw Boundary Conditions in this chapter. Draw Element Properties Use the Draw Element Properties button as a shortcut for the Draw Element Properties command. For more information about this command, see Draw Element Properties in this chapter. Draw Flux Sections Use the Draw Flux Sections button as a shortcut for the Draw Flux Sections command. For more information about this command, see Draw Flux Sections in this chapter. Draw Initial Water Table Use the Draw Initial Water Table button as a shortcut for the Draw Initial Water Table command. For more information about this command, see Draw Initial Water Table in this chapter. Sketch Lines Use the Sketch Lines button as a shortcut for the Sketch Lines command. For more information about this command, see Sketch Lines in this chapter. Sketch Circles Use the Sketch Circles button as a shortcut for the Sketch Circles command. For more information about this command, see Sketch Circles in this chapter. Sketch Arcs Use the Sketch Arcs button as a shortcut for the Sketch Arcs command. For more information about this command, see Sketch Arcs in this chapter. Sketch Axes Use the Sketch Axes button as a shortcut for the Sketch Axes command. For more information about this command, see Sketch Axes in this chapter. Sketch Text Use the Sketch Text button as a shortcut for the Sketch Text command. For more information about this command, see Sketch Text in this chapter.

GEO-SLOPE Office 5 89 Modify Text Use the Modify Text button as a shortcut for the Modify Text command. For more information about this command, see Modify Text in this chapter. Modify Pictures Use the Modify Pictures button as a shortcut for the Modify Pictures command. For more information about this command, see Modify Pictures in this chapter. Modify Objects Use the Modify Objects as a shortcut for the Modify Objects command. For more information about this command, see Modify Objects in this chapter.

View Preferences Toolbar The View Preferences toolbar, shown in Figure 4.3, contains buttons for setting viewing preferences such as nodes and elements and their numbers, material colors, flux sections, initial water table, sketch objects and text, pictures, text fonts, and the axes. Figure 4.3 The View Preferences Toolbar

All the buttons on the View Preferences toolbar are shortcuts for the options accessible using the View Preferences command. For more information about this command, see View Preferences in this chapter.

Grid Toolbar The Grid toolbar, shown in Figure 4.4, contains a button for toggling the display of grid points and controls for setting the x and y grid spacing. Figure 4.4 The Grid Toolbar

The Grid toolbar allows you to quickly change your background grid spacing. For example, if you are

90 SEEP/W drawing nodes and you wish to refine the background grid, click on the down-arrow beside the X or Y grid spacing edit box; the grid spacing is reduced by half and the background grid is redrawn. You can then continue to draw nodes. The toolbar controls are: Snap Grid Use the Snap Grid button as a shortcut for toggling both the grid display and snap to grid feature simultaneously. X and Y Grid Spacing Use the grid spacing controls to set the x and y grid spacing by either typing a value in the edit boxes or by using the spin controls adjacent to each edit box. Note that when the spacing value in one edit box is changed, the spacing value in the other edit box is automatically updated such that regular (i.e. square) grid will be generated on the display. Note also that if the drawing scale is different in the x- and y-directions, then the automatic updating of either the x- or y-spacing values will reflect this difference. For more information on changing the background grid, see Set Grid in this chapter.

Zoom Toolbar The Zoom toolbar, shown in Figure 4.5, contains buttons for zooming in and out of the drawing and a control for displaying and setting the zoom factor. Figure 4.5 The Zoom Toolbar

The toolbar controls are: Zoom In Use this button to zoom in on a user specified region. When the button is pressed, the cursor changes to a magnifying glass with a plus sign, ( ) and the status bar indicates that "Zoom In" is the current mode. You can then specify the region to be enlarged by using the mouse to drag a rectangle over the region. The display is then redrawn to show the region inside the specified rectangle. Zoom Out Use this button to return to the previously viewed region. If there is no previously set region, then the full page is displayed. Zoom Page Use this button to display the entire printable page. Zoom Objects Use this button to display all defined objects in the window. The smallest region that encompasses all objects (i.e., nodes, elements, flux sections, sketch objects, etc.) is calculated, and this region is displayed in the window. Zoom Control This control shows the current size at which the drawing is displayed. When you push one of the other buttons on the Zoom toolbar, this control shows the new drawing display size. You also can use this control to specify any other display size. For example, to show the drawing at its specified scale, click on the down-arrow and select 100%; to show the drawing at 175%, type 175 in the Zoom

GEO-SLOPE Office 5 91 control edit box and press the Enter key. The Set Zoom command can also be used to change the drawing display size. For more information, see Set Zoom in this chapter.

The File Menu The File menu commands are: ·

New Initializes DEFINE for a new problem. For more information about this command, see File New in this chapter.

·

Open Opens and reads an existing DEFINE data file. For more information about this command, see File Open in this chapter.

·

Import: Data File Imports data from a SEEP/W, SIGMA/W, TEMP/W, or PC-SEEP file. For more information about this command, see File Import: Data File in this chapter.

·

Import: Picture Imports a bitmap or metafile into the current drawing. For more information about this command, see File Import: Picture in this chapter.

·

Export Saves drawing in a format suitable for exporting to other programs. For more information about this command, see File Export in this chapter.

·

Save Saves the current problem definition. File Save writes the current problem definition to the data file name displayed in the DEFINE window title bar. If the current problem definition is untitled, the File Save As dialog box appears.

·

Save As Saves the current problem definition to an alternate data file. For more information about this command, see File Save As in this chapter.

·

Save Default Settings Saves current settings as default settings. For more information about this command, see File Save Default Settings in this chapter.

·

Print Prints the drawing. For more information about this command, see File Print in this chapter.

·

Print Selected Prints a selection portion of the drawing. For more information about this command, see File Print Selected in this chapter.

·

Most Recently Used File Allows quick opening of one of the last six files opened. Selecting a file from the list is a convenient method for opening a recently used file.

·

Exit File Exit quits DEFINE but does not quit Windows. You are prompted to save the current problem definition if any changes have been made.

File New Initializes DEFINE for a new problem. The File New command clears any existing problem definition data and initializes DEFINE for a new problem. You can initialize your new problem using DEFINE’s default settings or the default settings that you have saved with the File Save Default Settings command. Alternatively, you can use an old problem as a template for your new problem; all nodes, elements, material properties, and other settings in the old problem will be used as a default "template" for your new problem.

92 SEEP/W Ø

To create a new problem: 1. Choose New from the File menu. The following dialog box appears:

2. To create a new problem using the default settings that you have saved with File Save Default Settings, select User-Defined Default Settings in the list box. 3. To create a new problem using DEFINE’s default settings, select SEEP/W DEFINE Original Settings in the list box. 4. To create a new problem using an old problem as a template, select one of the filenames in the list box. If no file names are listed or if you wish to use a different file name as a template, select the Template button. The following dialog box appears:

Select the file name to use as a template, and then select the Open button. The selected file name will be displayed in the File New list box. Note: the files listed in the Choose Template box may appear with .SEP or .SEZ file endings, depending if you saved your files as compressed SEEP/W files or regular SEEP/W files. 5. Select OK in the File New dialog box to create the new problem based on the selected list box option.

File Open Opens and reads an existing DEFINE data file.

GEO-SLOPE Office 5 93 When you choose File Open, the following dialog box appears:

Ø

To open a file: ·

Type a name in the File Name edit box and then press OK. The file name may include a directory and a path. The file name extension must be omitted or entered as SEP or SEZ. -- or --

·

Click on a file name in the list box and then press OK. -- or --

· Ø

Double-click on a file name in the list box.

To change the current directory or drive: ·

Use the Look In box to select the drive and directory.

Use the other controls in the dialog box to navigate to the drive and directory containing the SEEP/W file you wish to open. NOTE: The SEEP/W File Open dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

DEFINE data file types The SEEP/W DEFINE data file begins with an extension of SEP. However, SEEP/W allows you to compress all of your data files for a problem into one "zipped" file with an extension of SEZ. All SEEP/W modules allow you to open either a SEP file or a compressed SEZ file. The compressed SEZ files are PK-ZIP compatible, and can be opened and extracted with third-party data compression programs like WinZip. To create a compressed copy of your data files, use the DEFINE File Save or File Save As commands and select a SEZ file extension.

Files Read by DEFINE Two files are read when a DEFINE data file is opened. One has a file name extension of SEP and the other has an extension of SE2.

94 SEEP/W The SEP file contains the data required for the finite element calculations. It is also read by SOLVE and CONTOUR. The SE2 file contains information relating to the graphical layout of the problem. (e.g. page size and units, engineering units and scale, sketch lines and text, and references to any imported picture files). It is also read by CONTOUR, but it is not required by SOLVE. NOTE: When you open a problem containing imported picture files, SEEP/W checks to see that the picture file names still exist. If a picture file has been moved or renamed, SEEP/W displays the Import Picture dialog box, allowing you to specify a different picture file name in its place. See File Import: Picture or Modify Pictures for more information on importing pictures.

Reading Files Created by Earlier Versions of SEEP/W When you open a data file created by SEEP/W Version 2, a message is displayed which warns that the data file was created by an earlier version of SEEP/W and tells you to check all functions to ensure that they are defined correctly. Because SEEP/W Version 3 and later use a more advanced spline interpolation technique than Version 2, you should use the KeyIn Functions command to view all functions created in SEEP/W Version 2. The spline curve passing through these data points may look different than it did in SEEP/W Version 2. When you open a SEEP/W Version 3 data file and re-sort the problem in SEEP/W Version 4, some of the element numbers may change due to the improved element sorting scheme in Version 4. If you re-sort and then save the problem and wish to analyze it using SOLVE, be sure to specify initial condition files that have been obtained using the re-sorted mesh. Otherwise, the data in the initial condition files may be incompatible with the re-sorted problem mesh. When you open a SEEP/W Version 3 data file, DEFINE does not read in the contributing area for q boundary nodes. In SEEP/W Version 4, the q contributing area is calculated in SOLVE; it is not stored in the SEP data file. See View Edge Boundary Conditions in this chapter for more information on q contributing area calculations.

File Import: Data File Imports data from a SEEP/W, SIGMA/W, TEMP/W, or PC-SEEP file. SEEP/W is integrated with other GEO-SLOPE finite element Windows products. With the File Import command, you can import the node and element data from a SEEP/W seepage analysis, a SIGMA/W stress analysis, or a TEMP/W geothermal analysis. This allows you to define a problem that is based on a previously defined mesh. You can also use the File Import command to import a data file created by PC-SEEP. PC-SEEP is a textbased seepage analysis program for the MS-DOS operating system. Information can be imported from PC SEEP Version 4 files. The procedures for importing a file are the same as for the DEFINE File Open command. Specify the file name to import and select OK. The data file type to import can be selected from the Files of Type dropdown list box in the Import dialog box. When you import a data file, SEEP/W clears all data from DEFINE and then reads the specified file. A material is created for each element material number. You must define the material properties for each material type. NOTE: The SEEP/W File Import dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

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Importing PC-SEEP Files When importing a PC-SEEP data file, SEEP/W reads as much of the PC SEEP information as possible. However, due to the differences between the two software packages, SEEP/W cannot interpret the PC SEEP flux sections, soil properties, nodal flux boundary conditions, and review boundary conditions. After you have imported a PC SEEP file, you should define the parameters not read from the PC SEEP file and check that the remaining parameters are defined correctly. Both SEEP/W and PC SEEP data files have an extension of SEP. When PC-SEEP Files (*.sep) is selected from the Files of Type drop-down list box, all data files with an extension of SEP are listed; therefore, some SEEP/W files may be listed as well. An error message is displayed if you try and import a SEEP/W data file. When a PC SEEP data file is imported, SEEP/W sets the engineering scale and problem extents so that the mesh will fit onto the default page size. To select the appropriate engineering units, SEEP/W compares the unit weight of water with the default values for the various units. Choose Set Scale and Set Page if you wish to modify any of these parameters.

File Import: Picture Imports a bitmap or metafile into the current drawing. File Import Picture allows you to place a bitmap or metafile picture on your drawing. For example, if you have a cross-section already defined in another Windows CAD or drawing program, you can save it as a WMF or EMF metafile, import it into SEEP/W, and use your previously-defined cross-section as a background for drawing your SEEP/W geometry. You also can use the File Import Picture command for inserting a company logo, photograph, or any other image into your SEEP/W drawing. Ø

To import a picture into the drawing: 1. Choose Import: Picture from the File menu. The following dialog box appears:

NOTE: The SEEP/W Import Picture dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

96 SEEP/W 2. In the Files of Type drop-down list box, select the file format of the picture to import. You can import AutoCad files (.DXF), Windows bitmaps (.BMP), Windows 3.1 metafiles (.WMF), or Windows 95/NT metafiles (.EMF). 3. Specify the file name to import and select Open. The Import Picture dialog box disappears, the cursor changes from an arrow to a cross-hair, and the status bar indicates that “Import Picture” is the current operating mode. 4. Move the cursor to the position on the drawing where you wish to place the imported picture, and click the left mouse button. The picture is placed on the drawing such that the bottom-left corner is aligned with the cursor position. The picture is placed on the drawing such that the bottom-left corner is aligned with the cursor position. 5. Choose the Modify Objects command if you wish to change the size or position of the imported picture. 6. Choose the Modify Pictures command if you wish to change the picture ordering, to remove the picture, to change the file name that the picture is referenced to, or to scale the picture to match the current engineering scale. NOTE: When you save your problem, SEEP/W stores the file name that the picture is referenced to, rather than a copy of the imported picture. Therefore, if you later move or rename the picture file that you have just imported, you will have to re-establish the link to the new picture file the next time you open the problem in SEEP/W.

Comments You can import the following 4 file formats into SEEP/W: 1. The DXF format, used by AutoCAD and many other engineering software products. 2. The bitmap (BMP) format, a common raster-based graphics format. If you have images from web sites in JPEG or GIF format, you can use an image editor to convert them to the bitmap format and then import them into SEEP/W. Bitmap files can potentially be quite large in size. 3. The Enhanced Metafile (EMF) format. The EMF format is a common Windows vector format that many Windows applications use for transferring graphical data. 4. The Windows Metafile (WMF) format. The WMF format is an older metafile format that was originally developed for use in Windows 3.1. It retains less information about the drawing than the EMF format.

To transfer your current SEEP/W drawing into other Windows applications, see the File Export or Edit Copy All commands. NOTE: The File Import Picture command cannot be used to import problem geometry from another GEO SLOPE application. Imported picture (i.e., WMF and EMF) files do not contain any soil line or property information; they are only useful for display purposes. To import a mesh from a GEO-SLOPE finite element application, choose the File Import: Data File command.

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File Export Saves drawing in a DXF, bitmap, or metafile format for exporting to other programs. File Export saves your drawing in a format that can be read by other programs. This feature allows you to include your drawing in reports and presentations and to enhance your drawing using other drawing or CAD software packages. The drawing can be exported in one of 4 formats: 1. The DXF format, used by AutoCAD and many other engineering software products. 2. The bitmap (BMP) format, a common raster-based graphics format that copies the drawing's screen "pixels" to a data file. The bitmap format is useful for creating images that can be converted to JPG or GIF files and used in web sites. Bitmap files can potentially be quite large, depending on the number of pixels that you specify. 3. The Enhanced Metafile (EMF) format. The EMF format is a common Windows vector format that many Windows applications use for transferring graphical data. 4. The Windows Metafile (WMF) format. The WMF format is an older metafile format that was originally developed for use in Windows 3.1. It retains less information about the drawing than the EMF format. The exported file formats contain a graphical representation of your drawing only; SEEP/W information (e.g., nodes, elements, and material properties) is not stored in the exported data files. Ø

To export the drawing: 1. Choose File Export from the DEFINE menu. The following dialog box appears:

2. In the Save as Type drop-down list box, select the file format in which to save the drawing. 3. If you wish to select a region of the drawing to export, check the Select Area check box. 4. Type the name you wish to give the exported file, including extension, and select the directory in which to save the file.

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5. Click OK. If the file name already exists, you may elect to over-write the existing file. If the Select Area check box is checked, then the cursor changes from an arrow to a cross-hair and the status bar indicates that the “Select Export Area” is the current mode; the area can now be selected. If the Select Area check box is cleared, then the entire drawing is exported to the specified file and a beep is sounded when the file export operation is completed. 6. The area of the drawing to export is defined by dragging a rectangle around the area. Move the cursor to the top-left corner of the area. Push the left mouse button down, but do not release it. Now move the mouse to the right, and a rectangle appears. "Drag" the mouse until the rectangle encompasses the area to export. 7. Release the left mouse button. A beep is sounded when the file export operation is completed.

Comments The File Export, Edit Copy All, and Copy Selection Button commands can all be used to transfer your drawing to another application. The command you use will depend on the import capabilities of the other Windows application. If you have imported any metafile pictures (using the File Import: Picture command), you should export your drawing using the EMF format, not the WMF format. Since the WMF format is incapable of storing embedded metafile pictures, you will not be able to see your imported pictures in an exported WMF file. NOTE: The File Export command cannot be used to transfer your problem data into another SEEP/W problem. WMF and EMF files do not contain any node or element information - only drawing primitives such as rectangles and lines. See the File New command for information on creating a new SEEP/W problem based on a previously-defined problem.

File Save As Saves the current problem definition to an alternate data file. File Save As allows you to save the problem definition to an alternate file if you do not wish to modify the current file. The file name extension must either be omitted or must be SEP. You can also compress the entire problem into one data file by selecting a SEZ file extension. All data files created by SOLVE and CONTOUR will also be inserted into this compressed file, eliminating the hundreds of data files that are sometimes created for an analysis. Ø

To save the drawing to an alternate data file: 1. Choose File Save As from the DEFINE menu. The following dialog box appears:

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2. Select one of the file types in the Save As Type drop-down box. A Compressed File format (.SEZ) will insert all data files for the problem into a compressed file with the same name. For example, if you save Problem.sep as Problem.sez, all Problem data files will be inserted into Problem.sez and then removed from the folder. You can choose to exclude the solution files if you wish to make a copy of your problem definition; this will significantly reduce the size of the compressed file. 3. Type the name you wish to give the file and select the directory in which to save the file. 4. Select OK. If the file name already exists, you may elect to over-write the existing file. NOTE: The SEEP/W File Save As dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

File Print Prints the drawing.

100 SEEP/W When you choose File Print, the following dialog box appears:

Printer The printer group box contains controls for selecting the printer and changing its properties. Use the Name combo box to select the printer and use the Properties button to set printer settings. Check the Print to File checkbox if you wish to sent the print job to a file for printing later. For more information about printer settings, see your Windows documentation. Zoom Percentage This group box defines the size at which to print the drawing and displays the number of pages required for printing. The size can be set to any percentage. The default size is equal to the currently displayed drawing size. When the Default button is pressed, the size is set to the default value. When the Fit to Page button is pressed, the size is changed so that the drawing will fill one entire printed page. Print Area This is the area of the drawing that you wish to print. The edit boxes define the lower-left and upper-right corners of the rectangular area to print. When you select All to print the entire drawing, the coordinates of the lower-left and upper-right corners of the drawing are copied into the edit boxes. When you select Window to print only the portion of the drawing being displayed in the DEFINE window, the coordinates of the corners of the window are copied into the edit boxes. Ø

To print the drawing: 1. Specify the area of the drawing to print in the Print Area group box. §

To print the entire drawing, select the All button.

§

To print only the portion of the drawing being displayed in the DEFINE window, select the Window button.

§

To print any other rectangular portion of the drawing, type the coordinates of the lower-left and upper-right corners of the region in the edit boxes. The Custom button is selected.

When the area to print is selected, the Print Information group box is updated with the number of pages required to print. 2. Specify the size at which to print. Press the Fit to Page button if the area to print is to be fit on one

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page. Otherwise, the area to print will be printed at the specified size on as many pages as necessary. When the Fit to Page button is pressed, the value in the Custom edit box is changed so that the drawing will fill one entire printed page, and the number of pages printed is set to 1. 3. Select OK. DEFINE begins to send the drawing to the printer. 4. Select Cancel if you wish to abort the printing.

Comments You can print the drawing at the exact engineering scale by printing at a size of 100%. Printing jobs can be canceled from Windows. For more information on canceling print jobs, see your Windows documentation. Only the objects currently displayed on the drawing are printed. The drawing is printed in the center of the printer page. The quickest way to specify a region to print is to select the Print Selection button from the Standard toolbar and drag a rectangle over the desired region. Typing the region coordinates in the Print Area edit boxes is useful if you already know the coordinate values. Changing printer settings can help to resolve printing problems. For example, HP LaserJet 4 Series printers may not print rotated TrueType fonts at the correct angle or position. This problem can be overcome by sending the TrueType fonts directly to the printer instead of allowing the printer to rasterize the fonts. In the Printer Setup dialog box, select the Options button, change the Graphics Mode to Raster, and send the TrueType fonts as graphics.

File Print Selected Prints a selected portion of the drawing. The File Print Selected command in CONTOUR operates the same as the File Print Selected command in DEFINE. Ø

To print a selected area of the drawing: 1. Choose the File Print Selected command. The cursor changes to a cross-hair and the status bar indicates that Print Selection is the current mode. 2. The area of the drawing to copy is defined by dragging a rectangle around the region. Move the cursor to the top-left corner of the region. Push the left mouse button down, but do not release it. Now move the mouse to the right, and a rectangle appears. Drag the mouse until the rectangle encompasses the region to copy. The following dialog box appears:

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For more information about the Print dialog box, see File Print in this chapter. 3. Click OK to send the selected area to the printer.

File Save Default Settings Saves the current settings as the defaults. This command allows you to save your current settings so that they can be used again when you define new problems. When you choose this command, the following settings are stored in the Windows registry: ·

Working page units

·

Engineering units

·

View preferences

·

Axis size and options

·

Grid spacing and options

·

Default colors used when specifying material colors

When you choose the File New command, you can initialize the new problem with your default settings or with DEFINE’s built-in default settings. For more information about initializing new problems, see File New in this chapter. NOTE: When you open a problem using File Open, the default settings are replaced by the settings stored in the problem data files.

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The Edit Menu The Edit menu commands are: ·

Undo Allows you to undo the previous action. For more information about this command, see Edit Undo in this chapter.

·

Redo Allows you to redo an action that was previously undone. For more information about this command, see Edit Redo in this chapter.

·

Copy All Copies the entire drawing to the Windows Clipboard. For more information about this command, see Copy All in this chapter.

·

Copy Selected Copies a portion of the drawing to the Windows Clipboard. For more information about this command, see Copy Selection in this chapter.

·

Edit Undo SEEPW maintains a list of each action that you have done in DEFINE. You can then undo each action in sequence to return to a previous problem state. You can also redo each action using the Edit Redo command. To specify the number of actions that you can undo or redo, choose the Tools Options command.

Edit Redo SEEP/W maintains a list of each action that you have done in DEFINE. The Redo command allows you to redo any action that you have undone using the Edit Undo command. To specify the number of actions that you can undo or redo, choose the Tools Options command.

Edit Copy All Copies the entire drawing to the Windows Clipboard. The Windows Clipboard provides temporary storage for information that you want to transfer between applications. The Edit Copy All command copies the entire drawing to the Clipboard for pasting into other applications. This is useful for preparing reports, slide presentations, or for adding further enhancements to the drawing. See your Windows documentation for further information on the Clipboard. To copy the entire drawing to the Clipboard, choose the Edit Copy All command from either the DEFINE menu or from the Standard toolbar. A beep is sounded when the drawing has been copied to the Clipboard.

Comments To display the contents of the Clipboard, run the Clipboard Viewer program from Windows. For more information on the Clipboard Viewer, see your Windows documentation. The Edit Copy All, Copy Selection Button button and the File Export command can all be used to transfer your drawing to another Windows application. The command you use will depend on the import capabilities of the other application.

104 SEEP/W You can also enhance your drawing by importing pictures into your drawing, rather than exporting your drawing to another Windows application for enhancement. See the File Import: Picture command for more information. NOTE: The Edit Copy All command cannot be used to transfer your problem data into another SEEP/W problem. The Clipboard memory does not contain any node or element information - only drawing primitives such as rectangles and lines. See the File New command for information on creating a new SEEP/W problem based on a previously-defined problem.

Copy Selection Use the Copy Selected command to copy a selected area of the drawing to the Windows Clipboard. For information about the Windows Clipboard, see your Microsoft Windows documentation. Ø

To copy a selected area of the drawing to the Clipboard: 1. Select Copy Selected from the Edit menu. The cursor changes to a cross-hair and the status bar indicates that Copy Selection is the current mode. 2. The area of the drawing to copy is defined by dragging a rectangle around the region. Move the cursor to the top-left corner of the region. Push the left mouse button down, but do not release it. Now move the mouse to the right, and a rectangle appears. Drag the mouse until the rectangle encompasses the region to copy. 3. Release the left mouse button. A beep is sounded when the selected region has been copied to the clipboard. The Copy button returns to its normal state.

The Set Menu The Set menu commands are: ·

Page Sets the size of the working area. For more information about this command, see Set Page in this chapter.

·

Scale Sets the engineering scale, units, and unit weight of water. For more information about this command, see Set Scale in this chapter.

·

Grid Creates a grid of points to assist in drawing objects. For more information about this command, see Set Grid in this chapter.

·

Zoom Increases or decreases the size at which the drawing is displayed. For more information about this command, see Set Zoom in this chapter.

·

Axes Defines scaled reference lines. For more information about this command, see Set Axes in this chapter.

Set Page Sets the size of the working area.

GEO-SLOPE Office 5 105 When you choose Set Page, the following dialog box appears:

Printer Page This group box displays the paper size used by the installed printer device. The paper size depends on the printer driver installed and on the printer setup configuration (see File Print to change the printer settings). These dimensions are displayed in the Printer Page group window to provide a guide for setting the working area. Working Area The working area represents the page size available for defining a problem. The printer page size is the size of a drawing that can be printed on one page with the installed printing device. If the working page is larger in height or width than the printer page, more than one sheet of paper is required to print the drawing at 100%. However, the drawing can be printed at a smaller size in order to fit on one page. Ø

To set the working area size: 1. Select the desired page units. 2. Type the desired width and height in the Width and Height edit boxes. Figure 4.6 shows the relationship between the printer page and the working area.

106 SEEP/W Figure 4.6 Definition of Working Area and Printer Page

Comments Choose the Zoom Page button to view the entire working area in the DEFINE window. You should select a working area that allows you to work at a convenient engineering scale. This means that often your working area will need to be larger than the printer page.

Set Scale Sets the engineering scale, units, and unit weight of water. When you choose Set Scale, the following dialog box appears:

Engineering Units The engineering units are the units used to measure the physical dimensions of the problem in the field.

GEO-SLOPE Office 5 107 Scale The scale is a ratio of the distance on a drawing to the actual physical distance in the field. For example, a 1:100 scale means that 1 unit on paper represents 100 units in the field. It could mean that 1 foot equals 100 feet or 1 meter equals 100 meters. Horz. 1: accepts the ratio of the horizontal drawing dimensions to the horizontal physical dimensions, and Vert. 1: accepts the ratio of the vertical drawing dimensions to the vertical physical dimensions. The scale ratio is not affected by the engineering units selected. When the scale is changed, the problem extents are also changed to reflect the new engineering dimensions. Problem Extents The problem extents define the engineering dimensions of your problem. All nodes, elements, and other problem data must be contained within the problem extents. The problem extents are increased whenever you increase the scale or the size of the working area. As you enter new values for the problem extents, the engineering scale is adjusted. This allows you to find an appropriate scale for the selected working area. When you enter the boundaries of your engineering problem in the Problem Extents edit boxes, the scale will be adjusted automatically. You can then adjust the scale to an even number of units. If the scale is too small, you may have to increase the size of the working area with the Set Page command. Lock Scales In Version 5 you have the option to lock the user input scale. This will allow only the "y" extents to change in the event the user changes the "x" extents (and visa versa for scaling the "x" extents when the "y" value is changed). NOTE: Do not specify the minimum problem extents as large values. Using a large starting x- or ycoordinate may affect the precision of the computed results due to round-off error. For example, it is better to specify the y-extents from 0 to 20 instead of from 7000 to 7020. For more information about round-off error, see Mesh Design in Chapter 7. Ø

To set the scale if the engineering scale is known: 1. Select the engineering units. 2. Type the minimum engineering coordinates in the Minimum-x and Minimum-y edit boxes. The Horz. and Vert. Scale values change to reflect the new engineering dimensions of the problem. 3. Type the scale ratio in the Horz. 1: and Vert. 1: edit boxes. The Maximum-x and Maximum-y values change to reflect the new engineering scale. 4. Select OK.

Ø

To set the scale if the extents are known: 1. Select the engineering units. 2. Type the minimum engineering coordinates in the Minimum-x and Minimum-y edit boxes. The Horz. and Vert. Scale values change to reflect the new engineering dimensions of the page. 3. Type the maximum engineering coordinates in the Maximum-x and Maximum-y edit boxes. The Horz. and Vert. Scale values change to reflect the new engineering dimensions of the page. 4. If necessary, adjust the scale ratios in the Horz. 1: and Vert. 1: edit boxes to be in even units (e.g., if the Horz. Scale is 1:201.92 and the Vert. Scale is 1:214.27, you might set both scale ratios to be 1:200).

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The Maximum-x and Maximum-y values change to reflect the new engineering scale. 5. Select OK. Unit Weight of Water The Unit Weight of Water must be specified for the purpose of converting pressure into head and vice versa. The units must be consistent with the units you selected for pressure and length. Table 4.1 gives examples and default values. Table 4.1 Default Values for Unit Weight of Water Water Pressure kN/m2 (kPa)

Length

Water Weight Units

Default Value

m

kN/m3

9.807

N/mm

mm

N/mm

9.807 ´ 10-6

lbs/ft2 (psf)

feet

lbs/ft3

62.4

lbs/in2 (psi)

inches

lbs/in3

0.03611

2

3

The default value is placed in the Unit Weight of Water edit box when you select the engineering units. This value may be changed by typing the appropriate value in the Unit Weight of Water edit box.

Set Grid Creates a grid of points to assist in drawing objects. When you choose Set Grid, the following dialog box appears:

The grid is a pattern of dots which can be displayed to assist you in drawing objects (e.g. nodes, elements, text, lines, etc.). When drawing an object, you can "snap" the object to the nearest grid point. This enables you to draw objects at precise coordinates. Ø

To display and snap to the grid: 1. Check the Display Grid check box. 2. Check the Snap to Grid check box. 3. Type the grid spacing in engineering units in the X and Y edit boxes. 4. Select OK. Grid Spacing (Eng. Units) The X and Y values represent the distance between each grid point in the horizontal and vertical directions respectively. When a value is entered, the other value is recalculated so

GEO-SLOPE Office 5 109 that the grid is evenly spaced. Actual Grid Spacing Displays the actual distance between each grid point in the DEFINE window. This assists you in selecting an appropriate grid spacing in engineering units. This distance is displayed in either millimeters or inches, depending on which system of units was chosen for the working page size. Display Grid Turns on and off the display of the grid on the drawing. Snap to Grid Turns on and off the capability to snap to the grid when defining objects. NOTE: Once you have used Set Grid to define your background grid, you will probably find the Grid toolbar to be a more convenient way of modifying the grid spacing and turning the grid on and off.

Comments To quickly enable or disable snapping to the background grid, click on the Snap Grid button in the Grid toolbar instead of choosing Set Grid. The Set Grid command is primarily used to change the spacing of the background grid. DEFINE will always display the grid when Snap To Grid is on. Snap To Grid cannot be on if Display Grid is off. If grid snapping is on, the cursor position displayed in the status bar reflects the position of the nearest grid point, not the actual cursor position. This allows you to see the position the cursor will snap to when you are drawing objects. Displaying the grid may require significant computing and drawing time when the points are closely spaced. You can reduce the drawing display time by turning off the grid. If the actual grid spacing is too small, the grid points will not be displayed. However, DEFINE will still snap to the grid when you draw objects.

Set Zoom Increases or decreases the size at which the drawing is displayed. When you choose Set Zoom, the following dialog box appears:

Choosing Set Zoom allows you to increase or decrease the size at which the drawing is displayed and printed. Clicking on 100% displays the drawing at its original size; clicking on a different percentage changes the drawing size to the specified percentage. The drawing can be displayed at any size by typing the desired percentage in the Specified edit box. The percentage must be a positive number greater than zero. The maximum percentage allowed is a function of the working page size, units, and scale; also, Windows NT allows you to specify a much larger zoom percentage than Windows 95. If you specify a zoom percentage that is too large, an error message will appear.

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Comments The simplest way to change the drawing display size is to use the Zoom toolbar. You may wish to use the Set Zoom command if the Zoom toolbar is not displayed. Node symbols are limited in size to 200%. For example, when the rest of the drawing is displayed at 500%, node symbols are displayed at 200%. This feature makes it possible to see the nodes when they overlap at smaller sizes.

Set Axes Defines scaled reference lines. Scaled and labeled reference axes can be generated at any suitable place on the drawing. Ø

To generate reference axes: 1. Choose Set Axes from the DEFINE menu. The following dialog box appears:

2. In the Display group box, check the sides of the axis you wish to display. For example, if you check Left Axis, Right Axis, Top Axis, and Bottom Axis, a rectangular axis is generated with tick marks on all four sides. Any combination of the four axes may be checked. Axes which are unchecked will not be drawn. 3. Check the Axis Numbers check box if you wish to number the axis tick marks. 4. Type a suitable title for the bottom and left sides of the axes in the Bottom X and Left Y edit boxes, respectively. 5. Select OK. The Axes dialog box appears.

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6. Type the appropriate values in the X-Axis and Y-Axis group boxes. §

Min Contains the minimum value displayed on the axis.

§

Increment Size Controls the spacing of the tick marks along the axis.

§

# of Increments Controls the length of the axis.

§

Max This is the highest value on the axis. It is displayed to provide a guide to selecting the increment size and number of increments along the axis.

7. Select OK. An axis is generated on the drawing. NOTE: Axes can be moved and resized with the Modify Objects command.

Comments Only one set of axes can be defined on a drawing. The View Preferences command allows you to change the font and the size of the axes numbers and labels. The axes can also be generated with the Sketch Axes command. You may find it convenient to first sketch the axes at an approximate location and size, and then choose Set Axes to refine the controlling parameters. Alternatively, you can move and resize the axes with the Modify Objects command once the axes are defined.

The View Menu The View menu commands are: ·

Node Information Displays information about the selected node. For more information about this command, see View Node Information in this chapter.

·

Element Information Displays information about the selected element. For more information about this command, see View Element Information in this chapter.

·

Edge Information Displays information about the selected element edge. For more information about this command, see View Edge Information in this chapter.

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·

Node Boundary Conditions Displays information regarding nodal head and flux boundary conditions. For more information about this command, see View Node Boundary Conditions in this chapter.

·

Edge Boundary Conditions Displays information regarding unit flux boundary conditions at edges of elements. For more information about this command, see View Edge Boundary Conditions in this chapter.

·

Preferences Identifies which items will be displayed on the drawing. For more information about this command, see View Preferences in this chapter.

·

Toolbars Displays or hides the DEFINE toolbars and the status bar. For more information about this command, see View Toolbars in this chapter.

·

Redraw Redraws the problem. For more information about this command, see View Redraw in this chapter.

View Node Information Displays information about the selected node. Ø

To view information defined at a node: 1. Choose the View Node Information command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "View Node Information" is the current mode. 2. Move the cursor near the desired node and click the left mouse button. The node is selected and the following dialog box is displayed, containing the node information:

The dialog box lists the nodal x, y, and z coordinates, as well as the boundary type (head, flux, or nodal flux), action value, function number, modifier function number, and review condition. The concentration at the node is only displayed if the current problem is a CTRAN/W density-dependent analysis. 3. To see all the node information, re-size the dialog box by dragging the bottom edge of the window down until all information is displayed. 4. Repeat Step 2 for every node that you wish to view. 5. To copy the node information to the Windows Clipboard, select Copy. The node information is copied

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to the Clipboard in the following text format: Node 15 X-Coordinate 8.0000e+000 Y-Coordinate 4.0000e+000 Z-Coordinate 0.0000e+000 Boundary Type H Boundary Action 1.1000e+001 Boundary Fn.#0 Boundary Mod. Fn.#0 Boundary Review by (none) 6. To print the node information on the current printer, select Print. The node information is printed in the same format as for copying to the Clipboard. 7. Select Done to finish viewing node information.

Comments To manually edit the node coordinates, choose KeyIn Nodes. To delete or move nodes, choose Modify Objects. To change the node boundary conditions, choose Draw Boundary Conditions. For information about displaying element or material information, see View Element Information in this chapter. For information about displaying edge information, see View Edge Information in this chapter.

View Element Information Displays information about the selected element. Ø

To view information defined at an element: 1. Choose the View Element Information command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "View Element Information" is the current mode. 2. Move the cursor inside the desired element and click the left mouse button. The element is selected and the following dialog box is displayed, containing the element information:

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The dialog box lists the primary and secondary nodes in the element, the element material properties (material number, Conductivity function number, Vol. Water Content function number, and the conductivity ratio and direction), the element integration order, element thickness, and the direction of x- and y-infinity within the element. 3. To see all the node information, re-size the dialog box by dragging the bottom edge of the window down until all information is displayed. 4. Repeat Step 2 for every element that you wish to view. 5. To copy the element information to the Windows Clipboard, select Copy. The element information is copied to the Clipboard in the following text format: Element 32 Primary Nodes 76, 78, 60, 58 Secondary Nodes 77, 65, 59, 64 Material #2 Conductivity Fn.#2 Vol. Water Content Fn.#0 Conductivity Ratio 1.0000e+000 Conductivity Direction 0.0000e+000 Integration Order 9 Thickness 1.0000e-001 X-Infinity Direction (none) Y-Infinity Direction (none) 6. To print the element information on the current printer, select Print. The element information is printed in the same format as for copying to the Clipboard. 7. Select Done to finish viewing element information.

Comments To change the primary and secondary nodes in the element, the element material number, the element integration order, or the element thickness, choose Draw Element Properties or KeyIn Elements. (You can also delete elements using the Modify Objects command and then regenerate them using Draw Single Elements or Draw Multiple Elements). To change the material associated with the element, use the Draw Element Properties command. To change the material properties of the element material number, use the KeyIn Material Properties command.

GEO-SLOPE Office 5 115 For information about displaying node information, see View Node Information in this chapter. For information about displaying edge information, see View Edge Information in this chapter.

View Edge Information Displays information about the selected element edge. Ø

To view information defined along an element edge: 1. Choose the View Edge Information command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "View Edge Information" is the current mode. 2. Move the cursor over an element edge and click the left mouse button. The side of the element is selected and the following dialog box is displayed, containing the element edge information:

The dialog box lists the nodes contained in the edge, the adjacent elements, and the q boundary conditions, if any, defined along the selected edge. 3. To see all the node information, re-size the dialog box by dragging the bottom edge of the window down until all information is displayed. 4. Repeat Step 2 for every element edge that you wish to view. 5. To copy the edge information to the Windows Clipboard, select Copy. The edge information is copied to the Clipboard in the following text format: Component Edge Nodes 3, 5 and 10 Adjacent Elements 3 Boundary Type (none) Boundary Action 0.0000e+000 Boundary Fn.#0 Modifier Fn.#0 6. To print the edge information on the current printer, select Print. The edge information is printed in the same format as for copying to the Clipboard. 7. Select Done to finish viewing edge information.

Comments To define q boundary conditions along an element edge, use the Draw Boundary Conditions command.

116 SEEP/W See View Edge Boundary Conditions for information on viewing a list of all q boundary conditions defined in the problem. For information about displaying node information, see View Node Information. For information about displaying element or material information, see View Element Information.

View Node Boundary Conditions Displays information regarding nodal head and flux boundary conditions. When you choose View Node Boundary Conditions, the following dialog box appears:

# The node number. Boundary Type The type of action at the boundary node. The types of action are: §

(none)

§

H (total head)

§

Q (total nodal flux)

§

q (unit nodal flux)

Action The magnitude of the head or flux that acts at the boundary node. Boundary Fn. # The number of a boundary function which the node will follow. Mod. Fn. # The number of a modifier function that modifies the boundary function parameters. Review Boundary The method of adjusting a flux boundary condition to a head boundary in response to computed results.

Comments Boundary conditions are defined using the Draw Boundary Conditions command. To view the boundary conditions at any node, use the View Node Information command. The head must be specified as total head; that is, pressure head plus elevation.

GEO-SLOPE Office 5 117 In the case of a density-dependent problem, the specified concentration of each head boundary condition is also presented. This concentration together with the specified head boundary condition is used by SOLVE to compute an equivalent freshwater head boundary condition. Unit nodal flux (q) boundary conditions can only be defined at nodes when doing a plan view analysis. For axisymmetric and 2-dimensional analyses, q boundary conditions are defined along element edges. See View Edge Boundary Conditions for information on viewing q boundary conditions along an element edge A boundary function can be specified only for a transient analysis. If you are doing a transient analysis and you specify a non-zero boundary function number, then the action and boundary type are obtained from the function definition. If the function number is zero, the action and boundary type given in the dialog box are used. When a flux boundary is reviewed, the solver determines if there is a net inflow or net outflow. If there is a net outward flux, this represents a seepage face. The node boundary condition is then modified which consists of setting the Action to the value of the y-coordinate and setting the type to head (H). This has the effect of setting the water pressure to zero.

View Edge Boundary Conditions Displays information regarding unit flux boundary conditions at edges of elements. Unit nodal flux, (q), boundary conditions are defined along an element edge for axisymmetric and 2 dimensional analyses. All other boundary conditions are defined at nodes. See View Node Boundary Conditions for information about viewing nodal boundary conditions. When you choose View Edge Boundary Conditions, the following dialog box appears:

Nodes 1 and 2 The two node numbers that define the edge. Elements 1 and 2 The two element numbers that contain the edge. If Element 2 is zero, then the edge belongs only to Element 1. Action The magnitude of the flux boundary condition specified along the edge. Boundary Fn. # The boundary function number used by the edge boundary condition. Mod. Fn. # The modifier function number that modifies the boundary function parameters over time.

Comments Boundary conditions can be set using the Draw Boundary Conditions command. For more information

118 SEEP/W about this command, see Draw Boundary Conditions in this chapter. A boundary function can be specified only for a transient analysis. If you are doing a transient analysis and you specify a non-zero boundary function number, then the action and boundary type are obtained from the function definition. If the function number is zero, the action and boundary type given in the dialog box are used. An edge or unit flux boundary condition is converted to a total nodal flux at the nodes that define the edge. The total nodal flux is computed by multiplying the unit flux value for the edge times the contributing area. The contributing area depends on the element type, edge length and element thickness, as shown in Figures 4.7 and 4.8. The contributing area and total nodal flux calculations are performed in SOLVE. Note that in the case of a plan view analysis, a unit nodal flux boundary (q) is specified at a node rather than at an edge. The contributing area represented by the node is computed by SOLVE based on numerical integration. Figure 4.7 Contributing Areas for Planar Two-Dimensional Elements with Width Equal to 1 Unit

GEO-SLOPE Office 5 119 Figure 4.8 Contributing Areas for Axisymmetric Elements Over 1 Radian

View Preferences Identifies which items will be displayed on the drawing. The View Preferences command allows you to display different types of objects on the drawing at the same time. All object types are displayed by default; however, you can turn off object types that you do not wish to view. This command also can be used to change the default font used for the problem, as well as the font size used for node and element numbers and for the axes. The default font is used for all text in the problem except text items created with Sketch Text.

120 SEEP/W When you choose View Preferences, the following dialog box is displayed:

NOTE: The View Preferences toolbar also provides access to the View Preferences dialog box. The toolbar is usually more convenient to use than the View Preferences menu command, since it also provides a toolbar button for each item type to view. This allows you to change the item types displayed on the drawing while you are using another command, such as Modify Objects. Ø

To select the items to view: ·

In the Items To View group box, check the items that you want displayed on the drawing. Any items that are cleared will remain in the problem definition but will not be displayed.

Nodes Displays nodes as small squares, triangles, or circles, depending on the node boundary condition type. Elements Displays elements. Node or Element Numbers Displays node or element numbers only if the nodes or elements are also displayed. Boundary Conditions Displays boundary conditions. Infinite Symbols Displays a dashed border along infinite element edges. The infinite elements are also filled with a vertical or horizontal hatch pattern, depending on the direction of infinity. Material Boundaries Displays material boundaries as different colors, depending on the material color assigned to the boundary. Material Colors Displays elements as different colors, depending on the material color assigned to the element. Flux Sections Displays flux sections as dashed lines with arrows. Sketch Objects Displays text, lines, circles, and arcs created by the Sketch command.

GEO-SLOPE Office 5 121 Axes Displays the axes. Pictures Displays imported bitmap or metafile pictures. CONTOUR Sketch Objects Displays all sketch objects created in CONTOUR. While these sketch objects can be viewed in DEFINE, you must use CONTOUR to edit or delete them..

Font Sizes Node numbers, element numbers, and axes numbers are displayed at the point sizes listed in the Font Size group box. Ø

To change a font size: ·

Click the down arrow to the right of the Node #, Element #, or Axes edit boxes and select a point size from the list, or type the desired point size in the edit box.

Points are the units commonly used for font size (72 points is equal to 1 inch). The point size that you enter represents the height of the node, element, or axis numbers at a zoom factor of 1.0.

Default Font SEEP/W uses the default font to display node numbers, element numbers, axes numbers, axes labels, and function graph numbers and labels. Ø

To change the default font: 1. Click on the Font button. The following dialog box is displayed:

All the fonts that are currently installed in Windows are displayed in the Font list box. To install or delete fonts, you must use the Windows Control Panel. See the Windows User's Guide for more information on Control Panel. 2. Select the desired font in the Font list box and style in the Font Style list box.

122 SEEP/W 3. Select OK to return to the View Preferences dialog box. The name of the selected font is displayed beside the Font button. NOTE: SEEP/W does not use the default font to display sketch text on the drawing. Therefore, when you select a new default font, all text defined with the Sketch Text command remains unchanged. This is undesirable if you wish to use one font for all text that appears on the drawing. Ø

To change the font for all sketch text to the default font: 1. Select the Convert All Sketch Text Fonts check box. 2. When you select the OK button in the View Preferences dialog box, the program asks if you wish to change all sketch text fonts to the default font. 3. Select Yes to change all sketch text fonts to the default font; select No to exit the View Preferences dialog box without changing the sketch text fonts; or select Cancel to return to the View Preferences dialog box.

Comments Only the items displayed are shown on paper when you print the drawing. This allows you to print any combination of items on your drawing. When you define an item, SEEP/W will check the item in View Preferences if you have not already checked it. For example, if you choose Draw Nodes, SEEP/W will check the Nodes option in View Preferences. This enables you to see the nodes that you define. SEEP/W may take a long time to redisplay the drawing when all items are being drawn. One item that may take a significant amount of time to display is Material Colors. If you find it inconvenient to display the material colors while developing the mesh, do so only after the mesh has been generated. This allows you to visually check that the correct material number has been assigned to each element before solving the problem.

View Toolbars Displays or hides the DEFINE toolbars and the status bar. Use the View Toolbars command to toggle the display of any toolbar, the status bar, or the toolbar tool tips. Ø

To change the toolbar and status bar display: 1. Select the Toolbars command from the View menu or right-click on a toolbar and select Toolbars from the pop-up context menu. The following dialog box appears:

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2. In the Toolbars list box, check the toolbars you wish to display, or uncheck the toolbars you wish to hide by clicking on the check boxes with the left mouse button. Each time you check an item, it appears in the DEFINE window; each time you uncheck an item, it is removed from the DEFINE window. 3. To show or remove the tool tips that are displayed when the mouse is over a toolbar button, check or uncheck the Show ToolTips check box. 4. To show or remove the status bar from the bottom of the DEFINE window, check or uncheck the Status Bar check box. The information displayed in the status bar is described below. 5. To show or remove the Analysis Information pane from the status bar, check or uncheck the Display Analysis Information in Status Bar check box. 6. When finished, click on the Close button. NOTE: You can quickly add or remove a toolbar or status bar by clicking the right mouse button on top of any toolbar or status bar. When the pop-up menu appears, select a toolbar or the status bar from the menu to toggle its display.

Status Bar The status bar contains either three or four panes and is displayed as follows:

Status Information Current status of the program. If the mouse cursor is above a menu item or toolbar button, the purpose of the menu item or toolbar button is displayed. If the program is in a "mode", then the current mode and suggested user action is displayed. The status bar above is shown in the default mode. Analysis View Current analysis view (2-Dimensional, Axisymmetric or Plan). Display of this pane is optional if more room on the status bar is required. For more information about setting the analysis view, see KeyIn Analysis Control in this chapter. Mouse Coordinates Mouse cursor coordinates in engineering units.

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View Redraw Redraws the problem. View Redraw clears the DEFINE window and re-displays the drawing in the window. This is sometimes needed when drawing objects or when you are scrolling, since objects may not be completely drawn in the window.

The KeyIn Menu The KeyIn menu commands are: ·

Analysis Settings Sets the type of analysis. For more information about this command, see KeyIn Analysis Settings in this chapter.

·

Material Properties Sets the material properties. For more information about this command, see KeyIn Material Properties in this chapter.

·

Functions: Conductivity Defines the relationship between pore-water pressure and hydraulic conductivity. For more information about this command, see KeyIn Functions Conductivity in this chapter.

·

Functions: Vol. Water Content Defines the relationship between pore-water pressure and the volumetric water content. For more information about this command, see KeyIn Functions Vol. Water Content in this chapter.

·

Functions: Grain Size Defines a function to modify the Grain Size. For more information about this command, see KeyIn Functions Grain Size in this chapter.

·

Functions: Boundary Defines the variation in boundary conditions as a function of time. For more information about this command, see KeyIn Functions Boundary in this chapter.

·

Functions: Modifier Defines a function to modify the flux boundary conditions in response to the previously computed negative pore-water pressures. For more information about this command, see KeyIn Functions Modifier in this chapter.

·

Nodes Sets the coordinates of finite element nodes. For more information about this command, see KeyIn Nodes in this chapter.

·

Elements Defines the geometry and properties of finite elements. For more information about this command, see KeyIn Elements in this chapter.

·

Flux Sections Identifies sections across which to compute the flow quantity. For more information about this command, see KeyIn Flux Sections in this chapter.

·

Initial Water Table Defines the location of the initial water table. For more information about this command, see KeyIn Initial Water Table in this chapter.

·

Generate Plan View Generates the nodal z-coordinates and element thickness for a plan view analysis. For more information about this command, see KeyIn Generate Plan View in this chapter.

KeyIn Analysis Settings Sets analysis settings such as project identification, analysis type, initial condition files, convergence information, and time step information.

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Project ID Tab: Identifies the problem and displays information about the selected options. When you choose KeyIn Analysis Settings, the following dialog box appears:

The File Header Information group box contains information that is saved as an identifying header in all output files created by SEEP/W SOLVE: Title and Comments Any text may be typed in the Title and Comments edit boxes to identify the problem. The Current Settings list box contains the current data file name, analysis type, and analysis view. To copy the Project ID information to the Windows Clipboard, select Copy. The File Header Information and Current Settings are copied to the Clipboard in the following text format: SEEP/W Learn Problem Seepage through a dam File Name: Dam.sez Last Saved Date: 9/24/2001 Last Saved Time: 10:10:21 AM Analysis Type: Transient Analysis View: 2-D NOTE: To print the Project ID information on the current printer, select Print. The Project ID information is printed in the same format as for copying to the Clipboard.

Comments The Modify Text and Modify Objects commands can be used to modify, move, or delete the Project ID text label created on the drawing.

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Type Tab: Sets the analysis type: Steady State or Transient. When you choose the Type tab from the KeyIn Analysis Settings dialog box, the following dialog box appears:

1. Set the analysis type to Steady-State for a non-time dependent analysis. If you specify this option, you do not need to enter time step information. 2. Set the analysis type to Transient if you intend to apply a fixed or time dependent boundary condition and/or you wish to monitor the change in ground temperatures at different times. You will have to enter time step information if you select this option. 3. A SIGMA/W Consolidation analysis is for a fully coupled SIGMA/W and SEEP/W solution of consolidation problems. This type of analysis requires that you also use SIGMA/W Version 4. The consolidation analysis processing is predominately controlled by SIGMA/W. 4. A CTRAN/W Density-Dependent analysis is for a coupled SEEP/W and CTRAN/W solution of density-dependent contaminant transport problems. This type of analysis requires that you also use CTRAN/W Version 4. The density-dependent analysis processing is predominately controlled by CTRAN/W. If performing a density-dependent analysis, the Density group box will be enabled and values for reference concentration and relative density should be input. For more information about densitydependent analyses, reference concentration and relative density, see Density-Dependent in Chapter 8. Initial Head File If you have a solved temperature file from a previous steady state or transient analysis using the SAME mesh, you can enter that file name here. Starting Time Step If you have a solved temperature file from a transient analysis using the SAME mesh, you can enter the starting time step for the current analysis. This option lets you carry on a previous analysis from some elapsed time step in that previous analysis.

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Control Tab: When you choose the Control tab from the KeyIn Analysis Settings dialog box, the following dialog box appears:

2-Dimensional A two-dimensional view analyzes a vertical cross-section. Axisymmetric An axisymmetric view analyzes a problem that is symmetrical around a vertical axis (e.g., a vertical pipe). The axisymmetric analysis is formulated per unit radian. Flux values need to be multiplied manually by 2· to calculate, for example, the total flux into a well when the element thickness is 1.0. When the element thickness is defined as 2· , the computed flux is the total flux for the entire circumferential area. Plan A plan view analysis is similar to a two-dimensional analysis, except that the analysis plane is horizontal. Choosing a plan view analysis allows you to define unit nodal flux (q) boundary conditions at any node. For axisymmetric and 2-dimensional analyses, q boundary conditions are defined along element edges. For more information, see Draw Boundary Conditions in this chapter.

Convergence Tab: When you choose the Convergence Tab from the Analysis Setting dialog box, the following dialog box appears:

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Max. # of Iterations - Convergence This parameter limits the number of iterations SOLVE will execute in an attempt to obtain a solution. Execution will come to a halt or move onto the next step if the iteration number reaches the maximum specified. Tolerance (%) - Convergence This parameter is the desired percentage difference in the norm of the nodal head vector between two successive iterations. The iteration process stops if the percentage difference is less than the specified tolerance. If the percentage difference is greater than the tolerance, the iteration process continues until it reaches the maximum number of iterations. Max. Conductivity Change This parameter is the maximum change in the log10 of the hydraulic conductivity between two successive iterations. A value of 1 (the default value) means the hydraulic conductivity can change as much as 1 order of magnitude between iterations. A value of 0.5 means the maximum change in hydraulic conductivity between iterations is half an order of magnitude. A value of 0.05 is 0.05 orders of magnitude, and so on. Rate of Conductivity Change This parameter controls the rate at which Max. Change diminishes with each oscillation reversal in the convergence process. A value of 1.1 means, for example, that after the first oscillation reversal, Max. Change is reduced to 0.91 (1.0/1.1). After the next oscillation reversal, Max. Change is reduced to 0.83 (0.91/1.1) and so forth until Max. Change is less than Min. Change. Thereafter, Max. Change is equal to Min. Change. Min. Conductivity Change This parameter puts a lower limit on the value to which Max. Change can diminish. A value of 0.0001 means that change in hydraulic conductivity from one iteration to the next is 0.0001 orders of magnitude. For more information about convergence criteria, see Handling Convergence Difficulties in Chapter 7. For more information about the iteration technique, see Iteration Scheme in Chapter 8. The reduction in the Max. Change parameter with each oscillation reversal can be deactivated by setting the Rate of Change to 1.0. Potential Seepage This parameter puts an upper limit on the number of times a single node can be reviewed for a possible change in flux to head boundary per time step. Max. # of Iterations - Solver This parameter limits the number of iterations the iterative mathematical equation solver will execute in an attempt to obtain a solution to the finite element equation. It is

GEO-SLOPE Office 5 129 different than the iterative technique used to solve the engineering problem described above.. Tolerance (%) - Solver This parameter is the desired percentage difference in heads sought by the equation solver as it solves the global finite element matrices. The solve iterations and tolerances should not be adjusted in most cases as they have been defaulted to values that will work for a wide range of problems.

Time Tab: When you choose the Time Tab from the Analysis Settings dialog box, the following dialog box appears:

SEEP/W solves transient (time dependent) problems by discretizing the time domain into a series of incremental time steps. You must specify the number and size of the time steps. Time increment sequences can be created in three ways:

Ø

·

By generating a time sequence on the basis of the Time Generation parameters.

·

By manually typing each step number and time increment.

·

By generating a time sequence and then manually modifying the sequence to suit specific requirements.

To generate a time sequence: 1. Type the number of increments in the # of Time Steps edit box. 2. Type the starting time in the Starting Time edit box. 3. Type the first increment in the Initial Increment Size edit box. 4. Type the amount by which the time increment should increase with each step in the Expansion Factor

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edit box. 5. If a maximum increment size is required, check the Max Inc. Size checkbox and type the maximum size of the time increment in the Max Inc. Size edit box. 6. If you wish to only save the results for specific time increments, type the first increment to save in the Start Saving at Step edit box, and type the multiples of increments to save in the Save Multiples Of edit box. 7. Select Generate. The time increment sequence is generated in the list box. Time Step 1 has an increment size of 2 and a total elapsed time of 2. Time Step 2 has an increment size equal to the increment for Step 1 multiplied by the expansion factor; that is, 2´2=4. The elapsed time is equal to the elapsed time in Step 1 plus the time increment in Step 2; that is, 2+4=6. Time Step 3 has an increment size of 4´2=8 and an elapsed time of 6+8=14. Time Step 4 has a computed time increment of 8´2=16. However, since 16 is greater than the maximum time increment specified in the Increment Limit edit box, the time increment is set to 10. The remaining time increments in the sequence are also set to 10. Time Step 2 is the first increment that will save the results to files, since the Start Saving at Step edit box is set to 2. Every third increment after Time Step 2 will also be saved, since the Save Multiples Of edit box is set to 3. Ø

To manually define a time sequence: 1. Type the increment number in the edit box at the bottom of the list box # column. 2. Type the time increment in the edit box at the bottom of the list box Increment Size column. 3. Specify whether the results from the time increment should be saved by selecting Yes or No in the Save drop-down list box. 4. Select Copy. The increment number, increment size, computed elapsed time, and save option are copied to the list box. 5. Repeat Steps 1 to 4 for all required time increments.

GEO-SLOPE Office 5 131 The following is an example of a manually created time sequence:

Each time you copy an additional time increment into the list box, the elapsed time sequence is recomputed and updated in the list box. Ø

To edit the time increment list: 1. In the list box, click the time increment you wish to edit. The selected line is highlighted, the Step # and Time Increment are copied into edit boxes, and the Save option is selected in the drop-down list box. 2. Type a new value in the Increment Size edit box. 3. Select Yes or No in the Save drop-down list box. 4. Select Copy. The new time increment value and save option are copied to the list box and the elapsed time sequence is updated.

Ø

To delete a time increment: 1. In the list box, click the time increment you wish to delete. 2. Select Delete. The selected time increment is deleted, the time increment list is compressed to again form a complete numerical sequence, and the elapsed time sequence is updated according to the new time increment sequence. Adaptive time steps (optional) If the user wishes to have the solver determine if extra time steps should be inserted between their defined time steps then they can activate the adaptive time stepping routine by checking the box.

132 SEEP/W The method of controlling the time steps must be selected and the control parameters have to be entered. Details about the adaptive time stepping option are given in the Modeling Guidelines Adaptive Time Stepping section of the on line help.

Comments In SEEP/W versions prior to Version 4, an option was available for specifying a single or double precision analysis. In SEEP/W Version 4 and later, all analyses are performed using double precision.

KeyIn Material Properties Sets the material properties. The characteristics of each finite element in a mesh are identified by a material number and displayed using a material color. KeyIn Material Properties specifies the properties and color of each material. When you choose KeyIn Material Properties, the following dialog box appears:

# The number of each material is displayed in the list box below this heading. K-Fn. The conductivity function number of each material is displayed in the list box below this heading. Each material may be characterized by any one of a series of conductivity functions. For example, Material 2 may be characterized by K-Fn. 5. For a description of the conductivity function, see KeyIn Functions Conductivity in this chapter. NOTE: If the material defined for an element has a conductivity function number of 0 (zero), then the element is not considered in the SOLVE analysis; SOLVE treats the element as if the element does not exist. The purpose of this feature is to allow for the removal of elements or the incremental addition of elements without renumbering the mesh. W.C. Fn. The vol. water content function number of each material is displayed in the list box below this heading. It is a number independent of the material number and conductivity function number. For a description of the volumetric water content function, see KeyIn Functions Vol. Water Content in this chapter.

GEO-SLOPE Office 5 133 K-Ratio The hydraulic conductivity ratio of each material is displayed in the list box below this heading. It is the ratio of the hydraulic conductivity in the y-coordinate direction to the hydraulic conductivity in the x-coordinate direction. In equation form,

(4.1) where Kx is taken from the conductivity function. For example, a K-Ratio of 5 means the hydraulic conductivity in the y-direction is 5 times greater than in the x-direction. A K-Ratio of 1.0 (the default value) means the hydraulic conductivity is the same in the x- and y-directions. A value of 0.1 means the y hydraulic conductivity is 10 times less than the x hydraulic conductivity. The hydraulic conductivity function always defines Kx. K-Direction The hydraulic conductivity direction of each material is displayed in the list box below this heading. It allows you to specify the hydraulic conductivity in a direction other than in the x-y coordinate directions. K Direction is the angle in degrees between the positive x-direction and the x'-direction as illustrated in Figure 4.9. Figure 4.9 Definition of K-Direction

Color The color of each material is displayed in the list box below this heading. Each material is assigned a default color. If the material has no K-Fn defined, then the material color is set to light gray, since it is a null material and will not be considered in the SOLVE analysis. Ø

To define material properties: 1. Type the material number in the # edit box. 2. Select the conductivity function number from the K-Fn # drop-down list box. 3. Select the vol. water content function number from the W.C. Fn # drop-down list box.

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4. Type the hydraulic conductivity ratio in the K-Ratio edit box. 5. Type the hydraulic conductivity direction (in degrees) in the K-Direction edit box. 6. Set the color by pressing the Set button and selecting a basic color or define a custom color. 7. Select Copy. The specified values are copied to the Material Properties list box. Ø

To change the default material color: 1. Select the desired material in the list box. The material properties and color are copied to the appropriate edit boxes. 2. Click on the Set button, located next to the material color edit box. The following dialog is displayed:

3. Click on one of the basic or custom colors in the dialog box, or select the Define Custom Colors button to select a different color. Click on the help button in the top-right corner of the Color dialog box to get context-sensitive help on any control in the dialog box. 4. Once you have chosen a color, select OK in the Color dialog box. The selected color is now displayed in the Material Properties color edit box. 5. Select Copy. The new material color is copied to the Material Properties list box. NOTE: The custom colors that you define in the Colors dialog box are stored in the problem data file when you choose File Save or File Save As and are stored in the Windows registry when you choose File Save Default Settings.

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Comments The material vol. water content function must be defined for a transient analysis. It is not required for a steady-state analysis unless you want to contour the volumetric water content. A null material is automatically created when you choose File New to start defining a new problem. You can use this material by adding a conductivity function to its definition.

KeyIn Functions Conductivity Defines the relationship between pore-water pressure and hydraulic conductivity. A conductivity function defines the relationship between pore-water pressure and hydraulic conductivity. Figure 4.10 shows a typical conductivity function. Figure 4.10 A Conductivity Function

A soil desaturates and the water content decreases when the pore-water pressure becomes negative; the ability of the soil to conduct water decreases as the water content decreases. The soil hydraulic conductivity consequently decreases as the pore-water pressure becomes increasingly negative. A conductivity function is defined by specifying a series of discrete data points and fitting a weighted spline curve to the data points in order to create a continuous function. Conductivity functions can be defined in SEEP/W in any of the following ways: ·

Specify each data point in the function by typing the coordinates or by clicking on the function graph. In Version 5 you can also copy two columns of x and y data from a spreadsheet program and use the right mouse button to paste the two columns of data directly into a function edit box.

·

Estimate the function from an existing volumetric water content function.

·

Import an existing conductivity function from the SEEP/W function database or from another SEEP/W problem and modify it.

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Defining Each Function Data Point Ø

To define each data point in a conductivity function: 1. Choose KeyIn Functions Conductivity. The following dialog box appears:

2. In the Function Number drop-down box, type the function number to define. 3. Select Edit. The following dialog box appears to let you enter the data points in the function:

Steps 4 to 7 define the extremities of the function, allowing you to later use the Graph window to visually define the function points. 4. Enter the minimum x- and y-coordinates by typing 1 in the # edit box, the minimum pressure value in the Pressure edit box, and the minimum hydraulic conductivity in the Conductivity edit box.

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5. Select Copy. The values in the edit boxes are copied into the list box. 6. Enter the maximum x- and y-coordinates by typing 2 in the # edit box, the maximum pressure value in the Pressure edit box, and the maximum hydraulic conductivity in the Conductivity edit box. 7. Select Copy. The values in the edit boxes are copied into the list box. The following list box contains two typical points:

8. Once the function extremities have been entered, select View to display the function graph.

When the View button is pressed, SEEP/W computes a graph scale encompassing the function extremities and a spline function through the data points. The arrows at the end of the data points represent how SEEP/W interprets the function beyond the extremities. 9. Use the buttons in the Graph toolbar to complete the conductivity function definition. The Graph toolbar allows you to add, move, and delete points interactively. You can also adjust the curvature of

138 SEEP/W the spline between data points and the degree to which the spline is fit to the data points. These features are discussed later in this section in more detail. The following graph shows a typical conductivity function:

10. Type an appropriate name for the function in the Description edit box. The function name is helpful when deciding which function to edit or import. 11. Double-click on the control-menu box to close the View window. 12. Select OK. The initial KeyIn Functions dialog box appears. 13. Select Done to exit this command or type a new function number and select OK to define another conductivity function.

Estimating a Conductivity Function Ø

To estimate a conductivity function from an existing volumetric water content function: 1. Repeat Steps 1 to 3 from the previous procedure. 2. Select the Estimate button in the Edit Conductivity Function dialog box. The following dialog box appears:

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3. In the Vol. W.C. Fn. drop-down list box, select the volumetric water content function to use for estimating the conductivity. 4. In the K (Pressure=0) edit box, type the saturated conductivity value. 5. In the Pressure Range edit boxes, type the minimum and maximum pressure values and the number of points to generate in the conductivity function. 6. Select OK. The conductivity function is estimated and the data points are displayed in the list box. To view the function graph, select the View button. Re-select the Estimate button if you wish to re-estimate the function.

Importing and Modifying a Conductivity Function It is often convenient to define a conductivity function by modifying an existing function. SEEP/W allows you to import a function from another problem or from the SEEP/W function database. The imported function can then be modified to suit the current problem. Ø

To import a function into the current problem: 1. Choose KeyIn Functions Conductivity. The following dialog box appears:

2. To import a function from the SEEP/W function database or an existing problem, select the Import button. The following dialog box appears:

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3. Select the problem data file that contains the conductivity function to import. If you wish to import a function from the SEEP/W function database, select FN_FEET.SEP (if your problem units are in feet) or FN_METRE.SEP (if your problem units are in metres). 4. Select OK in the Import Conductivity Functions dialog box. The following dialog box appears to enable you to select the functions to import:

5. In the dialog list box, select the functions to import. Select All to select all functions or None to remove the selection from all functions. You can also click on functions individually. A group of functions can be selected either by pressing the CTRL key and clicking on each function in the group or by pressing the SHIFT key and clicking on the first and last function in the group. 6. Select Import to import the selected conductivity functions into the current problem. The imported functions are added to the end of the list of existing conductivity functions in the Conductivity Functions edit box, and the first imported function number is selected in the Function Number edit box. Select Edit to modify the function.

GEO-SLOPE Office 5 141 Ø

To modify an existing conductivity function: 1. Choose KeyIn Functions Conductivity and select the function number to edit in the Function Number drop-down list box:

2. Select Edit. The Edit Conductivity Function dialog box appears, along with the Graph window, to let you modify the data points in the function:

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3. To move the function up or down, type a new saturated conductivity value in the K (Pressure=0) edit box, and press the TAB key. The function data points are moved up or down to reflect the new conductivity value at zero pressure. 4. To fit the curve more or less exactly to the data points, specify a new value in the Fit Curve to Data group box either by moving the scroll bar or typing a percentage value. When the curve is fit exactly (100%) to the data points, the spline passes through each data point. As the curve fitting is reduced, the spline shape approaches a straight line that passes close to each data point. This is useful when you want to approximate a spline through laboratory-measured data points without moving any of the data points. The following spline curve is fit to the data using a value of 30%:

GEO-SLOPE Office 5 143 5. To change the shape of the spline curve between data points, specify a new value in the Curve Segments group box either by moving the scroll bar or typing a percentage value. When the curve segments are curved (100%) between data points, the curve is defined as a natural spline. As the curve segments are made straighter, the curve segments approach a straight line between data points. Straightening the curve segments helps to prevent "spline overshoot" (extreme peaks or valleys in the spline). It also allows you to define "step" functions that have straight line segments between each data point. The following spline curve uses a curvature value of 30%:

More function editing techniques are discussed in the section that describes the Graph toolbar.

Copying Data Points to the Clipboard SEEP/W allows you to copy the function data points to the Windows clipboard so that they can be accessed by other Windows applications, such as Microsoft Word or Excel. Ø

To copy the function data points to the Windows Clipboard: 1. In the Edit Conductivity Function dialog box, click the right mouse button to display a contextsensitive pop-up menu:

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2. Select Copy All from the pop-up menu to copy all data coordinates into the clipboard. More function editing techniques are discussed in the following section that describes the Graph tool bar.

The Graph Window Toolbar The Graph window toolbar contains buttons for moving and deleting points, adding points, copying the graph to the Clipboard, and printing the graph.

To access a command from the toolbar, click the button with the left mouse button. Clicking on the Select button puts you in Select mode, while clicking on the Add button puts you in Add mode. The Copy and Print buttons can be used while you are in either mode. The toolbar commands are:

GEO-SLOPE Office 5 145 Select Select Mode allows you to select one or more function points for moving or deleting. This is the default mode for the Graph window. ·

To select a point, click the left mouse button near the point. To select a group of points, drag a rectangle around the points.

·

Once points are selected, they can be deleted by pressing the DELETE key. They can be moved by clicking on one of the selected points and holding the left mouse button down, dragging the mouse to a new position, and then releasing the left mouse button. Alternatively, you can move the points with the arrow keys. Whenever points are moved, SEEP/W recalculates the spline curve between the function data points.

·

Data points can also be selected in the dialog list box either by pressing the CTRL key and clicking on each point in the group or by pressing the SHIFT key and clicking on the first and last point in the group.

Add Add Mode allows you to add a function point to the graph. ·

To add a point, click the left mouse button at the desired position. SEEP/W adds the point to the graph and recalculates the spline curve between the function data points.

Copy Copies the graph to the Clipboard. ·

This button allows you to transfer the graph to another Windows application for creating reports, slide presentations, or enhancing the graph. A beep is sounded when the graph has been copied to the Clipboard. To display the contents of the Clipboard, run the Windows Clipboard Viewer program.

Print Prints the graph on the printer. ·

Select the Print button to print the graph. The following dialog box appears:

·

Select the printer from the Printer Name drop-down list box. If you wish to change the printer settings, select the Properties button.

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·

Select either the All, Graph, or Numerical Data from the Print range Options. If you select All, both the Graph and the Numerical Data (coordinates) will be printed

·

Select OK to print the graph and/or data. The graph is printed on the default printer at the size it is displayed on screen. Resizing the Graph window changes the printed size of the graph. If the graph is larger than the printer page size, the graph will be printed at the printer page size.

Whenever a point is selected, moved, deleted, or added in the Graph window, the dialog list box is updated to reflect the change. Likewise, when a point is modified in the dialog list box, the Graph window is also updated. This feature allows you to switch between the KeyIn Functions dialog box and the Graph window while you are defining the function. The points are sorted by their x-coordinates whenever points are moved, added, or deleted from the graph or from the dialog box. This feature allows you to move the points anywhere on the graph without destroying the function.

Comments Function numbers should be specified in a continuous series. For example, if you are defining three functions, assign them function numbers of 1, 2, and 3. While you may choose any integer as a function number, large integers will decrease the efficiency of SEEP/W. When specifying pore-water pressure values, note the following: ·

The pore-water pressure values must be entered as pressure, not as pressure head or total head.

·

No two pore-water pressure values should be the same.

·

The pore-water pressure values must be in ascending order. SEEP/W sorts the function points by the pore-water pressure values when you select View or OK.

The slope (gradient) of the conductivity function should be positive over its entire range. A straight line function can be defined by specifying only two data points. The Graph window can be resized to create a different size of graph or maximized to create the largest possible graph. When the window is enlarged horizontally, the graph appears to be flatter. This is because the x- and y-axes are always scaled to fit the entire window area; resizing the window does not affect the point coordinates. The font used in the Graph window can be changed by using the View Preferences command.

KeyIn Functions Vol. Water Content Defines the relationship between pore-water pressure and the volume of water stored in the soil pores. A vol. water content function describes the volume of water that a material can store as a function of the pore-water pressure. Figure 4.11 shows a typical vol. water content function.

GEO-SLOPE Office 5 147 Figure 4.11 A Volumetric Water Content Function

As the pore-water pressure moves from a positive to a negative state, the soil begins to desaturate, and water content decreases. The water content must be specified as the volumetric water content, which is defined as the porosity multiplied by the degree of saturation. In equation form: (4.2) where: = volumetric water content n = porosity s = degree of saturation Porosity is related to void ratio by the equation: (4.3) where e is the void ratio. The void ratio is related to the gravimetric water content by the equation:

(4.4) where: w = gravimetric water content Gs = particle specific gravity S = degree of saturation Volumetric water content functions are defined and modified in the same way as hydraulic conductivity functions and in Version 5 four techniques are available to estimate the function either based on the grain size function or on known closed form curve fit parameters. See the KeyIn Functions Conductivity section for more information about defining and modifying functions. See the Appendix A of this on line help for the theory associated with function estimation.

148 SEEP/W Vol. W.C. (at Saturation) This value is the volumetric water content in a saturated soil. It is equal to the porosity of the soil and is the water content value at a pressure of zero. SEEP/W uses this value for function estimation as well as for fully saturated transient solutions when entered with a Mv value and no function data points. Coef. of Vol. Compressibility (Mv) This value is slope of the water content function in the positive pressure range. As the value is usually quite small, the user can enter it as a fixed slope instead of trying to enter data points manually that give the correct Mv slope in the positive pressure range. Note: In a fully saturated analysis, the user can enter the Mv and Vol.W.C. value with no data points and the transient solution will proceed. The full function data points are only required if there is any desaturation of the ground. Log Suction For both the conductivity and storage functions, the user can select to view the negative pressure range on a log scale. This is often advantageous if the range is quite wide and the slope of the curve in the lower pressure range is sharply curved and you need to view the details of the curvature. This flag should be set prior to estimating the function as the function estimation methods spread the number of estimated points evenly over the "x" axis scale and it will appear different when viewed in log scale if all estimation is done in arithmetic scale.

Estimating the Volumetric Water Content Function

The dialogue box shown above is activated if the user wants to predict a water content function based on one of several methods. Two methods use the grain size functions if they have been defined and two use closed form function parameters. The theory for all methods is given in the Appendix A. Pressure Range When estimating functions, the user must enter the minimum and maximum pressure range to estimate the function over as well as how many points to include within this range. If the functions appear like they are not correct, try to increase the pressure range so that more of the function is visible.

Comments Function numbers should be specified in a continuous series. For example, if you are defining three functions, assign them function numbers of 1, 2, and 3. While you may choose any integer as a function number, large integers will decrease the efficiency of SEEP/W.

GEO-SLOPE Office 5 149 When specifying pore-water pressure values, note the following: ·

The pore-water pressure values must be entered as pressure, not as pressure head or total head.

·

No two pore-water pressure values should be the same.

·

The pore-water pressure values must be in ascending order. SEEP/W sorts the function points by the pore-water pressure values when you select View or OK.

The slope (gradient) of the vol. water content function must always be positive over its entire range. A straight line function can be defined by specifying only two data points. The Graph window can be resized to create a different size of graph or maximized to create the largest possible graph. When the window is enlarged horizontally, the graph appears to be flatter. This is because the x- and y-axes are always scaled to fit the entire window area; resizing the window does not affect the point coordinates.

KeyIn Functions Grain Size Defines the relationship between percent passing and mesh sizes as reported for standard grain size distribution test procedures. SEEP/W uses the grain size functions in its estimation procedures for the storage functions. Users can also compare their own grain size curves with those in the data base file in order to select one of many measured storage functions or hydraulic conductivity functions.

Defining Each Function Data Point In Version 5 you can copy two columns of x and y data from a spreadsheet program and use the right mouse button to paste the two columns of data directly into a function edit box. The following discussion illustrates how to enter individual points. Ø

To define each data point in a grain size function: 1. Choose KeyIn Functions Grain Size. The following dialog box appears:

2. In the Function Number drop-down box, type the function number to define. 3. Select Edit. The following dialog box appears to let you enter the data points in the function:

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Steps 4 to 7 define the extremities of the function, allowing you to later use the Graph window to visually define the function points. 4. Enter the minimum x- and y-coordinates by typing 1 in the # edit box, the minimum grain diameter value in the Grain Diameter edit box, and the minimum % passing in the % Passing edit box. 5. Select Copy. The values in the edit boxes are copied into the list box. 6. Enter the maximum x- and y-coordinates by typing 2 in the # edit box, the maximum grain diameter value in the Grain Diameter edit box, and the maximum % passing in the % Passing edit box. 7. Select Copy. The values in the edit boxes are copied into the list box. The following list box contains two typical points:

GEO-SLOPE Office 5 151

8. Once the function extremities have been entered, select View to display the function graph. Most Geo-Slope functions will automatically scale the viewed graph axis to fit the data. In the case of the grain size function, this is not applied to the vertical axis. The vertical axis is always displayed between zero and 100% to reflect the full range of possible y-values. 9. Use the buttons in the Graph toolbar to complete the grain size function definition. The Graph toolbar allows you to add, move, and delete points interactively. You can also adjust the curvature of the spline between data points and the degree to which the spline is fit to the data points. These features are discussed later in this section in more detail. The following graph shows a typical grain size function:

10. Type an appropriate name for the function in the Description edit box. The function name is helpful when deciding which function to edit or import. 11. Double-click on the control-menu box to close the View window. 12. Select OK. The initial KeyIn Functions dialog box appears. 13. Select Done to exit this command or type a new function number and select OK to define another conductivity function.

Importing and Modifying a Grain Size Function It is often convenient to define a grains size function by modifying an existing function. SEEP/W allows you to import a function from another problem or from the SEEP/W function database. The imported function can then be modified to suit the current problem. Ø

To import a function into the current problem: 1. Choose KeyIn Functions Grain Size. The following dialog box appears:

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2. To import a function from the SEEP/W function database or an existing problem, select the Import button. The following dialog box appears:

3. Select the problem data file that contains the grain size function to import. If you wish to import a function from the SEEP/W function database, select FN_FEET.SEZ (if your problem units are in feet) or FN_METRE.SEZ (if your problem units are in metres). 4. Select OK in the Import Grain Size Functions dialog box. The following dialog box appears to enable you to select the functions to import:

5. In the dialog list box, select the functions to import. Select All to select all functions or None to

GEO-SLOPE Office 5 153 remove the selection from all functions. You can also click on functions individually. A group of functions can be selected either by pressing the CTRL key and clicking on each function in the group or by pressing the SHIFT key and clicking on the first and last function in the group. 6. Select Import to import the selected grain size functions into the current problem. The imported functions are added to the end of the list of existing grain size functions in the Conductivity Functions edit box, and the first imported function number is selected in the Function Number edit box. Select Edit to modify the function. Ø

To modify an existing grain size function: 1. Choose KeyIn Functions Conductivity and select the function number to edit in the Function Number drop-down list box:

2. Select Edit. The Edit Grain Size Function dialog box appears, along with the Graph window, to let you modify the data points in the function:

3. To move the function up or down, type a new grain diameter value in the Grain Diameter edit box,

154 SEEP/W and press the TAB key. The function data points are moved up or down to reflect the new grain size value. 4. To fit the curve more or less exactly to the data points, specify a new value in the Fit Curve to Data group box either by moving the scroll bar or typing a percentage value. When the curve is fit exactly (100%) to the data points, the spline passes through each data point. As the curve fitting is reduced, the spline shape approaches a straight line that passes close to each data point. This is useful when you want to approximate a spline through laboratory-measured data points without moving any of the data points. The following spline curve is fit to the data using a fit value of 30%:

5. To change the shape of the spline curve between data points, specify a new value in the Curve Segments group box either by moving the scroll bar or typing a percentage value. When the curve segments are curved (100%) between data points, the curve is defined as a natural spline. As the curve segments are made straighter, the curve segments approach a straight line between data points. Straightening the curve segments helps to prevent "spline overshoot" (extreme peaks or valleys in the spline). It also allows you to define "step" functions that have straight line segments between each data point. The following spline curve uses a curvature value of 30%:

GEO-SLOPE Office 5 155

More function editing techniques are discussed in the section that describes the Graph toolbar.

Copying Data Points to the Clipboard SEEP/W allows you to copy the function data points to the Windows clipboard so that they can be accessed by other Windows applications, such as Microsoft Word or Excel. You can also paste in x-y data pairs in columns using the right mouse buttons Paste option. Ø

To copy the function data points to the Windows Clipboard: 1. In the Edit Conductivity Function dialog box, click the right mouse button to display a contextsensitive pop-up menu:

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2. Select Copy All from the pop-up menu to copy all data coordinates into the clipboard. More function editing techniques are discussed in the following section that describes the Graph tool bar.

The Graph Window Toolbar The Graph window toolbar contains buttons for moving and deleting points, adding points, copying the graph to the Clipboard, and printing the graph.

To access a command from the toolbar, click the button with the left mouse button. Clicking on the Select button puts you in Select mode, while clicking on the Add button puts you in Add mode. The Copy and Print buttons can be used while you are in either mode. The toolbar commands are: Select Select Mode allows you to select one or more function points for moving or deleting. This is the default mode for the Graph window. ·

To select a point, click the left mouse button near the point. To select a group of points, drag a rectangle around the points.

GEO-SLOPE Office 5 157

·

Once points are selected, they can be deleted by pressing the DELETE key. They can be moved by clicking on one of the selected points and holding the left mouse button down, dragging the mouse to a new position, and then releasing the left mouse button. Alternatively, you can move the points with the arrow keys. Whenever points are moved, SEEP/W recalculates the spline curve between the function data points.

·

Data points can also be selected in the dialog list box either by pressing the CTRL key and clicking on each point in the group or by pressing the SHIFT key and clicking on the first and last point in the group.

Add Add Mode allows you to add a function point to the graph. ·

To add a point, click the left mouse button at the desired position. SEEP/W adds the point to the graph and recalculates the spline curve between the function data points.

Copy Copies the graph to the Clipboard. ·

This button allows you to transfer the graph to another Windows application for creating reports, slide presentations, or enhancing the graph. A beep is sounded when the graph has been copied to the Clipboard. To display the contents of the Clipboard, run the Windows Clipboard Viewer program.

Print Prints the graph on the printer. ·

Select the Print button to print the graph. The following dialog box appears:

·

Select the printer from the Printer Name drop-down list box. If you wish to change the printer settings, select the Properties button.

·

Select either the All, Graph, or Numerical Data from the Print range Options. If you select All, both the Graph and the Numerical Data (coordinates) will be printed

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·

Select OK to print the graph and/or data. The graph is printed on the default printer at the size it is displayed on screen. Resizing the Graph window changes the printed size of the graph. If the graph is larger than the printer page size, the graph will be printed at the printer page size.

Whenever a point is selected, moved, deleted, or added in the Graph window, the dialog list box is updated to reflect the change. Likewise, when a point is modified in the dialog list box, the Graph window is also updated. This feature allows you to switch between the KeyIn Functions dialog box and the Graph window while you are defining the function. The points are sorted by their x-coordinates whenever points are moved, added, or deleted from the graph or from the dialog box. This feature allows you to move the points anywhere on the graph without destroying the function.

Comments Function numbers should be specified in a continuous series. For example, if you are defining three functions, assign them function numbers of 1, 2, and 3. While you may choose any integer as a function number, large integers will decrease the efficiency of SEEP/W. When specifying pore-water pressure values, note the following: ·

The pore-water pressure values must be entered as pressure, not as pressure head or total head.

·

No two pore-water pressure values should be the same.

·

The pore-water pressure values must be in ascending order. SEEP/W sorts the function points by the pore-water pressure values when you select View or OK.

The slope (gradient) of the conductivity function should be positive over its entire range. A straight line function can be defined by specifying only two data points. The Graph window can be resized to create a different size of graph or maximized to create the largest possible graph. When the window is enlarged horizontally, the graph appears to be flatter. This is because the x- and y-axes are always scaled to fit the entire window area; resizing the window does not affect the point coordinates. The font used in the Graph window can be changed by using the View Preferences command.

KeyIn Functions Boundary Defines the variation in boundary conditions as a function of time. Boundary function types can be a continuous splined function or a step function. Data for both functions is entered in the same manner. A splined function smooths the curve between successive data points, whereas a step function treats each data point as a horizontal "step" in the function with a vertical discontinuity between steps. For transient analyses, the boundary conditions can be defined as a function of time; that is, the boundary conditions can change with time. SEEP/W allows you to specify these relationships using boundary functions. When you are defining boundary conditions, you can select a boundary function to apply to a boundary node or boundary edge. For more information about defining boundary conditions, see Draw Boundary Conditions in this chapter.

GEO-SLOPE Office 5 159 Examples of transient boundary conditions are: ·

Annual cycles in the operation of irrigation canals.

·

Variations in the level of a water reservoir.

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Seasonal infiltration and exfiltration of precipitation on the ground surface.

·

Variable pumping rates from a well.

Irrigation Canal Example Consider the case of an irrigation canal that is being used only during the summer. At the start of the irrigation season, the water level in the canal is low. It increases to the full supply level as the demand increases. At the end of the season, water is slowly drained from the canal until, by the time winter arrives, there is no water left in the canal. Figure 4.12 illustrates a boundary function simulating the transient conditions in the canal. Figure 4.12 The Boundary Function for an Irrigation Canal

SEEP/W accommodates the following types of boundary functions: 1. Total head (H) versus time. 2. Total head (H) versus time with the condition that the boundary type is set to Q=0.0 if the function head is less than the elevation (y-coordinate) of the node. The If H < elevation, Q = 0 option must be selected to use this condition. 3. Total head (H) versus volume 4. Total head (H) versus volume with the condition that the boundary type is set to Q=0.0 if the function head is less than the elevation (y-coordinate) of the node. The If H < elevation, Q = 0 option must be selected to use this condition. 5. Nodal flux (Q) versus time. 6. Unit flux (q) versus time. 7. Unit flux (q) versus time with the condition that the boundary type is set to H=elevation (ycoordinate) of the node if the unit flux is greater than the saturated hydraulic conductivity.

160 SEEP/W Boundary functions are defined and modified in the same way as hydraulic conductivity functions, except that they cannot be estimated. For more information about defining and modifying functions, see the KeyIn Functions Conductivity section in this chapter. Boundary functions are different from other functions in that they have a type. The following dialog box is used to edit and define the boundary function type and data points:

A boundary function can be cycled over and over many times by checking the Cycle Fn option. Say, for example, that you have a boundary function defined for one year and that you want to apply this same annual variation for 10 years. By defining your time step sequence for ten years and selecting the Cycle Fn option, SEEP/W will use the same function for each annual cycle. With this feature you only need to define the boundary function for one cycle instead of the entire 10 cycles.

Comments To be able to define boundary functions, the analysis type must be set to transient. The KeyIn Functions Boundary command will be disabled in the DEFINE menu for a steady-state analysis. Function numbers should be specified in a continuous series. For example, if you are defining three functions, assign them function numbers of 1, 2, and 3. While you may choose any integer as a function number, large integers will decrease the efficiency of SEEP/W. A straight line function can be defined by specifying only two data points. The Graph window can be resized to create a different size of graph or maximized to create the largest possible graph. When the window is enlarged horizontally, the graph appears to be flatter. This is because the x- and y-axes are always scaled to fit the entire window area; resizing the window does not affect the point coordinates.

GEO-SLOPE Office 5 161 When specifying boundary functions: ·

Flow into the system (infiltration) must be specified as a positive value; flow out of the system (exfiltration) must be specified as a negative value.

·

The units of unit flux (q) must be consistent with the units of length and time. For example, if the dimensions are in meters and the hydraulic conductivity is in m/sec, then q must be in m/sec.

·

The total nodal flux (Q) must be specified in units of L3/t, where L is the unit of length and t is the unit of time.

SEEP/W SOLVE multiplies the unit flux by the contributing area to obtain the nodal flux. The nodal flux is required to solve the finite element equations. For guidelines on using boundary functions, see Boundary Conditions in Chapter 7.

KeyIn Functions Modifier Defines a function to modify the flux boundary conditions in response to the previously computed negative pore-water pressures. This command allows you to modify a boundary function that is applied to a node or edge as a boundary condition. See KeyIn Functions Boundary for more information about defining boundary functions and see Draw Boundary Conditions for more information about defining boundary conditions. When the soil near the ground surface dries out, the pore-water pressure becomes highly negative. The hydraulic conductivity in turn decreases, as described by the conductivity function. The decrease in conductivity reduces the chance for soil moisture to evaporate. For a particular site, it may be possible to define a potential evaporative flux versus time function. SEEP/W first computes the boundary flux on the basis of this function and then modifies the boundary flux on the basis of a modifier function, such as shown in Figure 4.13. Figure 4.13 Example of a Modifier Function

At the beginning of each time step, SEEP/W uses the starting or initial pore-water pressure conditions, together with the modifier function, to establish the ratio of the potential flux that will be applied to the boundary. The range of the function is 0 to 1.0. For positive pore-water pressures, the modifier value is 1.0. For negative pore-water pressures, the modifier is 1.0 or less.

162 SEEP/W The use of the modifier function is further discussed in Ground Surface Flux in Chapter 7.

Comments Function numbers should be specified in a continuous series. For example, if you are defining three functions, assign them function numbers of 1, 2, and 3. While you may choose any integer as a function number, large integers will decrease the efficiency of SEEP/W. When specifying pore-water pressure values, note the following: ·

The pore-water pressure values must be entered as pressure, not as pressure head or total head.

·

No two pore-water pressure values should be the same.

·

The pore-water pressure values must be in ascending order. SEEP/W sorts the function points by the pore-water pressure values when you select View or OK.

A straight line function can be defined by specifying only two data points. The Graph window can be resized to create a different size of graph or maximized to create the largest possible graph. When the window is enlarged horizontally, the graph appears to be flatter. This is because the x- and y-axes are always scaled to fit the entire window area; resizing the window does not affect the point coordinates.

KeyIn Nodes Sets the coordinates of finite element nodes. When you choose KeyIn Nodes, the following dialog box appears:

The primary method of defining nodes is by drawing them on the screen using the Draw Nodes command or automatically creating them when drawing elements. The main purpose of KeyIn Nodes is to:

Ø

·

View the node coordinates numerically.

·

Refine the coordinates after they have been drawn.

To define node data in the dialog box: 1. Type the node number and the x-, y-, and z-coordinates in the edit boxes.

GEO-SLOPE Office 5 163

2. Select Copy to transfer the data to the list box. 3. Repeat Steps 1 to 2 for all nodes. 4. Select OK. Nodes can also be edited or deleted. To delete all the nodes in the list box, select Delete All. To select multiple nodes in the list box for deletion, either press the CTRL key and click on each node to delete or press the SHIFT key and click on the first and last node to delete.

Comments Deleting a node will also delete all elements connected to the node. For information about deleting and moving nodes graphically, see Modify Objects in this chapter. To graphically view the coordinates at any node, use the View Node Information command. The z-coordinate is only required for a plan-view analysis. The z-coordinates can be generated on a plane with the KeyIn Generate Plan View command.

KeyIn Elements Defines the geometry and properties of finite elements. When you choose KeyIn Elements, the following dialog box appears:

The primary method of defining elements is by drawing them on the screen using the Draw Single Elements or Draw Multiple Elements commands. The main purpose of KeyIn Elements is to:

Ø

·

Check the data for specific element numbers.

·

Modify the element data.

To define element data in the dialog box: 1. In the edit boxes, type the element number and the node numbers contained in the element. 2. Select the element material number and integration order from the Matl. and I.O. drop-down list

164 SEEP/W

boxes. 3. Type a new value for the element thickness in the Thickness edit box if it is different than the default value of 1.0. 4. Select the x- and y- infinity directions from the X-Infinity and Y-Infinity drop-down list boxes. 5. Select Copy to transfer the data to the list box. 6. Repeat Steps 1 to 5 for all elements to define. 7. Select OK. Elements can also be edited or deleted. To delete all the elements in the list box, select Delete All. To select multiple elements in the list box for deletion, either press the CTRL key and click on each element to delete or press the SHIFT key and click on the first and last element to delete. For information about deleting elements graphically and resizing or moving groups of elements, see Modify Objects in this chapter. Defining Element Nodes Nodes 1, 2, 3, and 4 of an element are corner nodes. Nodes 5, 6, 7, and 8 are intermediate (secondary) nodes. This is illustrated in Figure 4.14. The difference between a triangular and a quadrilateral element is in the fourth node. If Node 4 is blank or zero, the element is triangular. If Node 4 is defined, the element is a quadrilateral. Figure 4.14 Definition of Element Node Locations

Integration Order The integration order option is 1 or 3 for triangular elements and 4 or 9 for quadrilateral elements. The options available in the drop-down list box change in accordance with the value in the Node 4 edit box. Thickness Thickness other than unity (1.0) is intended primarily for use in plan view analyses. For twodimensional analysis, it is best to adopt the default thickness of unity. In an axisymmetric analysis, a thickness of 1.0 means 1 radian. By setting the thickness to 2p, you can get the total flow for the entire circumferential area.

Comments Element properties (such as material numbers, integration order, and thickness) can be changed easily with the Draw Element Properties command. To graphically view the element definition and material properties of any element, use the View Element Information command.

GEO-SLOPE Office 5 165 The intermediate (secondary) nodes are optional and may be used in any combination. The following restrictions apply to the use of secondary nodes: ·

A secondary node must be located exactly at the midpoint of the two corner nodes.

·

Node 5 must be in between Nodes 1 and 2.

·

Node 6 must be in between Nodes 2 and 3.

·

Node 7 must be in between Nodes 3 and 4 if the element is quadrilateral; it must be in between Nodes 3 and 1 if the element is triangular.

·

Node 8 must be in between Nodes 4 and 1 for quadrilateral elements. Node 8 cannot be specified for triangular elements.

For more information about intermediate nodes and selecting the appropriate integration order, see Numerical Integration in Chapter 8 and Mesh Design in Chapter 7.

KeyIn Flux Sections Identifies sections across which to compute the flow quantity. A flux section is a series of line segments across which the seepage flow is to be computed by SOLVE. The primary method of defining flux sections is by drawing them on the screen with Draw Flux Sections. The main purpose of KeyIn Flux Sections is to:

Ø

·

View the sub-section endpoint coordinates numerically.

·

Refine the flux section x-y coordinates after they have been drawn.

·

Insert or delete points in the defined flux section.

To define a flux section in the dialog box: 1. Choose KeyIn Flux Sections. The following dialog box appears:

2. In the Flux Section Number edit box, type the flux section number to define. A list of flux sections already defined can be obtained by clicking the arrow to the right of the edit box. Select one of these numbers if you wish to modify a flux section that has already been defined. 3. Select OK. The following dialog box appears to let you enter the endpoints in the flux section:

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4. Type the point number and the x-y coordinates of the subsection endpoint in the edit boxes. 5. Select Copy to transfer the data to the list box. 6. Repeat Steps 4 to 5 for each desired flux subsection endpoint. 7. Select OK. The initial KeyIn Flux Sections dialog box appears. 8. Select Done to exit this command. Flux subsection endpoints can also be edited or deleted. To delete all the endpoints in the list box, select Delete All. To select multiple endpoints in the list box for deletion, either press the CTRL key and click on each endpoint to delete or press the SHIFT key and click on the first and last endpoint to delete.

Comments For information about deleting entire flux sections graphically and moving or resizing flux sections, see Modify Objects in this chapter. A flux section must not pass through a mesh node. For an axisymmetric analysis, the computed flux is per unit (one) radian if the element thickness is 1.0. If the element thickness is 2p, the computed flux is for the entire circumferential area.

KeyIn Initial Water Table Defines the position of an initial water table for use in estimating the initialtotal head conditions in a transient seepage analysis. An initial water table consists of a series of points. The primary method of defining an initial water table is by drawing it on the screen using the Draw Initial Water Table command. The main purpose of KeyIn Initial Water Table is to: ·

View the coordinates of each point numerically.

·

Insert or delete points in the defined initial water table.

GEO-SLOPE Office 5 167 Ø

To define an initial water table: 1. Choose KeyIn Initial Water Table. The following dialog box appears:

2. In the top edit box, type the maximum negative pressure head allowed in the initial condition. 3. Type the point number and the x-y coordinates of the point in the edit boxes. 4. Select Copy to transfer the data to the list box. 5. Repeat Steps 2 to 4 for each desired point. 6. Select OK to save the updated initial water table. To delete the initial water table, select Delete All; all points in the list box are deleted. To select multiple points in the list box for deletion, either press the CTRL key and click on each point to delete or press the SHIFT key and click on the first and last subsection to delete; then select the Delete button. NOTE: The initial water table can be moved, resized or deleted graphically with the Modify Objects command.

KeyIn Generate Plan View Generates the nodal z-coordinates and element thickness for a plan view analysis.

168 SEEP/W When you choose KeyIn Generate Plan View, the following dialog box appears:

SEEP/W can be used to analyze the lateral flow in an aquifer. To perform this type of analysis, it is necessary to define the vertical position and thickness of the aquifer. DEFINE can generate these two variables on a linear interpolation basis by specifying the x-, y-, and z-coordinates of three points in space. Ø

To generate plan view data: 1. Type the x-, y-, and z-coordinates for three points in the edit boxes. 2. Select Generate. A dialog box appears, allowing you to confirm the z coordinate and element thickness generation. 3. Select OK to generate new nodal z-coordinates and element thickness, or select Cancel to change the generation parameters. When you select OK, the z-coordinate of each node previously defined is generated by linear interpolation of the z-coordinates of the three points. Likewise, the thickness at the center of each element is generated by linear interpolation of the thickness values entered for the three points.

Comments It is recommended that you first define the complete finite element mesh before generating the nodal zcoordinates and element thickness with Generate Plan View. It may be useful to specify three points at which nodes are already defined. Specify the x- and ycoordinates of the nodes, the desired z-coordinates, and the desired thickness of elements defined at the nodes. The three defined points cannot lie on a straight line. This would define a line with an infinite number of planes running through it, making linear interpolation impossible.

The Draw Menu The main function of Draw is to define data by pointing, dragging, and clicking the mouse. The Draw menu commands are: ·

Nodes Sets the coordinates of finite element nodes. For more information about this command, see Draw Nodes in this chapter.

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·

Single Elements Defines elements one at a time. For more information about this command, see Draw Single Elements in this chapter.

·

Multiple Elements Generates a series of elements over a quadrilateral or triangular region. For more information about this command, see Draw Multiple Elements in this chapter.

·

Infinite Elements Defines infinite edges along existing elements. For more information about this command, see Draw Infinite Elements in this chapter.

·

Boundary Conditions Sets conditions along the problem boundaries. For more information about this command, see Draw Boundary Conditions in this chapter.

·

Element Properties Changes the material number, integration order and thickness of existing elements. For more information about this command, see Draw Element Properties in this chapter.

·

Flux Sections Identifies sections across which to compute the flow quantity. For more information about this command, see Draw Flux Sections in this chapter.

·

Initial Water Table Defines the location of the initial water table. For more information about this command, see Draw Initial Water Table in this chapter.

Draw Nodes Sets the coordinates of finite element nodes. Ø

To draw nodes: 1. Choose the Draw Nodes command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "Draw Nodes" is the current mode. 2. Move the cursor to the desired position and click the left mouse button. The cursor coordinates are displayed in the status bar. A small black square appears at the node position. 3. Repeat Step 2 for all desired nodes. 4. Press ESC or click the right mouse button to finish drawing nodes.

Comments You do not need to use the Draw Nodes command to define nodes if you are creating elements using Draw Single Elements or Draw Multiple Elements; SEEP/W will automatically create nodes when you draw elements using these commands. Using Draw Nodes is only necessary if you choose KeyIn Elements and need to specify the element node numbers. The node that you define will be placed at a grid point if the Snap to Grid option is on. To toggle the Snap to Grid option, use the Set Grid command or the Snap Grid button on the Grid toolbar. Nodes can be moved or deleted using the Modify Objects command. You can also choose KeyIn Nodes to change the x-y coordinates of a node.

Draw Single Elements Defines elements one at a time.

170 SEEP/W Single elements are drawn in two stages. First, the properties of the element, such as material type and integration order, are specified. Secondly, the element is drawn by clicking on the corner nodes of the element. Ø

To draw single elements: 1. Choose the Draw Single Elements command from either the DEFINE menu or from the Mode toolbar. The following dialog box appears:

2. Select Quadrilateral or Triangular as the type of element to draw. 3. Check the secondary nodes contained in the element. 4. Select the material number of the element from the drop-down list box. 5. Select the integration order of the element from the drop-down list box. 6. Type the element thickness in the edit box if it is different from the default value of 1.0. 7. Select OK. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "Draw Single Elements" is the current operating mode. 8. Draw the element one side at a time by clicking at each corner position of the element. If you click near an existing node, the node will be used as the element corner node; otherwise, a node is created at the cursor position and used as the element corner node. As you specify each corner node, the sides of the elements are drawn. When all the corner nodes have been defined (a quadrilateral element has 4 corner nodes and a triangular element has 3 corner nodes), the complete element is drawn, including any specified secondary nodes. 9. Repeat Step 8 to draw more elements with the specified properties. 10. Press ESC or click the right mouse button to finish drawing single elements.

Comments You can specify the corner nodes of the element in either a clockwise or counterclockwise direction around the element. When you verify the mesh with the Tools Verify/Sort command, the nodes in each element are rearranged in a counterclockwise direction.

GEO-SLOPE Office 5 171 If you draw elements without creating any materials first, the elements will be created as null elements using the default null material. Choose KeyIn Functions Conductivity and KeyIn Material Properties to define properties for the default material; once the default material is assigned a conductivity function, the generated elements are no longer null elements. You do not need to define any nodes before drawing elements, since nodes can be automatically created as you draw single elements.

Draw Multiple Elements Generates elements over a quadrilateral or triangular region. Use the Draw Multiple Elements command to generate quadrilateral or transitional (triangular) elements over a quadrilateral region, or a mix of quadrilateral and triangular elements over a triangular region as shown in Figures 4.15 through 4.17. Figure 4.15 Quadrilateral Elements Generated over a Quadrilateral Region

Figure 4.16 Transitional (Triangular) Elements Generated over a Quadrilateral Region

172 SEEP/W Figure 4.17 Quadrilateral and Triangular Elements Generated over a Triangular Region

Multiple elements are generated in two steps. Using the mouse, you first define a quadrilateral, (4-sided), or triangular, (3-sided), region over which the elements will be generated. Inside a dialog box, you then specified such information as the number of elements to generate, the element distribution within the region, whether secondary nodes should be generated, and the element properties (such as the material type, integration order and element thickness). When using the dialog box, you can apply the element generation specifications to preview the generated elements accepting them. Ø

To draw multiple elements: 1. Choose the Draw Multiple Elements command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, and the status bar indicates that "Draw Multiple Elements" is the current operating mode. 2. Using the mouse, click on four distinct points to define a quadrilateral region over which to generate elements. Each time you click, DEFINE creates a node and draws the element region side. If you click on a node, the cursor snaps to the closest node instead of creating a node. 3. If you wish to define a triangular region, click on three distinct points and then click the fourth time on top of the first node in the region. 4. After you have defined the multiple element region, the following dialog box appears:

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5. Specify the multiple element generation settings in the Draw Multiple Elements dialog box. Element Type The element type control specifies the types of elements which will be generated. For a quadrilateral multiple element region, either quadrilateral or transitional elements may be generated. For a triangular multiple element region, there is no choice for element type because a mix of quadrilateral and triangular elements are generated. Secondary Nodes The secondary node control specifies whether the generated elements will have secondary nodes. Side 1 & Side 2 For both quadrilateral and triangular multiple element regions, Side 1 is the side defined by the region vertex points 1 and 2 and Side 2 is defined by the region vertex points 2 and 3. When you click inside the edit boxes underneath the Side 1 heading, Side 1 of the element region is drawn with a thick, red line; likewise, clicking inside the Side 2 edit boxes highlights Side 2 of the multiple element region. # of Elements Element generation within the region is defined by specifying the number of elements to generate along Sides 1 and 2 of the multiple element region. Size Ratio The size ratio specifies the element distribution along each side of the multiple element region. The size ratio is the ratio of the length of the last element to that of the first element along the side. For example, if the size ratio is set to 1, then all the elements generated along the side will have equal length. If the size ratio is set to 5, then the last element on the side will be 5 times longer than the first element on the side. Similarly, if the size ratio is 0.2, then the last element will be 1/5th as long as the first element on the side. Material Type Specifies the material number assigned to the generated elements. Quad. Integration Order Specifies the integration order for quadrilateral elements. Tri. Integration Order Specifies the integration order for triangular elements. Element Thickness Specifies the element thickness assigned to the generated elements. 6. Select the Apply button to see the generated elements. The elements are generated within the specified region according to the element generation settings. 7. Repeat Steps 5 to 6 if you wish to change the element distribution with the region. 8. Select the OK button to accept the newly generated elements or Cancel to abort the element generation.

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Comments The element properties can be changed even after the elements have been generated. Choose Draw Element Properties if you wish to change the material number, integration order, or element thickness of the generated elements. Choose Modify Objects to move, delete, or resize any of the generated elements. A quadrilateral multiple element region does not need to be rectangular; it may be any quadrilateral shape. If you draw elements without creating any materials first, the elements will be created as null elements using the default null material. Choose KeyIn Functions Conductivity and KeyIn Material Properties to define properties for the default material; once the default material is assigned a conductivity function, the generated elements are no longer null elements. The following comments apply to the transitional, (triangular), element type: ·

They can be used as transition zones between quadrilateral regions to increase or decrease the element density.

·

They can only be generated as single rows or columns.

·

The region must be defined by the node sequence illustrated in Figure 4.18. The nodes must follow a counterclockwise sequence. Nodes 1 and 2 (the first two nodes clicked) must be on the widely spaced side and Nodes 3 and 4 (the last two nodes clicked) must be on the closely spaced side.

Figure 4.18 Node Order Sequence for Generating Triangular Patterns

Draw Infinite Elements Defines infinite edges along existing elements. Infinite elements, used along the boundaries of a mesh, allow you to define the behavior of your problem well beyond the extents of the finite element mesh. Infinite elements are defined by specifying a direction of infinity and then clicking on the element. SEEP/W uses the direction of infinity to determine the infinite edge(s) and displays the edge(s) as a thick, dashed line. The element is also filled with vertical

GEO-SLOPE Office 5 175 and/or horizontal lines, corresponding to the existence of x infinity and y infinity within the element. Ø

To draw infinite elements: 1. Choose the Draw Infinite Elements command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, the status bar indicates that "Draw Infinite Elements" is the current mode and. the following dialog box appears:

2. Determine the required direction of infinity. The direction of infinity that you choose will depend on which elements you are defining as infinite. For example, if you wish to make the left side of your mesh infinite, then you would specify x-infinity in the negative direction. If you are specifying the element in the top-left corner of the mesh as infinite in two directions, then you would choose both negative x-infinity and positive y-infinity. 3. If you are defining x-infinity, select Positive or Negative from the X-Infinity drop-down list box. 4. If you are defining y-infinity, select Positive or Negative from the Y-Infinity drop-down list box. 5. To specify the desired elements as infinite, click on each element individually or select a group of elements. To select a group of elements, hold the left mouse button down at the top-left corner of the region and drag the mouse until a rectangle completely encompasses the desired group of elements. When the left mouse button is released, all elements in the rectangle are assigned the specified infinite directions. Only eight-node quadrilateral elements can be specified as infinite. If you select a triangular element, the element will not be made infinite. If you select a quadrilateral element that has less than eight nodes, SEEP/W will generate the remaining secondary nodes. Once the first element is made infinite, SEEP/W creates an infinite element pole at the center of the mesh. SEEP/W uses the position of the pole to project the outer edge of the infinite elements to infinity. 6. If necessary, repeat Steps 2 to 5 to define the remaining infinite elements. 7. To remove all infinite properties from an element, select (none) in both the X-Infinity and Y-Infinity list boxes and select the element. 8. To change the position of the pole, check the Reset Pole check box and click the left mouse button at the new pole position. The pole symbol is redrawn at the new position. The pole can also be moved using the Modify Objects command. 9. Press ESC or select Done to finish defining Infinite Elements.

176 SEEP/W The following problem has infinite elements defined along the left and right boundaries of the mesh:

Comments Choose View Preferences to turn off the display of the infinite element edges and shading. SEEP/W requires that infinite element edges be defined by Nodes 1 and 4 within an element. If infinity is defined in two directions, then Node 1 must lie on both infinite sides (i.e., the corner of the mesh). DEFINE automatically reorders the element nodes when you define an infinite element. When you choose the Tools Verify/Sort command, the ordering of infinite elements is adjusted in case it was changed manually with KeyIn Elements. For more information about the required position of infinite element nodes is further discussed in Infinite Elements in Chapter 8. The position of the pole should be near the flow source or discharge point opposite the infinite boundary. An approximate position is adequate, since the analysis is quite insensitive to the pole position. Selecting a pole position is further discussed in The Pole Position in Chapter 7

Draw Boundary Conditions Sets conditions along the problem boundaries. Defining boundary conditions is done in two stages. First, specify the boundary conditions, such as the action, boundary type, and boundary function number. Second, select all nodes or edges on which to apply the boundary conditions. Ø

To draw boundary conditions: 1. Choose the Draw Boundary Conditions command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, the status bar indicates that "Draw Boundary Conditions" is the current mode, and the following dialog box appears:

GEO-SLOPE Office 5 177 The Concentration edit box only appears in the Draw Boundary Conditions dialog box when the analysis type is set to density-dependent. For more information about setting the analysis type, see the KeyIn Analysis Control command in this chapter. 2. Select the boundary type from the drop-down list box. 3. Select the boundary function from the Fn.# drop-down list box if the problem is a transient analysis and the boundary conditions change with time. 4. Select the modifier function from the Mod. Fn.# drop-down list box to modify the boundary function parameters over time. 5. Type the action value in the Action edit box. 6. If you are defining head boundary conditions for a CTRAN/W density-dependent analysis, a Concentration edit box is displayed. You must specify the concentration along the head boundary in the Concentration edit box. SOLVE requires both the boundary head and the concentration to convert the specified boundary heads into equivalent freshwater head boundary. 7. Select the review option from the drop-down list box if the boundary type is Q or q and the node is to be reviewed and modified in response to the computed results. 8. To set the boundary conditions at the desired nodes, click on each node individually or select a group of nodes. To select a group of nodes, hold the left mouse button down at the top-left corner of the region and drag the mouse until a rectangle encompasses the desired group of nodes. When the left mouse button is released, all nodes in the rectangle are assigned the specified boundary conditions. To select nodes along a straight line, press the SHIFT key and click on two nodes along the line. All nodes that lie on a straight line between the selected nodes are assigned the specified boundary conditions. If you are specifying a unit flux (q) boundary in 2-Dimensional or axisymmetric view problems, you must identify the side (edge) of the element. You can do this by clicking on the two corner nodes that define the side or by dragging a rectangle around a group of element sides. You can also select element sides along a line using the SHIFT key in the same way as for the other boundary types. Specifying a unit flux (q) boundary for a plan view problem is the same as specifying an H or Q boundary. You may click on the node individually or select a group of nodes. 9. If necessary, repeat Steps 2 to 8 to define the remaining boundary conditions. 10. Click the right mouse button (or select Done) to finish defining boundary conditions. When you define boundary nodes, the node symbols change from a black square to a circle or triangle, depending on the boundary conditions at the node. Table 4.3 displays the symbols representing each type of boundary condition.

178 SEEP/W Table 4.3 Symbols Used for Each Type of Boundary Condition Type (none)

Review (none)

Symbol

Description black square

H

no

solid red circle

H(density-dependent)

no

solid red circle with black border

H vs. Time or Volume

yes

open red circle

Q

no

solid blue triangle

Q

yes

open blue triangle

q

no

solid green triangle

q

yes

open green triangle

(if H < elev, Q=0)

Head nodes are circular and flux nodes are triangular. Non-review nodes are solid symbols and review nodes are open symbols.

Comments Nodes can be changed from boundary nodes to regular nodes by setting the boundary type to (none) and then specifying the boundary nodes. The node symbols change back to black rectangles. The H(P=0) boundary type is zero pressure head boundary. It has the same effect as the H boundary with action specified to be the same as the elevation of the node. You must specify the analysis type using KeyIn Analysis Control before you begin drawing unit flux (q) boundaries. For an axisymmetric or 2-dimensional analysis, q boundaries are specified along element edges, while for a plan view analysis, q boundaries are specified at individual nodes. When defining unit flux (q) boundary conditions along an element edge, DEFINE does not allow you to click on element secondary nodes; you must either click on the element edge or click on the corner nodes of an element (the two nodes that define the element edge). If the boundary Fn. # is non-zero, the action value is computed from the boundary function and the value in the Action edit box is not used by SOLVE. If the Fn. # is zero, SOLVE uses the value in the Action edit box. Flux type boundary nodes, (Q or q), can be set to a review boundary in which the nodes are checked to see if the nodes should be converted to a zero pressure boundary. For more information about boundary conditions and the use of boundary reviews, see Boundary Conditons and Boundary Reviews in Chapter 7. When a node is not specified with any boundary condition, a default boundary condition of Q=0 is assumed.

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Draw Element Properties Changes the material number, integration order and thickness of existing elements. Use the Draw Element Properties command to change the material number, the integration order, and/or the thickness of a single element or a group of elements. This command allows you to modify the properties of existing elements instead of deleting the elements and recreating them with new properties. Ø

To change element properties: 1. Choose the Draw Element Properties command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair, the status bar indicates that "Draw Element Properties" is the current mode, and the following dialog box appears:

2. Select the element properties that you want to change by checking the appropriate check boxes. By default, all element properties are unchecked; this means that no element properties will be modified unless you specifically check at least one of the check boxes. 3. For each element property that you want to change, specify the new values in the appropriate input boxes. For example, to change the material number, select the new element material number in the drop-down list box (you also would have checked the Material Number check box in the previous step). 4. To set the properties of the desired elements, click on each element individually or select a group of elements. To select a group of elements, hold the left mouse button down at the top-left corner of the region and drag the mouse until a rectangle encompasses the desired group of elements. When the left mouse button is released, all elements completely contained in the rectangle are assigned the specified material properties. 5. If necessary, repeat Steps 2 to 4 to change the properties of more elements. 6. Press ESC or select Done to finish modifying element properties. NOTE: If you wish to change an element property, make sure you first check the material property and specify a new value. For example, if you type in a new element thickness but forget to check the Thickness check box, the element thicknesses of the selected elements will not be changed.

Draw Flux Sections Identifies sections across which to compute the flow quantity. Flux sections are specified in two stages. First, the number of the flux section to draw is specified. Secondly, the flux section is drawn by clicking at each point in the section.

180 SEEP/W Ø

To draw flux sections: 1. Choose the Draw Flux Sections command from either the DEFINE menu or from the Mode toolbar. The following dialog box appears:

2. Type thesection number to draw in the edit box. 3. SelectOK. The cursor changesfrom an arrow to a cross-hair, the status bar indicates that “Draw FluxSections” is the current mode. 4. Click atthe starting point of the flux section. As you move thecursor, a dashed black line appears, indicating the flux section is being drawn. 5. Click at thesecond point of the flux section. 6. Click at allremaining points in the flux section if the section is not a straight line. 7. PressESC or click the right mouse button to finish drawing flux sections. The flux section isdrawn as a blue dashed line with arrows at the endpoint of each subsection.

Comments For information about deleting, moving, or resizing flux sections, see Modify Objects in this chapter. A flux section must not pass through a mesh node. For an axisymmetric analysis, the computed flux is per unit (one) radian if the element thickness is 1.0. If the element thickness is 2p, the computed flux is for the entire circumferential area.

Draw Initial Water Table Defines the position of an initial water table for use in estimating the initial total head conditions in a transient seepage analysis. The initial water table is specified in two stages. First, the maximum negative pressure head allowed in the initial condition is specified. Second, the initial water table is drawn by clicking at each point in the initial water table. Ø

To draw the initial water table: 1. Choose the Draw Initial Water Table command from either the DEFINE menu or from the Mode toolbar. The following dialog box appears:

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2. Type the maximum negative pressure head allowed for the initial conditions. 3. Select OK. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Draw Initial Water Table" is the current mode. 4. Click at the starting point of the initial water table. As you move the cursor, a dashed black line appears, indicating the initial water table is being drawn. 5. Click at the second point of the initial water table. 6. Click at all remaining points in the initial water table if it is not a straight line. 7. Press ESC or click the right mouse button to finish drawing the initial water table. The initial water table is drawn as a blue dashed line.

Comments The initial water table can be drawn from left to right or right to left. When the initial water table is drawn starting from the left, each point must be located to the right of the previous point. Similarly when the initial water table is drawn starting from the right, each point must be located to the left of the previous point. In other words the initial water table should be drawn smoothly, (generally horizontally), across the problem domain. Failure to draw a smooth initial water table will generate an error when using the Tools Verify Sort command. The initial water table should extend beyond the left and right boundary of the flow problem. If the initial water table terminates inside the flow system, SOLVE extends the end points horizontally when computing the initial condition from the initial water table. The initial water table can be moved, resized or deleted graphically with the Modify Objects command. Initial conditions are not required in a steady-state analysis. However, in a transient analysis, SOLVE uses the initial water table definition to establish the initial conditions. The initial total head at each node is computed proportionally to the vertical distance between the node and the defined water table. The effect is that the pore-water pressure varies hydrostatically with distance above and below the water table. Above the water table, the negative pore-water pressure can be set to a limit. For guidelines regarding specifying initial conditions, see Initial Conditions in Chapter 7. The initial water table information will not be used by SOLVE if you identify a file with the initial conditions. To make use of the water table, you must not open an initial conditions file in SOLVE. For more information about initial condition files , see the KeyIn Analysis Settings command.

182 SEEP/W

The Sketch Menu The main function of Sketch is: ·

To label, enhance, and clarify the problem definition.

·

To create graphic objects which can be used as guide lines for developing the finite element mesh.

The Sketch menu commands are: ·

Lines Sketches straight lines. For more information about this command, see Sketch Lines in this chapter.

·

Circles Sketches circles. For more information about this command, see Sketch Circles in this chapter.

·

Arcs Sketches arcs. For more information about this command, see Sketch Arcs in this chapter.

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Text Adds project labels or text labels to the drawing. For more information about this command, see Sketch Text in this chapter.

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Axes Sketches axes around a section of the drawing. For more information about this command, see Sketch Axes in this chapter.

Sketch Lines Sketches straight lines. Ø

To sketch a line on the drawing: 1. Choose the Sketch Lines command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Sketch Lines" is the current mode. 2. Click at the starting point of the line. As you move the cursor, a black line appears, indicating you are sketching a line. 3. Click at the next point of the line. 4. Click at all remaining points on the line if you are not sketching a straight line. 5. Click the right mouse button to finish sketching lines.

Comments If the Snap Grid button in the Grid toolbar is selected, the cursor will snap to a grid point each time you click at a point. Lines can be moved, resized, or deleted using the Modify Objects command.

Sketch Circles Sketches circles. Ø

To sketch a circle on the drawing: 1. Choose the Sketch Circles command from either the DEFINE menu or from the Mode toolbar.

GEO-SLOPE Office 5 183 The cursor changes from an arrow to a cross-hair and the status bar indicates that "Sketch Circles" is the current mode. 2. Click at the center point of the circle. As you move the cursor, a circle appears, indicating you are defining the radius of the circle. 3. Click at the desired radius of the circle. The circle is drawn. 4. Repeat Steps 2 to 3 for as many circles as you wish to sketch. 5. Press ESC or click the right mouse button to finish sketching circles.

Comments If the Snap Grid button in the Grid toolbar is selected, the cursor will snap to a grid point each time you click at a point. Circles can be moved, resized, or deleted using the Modify Objects command.

Sketch Arcs Sketches arcs. Ø

To sketch an arc on the drawing: 1. Choose the Sketch Arcs command from either the DEFINE menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair andthe status bar indicates that “Sketch Arcs” is the current mode 2. Click at the center point of the arc. As you move the cursor, a circle appears, indicatingyou are defining the radius and first endpoint of the arc. 3. Click at the first endpoint of the arc. A line is drawn from the center of the arc to the firstendpoint. As you move the cursor, another line appears, indicating you aredefining the second endpoint of the arc. 4. Move the cursor counterclockwise aroundthe circle and click at the second endpoint of the arc. An arc is drawn from the first endpointcounterclockwise to the second endpoint. 5. Repeat Steps 2 to 4 for as many arcs as youwish to sketch. 6. Press ESC or click the right mouse button tofinish sketching arcs.

Comments If the Snap Grid button in the Grid toolbar is selected, the cursor will snap to a grid point each time you click at a point. Arcs can be moved, resized, or deleted using the Modify Objects command.

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Sketch Text Adds project labels or text labels to the drawing. The Sketch Text command can be used to place the following types of text labels on your drawing:

Ø

·

Plain Text Label Allows you to type any text and place it on the drawing. You can also import text from other Windows applications via the Windows clipboard and place it on your drawing.

·

Project ID Label Allows you to label the drawing with the current project settings. When you change the project settings using KeyIn Analysis Settings, the corresponding label will be updated automatically with the new project information.

To place a plain text label on the drawing: 1. Choose the Text command from either the Sketch menu or from the Mode toolbar. The following dialog box appears:

2. Select the Text tab at the top of the dialog box, if it isn’t already selected. An edit window is displayed in the dialog box. 3. In the edit window, type the text that you wish to sketch. You can type more than one line of text by pressing the ENTER key after each line. 4. If you wish to sketch text that is in the Windows Clipboard, click the right mouse button in the edit window and select Paste from the pop-up menu; any text in the Windows Clipboard is displayed in the Sketch Text edit window. This feature allows you to place text from another Windows application, such as a word processor, into SEEP/W. You can also copy the text in the edit window to the Windows Clipboard by selecting the text, clicking the right mouse button in the edit window, and selecting Copy from the pop-up menu. 5. Specify the text orientation by selecting Horizontal or Vertical. 6. Move the cursor into the SEEP/W window and click at the position where you wish the text to appear.

GEO-SLOPE Office 5 185 The text label is placed above and to the right of the selected position, if the label orientation is horizontal; a vertical label is placed above and to the left of the selected position. The text font information is displayed in the dialog box underneath the Font button. 7. Repeat Step 6 if you wish to place the text at another position on the drawing. 8. To finish placing text, press ESC or select another operating mode from the Mode toolbar. Ø

To place a Project ID label on the drawing: 1. Choose the Text command from either the Sketch menu or from the Mode toolbar. The Sketch Text dialog box appears. 2. Select the Project ID tab at the top of the dialog box, if it isn’t already selected. The Project ID information is displayed in the dialog box as follows:

3. In the Settings list box, check the box next to each parameter that you wish to include in the Project ID label. 4. To change the title for a parameter, select the parameter in the Settings list box and then type a new title in the Title edit box. You can display a parameter without any title by removing the text from the Title edit box. 5. To change the separator between a parameter and its title, type a new character (or several characters) in the Sep. edit box. The new separator will be used for each parameter in the Project ID label. 6. To reset all parameter titles to the default titles, select the Reset Titles button. 7. To copy the current Project ID label to the Windows clipboard, select the Copy button. You can then paste the Project ID label into other Windows applications. 8. Specify the text orientation by selecting Horizontal or Vertical. 9. Move the cursor into the SEEP/W window and click at the position where you wish the Project ID label to appear.

186 SEEP/W The Project ID label is placed above and to the right of the selected position, if the label orientation is horizontal; a vertical label is placed above and to the left of the selected position. The text font information is displayed in the dialog box underneath the Font button. 10. Repeat Step 9 if you wish to place the Project ID label at another position on the drawing. 11. To finish placing text, press ESC or select another operating mode from the Mode toolbar. NOTE: If you change your project settings, your Project ID label will be automatically updated to show the current project settings. You can use KeyIn Analysis Settings or File Save As to change the project settings. Ø

To change the font of the text label: 1. In the Sketch Text dialog box, click on the Font button to change the text font. The following dialog box appears:

All the fonts that are currently installed in Windows are displayed in the Font list box. To install or delete fonts, you must use the Windows Control Panel. See the Windows online help for more information on Control Panel. 2. Select the desired font in the Font list box and style in the Font Style list box. 3. Select a point size from the Size list box or type any point size in the Size edit box. Points are the units commonly used for font size (72 points is equal to 1 inch). The point size that you enter represents the height of the text at a zoom factor of 1.0. 4 Select OK to return to the Sketch Text dialog box. The name and size of the selected font is displayed underneath the Font button. 5. Move the cursor into the SEEP/W window and click at the position where you wish the text label to

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appear. The text label is placed on the drawing using the selected font.

Comments Text labels can be moved, resized, or deleted using the Modify Objects command. Text labels can be changed using the Modify Text command. If you modify a Project ID label, you can add or remove any of the project settings that are displayed on the label. If the Snap Grid button in the Grid toolbar is selected, the cursor will snap to a grid point each time you click at a point.

Sketch Axes Sketches axes surrounding a section of the drawing. Sketching an axis on the drawing facilitates viewing the drawing and interpreting the drawing after it is printed. Ø

To sketch axes: 1. Choose the Sketch Axes command from either the DEFINE menu or from the Mode toolbar. The following dialog box appears:

2. In the Display group box, check axes that you wish to sketch. If all four sides are selected, the axes will form a box. 3. Check the Axis Numbers check box if you desire each tick mark on the axis to be labelled with its value. 4. Type an appropriate title for the bottom X-axis in the Bottom X edit box, if desired. 5. Type an appropriate title for the left Y-axis in the Left Y edit box, if desired. 6. Select OK. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Sketch Axes" is the current mode. 7. To define the rectangular region over which to sketch the axes, hold the left mouse button down at the top-left corner of the axes region, but do not release it. As you move the mouse, a rectangle appears.

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8. Drag the mouse to the bottom-right corner of the axes region and release the left mouse button. Axes are generated within the region.

Comments The number of increments along each axis is calculated by SEEP/W when the axes are generated. Choose the Set Axes command if you wish to override these values. If the Snap Grid button in the Grid toolbar is selected, the cursor will snap to a grid point each time you click at a point. This is useful for sketching an axis with exact increments. Axes can be moved, resized, or deleted using the Modify Objects command. The View Preferences command allows you to change the font and the size of the axes numbers and labels.

The Modify Menu Use the Modify menu to move, resize, or delete any group of selected objects or to change text items on the drawing. ·

Objects Moves, resizes, or deletes any group of selected objects, such as nodes, elements, the infinite element pole or sketch objects. For more information about this command, see Modify Objects in this chapter.

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Text Changes text labels that were placed on the drawing using the Sketch Text command. For more information about this command, see Modify Text in this chapter.

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Pictures Changes the ordering, file name, or scale of any picture imported with the File Import: Picture command. For more information about this command, see Modify Pictures in this chapter.

Modify Objects Moves, re-sizes, or deletes any group of selected objects, such as nodes, elements, the infinite element pole or sketch objects. Modify Objects is a powerful command that allows you to select any combination of objects on the drawing for moving, resizing, or deletion. Objects are defined as any item displayed on the drawing at specified engineering coordinates. Object types used in DEFINE are nodes, elements, text, lines, circles, arcs, flux sections, scaled axes, initial water table, and the infinite element pole. In CONTOUR, you can only modify Sketch objects and the axes. This command provides an interactive method of changing the engineering coordinates of any object or group of objects. For example, if you wish to make an element wider, you do not have to delete the element and redraw it; instead, you can select the element using Modify Objects and then stretch it to the desired width.

GEO-SLOPE Office 5 189 When you choose Modify Objects, the following dialog box appears:

Move Selection by X The x-distance, in engineering coordinates, to move the selected objects. Move Selection by Y The y-distance, in engineering coordinates, to move the selected objects. Move When this button is pressed, the selected objects are moved by the distance specified in the X and Y edit boxes. Auto-Fit Page When this option is checked and any objects are moved or scaled, the working area page size changes, if necessary, to encompass any objects that lie outside of the working area. If all objects are moved outside the working area, then the working area moves with the objects but doesn’t change in size. Select All When this button is pressed, all objects currently displayed on the drawing are selected. If you wish to select all objects of a specific type, such as elements, then use the View Preferences toolbar to only view elements and then press Select All. Delete When this button is pressed, all selected objects are deleted from the problem. Done When this button is pressed, you are exited from the Modify Objects operating mode. Alternatively, you can press the ESC key or select another operating mode from the Mode toolbar. Ø

To modify objects: 1. Choose the Modify Objects command from either the DEFINE menu or from the Mode toolbar. The cursor changes from a white arrow to a black arrow, the status bar indicates that "Modify Objects" is the current operating mode, and the Modify Objects dialog box appears. 2. In the DEFINE window, select the objects to modify using the left mouse button. 3. Apply the desired action to the selected objects, such as moving, scaling, or deleting them. For example, to delete the selected objects, select Delete in the dialog box or press the DELETE key on the keyboard. 4. To undo the last action, select Edit Undo in the menu or toolbar or press CTRL-Z on the keyboard. For example, if you deleted a group of objects and then select Undo, the objects will reappear. 5. If necessary, repeat Steps 2 to 4 for all objects that you wish to modify. 6. Select Done or press the ESC key to finish modifying objects.

Selecting Objects Ø

To select objects: ·

Click on any object with the left mouse button; the object is selected.

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-- or -·

Hold down the left mouse button and drag a rectangle around a group of objects; all objects completely inside the rectangle are selected. -- or --

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Click on the Select All button in the dialog box; all objects currently displayed on the drawing are selected. -- or --

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Select a series of nodes along a straight line by holding down the SHIFT key and clicking on the first and last nodes in the line; all nodes that lie along the line are selected.

Each time a new selection is made, all other objects are unselected. If you wish to keep the previous object selection, hold down the CTRL key while you select more objects. Selected objects are highlighted with a graphic symbol, usually a hollow rectangle; selected nodes are displayed as large rectangles, however, and selected elements are cross-hatched. Handles are drawn around the boundary of all selected objects - at the corners and at each side in between. These handles are used to resize and reshape the selected objects. TIP: When several objects are displayed on top of each other, it can be difficult to select the desired object. Use the View Preferences Toolbar to hide or show only the object types that you wish to modify. For example, before moving a sketch line, uncheck the View Nodes and View Elements toolbar buttons to hide the nodes and elements; this will prevent you from inadvertently selecting nodes or elements when you are trying to select sketch lines.

Moving Objects Ø

To move objects: ·

Click on any unselected object, holding down the left mouse button, and drag the object to its new position. A dashed, rectangular border appears around the selected object and moves as you drag the object. -- or --

·

Click down on an object that is already selected and drag the selected objects to their new positions. A dashed, rectangular border appears around the group of selected objects and moves as you drag the objects. -- or --

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In the Modify Objects dialog box, type in the x- and y-distance (in engineering coordinates) to move all selected objects and press the Move button.

If the background grid is turned on, the selected object being dragged by the mouse will be snapped to the closest grid point when the left mouse button is released. For objects such as elements and sketch lines, the corner of the object that is nearest to the mouse cursor is snapped to the closest grid point; for text items, the bottom-left corner of the text is snapped to the grid point; for circles and arcs, the center is snapped to the grid point. Ø

To move the entire drawing a specified distance: 1. Make sure all object types are currently displayed in the View Preferences toolbar or dialog box.

GEO-SLOPE Office 5 191 2. In the Modify Objects dialog box, press the Select All button. All objects on the drawing are selected. 3. In the Move Selection By edit boxes, type the x- and y-distance, in engineering coordinates, to move the drawing. For example, if you defined your problem at an origin of (0,0) and wish to change the elevation at the origin to 400 meters, type 400 in the Y edit box. 4. Make sure the Auto-Fit Page option is checked in the dialog box. 5. Press the Move button. All objects in the drawing are moved by the specified distance, and the working area is adjusted as necessary to fit around all objects in the drawing.

Resizing Objects Ø

To resize objects: 1. Select the objects to resize. 2. Click down on one of the eight handles displayed around the selected objects. The cursor changes to an arrow, indicating the direction in which the objects will be scaled. A dashed, rectangular boundary is displayed around the selected objects. 3. Drag the mouse in the desired direction. As you drag, the rectangular boundary is resized. 4. Release the left mouse button when you are satisfied with the new scale. All the selected objects are modified to fit inside the new rectangular boundary. 5. If you wish to return the selected objects to their previous size, select Edit Undo in the menu or toolbar or press CTRL-Z on the keyboard.

Deleting Objects Ø

To delete objects: 1. Select the objects to delete. 2. To delete the objects, press the DELETE key or press the Delete button in the dialog box. All the selected objects are deleted from the problem. 3. If you wish to recreate the deleted objects, select Edit Undo in the menu or toolbar or press CTRL-Z on the keyboard. Deleting elements requires you to select the elements without selecting any nodes. Otherwise, the element nodes will be deleted, resulting in adjacent elements also being deleted.

Ø

To delete elements: 1. Turn off the display of nodes by unchecking the View Nodes button in the View Preferences toolbar. 2. Select the desired elements. 3. To delete the selected elements, press the DELETE key or press the Delete button in the dialog box.

Modify Text Changes text labels that were placed on the drawing using the Sketch Text command.

192 SEEP/W Ø

To modify text: 1. Choose the Text command from either the Modify menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Modify Text" is the current operating mode. 2. Click the left mouse button inside a text label on the drawing that you wish to modify. If you clicked on a plain text label, the following dialog box appears:

If you clicked on a Project ID label, the following dialog box appears:

3. Change any of the text label information. For information on how to change each type of text label, see the Sketch Text section. 4. Select OK when you are finished changing the text label information. The text is redrawn to reflect the changes made.

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5. Repeat Steps 2 to 4 for each text label to modify. 6. To finish modifying text, press the ESC key or select another operating mode from the Mode toolbar.

Modify Pictures Changes the ordering, file name, or scale of any picture imported with the File Import: Picture command. The Modify Pictures command allows you to change the following attributes of imported pictures: ·

The order in which pictures are displayed on the drawing can be changed. This is useful if a picture overlaps with another picture or with part of the drawing.

·

The file name that a picture is linked to can be changed. This is useful if you wish to rename or move the linked file or if you have an updated file that you wish to link the picture to.

·

The scale (i.e., the size) of a picture can be changed by mapping engineering coordinates on the picture to coordinates on the drawing. This is useful if you have imported a picture of your seepage problem and you wish to define your SEEP/W mesh on top of the imported picture.

If you wish to move a picture or change its size, choose the Modify Objects command. The Modify Pictures command is disabled if no pictures were previously imported with the File Import: Picture command. Ø

To select a picture to modify: 1. Choose the Pictures command from either the Modify menu or from the Mode toolbar. The cursor changes to a black selection arrow and the status bar indicates that "Modify Pictures" is the current operating mode. The following dialog box appears:

The Picture Files list box displays a list of the imported pictures. The SEEP/W Objects item is displayed so that you can move a picture in front of or behind the rest of the SEEP/W drawing. 2. To see all the picture file information, re-size the dialog box by dragging one of the window edges until all the information is displayed in the Picture Files list box. 3. Select the picture that you wish to modify. You can either select the picture file name in the dialog box or you can click on the picture itself in the SEEP/W window. A rectangle is drawn around the selected picture in the SEEP/W window.

194 SEEP/W Ø

To change the order in which the selected picture is displayed on the drawing: 1. If the selected picture is obscured by other objects on the drawing, select the Up button to display it on top of other pictures in the drawing. Each time you move the picture up in the list, it is redrawn in the SEEP/W window. You can continue selecting Up until the picture is displayed on top of all other objects, including the SEEP/W drawing itself. 2. Select Down if you wish to move the picture towards the back of the drawing.

Ø

To change the file name that the selected picture is linked to: 1. Once you have selected a picture, click on the Link button in the Modify Pictures dialog box. The following dialog box appears:

NOTE: The SEEP/W Link Picture dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window. 2. Select the new file name that you wish to link to the picture. In the Files of Type drop-down list box, select the format of the picture files you wish to display. 3. Once you have specify the new picture file name in the File Name edit box, select Open. The new file name for the selected picture is displayed in the Modify Pictures dialog box. The new picture is shown on the SEEP/W drawing. Ø

To scale the selected picture to match the current engineering scale: Scaling a picture is useful when you have imported a picture of your problem and you wish to define your SEEP/W mesh on top of the imported picture. 1. Once you have selected a picture, click on the Scale button in the Modify Pictures dialog box.

GEO-SLOPE Office 5 195 The following dialog box appears, and the cursor changes to a cross-hair, indicating that you need to locate two reference points on the picture:

2. Click on the selected picture to define Point A, the first reference point. Once you have defined Point A, its SEEP/W engineering coordinates are displayed in the Point A edit boxes. The reference point is marked on the drawing with the letter A and a cross-hair. NOTE: Typically, Point A should be located near the lower-left corner of the picture at a position where you know the engineering coordinates on the picture. For example, if you have imported a picture of a seepage problem that was created from an origin of (0,0), define Point A at the (0,0) position on the picture. (The actual SEEP/W engineering coordinates of Point A, as displayed in the Modify Pictures dialog box, will be different; for example, they may be shown in the edit boxes as (2,2).) 3. Click on the selected picture to define Point B, the second reference point. The engineering coordinates of the second reference point are displayed in the Point B edit boxes. The second reference point is marked on the drawing with the letter B and a cross-hair. Once you have defined Point B, its SEEP/W engineering coordinates are displayed in the Point B edit boxes. The reference point is marked on the drawing with the letter B and a cross-hair. NOTE: Typically, Point B should be located near the upper-right corner of the picture at a position where you know the engineering coordinates on the picture. For example, if you have imported a picture of a problem that extends to an elevation of 15 and a width of 20, define Point B at the (15,20) position on the picture. (The actual SEEP/W engineering coordinates of Point B, as displayed in the Modify Pictures dialog box, will be different; for example, they may be shown in the edit boxes as (30,40).) 4. Type the new coordinates for Point A in the corresponding X and Y edit boxes. For example, if you defined Point A at the (0,0) coordinate on the picture, enter (0,0) as the new coordinates for Point A. 5. Type the new coordinates for Point B in the corresponding X and Y edit boxes. For example, if you defined Point B at the (15,20) coordinate on the picture, enter (15,20) as the new coordinates for Point A. 6. Select the Apply button to resize or move the picture. SEEP/W matches Point A and B on the picture to their new coordinates. For example, assume that Point A on the picture is located at (2,2) on the drawing and Point B is located at (30,40). You have just entered (0,0) as the new coordinates for Point A and (15,20) as the new coordinates for Point B. When you click on Apply, the picture is moved and resized so that Point A on the picture is now located at (0,0) and Point B is now located at (15,20). You can verify that this is true by moving your

196 SEEP/W cursor above Point A on the picture and checking that the SEEP/W status bar displays an X and Y position of (0,0). 7. If the picture was not scaled properly, repeat Steps 4 to 6 in order to enter new coordinates for Point A and B. If you need to reposition the picture reference points, repeat Steps 2 to 6. 8. When you are satisfied with the scaled picture, select the Close button in order to return to the Modify Pictures dialog box. Ø

To delete a selected picture from the drawing: ·

Ø

Select the Delete button in the Modify Pictures dialog box. The picture will be removed from the drawing and from the Picture Files list box.

To import a new picture into the drawing: ·

Select the Import button in the Modify Pictures dialog box. This button is a shortcut for the File Import: Picture command. See this command for more information on importing a picture into the drawing. Once you have placed the imported picture into the drawing, the picture file name will be displayed in the Modify Pictures dialog box.

NOTE: Once you are finished modifying pictures, be sure to press the OK button in the dialog box to save your changes. All changes made to the pictures will be lost if you select Cancel, press the ESC key, or select another operating mode from the Mode toolbar.

The Tools Menu Use the Tools menu to perform tasks such as verification and/or sorting of nodes and elements and switching to SOLVE or CONTOUR. ·

Verify/Sort Verifies the correctness of the node and element data and sorts the node and element numbers vertically or horizontally. For more information about this command, see Tools Verify/Sort in this chapter.

·

SOLVE Launches SOLVE and opens the file currently being edited in DEFINE. For more information about this command, see Tools SOLVE in this chapter.

·

CONTOUR Launches CONTOUR and opens the file currently being edited in DEFINE. For more information about this command, see Tools CONTOUR in this chapter.

·

Options Provides options for automatically launching and closing SOLVE, setting the Undo/Redo levels. For more information about this command, see Tools Options in this chapter.

Tools Verify/Sort Verifies the correctness of the node and element data and sorts the node and element numbers vertically or horizontally. Ø

To verify or sort the node and element data: 1. Choose the Tools Verify/Sort command from either the DEFINE menu or from the Standard toolbar. The following dialog box appears:

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2. In the Sort drop-down list box, select the sort direction. Select Vertically if the horizontal dimension of your mesh is greater than the vertical dimension; select Horizontally if your mesh has a vertical dimension greater than its horizontal dimension. NOTE: Sorting in the direction of the minimum problem dimension minimizes the node number difference within each element; this reduces the memory requirements in SOLVE. Keeping the node number difference in an element to the lowest possible also minimizes round-off errors when solving the finite element equations. So even if your computer has lots of memory, you should nonetheless always sort the mesh so that the nodal difference is as low as possible. 3. Select the Verify/Sort button to verify and sort the mesh in the specified sort direction Messages appear in the Information list box stating which verification or sorting step is being performed. Error messages will also appear in the list box as necessary. Select Stop if you wish to stop the verification or sorting. A beep is sounded when the verification and sorting is finished. SEEP/W performs the following steps when sorting the data: 1. Elements are deleted if they contain node numbers that are non-existent. 2. The node numbers are sorted vertically or horizontally. The node numbers are sorted vertically by using the x-coordinate as the primary key and the y-coordinate as the secondary key for all nodes with equal x-coordinates. The node numbers are sorted horizontally by using the y-coordinate as the primary key and the x-coordinate as the secondary key for all nodes with equal y-coordinates. 3. The element numbers are sorted vertically or horizontally. The element numbers are sorted vertically by using the x-coordinate of the first node as the primary key and the y-coordinate of the first node as the secondary key for all elements with equal x coordinates. The element numbers are sorted horizontally by using the y-coordinate of the first node as the primary key and the x-coordinate of the first node as the secondary key for all elements with equal y-coordinates. 4. Duplicate nodes with the same x-y coordinates are merged into one node. 5. Any duplicate edges are merged into one edge. 6. Node numbers are compressed into a continuous sequence. 7. Element numbers are compressed into a continuous sequence.

198 SEEP/W SEEP/W performs the following steps when verifying the data: 1. SEEP/W verifies that every node is attached to at least one element and that every element contains unique node numbers. You should delete any nodes that are "free" by choosing the Modify Objects command or the KeyIn Nodes command. 2. SEEP/W verifies that all infinite elements are 8-noded quadrilaterals, adding secondary nodes to each infinite element as necessary. The ordering of nodes within each infinite element is also reset, if necessary, so that the first and fourth element nodes lie along the infinite edge. Corner elements with two infinite edges are numbered such that the first element node lies on both infinite edges. 3. Element secondary nodes are deleted if they are not at the midpoint of the corner nodes. 4. If the edge along two adjoining elements contains a secondary node, SEEP/W checks that both elements contain the secondary node. If only one element contains the secondary node, the secondary node is added along the other element's side. 5. SEEP/W verifies element compatibility by checking that a node defined as a secondary node in a particular element cannot also be a primary node in another element. 6. The node number order around an element is arranged counterclockwise so that the computed area of the element is positive. If an element's computed area is 0, an error message is displayed. 7. SEEP/W verifies that the integration order is valid for the element type (quadrilateral or triangular). 8. SEEP/W verifies that all elements are not null elements.; at least one element must have an active material number assigned to it. 9. For a transient analysis, SEEP/W verifies that all materials have a volumetric water content function defined. 10. For axisymmetric and 2-dimensional analyses, SEEP/W checks that all q boundary nodes are attached to q boundary edges; any q boundary nodes not attached to q boundary edges are reset to have no boundary condition. 11. SEEP/W checks if a flux section passes through a node. A warning message is displayed if a node lies on a flux section. 12. If an initial water table exists, SEEP/W verifies that it does not reverse direction; that is, for every x coordinate on the initial water table, a unique y-coordinate must exist. 13. SEEP/W verifies the nodal coordinate range for the problem to check that SOLVE will not lose more than one significant digit of precision by floating point round-off error. SOLVE performs its computations using single precision floating point values, which carry at least 6 significant digits of precision. Many computations are performed in SOLVE by subtracting and adding nodal coordinates. If you define your problem, for example, from an elevation of 1000m to an elevation of 1020m, SOLVE will only be able to store the results to the second decimal place (e.g., 1009.01). If you re-define this same problem from 0m to 20m, SOLVE will be able to store the results to the fourth or fifth decimal place (e.g., 9.00001). For a more detailed discussion of floating point roundoff issues, see Mesh Design in Chapter 5. NOTE: Verify is a tool to help you with your mesh generation and problem definition. It is a very powerful and useful tool but it does not guarantee that you have an error free mesh or a perfect problem definition. In the end it is still up to you to ensure that the model is correct. Do not make the assumption that everything is perfect after you have run Verify.

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Tools SOLVE Launches SOLVE and opens the file currently being edited in DEFINE. The first time that you choose the Tools SOLVE command, you are prompted to save the data file currently being edited in DEFINE; SOLVE will then run and will open this data file. To solve the problem, click on the Start button in the SOLVE window. The launched SOLVE window is linked to the DEFINE window. For example, the next time that you choose Tools SOLVE, the existing SOLVE window (with the current problem) is selected for you; a new copy of SOLVE is not started. If you open a new problem in DEFINE using File Open, the SOLVE window automatically opens the new problem as well. This allows you to use the Tools SOLVE command to easily switch between DEFINE and SOLVE for the same problem. If you do not want SOLVE to be linked to DEFINE, you can start the SOLVE program from the Windows Start menu. You can also run SOLVE from the command line, allowing you to create batch files that solve several problems one after the other. Since all problem settings are specified in DEFINE, SOLVE begins the solve process automatically as soon as it’s launched. See the Running SOLVE section for more information on SOLVE command line options. See the Tools Options command if you wish to automatically run the analysis and close the SOLVE window each time that you choose Tools SOLVE.

Comments You do not need to launch SOLVE each time you save your problem in DEFINE; SOLVE will read the new problem data files each time you press the Start button to begin the problem analysis.

Tools CONTOUR Launches CONTOUR and opens the file currently being edited in DEFINE. The first time that you choose the Tools CONTOUR command, you are prompted to save the data file currently being edited in DEFINE; CONTOUR will then run and display the results for this data file. The launched CONTOUR window is linked to the DEFINE window. For example, the next time that you choose Tools CONTOUR, the existing CONTOUR window (with the current problem) is selected for you; a new copy of CONTOUR is not started. If you open a new problem in DEFINE using File Open, the CONTOUR window automatically opens the new problem as well. This allows you to use the Tools CONTOUR command to easily switch between DEFINE and CONTOUR for the same problem. If you do not want CONTOUR to be linked to DEFINE, you can start the CONTOUR program from the Windows Start menu.

Comments Each time you save your problem in DEFINE, the CONTOUR window title bar will display a message indicating that the displayed results are now out of date. This is because the DEFINE data file contains new information not analyzed by SOLVE. To remove this message, use the Tools SOLVE command to run SOLVE; the CONTOUR window will then be automatically updated with the new results.

Tools Options Set the preferences for launching SOLVE and the Undo/Redo levels.

200 SEEP/W When you choose Tools Options, the following dialog box appears:

To set the options: 1. Check "Automatically start solving" if you want SOLVE to automatically solve the problem when you select the Tools SOLVE command. This will over-write all previous results for the problem. 2. Check "Automatically close when done" if you want SOLVE to close automatically when it is finished solving. 3. In the "Undo/Redo levels" edit box, enter the maximum number of commands that you wish to store in the Undo/Redo command list. You can then undo and redo these commands using Edit Undo and Edit Redo. There is no limit on the number of commands in the Undo/Redo list.

The Help Menu The Help menu commands are: ·

Help Topics Displays on-line help. Use the Help Topics command to access the on-line help system. Help topics may be accessed from the table of contents, from an index, or by searching for specific words. For more information on using Windows help, see the Windows documentation.

·

Using Help Displays the help system with information about using the on-line help system. For more information about using on-line help, see Using Online Help in Chapter 2.

·

About SEEP/W Displays information about SEEP/W, such as the version and serial number. Use the System Information button in the About dialog box to quickly display information about your computer, such as the version of Windows, the processor type, and the amount of memory.

Chapter 5 SOLVE Reference Introduction SOLVE is the function that computes the finite element solution after the problem has been defined with the DEFINE function. SOLVE reads the data file created by DEFINE and stores the results in a series of files. The SOLVE window does not display a drawing of the problem, like other SEEP/W functions, but instead displays a dialog box for controlling the solving process.

This chapter describes the following: ·

How to run SOLVE.

·

The information displayed during the processing.

·

The output files created by SOLVE.

The File Menu The File menu commands are: ·

New Initializes SOLVE for starting a new analysis. The File New command clears all file names and settings in SOLVE. New has the same action as quitting SOLVE and then restarting SOLVE.

·

Open Data File Selects the DEFINE data file to solve. For more information about this command, see File Open Data File in this chapter.

202 SEEP/W

·

Exit Quits SEEP/W SOLVE but does not quit Windows.

File Open Data File Selects the DEFINE data file to solve. The File Open Data File command is disabled if you have started SOLVE from DEFINE; you can solve a new problem by opening the problem in DEFINE with File Open, and SOLVE will automatically open the problem as well.

To open the SEEP/W data file if SOLVE launched without DEFINE: When you choose File Open Data File, the following dialog box appears:

·

Type a name in the File Name edit box and then press Open. The file name may include a directory and a path. The file name extension must be omitted or entered either SEP or SEZ. -- or --

·

Click on a file name in the list box and then press Open. -- or --

· Ø

Double-click on a file name in the list box.

To change the current directory or drive: ·

Use the Look In box to select the drive and directory.

Files Read by SOLVE Only the specified SEP data file is read, and not the secondary SE2 file. The SEP file contains the data required for the finite element calculations, while the SE2 file contains graphical data not required by SOLVE. Please note that when a .SEZ file is selected, SEEP/W automatically unzips the .SEZ file to read in the .SEP data file. When the analysis is completed, SEEP/W then zips the data file and all output file together to form the .SEZ file. Using the .SEZ file format make project and file management easy, this is particularly true in the cases of transient analysis.

The Help Menu The commands available in the SOLVE Help menu operate identically to those available in the DEFINE

GEO-SLOPE Office 5 203 Help menu. For more information about this menu and its commands, see The Help Menu in Chapter 4.

Running SOLVE Running an analysis from the SOLVE window The SOLVE window can be launched from DEFINE using the Tools SOLVE command or it can be run from the Windows Start menu. 1. Open the DEFINE data file by choosing File Open Data File. 2. Click the Start button in the SOLVE window to start processing the solution. When the processing starts, the Stop button becomes active and the Start button is grayed. A green dot starts flashing between the Start and Stop buttons. The processing can be halted at any time by clicking the Stop button.

Running an analysis from the command line You can automate the analysis of many SEEP/W problems by running SOLVE from the command line or in a batch file. For example, if you have 5 large problems to analyze, you could create a batch file that runs each problem, and then start the batch file before leaving your computer. Using batch files requires that you know how to use a command window; for more information on the command window, please consult your Windows documentation. The following options can be used with SEEP2 on the command line: - s: starts solving the analysis as soon as the file is opened - x: closes SOLVE as soon as the analysis is completed Ø

To run an analysis from the command line: 1. Open a command window in Windows. 2. Make sure that your PATH environment variable includes the folder where SOLVE exists. For example, at the command line, type: PATH=%PATH%;"C:\Program Files\GEO-SLOPE\OfficeV5\Bin" 3. Type "SEEP2" followed by the options and filename that you wish to analyze. For example, at the command line, type: SEEP2 -s -x C:\MyData\MyExample.sez To run many analyses from a batch file: 1. Create a batch file with commands to solve each analysis. For example: SEEP2 SEEP2 SEEP2 SEEP2

-s -s -s -s

-x -x -x -x

C:\MyData\MyExample1.sez C:\MyData\MyExample2.sez C:\MyData\MyExample3.sez C:\MyData\MyExample4.sez

2. Save the batch file and run it. The SOLVE window lists the data file and initial conditions file(s) as specified in DEFINE. While the calculations are in progress, the SOLVE window also displays information about the convergence

204 SEEP/W progress of the solution, the position in the time sequence if it is a transient analysis, and the boundary conditions that are being reviewed and adjusted.

Step # Step number is the position in the time sequence. For a steady-state analysis, Step # is 0 (zero). Review # Review number is the number of times the review boundary conditions have been adjusted within the current time step. Iteration # Iteration number is the number of times the finite element equations are solved during the iteration process. Residual The iteration process is controlled by the residual of the head vector. The Residual is defined as:

(5.1) where: R = residual n = total number of nodes j = node number Dh = nodal total head difference between two consecutive iterations The residual is a measure of the size of the total head difference between iterations. In a normal convergence process, the residual will be decreasing and approaching a zero value. The solution is deemed to have converged when the residual is less than a user-specified convergence tolerance.

GEO-SLOPE Office 5 205 When analyzing problems with potential seepage boundaries, a converged solution is reviewed to check if a seepage face has developed on potential seepage boundaries. As a result, boundary conditions on potential seepage boundaries may be adjusted, and the iteration process may be repeated until all potential seepage boundaries satisfy the adaptive iteration. The processing continues until the following conditions are met: ·

The solution converges or reaches the maximum specified number of iterations.

·

All boundary conditions are reviewed and adjusted. After the solution has converged or reached the maximum specified number of iterations, SOLVE reviews and adjusts the boundary conditions, if necessary. SOLVE displays a message indicating how the boundary conditions are modified at each node. A typical message is: Node 20 adjusted to H = 2.5000E+000.

·

The step number reaches the end of the time sequence (in the case of a transient analysis).

Nodes connected only to null elements (no conductivity function) are not included in the vector norm calculation. Time Step Information For a transient analysis with adaptive time stepping, the current time step, the current elapsed time, and the target elapsed time are also displayed. The target elapsed time is the value entered by the user when the time steps were set up. Adaptive time steps are inserted between target time steps if necessary. If no adaptive time stepping is activated, the current elapsed time will always equal the target elapsed time since no extra time steps are added during the solve process. At the start of an analysis, SOLVE deletes all old output files in the current directory with the same problem name as the current DEFINE data file name. This is to prevent any mix up of output files between different runs. If you want to keep the solutions from previous runs, you should use different problem names for different runs. When the processing is finished, the green dot between the Start and Stop buttons stops flashing and a beep is sounded. The Stop button can be used at any time to stop the problem analysis. When the Stop button is clicked, SOLVE halts the analysis without storing the results for the current time step. The Halt Iteration button can be used at any time to stop the iteration process. When the Halt Iteration button is clicked, SOLVE stores the computed results for the most recent time step iteration. For more information about this feature, see Halt Iteration in this chapter. The Graph button can be used to graphically display the SOLVE convergence process. When the Graph button is clicked, a window is displayed showing a plot of the Residual versus Iteration Number or K versus Suction. These graphs are useful in determining if a solution has been converged. For more information about this feature, see Graph. in this chapter.

Stop-Restart SEEP/W has a powerful Stop-Restart feature. The processing may be stopped at any time step and then restarted after making changes in the problem. For example, consider a transient problem with 10 time steps, and that you click the Stop button after the 5th time step is complete. You can then make changes with DEFINE and re-save the problem.

206 SEEP/W Ø

To restart the SOLVE processing at the 6th time step: 1. Open the data file in DEFINE, Choose KeyIn Analysis Settings and from the Type tab, set the Starting Time Step to Step 6. SEEP/W will automatically select the initial conditions files for the previous step, Step 5, as shown below:

2. Click the Start button to continue the analysis at Step 6.

Halt Iteration The iteration process for the current time step can be halted by clicking the Halt Iteration button. SOLVE uses the results from the last iteration to create the output files (if necessary) for the current time step; if you are running a transient analysis, SOLVE then continues analyzing the next time step. To halt a transient analysis at the current time step, you should press the Halt Iteration button and wait until the next time step is being analyzed; then, press the Stop button. This allows SOLVE to create the necessary output files for the current time step. If you press the Stop button before the next time step is processed, the analysis may be stopped before SOLVE can create the output files. To restart the analysis at the next time step (e.g., Step 6), you must choose KeyIn Analysis Settings in DEFINE and select Step 6 as the starting time. See the Stop-Restart section for more information.

GEO-SLOPE Office 5 207

Comments The iteration number is reset to 1 after you restart the processing.

Graph Viewing the Graph By clicking the Graph button in the solve window, a K versus Suction graph is shown. Alternatively, under the set menu, you may choose to view a Residual versus Iteration graph. Both these graphs are particularly useful when you are analyzing highly nonlinear flow problems (i.e., problems with steep conductivity functions). The graphs can be displayed and updated as the problem is being analyzed, or you can open a data file and display the graph for a previously-computed problem. The estimated hydraulic conductivity at a Gauss point can be quite different than the actual K function specified by the users. When the iteration process converged, however, the estimated K will be very close to the specified K function. A plot of K versus Suction serves as a handle tool to judge if a solution has converged. Similarly, the residual may oscillate substantially at the beginning of the iteration process. A plot of the Residual versus Iteration # makes it possible to graphically watch the convergence process and visually judge the convergence. Figure 5.1 shows the convergence graph for KISCH.SEP, one of the SEEP/W example problems that has a steep conductivity function. Figure 5.1 K versus Suction Graph

208 SEEP/W Figure 5.2 Residual versus Iteration Graph

The Graph window contains a menu with the following commands: ·

File Print Prints the graph on the default printer. The default printer is specified with the Windows Control Panel Application.

·

File Close Closes the Graph window.

·

Edit Copy Copies the graph to the Windows Clipboard for use in other Windows applications. For more information about copying to the clipboard, see Edit Copy All in Chapter 4.

·

Set Options Select type of graphs to be plotted and specifies the options to use when displaying the graph.

·

Update Updates the graph during the iteration process. The graph also can be updated automatically by using the Set Options command.

Changing the Graph Display Ø

To specify the graph display options: 1. Choose Set Options from the Graph window menu. The following dialog box appears:

GEO-SLOPE Office 5 209

2. To select a convergence graph type, select one of the three graph type options. 3. To specify the time step to plot, select the time step number from the Select Data drop-down list box. 4. To specify the range of iteration numbers to plot on the graph, type the starting and ending iteration numbers in the Select Data edit boxes. 5. If you are displaying the graph while SOLVE is analyzing the problem, select Manually or Automatically in the Update Graph group box. If the graph is updated manually, you must select Update! from the Graph menu whenever you want the graph redrawn to reflect all computed vector norms. If the graph is updated automatically, SOLVE will redraw the graph after every n iterations, where n is the value specified in the Update Graph edit box. SOLVE will compute the solution faster when the graph is updated less frequently, since less computer time is spent displaying the graph. 6. In the Display group box, select the graph display options. Check Symbols to display a symbol at each point, check Color to display a color plot, or check Thick Lines to display the plot as a thick line. 7. To change the font, select the Font button. The following dialog box appears:

210 SEEP/W

All the fonts that are currently installed in Windows are displayed in the Font list box. To install or delete fonts, you must use the Windows Control Panel. See the Windows documentation for more information on Control Panel. 8. Select the desired font in the Font list box and style in the Font Style list box. 9. Select a font size from the Size list box or type the desired font size in the Size edit box. The font size units are relative to the size of the Graph window (i.e., whenever the Graph window is enlarged, the text in the window is also enlarged). Select a font size that results in the graph titles being displayed at a suitable size. 10. Select OK when you have finished selecting the graph display options. The graph is redrawn using the new options.

Comments You can view the convergence graphs interactively while the problem is being analyzed, or you can view the convergence record after the processing has completed. This makes it possible to view the convergence record for any problem that has been solved. When a problem that uses review nodes is analyzed, the convergence record is reset to Iteration 1 whenever a node condition is reviewed. The convergence record for the entire time step can be viewed once the review process has completed.

Files Created The results from the SOLVE analysis are stored in a series of files. All files have the same prefix as the problem definition file created by DEFINE. The file name extension identifies the file type and the time step number. Table 5.1 lists the file types and file name extensions.

GEO-SLOPE Office 5 211 Table 5.1 SOLVE File Types and File Name Extensions File Type

File Name Extension

Problem Definition File

SEP

Head File

H??

Velocity File

V??

Material Properties File

M??

Flux File

F??

Convergence File

CNV

Initial Head File

HIN

Initial Velocity File

VIN

Initial Material Properties File

MIN

Initial Flux File

FIN

SEEP/W Zipped File

SEZ

The questions marks (??) are replaced by digits that represent the time step. The digits 00 mean the analysis is steady-state. The digits 01 mean the results are for Time Step 1, 02 for Time Step 2, 03 for Time Step 3, and so on. The SEZ file is an zipped version of the entire project, it contains the problem definition file and all the output files. Selecting the SEZ file format make project and file management easy, this is particularly true in the cases of transient analysis.

Head File The head (H) file lists the computed total head at each node, as well as the nodal flux (Q) and the sum of the seepage volume (VS) at each boundary node after a certain elapsed time. The sum of the seepage volume (VS) at each node is calculated as follows:

(5.2) where: n = time step number T = elapsed time Q = total flux VS = sum of the seepage volume For a steady-state analysis, since there is no time step, the sum of the seepage volume is zero. The VS information is required when a Head versus Volume boundary condition is selected in a transient analysis. The following illustrates the head file information: SEEP/W User's Guide Example Seepage through Earth Dam with Toe Drain DATESTAMP 7/17/01 TIMESTAMP 5:45:07 PM

212 SEEP/W 0

+0.0000E+000

= Step Number, Elapsed time

Node# Head Flux(Q) Sum_Volume ================================================== 1 +4.000000E+001 +3.440592E-006 +0.000000E+000 2 +3.997936E+001 +0.000000E+000 +0.000000E+000 3 +4.000000E+001 +5.816232E-005 +0.000000E+000 4 +3.984068E+001 +0.000000E+000 +0.000000E+000 5 +3.988453E+001 +0.000000E+000 +0.000000E+000 6 +4.000000E+001 +1.826675E-004 +0.000000E+000 7 +3.951929E+001 +0.000000E+000 +0.000000E+000 8 +3.957288E+001 +0.000000E+000 +0.000000E+000 9 +3.973953E+001 +0.000000E+000 +0.000000E+000 10 +4.000000E+001 +3.585010E-004 +0.000000E+000 11 +3.895414E+001 +0.000000E+000 +0.000000E+000 12 +3.901986E+001 +0.000000E+000 +0.000000E+000 13 +3.921607E+001 +0.000000E+000 +0.000000E+000 14 +3.955074E+001 +0.000000E+000 +0.000000E+000 15 +4.000000E+001 +5.806784E-004 +0.000000E+000 16 +3.809638E+001 +0.000000E+000 +0.000000E+000 17 +3.817135E+001 +0.000000E+000 +0.000000E+000 18 +3.839769E+001 +0.000000E+000 +0.000000E+000 19 +3.877648E+001 +0.000000E+000 +0.000000E+000 20 +3.931968E+001 +0.000000E+000 +0.000000E+000 21 +4.000000E+001 +8.505689E-004 +0.000000E+000 22 +3.690319E+001 +0.000000E+000 +0.000000E+000 23 +3.698563E+001 +0.000000E+000 +0.000000E+000 24 +3.723408E+001 +0.000000E+000 +0.000000E+000 25 +3.765310E+001 +0.000000E+000 +0.000000E+000 26 +3.824791E+001 +0.000000E+000 +0.000000E+000 27 +3.903902E+001 +0.000000E+000 +0.000000E+000 28 +4.000000E+001 +1.184364E-003 +0.000000E+000 29 +3.534204E+001 +0.000000E+000 +0.000000E+000 30 +3.542918E+001 +0.000000E+000 +0.000000E+000

Velocity File The velocity (V) file lists the velocity and hydraulic gradients for each Gauss integration point in each element. The following illustrates the velocity file information: SEEP/W User's Guide Example Seepage through Earth Dam with Toe Drain DATESTAMP 7/17/01 TIMESTAMP 5:45:07 PM 0 +0.0000E+000 = Step Number, Elapsed time Elem# Pnt# Velocity X Velocity Y Gradient X Gradient Y ====================================================================== 1 1 +1.376237E-006 -2.064355E-006 +2.752474E-003 -4.128710E-003 1 2 +1.376237E-006 -2.064355E-006 +2.752474E-003 -4.128710E-003 1 3 +1.376237E-006 -2.064355E-006 +2.752474E-003 -4.128710E-003 2 1 +8.917956E-006 -3.894003E-006 +1.783591E-002 -7.788006E-003 2 2 +8.025025E-006 -3.894003E-006 +1.605005E-002 -7.788006E-003 2 3 +8.025025E-006 -2.554608E-006 +1.605005E-002 -5.109216E-003 2 4 +8.917956E-006 -2.554608E-006 +1.783591E-002 -5.109216E-003 3 1 +7.698190E-006 -1.154729E-005 +1.539638E-002 -2.309457E-002 3 2 +7.698190E-006 -1.154729E-005 +1.539638E-002 -2.309457E-002 3 3 +7.698190E-006 -1.154729E-005 +1.539638E-002 -2.309457E-002 4 1 +2.128912E-005 -5.153527E-006 +4.257824E-002 -1.030705E-002 4 2 +2.091369E-005 -5.153527E-006 +4.182738E-002 -1.030705E-002 4 3 +2.091369E-005 -4.590381E-006 +4.182738E-002 -9.180763E-003 4 4 +2.128912E-005 -4.590381E-006 +4.257824E-002 -9.180763E-003 5 1 +2.005529E-005 -1.558341E-005 +4.011058E-002 -3.116682E-002

GEO-SLOPE Office 5 213 5 5 5 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9

2 3 4 1 2 3 1 2 3 4 1 2 3 4 1 2 3 4

+1.808552E-005 +1.808552E-005 +2.005529E-005 +1.736454E-005 +1.736454E-005 +1.736454E-005 +3.750557E-005 +3.703912E-005 +3.703912E-005 +3.750557E-005 +3.645184E-005 +3.531381E-005 +3.531381E-005 +3.645184E-005 +3.385188E-005 +3.099586E-005 +3.099586E-005 +3.385188E-005

-1.558341E-005 -1.262876E-005 -1.262876E-005 -2.604681E-005 -2.604681E-005 -2.604681E-005 -6.315437E-006 -6.315437E-006 -5.615754E-006 -5.615754E-006 -1.899675E-005 -1.899675E-005 -1.728971E-005 -1.728971E-005 -3.189890E-005 -3.189890E-005 -2.761487E-005 -2.761487E-005

+3.617105E-002 +3.617105E-002 +4.011058E-002 +3.472908E-002 +3.472908E-002 +3.472908E-002 +7.501115E-002 +7.407824E-002 +7.407824E-002 +7.501115E-002 +7.290367E-002 +7.062761E-002 +7.062761E-002 +7.290367E-002 +6.770377E-002 +6.199173E-002 +6.199173E-002 +6.770377E-002

-3.116682E-002 -2.525752E-002 -2.525752E-002 -5.209362E-002 -5.209362E-002 -5.209362E-002 -1.263087E-002 -1.263087E-002 -1.123151E-002 -1.123151E-002 -3.799351E-002 -3.799351E-002 -3.457942E-002 -3.457942E-002 -6.379780E-002 -6.379780E-002 -5.522974E-002 -5.522974E-002

The velocity listed is the Darcian velocity (or specific discharge).

Material Properties File The material properties (M) file lists for each integration point in each element the pore-water pressure and the corresponding conductivity and function values used in the analysis. The following illustrates the material properties file information: SEEP/W User's Guide Example Seepage through Earth Dam with Toe Drain DATESTAMP 7/17/01 TIMESTAMP 5:45:07 PM 0 +0.0000E+000 = Step Number, Elapsed time Elem# Pnt# Pressure Conductivity Slope of W/C WaterContent ====================================================================== 1 1 +2.443785E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 1 2 +2.443141E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 1 3 +2.287785E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 2 1 +2.422467E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 2 2 +2.243737E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 2 3 +2.248074E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 2 4 +2.427287E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 3 1 +2.130799E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 3 2 +2.127196E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 3 3 +1.974799E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 4 1 +2.404988E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 4 2 +2.226711E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 4 3 +2.238013E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 4 4 +2.416492E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 5 1 +2.097579E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 5 2 +1.923060E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 5 3 +1.932833E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 5 4 +2.108417E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 6 1 +1.817291E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 6 2 +1.809165E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 6 3 +1.661291E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 7 1 +2.373090E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 7 2 +2.195232E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 7 3 +2.215248E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 7 4 +2.393358E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 8 1 +2.066703E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 8 2 +1.893414E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 8 3 +1.912497E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 8 4 +2.086402E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 9 1 +1.768259E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000

214 SEEP/W 9 9 9

2 +1.599618E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 3 +1.616368E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000 4 +1.786552E+003 +5.000000E-004 +0.000000E+000 +0.000000E+000

The water content and the slope are set to zero if no volumetric water content curve has been specified for a material.

Flux File The flux (F) file lists the flux calculation results for all specified flux sections. The file contains the computed total flux across each flux sectionSince a flux section may cut through many elements, the computed flux across each element along each flux section is also presented. The following illustrates the flux file information: SEEP/W User's Guide Example Seepage through Earth Dam with Toe Drain DATESTAMP 7/17/01 TIMESTAMP 5:45:07 PM 0 +0.0000E+000 = Step Number, Elapsed time Flux Summary Data: Total Seepage Storage Gravity ======================================================================= Section

1 :

6.7170E-003

6.7170E-003

0.0000E+000

0.0000E+000

Section Element Total Seepage Storage Gravity ======================================================================= 1 46 -8.3512E-004 -8.3512E-004 +0.0000E+000 +0.0000E+000 1 47 -8.3278E-004 -8.3278E-004 +0.0000E+000 +0.0000E+000 1 48 -8.2975E-004 -8.2975E-004 +0.0000E+000 +0.0000E+000

The Seepage flux represents the flux across a section due to total head difference between the nodes, the Storage flux represents the flux across a section due to a change in nodal total head between the start and end of a time step, the Gravity flux represents the flux across a section due to a change in body force. The Total flux represents the net seepage flux across a section and is the summation of seepage flux, storage flux and gravity flux. NOTE: The storage flux is always zero in a steady-state analysis, and the gravity flux is always zero in a non density-dependent analysis. In the Flux Summary Data section, the total flow across the entire section is presented as a positive quantity. This is done in order to give the sign of the storage flux a consistent meaning regardless of the direction of the flux section. The sign of the storage flux depends on whether the water content is increasing or decreasing. A positive storage flux represents the rate at which the water content decreases, and a negative storage flux represents the rate at which the water content increases. The storage flux is zero for a steady-state analysis. The flux file also gives the flow rate through each element. The sign of the total element flux can be positive or negative, depending on the direction of the flux section through the element. Positive elemental flow is from right to left (when looking along the flux section in the direction of the arrowhead); negative elemental flow is from left to right. When the total elemental flux is negative, the sign (plus or minus) of the elemental storage flux has the opposite meaning from that described above. That is, a positive storage flux represents the rate at which the water content increases, while a negative storage flux represents the rate at which the water content decreases.

GEO-SLOPE Office 5 215

NOTE: If you do not specify the thickness of the elements when defining the finite element mesh, by default the thickness is set to 1.0 units for two-dimensional sections and plan view problems, and 1.0 radian for axisymmetric problems. As a result the computed flux quantity is the flux per unit thickness. To estimate the flux quantity of the flow problem, you can multiply the computed flux quantities with the actual thickness of the problem. For example, if the thickness of a two-dimensional section or plan view section is 10 m, you can multiply the computed flux by 10. In an axisymmetric problem with a pumping well and the center, you can multiply the computed flux by 6.2832 (i.e., 2 Pi radian).

Convergence File The convergence (CNV) file lists the convergence information displayed in the SOLVE window. This file is created only for reference purposes. The following illustrates the convergence file information: SEEP/W User's Guide Example Seepage through Dam Foundation Cutoff DATESTAMP 7/5/2001 TIMESTAMP 10:29:24 AM Convergence information. ========================================================== StepNum: 0 ItNum: 1 Total Residual: 6.058877E+002 StepNum: 0 ItNum: 2 Total Residual: 0.000000E+000

Initial Condition Files A series of initial condition files are created by SOLVE during a transient analysis. The purpose of these files is to provide a record of the head conditions at the start of the analysis. This allows you to view or plot the initial conditions in addition to the results of the entire transient analysis. To avoid unnecessary duplication of the initial condition file, SOLVE does not create these initial condition files for a Stop Restart analysis. SOLVE identifies this situation by checking if the data file (SEP) and the initial condition H file have the same name and if the starting time step is larger than 1. Whenever an initial head (HIN) file is created, SEEP/W also checks if other output files of the initial conditions are available in the same directory. If these files are available, SEEP/W will store these files as initial files. This will allow SEEP/W to display the solutions of the initial condition in CONTOUR. For example, an initial condition may consist of a head file (H00), a material properties file (M00), a velocity file (V00) and a flux file (F00) stored in the same directory, When the head file is selected as the initial condition of a transient analysis, SEEP/W creates an initial head file (HIN), an initial material properties file (MIN), an initial velocity file (VIN) and an initial flux file (FIN).

Chapter 6 CONTOUR Reference Introduction SEEP/W CONTOUR graphically displays the seepage analysis results computed by SOLVE. The results can be presented as contours, graphs, tables of values, velocity vectors, flux values, and a series of piezometric lines in the case of a transient analysis.You can run CONTOUR by choosing Tools CONTOURin DEFINE or by launching it from the Windows Start menu. This chapter describes the purpose and operation of each SEEP/W CONTOUR command. CONTOUR has many features for viewing, labeling, and printing the drawing that are similar to those in DEFINE. This chapter refers you to the appropriate section in Chapter 4 for CONTOUR commands that are identical to DEFINE commands. All of the CONTOUR commands are accessed by selections from the CONTOUR menu bar or toolbars. The toolbars contain icons which provide a quick way to access many commands available in the menus. The menus available and the function of each are: ·

File Opens and saves files, imports pictures and prints the drawing. For more information about this command, see The File Menu in this chapter.

·

Edit Copies the drawing to the Clipboard. For more information about this command, see The Edit Menu in this chapter.

·

Set Sets grid, zoom and axes settings. For more information about this command, see The Set Menu in this chapter.

·

View Controls viewing options and displays node and element information. For more information about this command, see The View Menu in this chapter.

·

Draw Draws contours, graphs, vectors, flux values and flow paths on the drawing. For more information about this command, see The Draw Menu in this chapter.

·

Sketch Defines graphic objects to label, enhance, and clarify the problem results. For more information about this command, see The Sketch Menu in this chapter.

·

Modify Allows graphic and text objects to be moved or deleted and text objects or pictures to be modified. For more information about this command, see The Modify Menu in this chapter.

·

Help Displays the online help system and information about SEEP/W. For more information about this command, see The Help Menu in this chapter.

In the remainder of this chapter, the commands in the toolbars and in each of these menus are presented and described.

Toolbars For general information about toolbars, see Toolbars in Chapter 4. In CONTOUR, five toolbars are available for performing various tasks as follows: Standard Toolbar Contains buttons for file operations, printing, copying and redrawing the display. For more information about this toolbar, see Standard Toolbar in this chapter.

220 SEEP/W Mode Toolbar Contains buttons for entering different operating modes which are used to display and edit graphic and text object data. For more information about this toolbar, see Mode Toolbar in this chapter. View Preferences Toolbar Contains buttons for toggling various display preferences. For more information about this toolbar, see View Preferences Toolbar in this chapter. Grid Toolbar Contains controls for specifying the display of a drawing grid. The Grid toolbar in CONTOUR operates identically to the Grid toolbar in DEFINE. For more information about this toolbar, see Grid toolbar in Chapter 4. Zoom Toolbar Contains controls for zooming in and out of the drawing. The Zoom toolbar in CONTOUR operates identically to the Zoom toolbar in DEFINE. For more information about this toolbar, see Zoom toolbar in Chapter 4.

Standard Toolbar The Standard toolbar, shown in Figure 6.1, contains commands for initializing new problems, opening previously saved problems, saving a current problem’s CONTOUR settings, printing the current problem, copying the current problem to the Windows clipboard and redrawing the display. Figure 6.1 The Standard Toolbar

The toolbar buttons are: New Problem Use the New Problem button to clear any existing problem definition data and reset the CONTOUR settings back to their defaults. This places the program in the same state as when it was first invoked. This button is a shortcut for the File New command. For more information about is command, see The File Menu in this chapter. Open Use the Open button as a shortcut for the File Open command. For information about this command, see File Open in this chapter. Save Use the Save button as a shortcut for the File Save command. For information about this command, see The File Menu in this chapter. Print Use the Print button as a shortcut for the File Print command. For more information about this command, see The File Menu in this chapter. Print Selection Use the Print Selection button to print a selected area of the drawing. The Print Selection button operates identically to the Print Selection button on the Standard toolbar in DEFINE. For more information about this button, see Print Selected in Chapter 4.

GEO-SLOPE Office 5 221 Copy All Use the Copy All button as a shortcut for the Edit Copy All command. For information about this command, see The Edit Menu in this chapter. Copy Selection Use the Copy Selection button to copy a selected area of the drawing to the Windows Clipboard. The Copy Selection button operates identically to the Print Selection button on the Standard toolbar in DEFINE. For more information about this button, see Copy Selection Button in Chapter 4. Redraw Use the Redraw button as shortcut for the View Redraw command. For information about this command, see The View Menu in this chapter.

Mode Toolbar The Mode toolbar, shown in Figure 6.2, contains buttons that put CONTOUR into "modes" used to accomplish specific tasks such as setting time steps to be viewed, viewing node and element information, drawing and modifying graphics objects (such as contours, contour line labels, flow vectors, flux section labels, flow paths, graphs and sketch objects), and adding and modifying text and pictures. Figure 6.2 The Mode Toolbar

The toolbar buttons are: Default Mode Use the Default Mode button to quit any current mode and return to the default mode. View Time Increments Use the View Time Increments button as a shortcut for the View Time Increments command. For information about this command, see View Time Increments in this chapter. View Node Information Use the View Node Information button as a shortcut for the View Node Information command. For information about this command, see View Node Information in this chapter. View Element Information Use the View Element Information button as a shortcut for the View Element Information command. For information about this command, see View Element Information in this chapter. Draw Contours Use the Draw Contours button as a shortcut for the Draw Contours command. For more information about this command, see Draw Contours in this chapter. Draw Contour Labels Use the Draw Contour Labels button as a shortcut for the Draw Contour Labels command. For more information about this command, see Draw Contour Labels in this chapter.

222 SEEP/W Draw Vectors Use the Draw Vectors button as a shortcut for the Draw Vectors command. For more information about this command, see Draw Vectors in this chapter. Draw Flux Labels Use the Draw Flux Labels button as a shortcut for the Draw Flux Labels command. For more information about this command, see Draw Flux Labels in this chapter. Draw Flow Paths Use the Draw Flow Paths button as a shortcut for the Draw Flow Paths command. For more information about this command, see Draw Flow Paths in this chapter. Graph Use the Graph button as a shortcut for the Draw Graph command. For more information about this command, see Draw Graph in this chapter. Sketch Lines Use the Sketch Lines button as a shortcut for the Sketch Lines command. For more information about this command, see The Sketch Menu in this chapter. Sketch Circles Use the Sketch Circles button as a shortcut for the Sketch Circles command. For more information about this command, see The Sketch Menu in this chapter. Sketch Arcs Use the Sketch Arcs button as a shortcut for the Sketch Arcs command. For more information about this command, see The Sketch Menu in this chapter. Sketch Axes Use the Sketch Axes button as a shortcut for the Sketch Axes command. For more information about this command, see The Sketch Menu in this chapter. Sketch Text Use the Sketch Text button as a shortcut for the Sketch Text command. For more information about this command, see The Sketch Menu in this chapter. Modify Text Use the Modify Text button as a shortcut for the Modify Text command. For more information about this command, see The Modify Menu in this chapter. Modify Pictures Use the Modify Pictures button as a shortcut for the Modify Pictures command. For more information about this command, see The Modify Menu in this chapter. Modify Objects Use the Modify Objects button as a shortcut for the Modify Objects command. For more information about this command, see The Modify Menu in this chapter.

View Preferences Toolbar The View Preferences toolbar, shown in Figure 6.3, contains buttons for setting viewing preferences such as nodes and elements and their numbers, material colors, flux sections, the computed water table, sketch objects and text, pictures, text fonts, and axes.

GEO-SLOPE Office 5 223 Figure 6.3 The View Preferences Toolbar

All the buttons on the View Preferences toolbar are shortcuts for the options accessible using the View Preferences command. For more information about this command, see View Preferences in this chapter.

The File Menu The File menu commands are: ·

New Initializes CONTOUR for a new problem. File New clears any existing problem definition data and resets the CONTOUR settings back to their defaults. This command places CONTOUR in the same state as when it was first started.

·

Open Opens and reads existing data files. For more information about this command, see File Open in this chapter.

·

Import Picture Imports a bitmap or metafile into the current drawing. The File Import Picture command in CONTOUR operates the same as the File Import Picture command in DEFINE. For more information about this command, see File Import Picture in Chapter 4.

·

Export Saves drawing in a format suitable for exporting to other programs. The File Export command in CONTOUR operates the same as the File Export command in DEFINE. For more information about this command, see File Export in Chapter 4.

·

Save Saves the current contour drawing information. File Save writes the graphical layout information of the data file name displayed in the CONTOUR window title bar to the SE3 file. If no problem definition has been opened, this command is disabled.

·

Save Default Settings Saves current settings as default settings. The settings saved include the contour parameters, default font, graph parameters, vector size, and view preferences. These settings are used when you open a problem in CONTOUR and choose to not read the SE3 file.

·

Print Prints the drawing. The File Print command in CONTOUR operates the same as the File Print command in DEFINE. For more information about this command, see File Print in Chapter 4.

224 SEEP/W

·

Most Recently Used File Allows quick opening of one of the last six files opened. This area of the File menu lists the last six files opened. Selecting a file from the list is a convenient method for opening the file.

·

Exit Quits CONTOUR but does not quit Windows. You are prompted to save the current problem data if any changes have been made.

File Open Opens and reads existing data files. File Open enables CONTOUR to open a DEFINE data file and display all of the results computed by SOLVE. The File Open command is disabled if you have started CONTOUR from DEFINE; you can view results for a new problem by opening the problem in DEFINE with File Open, and CONTOUR will automatically open the problem as well. When you choose File Open, the following dialog box appears:

Ø

To open a file: ·

Type a name in the File Name edit box and then press Open. The file name may include a directory and a path. The file name extension must be omitted or entered as SEP or SEZ. -- or --

·

Click on a file name in the list box and then press Open. -- or --

· Ø

Double-click on a file name in the list box.

To change the current directory or drive: ·

Use the Look In box to select the drive and directory.

Use the other controls in the dialog box to navigate to the drive and directory containing the SEEP/W file you wish to open. NOTE: The SEEP/W File Open dialog box is a common dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

GEO-SLOPE Office 5 225 If you check the Read SE3 File check box, SEEP/W will look for an SE3 file containing previous CONTOUR settings and, if found, will read the settings. This is normally the preferred option. However, if the SE3 file contains settings for an earlier problem that has the same file name, you may wish to uncheck the Read SE3 File check box, since the CONTOUR settings (contour values, flux values, etc.) may no longer be relevant to the current problem. SEEP/W will then read the SE2 file to initialize the page size, scale, default font, etc. When you have selected the file, CONTOUR reads the data (SEP) file, the secondary file (SE2 or SE3), the head (H) file, the velocity (V) file, the flux (F) file, and the material properties (M) file. If the problem is transient, you must select which time increment(s) to view. SEEP/W will then read the appropriate data files for the specified time increment(s). If the problem is steady-state and an initial conditions head file was created by SOLVE, you must choose to view either the steady-state head conditions (Increment 0) or the initial head conditions. Ø

To view the time increment(s): 1. Open the DEFINE data file. When you select Open, the following dialog box appears:

2. In the Increments available multiple-selection list box, select the increment(s) you wish to view. More than one increment can be selected at a time. 3. Select the Add button or double-click on an increment number to copy the selected increment(s) into the Increments to view list box. If you wish to view all of the increments, select the Add All button to copy all increments. 4. If you wish to remove increments from the Increments to view list box, select the increment(s), and then select the Remove button, or double-click on an increment number. Select the Remove All button to remove all increments. 5. Select OK to view all increments contained in the Increments to view list box. SEEP/W reads the appropriate files that match the selected increment numbers. If one increment is viewed, then contours, vectors and flux values can be drawn if the corresponding files exist. If you view more than one time increment, you cannot draw contours, vectors, and flux section values; however, the water table is calculated for each selected time step and shown on the drawing. You can always draw graphs regardless of the number of time increments being viewed.

226 SEEP/W

CONTOUR data file types If you have saved your SEEP/W analysis as a compressed data file using File Save As, all results data files are compressed into the same file as the problem definition. CONTOUR can open a compressed data file and view all of the results. The benefit of a compressed SEEP/W file is that you will only have to manage one compressed file for each problem rather than managing hundreds of results data files separately. The SEEP/W data file begins with an extension of SEP. However, SEEP/W allows you to compress all of your data files for a problem into one "zipped" file with an extension of SEZ. CONTOUR can open a compressed data file and view all of the results. The benefit of a compressed SEEP/W file is that you will only have to manage one compressed file for each problem rather than managing hundreds of results data files separately. The compressed SEZ files are PK-ZIP compatible, and can be opened and extracted with third-party data compression programs like WinZip. To create a compressed copy of your data files, use the DEFINE File Save or File Save As commands and select a SEZ file extension.

Files Read By CONTOUR The following files, created by DEFINE, are read when a data file is opened: ·

The SEP file contains the data required for the finite element calculations. It is also read by DEFINE and SOLVE.

·

The SE2 file contains information relating to the graphical layout of the problem (e.g., page size and units, engineering units and scale, sketch lines and text, and references to any imported picture files). It is also read by DEFINE, but it is not required by SOLVE.

·

The SE3 file contains the information in the SE2 file as well as information unique to CONTOUR. It is created by choosing File Save. The SE3 file is read if it exists and if the Read SE3 File check box is checked; otherwise, the SE2 file is read.

NOTE: When you open a problem containing imported picture files, SEEP/W checks to see that the picture file names still exist. If a picture file has been moved or renamed, SEEP/W displays the Import Picture dialog box, allowing you to specify a different picture file name in its place. See File Import: Picture or Modify Pictures for more information on importing pictures. The following files, created by SOLVE, are read when a data file is opened. Each file extension begins with one letter (e.g., H) followed by the number of the time step. SOLVE creates the files for each time step that is designated as needing to be saved (See the KeyIn Analysis Setting command in Chapter 4 for more information on saving data at specific time steps): ·

The head (H) files contain the total head at the nodes and the nodal flux. The extension of each head file begins with H. The head file information can be contoured, plotted, and viewed at each node. When more than one increment is viewed, SEEP/W uses the head file information to display the water table for each time step.

·

The velocity vector (V) files contain the flow velocity and gradient at each element integration point. The extension of each vector file begins with V. The vector file information can be contoured, plotted, and viewed at each element Gauss region or approximated at each node.

·

The flux (F) files contain the total flux across each specified flux section. The extension of each flux file begins with F. The flux file information can be used to display the total flux across any flux section.

GEO-SLOPE Office 5 227

·

The material property (M) files contain the pore-water pressure, hydraulic conductivity, slope of the Volumetric Water Content function, and volumetric water content at each element integration (Gauss) point. The extension of each material property file begins with M. The material property information can be contoured, plotted, and viewed at each element Gauss region or approximated at each node.

Comments: The compressed data file feature was developed with the Zip Archive C++ Library version 1.1, used with permission from Tadeusz Dracz.

The Edit Menu The Edit menu commands are: ·

Copy All Copies the entire drawing to the Windows Clipboard. The Edit Copy All command in CONTOUR operates the same as the Edit Copy All command in DEFINE. For more information about this command, see The Edit Menu in Chapter 4.

·

Copy Selected Copies a portion of the drawing to the Windows Clipboard. The Edit Copy Selected command in CONTOUR operates the same as the Edit Copy Selected command in DEFINE. For more information about this command, see The Edit Menu in Chapter 4.

The Set Menu The Set menu commands are: ·

Grid Creates a grid of points to assist in drawing objects. The Set Grid command in CONTOUR operates the same as the Set Grid command in DEFINE. For more information about this command, see Set Grid in Chapter 4.

·

Zoom Increases or decreases the size at which the drawing is displayed. The Set Zoom command in CONTOUR operates the same as the Set Zoom command in DEFINE. For more information about this command, see Set Zoom in Chapter 4.

·

Axes Defines scaled reference lines. The Set Axes command in CONTOUR operated the same as the Set Axes command in DEFINE. For more information about this command, see Set Axes in Chapter 4.

The View Menu The View menu commands are: ·

Time Increments Identifies the time increments for which results should be displayed. For more information about this command, see View Time Increments in this chapter.

·

Element Regions Identifies areas of the mesh to be viewed. For more information about this command, see View Element Regions in this chapter.

·

Node Information Displays computed values at the selected node. For more information about this command, see View Node Information in this chapter.

·

Element Information Displays computed values at the selected element Gauss point. For more information about this command, see View Element Information in this chapter.

·

Preferences Identifies which items will be displayed on the drawing. For more information about this command, see View Preferences in this chapter.

228 SEEP/W

·

Toolbars Displays or hides the CONTOUR toolbars and the status bar. For more information about this command, see View Toolbars in this chapter.

·

Redraw Redraws the problem. Use the View Redraw command to clear the CONTOUR window and re-display the drawing in the window. This is sometimes needed when drawing objects or when scrolling, since objects may not be completely drawn in the window.

View Time Increments Identifies the time increments for which results should be displayed. When you first open a transient problem data file, you select the time step(s) for which to view the analysis results. If the problem is steady-state and an initial conditions head file was created by SOLVE, you must then choose to view either the steady-state head conditions (Increment 0) or the initial head conditions. In either of these cases, View Time Increments allows you to specify the increment to display. Ø

To view different time increment(s): 1. Choose View Time Increments from the CONTOUR menu or from the Mode toolbar. The following dialog box appears:

The increment(s) currently viewed is listed in the Increments to view list box. 2. In the Increments available multiple-selection list box, select the increment(s) you wish to view. More than one increment may be selected at a time. 3. Select the Add button or double-click on an increment number to copy the selected increment(s) into the Increments to view list box. If you wish to view all of the increments, select the Add All button to copy all increments. 4. If you wish to remove increments from the Increments to view list box, select the increment(s), and then select the Remove button, or double-click on an increment number. Select the Remove All button to remove all increments. 5. Select OK to view all increments contained in the Increments to view list box. SEEP/W reads the appropriate files that match the selected increment numbers. If one increment is viewed, then contours, vectors and flux sections can be drawn if the corresponding files exist. If more than one increment is viewed, then contours, vectors and flux sections cannot be

GEO-SLOPE Office 5 229 drawn. However, the water table at each time step is calculated from the increments and shown on the drawing. You can always draw graphs regardless of the number of time increments being viewed.

Files Read by CONTOUR When Viewing New Time Increments For information regarding the files read by CONTOUR when viewing new time increments, see Files Read by CONTOUR in File Open in this chapter.

View Element Regions Identifies the element regions to be viewed. Use the View Element Regions command to display contours, velocity vectors, node and element information, and graphs for specific element regions. You can specify the elements to view by selecting the material numbers that you wish to view and by choosing whether or not to view infinite elements. Sometimes it is desirable to view the results only for specific regions. You may wish, for example, to only view the pore-water pressure distribution in the core of a dam, or you may wish to not portray the results in the infinite elements. The View Element Regions command gives you this option. Selectively viewing specific regions can affect the results when you are contouring or graphing secondary parameters computed at Gauss points (for example, velocity, gradient or conductivity). For contouring and graphing purposes, these values are projected from the Gauss points to the nodes and then averaged at the nodes. Not viewing some regions consequently affects the projected nodal values along the interface between the viewed and non-viewed regions. The difference will be the most noticeable when you have highly contrasting material properties next to each other. The nodal average of the projected Gauss values may vary significantly when such two materials are viewed together or separately. For more information about how secondary parameters at Gauss points are projected to the nodes, see Projecting Gauss Point Values to Nodes in Draw Contours in this chapter. Ø

To select the element regions to be viewed: 1. Select the View Element Regions command from the CONTOUR menu or the Mode toolbar. The following dialog box appears.

2. In the View Materials multiple-selection list box, select the materials to view. By default, all materials are selected. 3. Uncheck the View Infinite Elements check box if you do not wish to view the computed values

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within the infinite elements. By default, the infinite elements are viewed. 4. Select OK. The head, velocity, flux, and material properties files are read again for the selected time step in order to recalculate the nodal values from the element Gauss values. The contour range is recalculated based on the elements being viewed; new contours are then generated in these elements. Flow paths are regenerated if the flow path was originally drawn inside the displayed element region. NOTE: Since the View Element Regions command changes the displayed nodal data, the following commands will give results that differ according to which elements are displayed: Draw Contours, Draw Vectors, Draw Flow Paths, Draw Graph, and View Node Information.

View Node Information Displays computed values at the selected node. Ø

To view the computed values at a node: 1. Select View Node Information from the CONTOUR menu or the Mode toolbar. The cursor changes from an arrow to a cross-hair, the status bar indicates that "View Node Information" is the current mode and an empty Node Information dialog box is displayed. 2. Move the cursor near the desired node and click the left mouse button. The node is selected and the Node Information dialog box is displayed with node information as follows:

The dialog box lists the nodal x, y, and z coordinates, as well as the computed parameter values for the currently displayed time step. The parameters listed are total head, pressure, pressure head, boundary flux, velocity, gradient, conductivity, volumetric water content, and the slope of the Vol. Water Content function. If you are viewing a transient analysis, you can choose View Time Increments to display the results for a different time step.

GEO-SLOPE Office 5 231 3. To see all the node information, re-size the dialog box by dragging the bottom edge of the window down until all information is displayed. 4. Repeat Step 2 for every node that you wish to view. 5. To copy the node information to the Windows Clipboard, select Copy. The node information is copied to the Clipboard in the following text format: Node 153, Step 12 X-Coordinate 3.6000e+001 Y-Coordinate 2.0000e+000 Z-Coordinate 0.0000e+000 Total Head 1.5810e+000 Pressure -4.1093e+000 Pressure Head -4.1902e-001 Boundary Flux 0.0000e+000 X-Velocity 1.0342e-003 Y-Velocity 1.5920e-004 XY-Velocity 1.0464e-003 X-Gradient 1.1903e-001 Y-Gradient 1.8832e-002 XY-Gradient 1.2051e-001 X-Conductivity 8.7280e-003 Y-Conductivity 8.7280e-003 Vol. Water Content 3.7784e-001 Vol. W.C. Fn. Slope 7.0944e-004 6. To print the node information on the current printer, select Print. The node information is printed in the same format as it is copied to the Clipboard. 7. Press ESC or select Done to finish viewing node information.

Comments To contour any of the parameters in the Node Information dialog box, choose Draw Contours. To create a graph of any of the parameters, choose Draw Graph. The secondary parameters, (velocity, gradient, conductivity, volumetric water content, and the slope of the Volumetric Water Content function) are computed at element Gauss points. The parameter values at Gauss points are projected to the nodes for contouring and graphic purposes. For more information about the projection of Gauss point values to the nodes, see Projecting Gauss Point Values to Nodes in Draw Contours in this chapter. For more information about selecting specific element regions to use for projecting secondary parameter values to nodes, see View Element Regions in this chapter. For more information about viewing the computed secondary parameters values at the element Gauss points, see View Element Information in this chapter.

View Element Information Displays computed values at the selected element Gauss point. Ø

To view the computed values at an element Gauss point: 1. Select View Element Information from the CONTOUR menu or from the Mode toolbar.

232 SEEP/W The cursor changes from an arrow to a cross-hair, the status bar indicates that "View Element Information" is the current mode and an empty Element Information dialog box is displayed. 2. Move the cursor inside the desired element Gauss region and click the left mouse button. The element Gauss region is selected and the Element Information dialog box is displayed with element information as follows:

The dialog box lists the computed parameter values at the element Gauss point for the currentlydisplayed time step. The parameters listed are pressure, velocity, gradient, conductivity, volumetric water content, and the slope of the Vol. Water Content function. If you are viewing a transient analysis, you can choose View Time Increments to display the results for a different time step. 3. To see all the element Gauss point information, re-size the dialog box by dragging the bottom edge of the window down until all information is displayed. 4. Repeat Step 2 for every element Gauss point that you wish to view. 5. To copy the element information to the Windows Clipboard, select Copy. The element Gauss point information is copied to the Clipboard in the following text format: Element 32, Gauss Pt. 9, Steady-State Pressure 2.5002e-002 X-Velocity -1.5706e-005 Y-Velocity -9.9435e-005 XY-Velocity 1.0067e-004 X-Gradient -2.8556e-001 Y-Gradient -1.8079e+000 XY-Gradient 1.8303e+000 X-Conductivity 5.5000e-005 Y-Conductivity 5.5000e-005 Vol. Water Content 0.0000e+000 Vol. W.C. Fn. Slope 0.0000e+000 6. To print the element Gauss point information on the current printer, select Print. The information is printed in the same format as it is copied to the Clipboard. 7. Press ESC or select Done to finish viewing element Gauss point information.

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Comments The computed head values are stored at each node and can be viewed with the View Node Information command.

View Preferences Identifies which items will be displayed on the drawing. Use the View Preferences command to select items to view, change font sizes and changing the default font. When you select the Preferences command from the View menu or from the Mode toolbar, the following dialog box is displayed:

Ø

To select the items to view: ·

In the Items To View group box, check the items that you want displayed on the drawing. Any items that not checked will not be displayed.

Nodes Displays nodes as small squares, triangles, or circles, depending on the node boundary type. Elements Displays elements. Node or Element Numbers Displays node or element numbers only if the nodes or elements are also displayed. Boundary Conditions Displays boundary conditions. Infinite Symbols Displays a dashed border along infinite element edges. The infinite elements are also filled with a vertical or horizontal hatch pattern, depending on the direction of infinity. NOTE: To not display the computed results inside infinite elements, use the View Element Regions command. For information about this command, see View Element Regions in this chapter.

234 SEEP/W Material Colors Displays elements as different colors, depending on the material colors defined for each material type in DEFINE. Contour Shading Displays color shading between the contour lines. Material Boundaries Displays a thick boundary line between materials. NOTE: Material colors and contour shading cannot be displayed simultaneously. Contour Lines Displays contours through all element regions currently viewed. See View Element Regions for information on viewing groups of elements. Water Table Displays the water table (zero pressure) contour(s). If you are viewing more than one time increment, the water table is displayed for each displayed time increment. Vectors Displays flow velocity vectors in each element. Flow Path Displays flow paths as solid lines. Flux Sections Displays flux sections as dashed lines with arrows. The total flux across each section is displayed in the section if it was drawn using the Draw Flux Labels command. Sketch Objects Displays text, lines, circles, and arcs created by the Sketch commands. Axes Displays the axes. Pictures Displays imported bitmap or metafile pictures. DEFINE Sketch Objects Displays all sketch objects created in DEFINE. While these sketch objects can be viewed in CONTOUR, you must use DEFINE to edit or delete them. The modified sketch objects will then appear in both DEFINE and CONTOUR.

Font Sizes Font sizes for node numbers, element numbers, axes numbers, contour labels, and flux section labels are displayed at the point sizes listed in the Font Size group box. Ø

To change a font size: Click the down arrow to the right of the Node #, Element #, Contours, Flux, or Axes edit boxes and select a point size from the list, or type the desired point size in the edit box. Points are the units commonly used for font size (72 points is equal to 1 inch). The point size that you enter represents the height of the node numbers, element numbers, contour values, flux values, or axis numbers at a zoom factor of 1.0.

Default Font SEEP/W uses the default font to display node numbers, element numbers, axes numbers, axes labels, contour labels, and flux section labels. Ø

To change the default font: 1. Click on the Font button. The following dialog box is displayed:

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All the fonts that are currently installed in Windows are displayed in the Font list box. To install or delete fonts, you must use the Windows Control Panel. See the Windows documentation for more information on Control Panel. 2. Select the desired font in the Font list box and style in the Font Style list box. 3. Select OK to return to the View Preferences dialog box. The name of the selected font is displayed beside the Font button. NOTE: SEEP/W does not use the default font to display sketch text on the drawing. Therefore, when you select a new default font, all text defined with the Sketch Text command remains unchanged. This is undesirable if you wish to use one font for all text that appears on the drawing. Ø

To change the font for all sketch text to the default font: 1. Select the Convert All Sketch Text Fonts check box. 2. When you select the OK button in the View Preferences dialog box, the program asks if you wish to change all sketch text fonts to the default font. 3. Select Yes to change all sketch text fonts to the default font; select No to exit the View Preferences dialog box without changing the sketch text fonts; or select Cancel to return to the View Preferences dialog box. The Convert All Sketch Text Fonts check box is disabled if there are no sketch text items defined on the drawing.

Comments Only the items displayed are shown on paper when you print the drawing. This allows you to print any combination of items. When you define an item, SEEP/W will check the item in View Preferences if you have not already

236 SEEP/W checked it. For example, if you choose Draw Contours, SEEP/W will check the Contours option in View Preferences. This enables you to see the contours that you define. SEEP/W may take a long time to redisplay the drawing when all items are being drawn, especially if Contour Shading or Material Colors are viewed. Uncheck any unnecessary items to view in order to minimize the time required to redraw the display.

View Toolbars Displays or hides the CONTOUR toolbars and the status bar. Use the View Toolbars command to toggle the display of any toolbar, the status bar, or the toolbar tool tips. Ø

To change the toolbar and status bar display: 1. Select the Toolbars command from the View menu or right-click on a toolbar and select Toolbars from the pop-up context menu. The following dialog box appears:

2. In the Toolbars list box, check the toolbars you wish to display, or uncheck the toolbars you wish to hide by clicking on the check boxes with the left mouse button. Each time you check an item, it appears in the CONTOUR window; each time you uncheck an item, it is removed from the CONTOUR window. 3. To show or remove the tool tips that are displayed when the mouse is over a toolbar button, check or uncheck the Show ToolTips check box. 4. To show or remove the status bar from the bottom of the CONTOUR window, check or uncheck the Status Bar check box. The information displayed in the status bar is described below. 5. To show or remove the Time Step pane from the status bar, check or uncheck the Display Time Step in Status Bar check box. 6. When finished, click on the Close button. NOTE: You can quickly add or remove a toolbar or status bar by clicking the right mouse button on top of any toolbar or status bar. When the pop-up menu appears, select a toolbar or the status bar from the menu to toggle its display.

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Status Bar The status bar contains either three or four panes and is displayed as follows:

Status Information Current status of the program. If the mouse cursor is above a menu item or toolbar button, the purpose of the menu item or toolbar button is displayed. If the program is in a "mode", then the current mode and suggested user action is displayed. The status bar above is shown in the default mode. Time Step Currently selected range of time steps for transient analyses. Display of this pane is optional if more room on the status bar is required. For more information about viewing results at specified time steps, see View Time Increments. Mouse Coordinates Mouse cursor coordinates in engineering units.

The Draw Menu The function of Draw is to draw and label contours, draw velocity vectors, label flux sections, draw flow paths and plot graphs using the computed parameter values. All Draw commands except Draw Contour Labels and Draw Graph are disabled when more than one time increment is being viewed, since only the water table contours are displayed on the drawing. Graphs, however, can always be plotted, regardless of the number of time increments being viewed. The Draw menu commands are: ·

Contours Specifies the contours to draw. For more information about this command, see Draw Contours in this chapter.

·

Contour Labels Labels the contours. For more information about this command, see Draw Contour Labels in this chapter.

·

Vectors Sets the dimensions of the velocity vectors and displays the vectors. For more information about this command, see Draw Vectors in this chapter.

·

Flux Labels Labels the flux sections. For more information about this command, see Draw Flux Labels in this chapter.

·

Flow Paths Specifies the flow paths to draw. For more information about this command, see Draw Flow Paths in this chapter.

·

Graph Plots graphs using the computed parameter values. For more information about this command, see Draw Graph in this chapter.

Draw Contours Generates contour lines and/or contour shading. Use the Draw Contours command to draw contour lines, contour shading, or both, for a specified parameter over the problem area. The contour range, (i.e. the lowest and highest contour value), may be specified to cover the entire data range of the parameter being contoured, or the contour range may only cover a portion of the data range. For contour shading, five different methods are available for

238 SEEP/W interpolating the color sequence between user specified start and end colors. In addition, the number of contour shades per contour interval may be specified, allowing the contour shades to be clearly distinct, or to smoothly blend from one color to the next. Finally, the effects of the specified contour settings may be displayed before accepting them. Ø

To draw contours: 1. Choose Draw Contours from the CONTOUR menu or from the Mode toolbar. The following dialog box appears:

2. Edit the settings in the Draw Contours dialog box. Contour Parameter Specifies the parameter to contour. For more information regarding contour parameters, see Contour Parameters and Projecting Gauss Point Values to Nodes below. Data Range Indicates the minimum and maximum data values for the parameter to be contoured. The data range depends on the contour parameter selected and the element regions being viewed. For more information about viewing element regions, see Contouring Specific Element Regions below. Starting Contour Value Specifies the starting, or minimum, contour value (level). Increment by Specifies the contour increment. This value must be a positive number greater than zero. Number of Contours Specifies the number of contouring levels. This value must be a positive number greater than or equal to zero. Note that if the number of contours is one, then no contour shading can be defined and only a single contour line will be generated at the starting contour value (level). If the number of contours is zero, no contours lines or shading are generated. Ending Contour Value Indicates the ending, or maximum, contour value (level). This value depends on the starting contour value, the contour increment and the number of contours.

GEO-SLOPE Office 5 239 Contour Shading Method Specifies the contour shading method. For more information about contour shading methods, see Contour Shading Methods below. Colors Per Interval Specifies the contour shading per interval. Use a value of one to generate one color per contour interval. Increasing the number of shades per interval will smooth the color gradation from one color to the next. Start Color and End Color Specifies the starting and ending colors for the contour shading method. To change a color, hit the corresponding Set button to display the Color dialog box. Use the Color dialog box to select a color or define a custom color. 3. Select the Apply button to see the effects of the contour settings. 4. Repeat Steps 2 to 3 if you wish to change any of the displayed contours. 5. Select OK to accept the contour settings.

Contour Parameters The following parameters may be contoured: ·

total head

·

pressure

·

pressure head

·

x velocity (log)

·

y-velocity (log)

·

xy-velocity (log)

·

x-gradient (absolute)

·

y-gradient (absolute)

·

xy-gradient (absolute)

·

x-conductivity (log)

·

y-conductivity (log)

·

volumetric water content

Projecting Gauss Point Values to Nodes SEEP/W performs contouring calculations based on parameter values at the nodes. Since the primary parameters, (total head, pressure, and pressure head), are computed at the nodes, these parameters can be contoured directly. However, secondary parameters, (velocity, gradient, conductivity, and volumetric water content), are computed at the element Gauss points and must therefore be projected to the nodes for contouring purposes. In triangular elements, the Gauss point values are projected on the basis of a plane that passes through the three Gauss points. For one-point integration, the value at the Gauss point is also taken to be the value at the nodes (i.e., the Gauss point value is constant within the element). In quadrilateral elements, the Gauss point values are projected using the interpolating functions. (For

240 SEEP/W more information about interpolating functions, see Interpolating Functions in Chapter 8). In equation form, (6.1) where: x = projected value outside the Gauss points at a local coordinate greater than 1.0 = matrix of interpolating functions {X} = value of Gauss point variable The local coordinates at the element nodes are the reciprocal of the Gauss point local coordinates when forming the element characteristic matrix. Figure 6.4 is an example of the local coordinates at the element corner nodes when projecting outwards from the four Gauss points in the element. The value of 1.7320 is the reciprocal of the Gauss point coordinate 0.57735. Figure 6.4 Local Coordinates at the Corner Nodes of an Element with Four Integration Points

This projection technique can result in some over-shoot at the corner nodes when variation in the parameter values at the Gauss points is large. For example, consider that we wish to contour volumetric water content and that in some elements, the water content at the Gauss points varies over the complete range of the volumetric water content function. Projecting such a large variation to the nodes can result in a water content beyond the range of the volumetric water content function. Extreme changes in the parameter values at the Gauss points within an element often indicate numerical difficulties (the over-shoot at the nodes being just a symptom of the problem). This over-shoot can potentially be reduced by a finer mesh discretization. Smaller elements within the same region will result in a smaller variation of parameter values within each element, therefore lowering the potential for encountering unrealistic projections.

Contouring Specific Element Regions In some cases, it may be desirable to contour only within specific materials or within non-infinite elements. The View Element Regions command controls which element regions will be viewed and contoured. The data range in the Draw Contours dialog box reflects the data range within the currently displayed element region. If no elements are displayed, an error message appears when you choose Draw Contours.

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Contour Shading Methods The series of colors used for contour shading (i.e., the contour shading color spectrum) is determined by the selection of a contour shading method. Each contour shading method represents a different way to traverse the color wheel from a starting color to an ending color. The color wheel is a circular representation of visible colors where pure red, yellow, green, cyan, blue and magenta are located on the outside of the wheel in a counter clockwise direction, and gray is in the middle of the wheel. A starting color and an ending color represent positions on the color wheel. Given these starting and ending positions, there are five different paths by which to traverse from the starting color to the ending color on the color wheel. The five traversal paths lead to the following contour shading methods: Wide Rainbow The traverse path follows the longest path around the color wheel from the starting color to the ending color. Narrow Rainbow The traverse path follows the shortest path around the color wheel from the starting color to the ending color. Fade The traverse path follows a direct straight line path across the color wheel from the starting color to the ending color. Full Rainbow The traverse path follows a clockwise path around the color wheel from the starting color back to the starting color. Full Rainbow (Reverse) The traverse path follows a counter clockwise path around the color wheel from the starting color back to the starting color. In the Draw Contours dialog box, a graphic shows the traversal direction on the color wheel for the selected contour shading method.

Changing Starting and Ending Colors You can specify the starting and ending colors for contour shading, giving you complete control over the contour shading colors. Ø

To change the starting and/or ending colors: 1. Press the Set button corresponding to the starting or ending color. The Colors dialog box appears. 2. Select one of the predefined basic colors. -- or -Press the Define Custom Colors button to define a custom color. 3. Select OK to accept the new color. TIP: For printed output on black and white printers, use light and dark gray for start and end colors. Also, very light colors will produce better printouts than dark colors.

Draw Contour Labels Labels the contours with contour values Use the Draw Contour Labels command to place a label of the contour value at any point on a contour line.

242 SEEP/W Ø

To add contour labels to contour lines: 1. Choose Draw Contour Values from the CONTOUR menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Draw Contour Labels" is the current operating mode. 2. Place the cursor at any convenient point on a contour line and click the left mouse button. The value of the contour will be displayed on the line. 3. Repeat Step 2 for each contour label you wish to add. 4. Press ESC or click the right mouse button to finish drawing contour labels.

Ø

To delete contour labels from contour lines: ·

Ø

Follow the above procedure, except click on an existing contour label, and the label will be removed.

To change the contour label font: ·

The default font is used to display contour labels and can be changed using the View Preferences command.

Draw Vectors Sets the dimensions of the velocity vectors and displays the vectors. Ø

To display velocity vectors: 1. Choose Draw Vectors from the CONTOUR menu or the Mode toolbar. The following dialog box appears:

The value of the maximum velocity is displayed in engineering units per time. 2. Select inches or mm as the units of the vector length. 3. In the Max. Length edit box, type the length that the maximum velocity vector will be drawn on screen. All other vectors will be less than or equal to this length. When a Max. Length value is entered, the value in the Magnification edit box changes. The Magnification value is the scale at which the vectors are drawn. If you change the Magnification value, the Max. Length value will also change. 4. Select OK. The vectors are displayed on the drawing.

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Comments Specifying a Magnification value allows you to control the scale at which all vectors are drawn. When you type a value in the Magnification edit box, the Max. Length edit box is updated to display the length at which the maximum vector will be drawn. You can control the vector length either by specifying a Magnification value or by specifying a Max. Length value. The Magnification value is computed according to the following general relationship:

Vectors are only drawn in element regions being viewed. Choose View Element Regions if you wish to view different materials or to not view infinite elements . If no elements are viewed, an error message appears when you choose Draw Vectors. For each element, the average x-velocity and average y-velocity from the Gauss point velocity values are computed and then vectorially summed to obtain an average velocity vector for the element. This average velocity vector is plotted with the tail of the vector at the center of the element. CONTOUR finds the maximum velocity vector and draws it at the length specified in the Draw Vectors dialog box. All other vectors are drawn in proportion to the element velocity relative to the maximum velocity. For example, if the element velocity is one quarter of the maximum velocity, then the length of the velocity vector is one-quarter of the length specified in the Draw Vectors dialog box.

Draw Flux Labels Labels the flux sections. Ø

To add a flux label to a flux section: 1. Choose Draw Flux Labels from the CONTOUR menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair and the status bar indicates that the "Draw Flux Labels" is the current mode. 2. Place the cursor at any convenient point on a flux section and click the left mouse button. The total flux across the section will be displayed at the cursor position. Only one flux label can be displayed for each sub-section. 3. Repeat Step 2 for each flux label you wish to display. 4. Press ESC or click the right mouse button to finish adding flux labels.

Ø

To delete a flux value displayed on a flux section: ·

Follow the above procedure, except click on an existing flux label, and the label will be removed.

Draw Flow Paths Draws paths that a drop of water would follow under steady-state conditions This command allows you to draw paths that a drop of water would follow under steady-state conditions from the point of entrance into the flow regime to the point of exit.

244 SEEP/W Ø

To draw flow paths: 1. Choose Draw Flow Paths from the CONTOUR menu or from the Mode toolbar. The cursor changes from an arrow to a cross-hair and the status bar indicates that "Draw Flow Path" is the current operating mode.. 2. Move the cursor to any position in the flow regime and click the left mouse button. A flow path will be drawn in both directions from the point you click. 3. Click at each point you want to draw a flow path. You can place the cross-hair cursor on an existing path and click the left mouse button to remove an existing flow path. Alternatively, you can move the cursor outside the flow regime, hold down the left mouse button and drag a rectangle over all flow paths that you want to remove. Dragging a rectangle over the entire problem removes all flow paths. The rectangle has to encompass the point at which you initially clicked to draw the flow line. 4. Press ESC or click the right mouse button to quit drawing flow paths.

Comments The SEEP/W flow paths are not flow lines or stream lines as in a traditional flow net. In many cases the flow paths are a very good approximation of stream lines but they are not the same. The flow paths are simply a line based on velocity vectors in an element that a drop of water would follow under steadystate conditions. A message will be displayed if you attempt to draw a flow path in an area where there is little or no flow. After accepting the message, the flow path will be drawn but it may not be complete; that is, the path will end inside the flow regime. This message will also be displayed if the flow path encounters a no flow perimeter boundary. Flow paths may cross a water table (zero-pressure contour). This is acceptable since in a saturated/unsaturated analysis the phreatic surface is not a flow line as in a traditional unconfined flow net. Flow can cross the water table (phreatic surface) in a SEEP/W analysis. For more information on the use and interpretation of flow paths, see Flow Paths in Chapter 7.

Draw Graph Plots graphs using the computed parameter values. The Draw Graph command allows you to plot a graph containing any of the following computed parameter values: total head, pressure, pressure head, x velocity, y-velocity, xy velocity, x gradient, y gradient, xy-gradient, x conductivity, y conductivity, and volumetric water content. These parameters are the dependent variables of the graph. Any of the dependent variables can be plotted versus the following independent variables: nodal x coordinates, nodal y coordinates, and the distance between nodes (starting at the first selected node). If your problem is a transient analysis, you can also plot a dependent variable versus time. Draw Graph also can be used to extract selected parameter values over many time steps or for many nodes. These values can be saved as an ASCII text file or copied to the Windows Clipboard and then taken into other Windows graphing applications (e.g., Microsoft Excel). Ø

To draw a graph using computed parameter values: 1. Choose Draw Graph from the CONTOUR menu or from the Mode toolbar. The following dialog box appears:

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2. In the Graph Type group box, select the graph parameters from each drop-down list box. 3. In the Select Time Steps group box, select the time steps to include in the graph if the problem is a transient analysis. The All button selects all time steps, and the None button unselects all time steps. At least one time step must be selected in order to create the graph. 4. In the CONTOUR window, select the nodes used to plot the graph. When you move the cursor out of the dialog box and into the CONTOUR window, it changes to a black arrow, indicating that you can select nodes. To select the nodes to graph, click on each node individually or select a group of nodes. To select a group of nodes, hold the left mouse button down at the corner of the region and drag the mouse until a rectangle encompasses the desired group of nodes. When the left mouse button is released, all nodes in the rectangle are selected. Each time you select nodes, all other nodes are unselected. If you wish to keep the previous node selection, hold down the CTRL key while you select more nodes. To select nodes along a straight line, press the SHIFT key and click on two nodes along the line. All nodes that lie on a straight line between the selected nodes are selected. 5. Select the Graph button to display a graph of the selected parameters. The following graph contains a plot of pressure vs. the y coordinate for eleven selected nodes and three selected time steps:

246 SEEP/W

NOTE: For some parameters, the computed values will be zero for selected nodes that are within elements not currently being viewed. This is because CONTOUR graphs nodal values, while some parameters are stored at element Gauss regions and averaged to the nodes. For more information, see View Element Regions and Projecting Gauss Point Values to Nodes in Draw Contours in this chapter. The independent graph variable that you choose affects how the selected nodes and time steps are used in the graph: ·

If the graph independent variable is x coordinate, y coordinate, or distance, then the parameter value at each selected node is plotted versus the nodal coordinate or the distance between nodes. Each selected time step is plotted as a separate line on the graph.

·

If the graph independent variable is time, then the parameter value at each selected node is plotted versus the elapsed time for each of the selected time steps. Each selected node is plotted as a separate line on the graph.

The Graph window contains a menu with the following commands: ·

File Print Prints the graph on the selected printer. NOTE: File Print displays a common Print dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window.

·

File Close Closes the Graph window and returns to the Draw Graph dialog box.

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·

Edit Copy Copies the graph to the Windows Clipboard for use in other Windows applications. See Edit Copy All in Chapter 4 for further information on copying to the clipboard.

·

Set Options Specifies the options to use when displaying the graph.

Changing the Graph Display Ø

To specify the graph display options: 1. Choose Set Options from the Graph window menu. The following dialog box appears:

2. To change the titles, type a new graph title or axis title in the edit boxes. 3. To change the font, select the Font button. The following dialog box appears:

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All the fonts that are currently installed in Windows are displayed in the Font list box. To install or delete fonts, you must use the Windows Control Panel. See the Windows documentation for more information on Control Panel. 4. Select the desired font in the Font list box and style in the Font Style list box. 5. Select a font size from the Size list box or type the desired font size in the Size edit box. The font size units are relative to the size of the Graph window (i.e., whenever the Graph window is enlarged, the text in the window is also enlarged). Select a font size that results in the graph titles being displayed at a suitable size. 6 Select OK to return to the Set Graph Options dialog box. The name of the selected font is displayed underneath the Font button. 7. To change the graph display options, check any of the following check boxes in the Graph Display group box: §

Semi-Log Displays the vertical axis at a log scale. This option is not available if any of the values along the vertical axis are negative or equal to zero.

§

Grid Lines Displays background grid lines on the graph.

§

Legend Displays a legend describing each line on the graph

§

Rotate 90° Plots the independent variable along the vertical axis and the dependent variable along the horizontal axis. This is the default option when the independent variable is the nodal y coordinates.

8. To specify how the lines are plotted on the graph, check any of the following check boxes in the Lines group box: §

Symbols Displays symbols at each point on each graph line.

GEO-SLOPE Office 5 249 §

Color Displays the lines and symbols on the grid in color.

§

Thick Lines Displays each graph line as a thick line. This option cannot be used in combination with Styled Lines.

§

Styled Lines Displays each graph line as a styled (dashed or dotted) line. This option cannot be used in combination with Thick Lines.

9. Select OK when you have finished selecting the graph display options. The graph is redrawn using the new options.

Extracting the Graph Data Draw Graph also gives you access to the data used in plotting the graph. This allows you to use the results computed by SOLVE in other applications (e.g., word processors, spreadsheets, or graphing applications) for presentation purposes. Ø

To access the data used in plotting the graph: 1. In the Draw Graph dialog box, select the Extract All Data check box if you wish to extract the nodal x and y coordinates and the elapsed time values in addition to the graph data. If this option is not selected, then only the graph data points will be extracted. 2. Select the Data button. The following dialog box appears:

If the Extract All Data option was selected, the Graph Data dialog box will also list the x and y coordinates at each node and the elapsed time for each selected time step. The remaining steps describe how to export the data in the list box to the Windows Clipboard or as an ASCII text file. 3. In the Export Delimiter group box, select the character to use as the field delimiter between list box

250 SEEP/W

columns. Many spreadsheets and databases use a special character to separate data into fields. For example, to import the graph data into Microsoft Excel, select the TAB character. If your application uses a delimiting character that is not listed in the group box, select Custom and type the character in the adjacent edit box. 4. To export a portion of the graph data displayed in the list box, check the Selected Only check box and select the desired lines in the list box. A group of lines can be selected either by pressing the CTRL key and clicking on each line in the group or by pressing the SHIFT key and clicking on the first and last line in the group. If Selected Only is not checked, the entire list box will be exported. 5. To copy the list box contents to the Windows Clipboard, select the Copy button. A beep is sounded when the data points have been copied to the clipboard. 6. To export the list box contents to an ASCII text file, select the Save As button. The following dialog box appears:

NOTE: The File Save As dialog box is a dialog used by many other Windows applications. To get help on using the dialog box, click on the question-mark in the top-right corner; your cursor then becomes a question mark. Then, click on the dialog control that you need explained; a pop-up window appears with a description of the dialog control. Click anywhere else in the dialog box to remove the pop-up window. 7. Type the name you wish to give the file and select the directory in which to save the file. 8. Select Save to export the graph data to the specified ASCII file. The Graph Data dialog box is redisplayed when the file has been saved. 9. Select Done in the Graph Data dialog box when you are finished extracting data.

The Sketch Menu The commands available in the CONTOUR Sketch menu operate identically to those available in the

GEO-SLOPE Office 5 251 DEFINE Sketch menu. For more information about this menu and its commands, see The Sketch Menu in Chapter 4.

The Modify Menu The commands available in the CONTOUR Modify menu operate identically to those available in the DEFINE Modify menu. For more information about this menu and its commands, see The Modify Menu in Chapter 4.

The Help Menu The commands available in the CONTOUR Help menu operate identically to those available in the DEFINE Help menu. For more information about this menu and its commands, seeThe Help Menu in Chapter 4.

Chapter 7 Modelling Guidelines Introduction A finite element analysis is accomplished in two steps. The first step is to model the problem. This involves designing the finite element mesh, defining the material properties, and specifying the boundary conditions. The second step is to analyze the model by formulating and solving the finite element equations. The SEEP/W SOLVE function accomplishes the second step. It is the user's responsibility to properly model the problem. This chapter presents some general modelling guidelines. The information presented is not an exhaustive statement on the "how-to" of modelling. Instead, it is intended to provide suggestions on how you might model various conditions, as well as to outline the implications and consequences of certain modelling specifications.

Modelling Progression One of the most important rules to follow in finite element modelling is to progress from the simple to the complex. It is good practice to initially define a simplified version of the problem and then add complexity in stages. Moving from the simple to the complex makes it easier to pinpoint difficulties with the model when the results of the analysis are unrealistic. Determining what causes unrealistic results can be difficult if all of the possible complexities are included at the start of the problem analysis. Furthermore, in finite element modelling, it is important that the results obtained are of a form similar to results obtained from simple hand calculations. It is easier to make this judgment if you start with a simplified version of the problem. The principle of moving from the simple to the complex can be illustrated in the analysis of seepage through a zoned earth dam. Initially, the modelling task can be simplified by assigning all of the materials the same properties, which is equivalent to making the section homogeneous. Once the solution appears reasonable, complexity can be added to the problem by changing the properties of the various zones in stages. This stepped approach not only helps to evaluate the results but also provides information on the effect of the various zones. In the case of large soil system with very steep conductivity functions, the problem may be extremely nonlinear and convergence of the problem can be a challenge. In this situation, rather than fighting to get a converged solution, it may be useful to obtain a converged solution with a flat K function first and increase the steepness of the function gradually.

Units Any system of units can be used for a seepage analysis; the only requirement is that you must be consistent. Fundamentally, you must select the units for length (geometry), time, and force. Once you have selected units for these parameters, all other units must be consistent. Tables 7.1 and 7.2 present some typical sets of consistent units.

254 SEEP/W Table 7.1 Consistent SI Units Parameter

Symbol

Units

Length

L

metres

Time

t

seconds

Force

F

kN

Pressure

F/L2

kN/m2

Unit Weight of Water

F/L3

kN/m3

Hydraulic conductivity

L/t

m/sec

Total / Pressure head

L

m

Nodal Flux (Q)

3

L /t

m3/sec

Boundary Flux (q)

L/t

m/sec

Flux Section

L3/t

m3/sec

Volume

L3

m3

Parameter

Symbol

Units

Length

L

feet

Time

t

hours

Force

F

Table 7.2 Consistent Imperial Units

Pressure

lbs 2

psf

3

F/L

Unit Weight of Water

F/L

pcf

Hydraulic conductivity

L/t

ft/hr

Total / Pressure head

L

ft

Nodal flux

3

L /t

ft3/hr

Boundary Flux (q)

L/t

ft/hr

Flux Section

L3/t

ft3/hr

Volume

L3

ft3

The units of time are established once you select the units for hydraulic conductivity. The units of pressure are established once you select the unit weight of water. Generally, all units are defined by selecting the units of length for the problem geometry, units for hydraulic conductivity, and the units for the unit weight of water. In summary, the key requirement is that the system of units be consistent.

Mesh Design The amount of computer memory storage and processing time required to solve the finite element equations is proportional to the number of nodes in the problem, the nodal point difference in each element, and the integration order. Furthermore, the accuracy of the results is affected to some extent by

GEO-SLOPE Office 5 255 the shape of the elements and by the mixing of the different element types. Consequently, care should be exercised in generating the finite element mesh. The nodal point difference can be minimized by generating the elements in horizontal rows and vertical columns. SEEP/W organizes the nodes by sorting them in a vertical or horizontal direction. The consequence of this is that the nodal difference in an element can be higher in a mesh on a slant than for the same mesh in an upright position. Figure 7.1 illustrates this effect. In addition to the maximum nodal point difference being higher, it is also more difficult to locate a particular node in a slanted mesh than in an upright mesh. It is good practice to choose a balance between ease of mesh generation and efficiency of processing. Directing a large amount of effort at mesh generation to gain marginal processing efficiency is likely not warranted. However, total disregard for computer memory storage and processing efficiencies may result in a large amount of unnecessary computing time. As a general guideline, some thought should be given to processing efficiency but not at the expense of complicating the mesh generation. The accuracy and performance of an element is affected to some extent by its shape. For quadrilateral elements, the best performance is achieved when the interior angles are all 90 degrees (a rectangle); for triangular elements, the best performance is achieved when one interior angle is 90 degrees and the other two angles are 45 degrees. Acceptable performance can be obtained for elements with interior angles that deviate from 45 and 90 degrees; however, the performance of the elements deteriorates rapidly if any interior angle approaches zero or 180 degrees. In the case of quadrilateral elements, interior angles equal to or greater than 180 degrees are unacceptable. Figure 7.2 shows the shape and performance rating of elements. The aspect ratio (length to height) of elements can also affect the performance. As the aspect ratio increases, the element performance deteriorates. The best performance of long, thin elements is achieved by quadrilateral elements with eight nodes and nine point integration. The poorest performance comes from three-noded long, thin elements with one point integration. Generally, the higher order elements should be used when the aspect ratio is high. SEEP/W has no restrictions on the aspect ratio. It is a parameter that you must choose in light of conditions specific to the problem. In general, an aspect ratio of 1 gives the best performance. Long, thin elements with aspect ratios much greater 5 can lead to poor results. If you are going to use elements with very high aspect ratios, you should satisfy yourself that the results are realistic by trying different aspect ratios. Difficulties with aspect ratios can easily arise when you are working at a vertically exaggerated scale. Say, for example, you are working at a vertical exaggeration of 10 (e.g., 1:1000 in the horizontal and 1:100 in the vertical direction), and that you have drawn nice square elements. In actual fact, the elements have an aspect ratio of 10. As far as the main processor SOLVE is concerned, the elements are 10 times greater in one direction than in the other. To get a good appreciation of what actually is being analyzed, you should set the aspect ratio to 1 by choosing Set Scale in DEFINE and specifying the scale to be the same in both directions (e.g., 1:100 in both the horizontal and vertical directions) before you run SOLVE. Once you are satisfied that the mesh is acceptable, you can change the scale back to something more convenient for presentation.

256 SEEP/W Figure 7.1 The Effect of Mesh Layout on Node Numbering

The memory and disk space requirements and the processing time can be significantly reduced by selectively using different element types and sizes in various regions of the mesh. In the transition zones, care must be taken to ensure that compatibility is maintained between elements. This is done by ensuring that the interpolating function between two corner nodes common to the elements is of the same order. The function must either be linear in both elements or nonlinear in both elements.

GEO-SLOPE Office 5 257 Figure 7.2 Element Slopes and Performance

Figure 7.3 illustrates the requirements for compatibility. In Figure 7.3a the interpolating function between Nodes A and C for Element 3 is nonlinear, while the interpolating function between Nodes A and B in Element 1 and between Nodes B and C in Element 2 is linear. It is therefore an unacceptable transition arrangement. In Figure 7.3b the interpolating function is linear between Nodes A and B and linear between Nodes B and C in Elements 1, 2, 4, and 5. As a result compatibility is maintained between the elements. The potential for creating unacceptable transition elements can be reduced by using triangular elements. Quadrilateral transition elements can lead to unacceptable arrangements, such as illustrated in Figure 7.3a.

258 SEEP/W Figure 7.3 Element Transitions and Compatibility

Another factor that should be considered in the design of a mesh is the selection of starting x and ycoordinates (datum) of a problem. Using a large starting x- or y-coordinate may affect the precision of the computed results due to round-off error. Round-off error occurs when a small number is added to a large number. Since there are many computations in SOLVE involving the additions and subtractions of nodal coordinates, it is important to minimize unnecessary round-off error due to the poor selection of datum. The easiest way to minimize round-off error is ensure that both the starting x- and y coordinates are as close to zero as possible. During the verification process, DEFINE determines the x- and y-nodal coordinate ranges of the mesh and issues a warning message if more than one significant digit of precision will be lost due to floating point round-off error. For more information about the verification process, see Verify/Sort in Chapter 4.

Relevant Materials Thought must be given to the relevance of each material included in the analysis. In certain cases, the analysis and modelling can be simplified by excluding irrelevant materials. A valid question to ask is, "Does the material contribute to the energy (head) dissipation?" If not, there may be little or no value in including the material in the analysis. For example, consider a rock-filled dam with a clay core and a downstream granular drainage blanket as illustrated in Figure 7.4. The hydraulic conductivity of the rockfill and granular drain is much higher than for the clay core. On the upstream side of the dam, there is essentially zero head dissipated in the upstream shell, since the rockfill is considerably more pervious than the core. Therefore, the head at all nodes in the shell zone is equal to the reservoir level. Conditions along the boundary between the upstream shell and the core, and between the shell and the foundation, are known and can be specified. Consequently, there is no need to

GEO-SLOPE Office 5 259 include the upstream shell in the analysis. Figure 7.4 Rockfill Dam with Clay Core

Assuming that the downstream drainage blanket is constructed in such a way that it can carry away any seepage that comes through the core, there will be no buildup of head in the drain. Stated another way, since the granular drain in no way impedes the drainage through the core, none of the reservoir head is dissipated in the granular drain. Therefore, there is no need to include the granular drain in the analysis. Furthermore, if the drain can carry away all of the seepage that comes through the core, there is no need to include the downstream shell. The head in the horizontal portion of the drain will be equal to the elevation of the tail water when the drain functions as intended. Consequently, conditions along the contact between the drain and the foundation are known and can be specified. Conditions on the downstream face of the core are unknown but can be established by SEEP/W with the use of review nodes. This example problem analysis has been greatly simplified by excluding materials that do not contribute to dissipating the head. As a result, the required mesh is much smaller, and the processing time required is significantly reduced. Materials such as rockfill essentially have an infinitely steep (vertical) conductivity function. Portions of the material that are below the water table have a relatively high hydraulic conductivity while portions above the water table have an infinitely low hydraulic conductivity. In other words, there is no flow when the rockfill is totally unsaturated. Including materials with excessively steep conductivity functions can lead to wide oscillation in the solution and create unmanageable problems with convergence. As previously mentioned, the key issue in deciding if a particular material is relevant to a problem analysis is whether the material contributes to dissipating the excess head. If so, the material must be included in the analysis. If not, it may be possible to obtain a faster and better solution by not including the material in the seepage analysis. Regions with common material properties can be excluded from an analysis either by not including the region in the mesh or by assigning the material a zero conductivity function number. The latter alternative may be the preferred method if the mesh is to be used in another application, such as a stress analysis. When it is essential to include materials with widely contrasting hydraulic conductivity properties, the associated convergence difficulties can be reduced by including transition zones between the material types. For example, modelling clay immediately up against coarse gravel can create unmanageable convergence problems. In reality, there will likely be a gradual transition zone between the materials. Including a transition zone in the analysis to reduce the contrast in conductivity functions can assist in overcoming convergence difficulties.

260 SEEP/W As a general rule, convergence difficulties often arise when you attempt to model conditions that would not normally exist in the field.

Basic Solution Requirements The basic requirements for performing a steady state analysis are: ·

finite element discritization of the flow domain

·

the hydraulic conductivity function of the materials (K-functions)

·

the boundary conditions specification

The additional basic requirements for performing a transient analysis are: ·

the soil-water characteristic curve of the materials (Volumetric water content function)

·

the initial conditions of the flow domain

·

the time step specification

Furthermore, since SEEP/W is formulated using total head as the primary variable, in order to obtain a unique solution to a flow problem, the total head value of at least one node must be known and specified. Therefore, when SEEP/W calculates the total head at all nodes in the flow problem, the total head at all other nodes can be calculated with reference to the known head. In a steady state analysis, the above requirement suggest that at least a region node, a region edge or a region surface must be specified with a head boundary condition. However, in a transient analysis, since the initial condition of the flow system must be known and specified, a unique solution can be obtained with reference to the known initial head. In other words, you may obtain a unique solution in a transient analysis even if all the boundaries are specified as flux boundary conditions.

Incremental Time Sequences An incremental time sequence is required for all transient analyses. The appropriate time sequence is problem dependent. In most cases it will likely be necessary to try a reasonable sequence and then adjust the sequence as necessary in response to the computed results. For example, if the migration of the wetting front is too rapid, the time steps need to be decreased; if the migration is too slow, the time steps need to be increased. The accuracy of the computed results is dependent to some extent on the size of the time step. Over the period of one time increment, the process is considered to be linear. Each time step analysis is equivalent to a mini steady-state analysis. The incremental stepping forward in time is in reality an approximation of the nonlinear process. For the same rate of change, large time steps lead to more of an approximation than small time steps. It follows that when the rate of change is high, the time steps should be small, and when the rate of change is low, the time steps should be large. Many seepage processes related to the dissipation of excess pore-water pressures and infiltration follow an exponential form. The dissipation or infiltration is rapid at first and then decreases with time. A typical example is the consolidation of a soil. To model this situation, the time step sequence should approximately follow an exponential form. The time steps should be small at first and then progressively increase.

GEO-SLOPE Office 5 261

Conductivity Function Requirements A hydraulic conductivity function should be specified for all materials in a problem that will have an unsaturated zone. Even if the hydraulic conductivity function is an estimate, the results will be more realistic than if the function is omitted. Adopting a perfectly flat hydraulic conductivity function (i.e., a constant conductivity) for an unsaturated soil can lead to unrealistic results. The phreatic surface may end up at an unrealistic position, and the proportion of flow through the unsaturated zone may be too high. This occurs because water can flow through the unsaturated zone with the same ease as through the saturated zones when a flat hydraulic conductivity function is used. Stated another way, for a given constant head differential, the volume of flow is the same in the unsaturated zone as in the saturated zone when the hydraulic conductivities in the two zones are the same. In general, water cannot flow through unsaturated soil with the same ease as through saturated soil, because the unsaturated hydraulic conductivity is lower than that of a saturated soil. To illustrate the effect of assuming that hydraulic conductivity is independent of negative pore-water pressure (i.e., a perfectly flat conductivity function), consider the example of seepage flow through a rectangular screened box, as shown in Figure 7.5. Initially, the box is filled with clay. The phreatic surface will have the form of a hyperbolic curve (Figure 7.5a). In Figure 7.5b, the box is enlarged, the upstream half is filled with clay, and the downstream half is filled with sand. The sand is assigned a perfectly flat hydraulic conductivity function. In this case, the phreatic surface in the clay will be at a lower position. The reason for this is that a significant portion of the flow passes through the unsaturated sand. Since the resistance to flow is the same in the unsaturated sand as in the saturated sand, there is no reason for the sand to be saturated in order to conduct the water. Intuition alone reveals that this is not the case. The phreatic surface in the clay should be approximately the same in both configurations, and the seepage that arrives at the clay-sand contact should flow vertically down the contact and then horizontally along the bottom of the box to the exit point at the lower right corner. To model the clay-sand configuration, the sand needs to be assigned a very steep function, such that as soon as the sand desaturates, the hydraulic conductivity drops dramatically. This ensures that there is no significant flow in the unsaturated sand. However, a nearly vertical function may cause convergence difficulties. A compromise would be to use a moderately steep hydraulic conductivity function, which would eliminate the majority of the flow in the unsaturated sand and yet produce a reasonable result. It would certainly be closer to the correct solution than for the first case where the sand has a perfectly flat hydraulic conductivity function. Coarse granular materials have essentially an infinitely steep (vertical) hydraulic conductivity function when unsaturated. The soil desaturates completely when the pore-water pressure is zero or negative; consequently, no flow passes through such a soil when it is unsaturated. As a result, the hydraulic conductivity in the unsaturated zone should be infinitely low. Whenever a problem contains a coarse granular soil that ideally has a near vertical hydraulic conductivity function when unsaturated, it is necessary to ask the question, "Does the material contribute to the dissipation of the head?" If it does not, then consideration should be given to excluding the material from the analysis. In the clay-sand box example, the sand may not contribute to dissipating the head. Consequently, a reasonable solution might be obtained by excluding the sand from the analysis and treating the vertical contact between the two materials as a boundary. The decision as to whether the sand should be included in the analysis must also be made in light of the question, "Does the negative porewater pressure in the sand contribute to increasing the gradient in the clay?" If it does, the sand must be included in the analysis.

262 SEEP/W Figure 7.5 Effect of No Hydraulic Conductivity Function

The accuracy with which the hydraulic conductivity needs to be specified depends to some extent on the objective of the analysis. If the primary objective is to compute the distribution of pore-water pressure, then an approximate function may be adequate. On the other hand, if the objective of the analysis is to make reliable time predictions, then it may be necessary to define the storage and hydraulic conductivity with the assistance of laboratory tests. The level of effort required to define the material functions can be evaluated by performing several analyses with different assumed functions. Performing such a sensitivity analysis can greatly increase the confidence level of the computed results. Sample hydraulic conductivity functions, listed in Appendix A, are included with SEEP/W and are contained in the FN_FEET.SEP and FN_METRE.SEP data files. These conductivity functions are estimated from laboratory-determined volumetric water content functions (Soil-Water Characteristic Curves) for various materials. You can select or modify any of these functions and use them in your analysis. On top of the function library, SEEP/W DEFINE also provides a few estimation methods that you may like to use to estimate your conductivity function. For example, if you know the grain size curve of a material, you may use these methods to estimate both the volumetric water content and conductivity functions of the material. Please refer to Appendix A for details of these estimation methods. In summary, a hydraulic conductivity function must be specified for each material included in an analysis, even if the function is only an approximation. Using an approximated, curved relationship in the unsaturated zone results in a much better solution than using a straight, horizontal line for the conductivity function.

Initial Conditions For a transient analysis it is essential to define the initial, (or starting), total head at all nodes. SEEP/W allows you to specify the initial conditions by either reading the data from an initial conditions file, or by drawing the initial water table. It is important to recognize that the initial conditions for a transient

GEO-SLOPE Office 5 263 analysis can have a significant effect on the solution. Unrealistic initial conditions will lead to unrealistic solutions which may be difficult to interpret, especially in the early stage of the transient analysis.

Using an Initial Conditions File With this option, you specify an initial conditions file by using the KeyIn Analysis Settings command in SEEP/W DEFINE. The initial conditions file must be one of the following: ·

A head file created by a steady-state seepage analysis, (e.g. DAM.H00).

·

A head file created by a transient seepage analysis at a specific time step, (e.g. FILL.H12).

·

A pore-water pressure file created by a SIGMA/W stress/deformation analysis, (e.g. EMBANK.U12).

·

A pore-water pressure file created by a QUAKE/W earthquake dynamic analysis, (e.g. SLOPE.Z50).

NOTE: The initial conditions file name may be different than the data file name, (e.g. MYDAM.H00 and MYFILL.SEP, respectively), but it is critical that both files be based on the same finite element mesh. In most cases, the initial conditions can be established by running a steady-state analysis. Figure 7.6 illustrates two examples of steady-state flow problems that can be used to define the initial conditions for a transient analysis. The initial conditions for seepage from a pond (Figure 7.6a) might be the steadystate regional groundwater flow defined by the water table elevation underneath the pond. The initial conditions for seepage through a dam (Figure 7.6b) might be the steady-state flow condition of the dam due to the small water impoundment upstream from the dam. In a steady-state analysis, the pore-water pressure in the unsaturated zone above the water table will vary in a linear manner when the surface flux is specified as zero, as shown in Figure 7.7a. This means that the negative pore-water pressure near the surface may become too high. A more realistic estimate of the initial negative pore-water pressure can be established by specifying a small infiltration along the ground surface. The small surface flux has the effect of changing the pore-water pressure profile as illustrated in Figure 7.7b. The magnitude of the maximum negative pore-water pressure is dependent on the shape of the hydraulic conductivity function and, to a lesser extent, on the rate of infiltration. The infiltration rate must be less than the saturated conductivity. In general, applying a small non-zero surface flux tends to give a more realistic initial pore-water pressure estimates than a zero surface flux. Initial conditions can also be obtained from a SIGMA/W or QUAKE/W pore-water pressure file. Alternatively, the initial head file can be defined manually by editing any previously computed head file using a text editor such as Windows Notepad or Write and saving the file in text format.

264 SEEP/W Figure 7.6 Establishing Initial Conditions

GEO-SLOPE Office 5 265 Figure 7.7 Effect of Surface Flux on Negative Pore-Water Pressures under Steady-State Conditions

Drawing the Initial Water Table With this option, you specify initial conditions directly by using the Draw Initial Water Table command in SEEP/W DEFINE. This is particularly useful when the location of the initial water table is known in advance. When you define an initial water table, the initial total head at each node is computed proportionally to the vertical distance between the node and the defined water table. The effect is that the pore-water pressure varies hydrostatically with distance above and below the water table. Above the water table, the negative pore-water pressure can be set to a limit to produce a pressure distribution such as shown in Figure 7.7b. The definition of an initial water table gives an accurate pore-water pressure distribution when the water table is perfectly horizontal. If the water table is curved, this option gives an approximation of the actual initial conditions. Whether this approximation is or is not acceptable will depend on the nature of the problem. If this approximation is not considered adequate, then you will have to perform a SEEP/W analysis to establish the initial conditions.

266 SEEP/W No Initial Condition In the event if no initial condition is specified, SEEP/W will process with the transient analysis assuming that all nodes are at zero pressure conditions. In other words, the initial total head is equal to the elevation head. This initial condition may not be reasonable and may give unrealistic results especially in the early time steps. In summary, a reasonable initial condition must be specified in a transient analysis.

Adaptive Time Stepping Version 5 of SEEP/W will permit the use to activate an adaptive time stepping routine that will insert extra time steps between the user specified time steps in the event the heads between successive time steps are changing by more than the user specified percentage. There are two schemes that can be used to monitor the allowable change in nodal heads . The first option will scan every node in the mesh to see if the allowable percent head change is upheld. If it is not at any given node, then the time steps will be reduced such that the percent change is upheld. In the second option, the vector norm of nodal heads is used as the criteria. The vector norm considers all heads simultaneously. Experience should show that the vector norm approach is faster for a large mesh with two dimensional water flows. Analysis of a column study or a mesh with water flow primarily in one direction is better solved with the individual nodal head comparison. In the adaptive scheme, the time steps are reduced for the first 2 iterations and are then held constant until convergence is reached. The time stepping scheme adopted in SEEP/W is that proposed by Milly (1982). P.C.D. Milly, 1982. Moisture and heat transport in hysteretic, inhomogeneous porous media: A matric head based formulation and a numerical model. Water Resources Research, 18(3): 489-498.

The adaptive scheme will always insert just enough time steps to return to the increments established by the user. This way, no write out data steps are missed and the user still has control over the general time stepping of the solution. In order to activate adaptive time stepping the user must set up their time steps with preferred "save" time steps. Then the user checks the adaptive time stepping box and time step criteria as well as the maximum

GEO-SLOPE Office 5 267 allowable change in nodal head per time step and the minimum allowable time step. The minimum step is entered in the same time units as the hydraulic conductivity. As a general rule, nodal heads should not be allowed to vary more than 5 or 10 percent over any given time step. Keep in mind that this criteria depends somewhat on the actual heads being solved. For example, 5% of 1 meter is 0.05 meters. 5% of 100 meters is 5 meters. A tighter tolerance may be necessary for problems with an overall higher head range.

An Example With and Without Adaptive Time Stepping The Rapid example included with the program CD provides a good illustration of how adaptive time stepping can work to your advantage. The two figures below show the time stepping schemes selected for both cases. No adaptive time stepping.

268 SEEP/W With adaptive time stepping.

In the first case, the user has had to enter a time stepping scheme that will hopefully lead to a converged solution. They have entered 12 time steps with several "save" periods and a total elapsed time at the end of the simulation of 1970 days. In the second case, the user does not worry about appropriate time steps early on in the simulation but selects, for convenience, "save" time at 1970 days. The percent allowable head change between time steps is set at 2.5% and the minimum allowable time step is set to 2 days. The two figures below compare results after 1970 days for both cases. There are small differences but not significant in the scope of this example. For problems where there are closed form "exact" solutions, the adaptive time stepping can yield more accurate results in some cases compared to a time stepping scheme that the user must set up on a trial and error basis in order to replicate "exact" results. Water table profile after 1970 days with user selected time increments (above).

GEO-SLOPE Office 5 269 Water table profile after 1970 days with adaptive time steps.

Boundary Conditions Upstream Vertical Boundary A common problem is the impact of a manmade water retention structure on the natural groundwater regime. For example, consider the case of an irrigation canal, as illustrated in Figure 7.8. Leakage from the canal may cause the water table to rise. The problem is how to model the water table rise along the left vertical boundary.

270 SEEP/W Figure 7.8 Upstream Boundary Specification

One approach is to specify a flux across the boundary equal to the amount of natural groundwater flow. The environment upstream that created the natural regime will likely not change as a result of the canal, and the natural flow that arises at the left boundary will remain the same after the canal is in place. This approach is reasonable if the upstream boundary is extended far enough from the canal. To achieve the constant natural inflow to the system, the gradient must be maintained; to maintain the gradient, the water table must rise at the left. To find the natural groundwater flow quantity, it is necessary to define a flux section near the upstream end of the mesh and perform a steady-state analysis without infiltration from the canal. An additional benefit of performing the natural steady-state analysis is that it defines the initial conditions for a transient seepage analysis from the canal. An alternative is to use infinite elements along the left (upstream) boundary and specify the far field water table (head) conditions.

Downstream Vertical Boundary The downstream vertical boundary condition is difficult to establish when the boundary is relatively close to the surface infiltration source. It is incorrect to define the boundary as a zero flux boundary, since this will force all of the flow to the surface, as illustrated in Figure 7.9a. An exception to this situation is the case where the water table is at the ground surface. In this case, a zero flux on the downstream vertical boundary is perhaps appropriate.

GEO-SLOPE Office 5 271 Figure 7.9 Effect of Q and H Specification on a Downstream Vertical Boundary

Defining the downstream vertical boundary as a head boundary may also not represent actual conditions. Specifying a head on the lower portion of the vertical boundary has the same effect as if a water-filled trench exists next to the boundary and water is removed from the trench to maintain the constant head specified (Figure 7.9b). Specifying a head boundary also implies that there is no further resistance to flow beyond the vertical boundary. This is usually not the case. When the seepage discharge point is a long distance from the region of interest, it is best to model the far-field condition using infinite elements.

Fluctuating Reservoir A typical situation encountered in seepage modelling is the rise and fall in the level of a reservoir. The result is that certain boundary nodes become submerged as the water level rises and become exposed as the water level falls. The fluctuation in the reservoir level can be described by a boundary function of head versus time. Each node in contact with the reservoir is assigned a head depending on the function and the elapsed time. Exposed nodes that follow the boundary function can be assigned one of two conditions. The first option is to adopt the head as defined by the boundary function; the second option is to assign all nodes above the reservoir level a boundary type of Q=0. For example, assume that the reservoir level is at a head (y-coordinate) of 20 and that there is a node at y coordinate 22 that was submerged and is now exposed. Assigning the node a head equal to 20 as per the boundary function means the boundary condition is specified as -2 units of pore-water pressure. The alternative is to set the boundary condition to Q=0 for the exposed node. This might be more realistic than specifying a negative pore-water pressure. It is difficult to predict the pore-water pressure at a node that becomes exposed. Therefore, the choice of

272 SEEP/W which boundary condition to use must be made in light of the problem being analyzed. Alternatively, the fluctuation in the reservoir level can be described by a boundary function of head versus volume. This approach is particularly useful when the fluctuation in the reservoir level is induced by draining and filling of the reservoir. In a transient analysis, SEEP/W computes the total flux volume gained or lost from the reservoir and automatically updates the boundary head of the reservoir according to the specified function. Figure 7.10 illustrates a head versus volume boundary function. Note that the head (i.e., elevation of the reservoir water level) at zero volume is the head in the reservoir at the beginning of the transient process. Figure 7.10 shows that as the reservoir gains volume (i.e., fills), the head in the reservoir increases; similarly, as the reservoir loses volume (i.e., drains), the head in the reservoir decreases. Figure 7.10 A Boundary Function of Head vs. Volume

Nonzero Flux Boundary To model the infiltration of precipitation it is possible to specify a unit flux on the boundary, such as 0.015m of rain per hour. The amount of precipitation that can infiltrate the ground is partially controlled by the saturated hydraulic conductivity of the soil. In many cases, specifying a flux greater than the saturated hydraulic conductivity will result in excess head at the boundary, which is equivalent to ponding on the surface. When the rainfall rate is greater than the saturated hydraulic conductivity, the amount that can potentially infiltrate the ground is approximately equal to the saturated hydraulic conductivity; the remaining portion disappears as runoff. If there is runoff, then there is sufficient precipitation to ensure that the pore-water pressure at the surface is zero or that the head is equal to the elevation (y coordinate) of the ground surface. Specifying the boundary condition as head equal to the elevation of each node is a simpler method than attempting to specify a flux that will result in a zero pressure boundary . To model this type of situation, SEEP/W allows the unit flux to be defined as a boundary function. The boundary condition can be set to head equal to the elevation (y coordinate) of the node if the unit flux (q) from the boundary function is greater than the saturated hydraulic conductivity of the materials surrounding the node. When this condition is selected, SEEP/W determines the average saturated hydraulic conductivity for all elements connected to a particular boundary node. It then sets the boundary type of the node to head with a value equal to the y coordinate if the applied boundary q value is greater than the average saturated hydraulic conductivity at the node. This option can be selected by checking the if q > Ksat, H = elevation option in the Boundary Functions dialog box.

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Internal Boundary Conditions It is possible to specify a head, a nonzero flux or a review boundary at any node in the entire mesh. This makes it convenient to model such features as an injection well or a drainage tile. If a tile drain functions as designed, the water pressure in the drain is a known value. In most cases, the drain will be designed to remove all water that seeps into the drain. Under this condition the water pressure in the drain is zero. Therefore, a drain can be modelled by setting the head equal to the y coordinate value of any node located at the drain. (A node must exist at the drain location). An injection well can be modelled by specifying the amount of the injection as the boundary condition for the node at which the fluid is injected. The amount of seepage into a drain can be determined by defining a flux section around the drain, as illustrated in Figure 7.11. Alternatively, you can determine the amount of seepage into a drain using the View Node Information command in CONTOUR; the total nodal flux is displayed beside the Boundary Flux label in the dialog box. If the size of the drain is large with respect to the modelled flow system, the size of the drain should be modelled with more than one node. An opening must be incorporated into the mesh and the head must be specified along the perimeter of the opening. In general, more accurate solutions can be obtained when an opening is modelled for internal drains. Figure 7.11 Flux Section for Computing Flow into a Drain

Ground Surface Flux There are features pertaining to the ground surface flux to be aware of when including ground surface flux in a SEEP/W analysis. The net infiltration or evaporation flux at the ground surface is related to a complex interaction between atmospheric conditions, ground surface cover, and soil conditions in the first meter below the ground surface. Generally, only a portion of the precipitation that falls as rain or sprinkler irrigation enters the ground. The amount that enters the ground is related to the rainfall rate and duration. The infiltration rate may initially be equal to the rainfall, but it may then decrease as the soil approaches saturation at the surface (Freeze and Cherry, 1979, p. 214). Furthermore, plants may intercept a portion of the rainfall, thereby reducing the amount of water available for infiltration. Water not entering the ground may be lost due to evapotranspiration. This loss contributes to reducing the amount of precipitation that is ultimately added to the groundwater regime. Further amounts of water entering the ground may later leave as a result of evaporation. As the surface dries, the pore-water pressure near the surface becomes highly negative. This draws water to the surface which is potentially lost through evaporation. Water may migrate in the form of a fluid or vapor and then ultimately be lost to the atmosphere as vapor.

274 SEEP/W Wilson, 1990, has shown that the pore-water pressure at the ground surface can become highly negative, as illustrated in Figure 7.12. The result is a thin, highly desiccated layer at the surface which can greatly reduce the potential water loss through evaporation. Figure 7.12 Negative Pore-Water Pressure near the Ground Surface

Near the ground surface, water is lost in vapor form. To model this type of water loss, it is necessary to consider heat flow as well as water flow, (Wilson, 1990). SEEP/W is not formulated to model vapor flow. A separate computer software package is required to compute the ground surface flux. The results from such a program could be used as the boundary conditions for a SEEP/W analysis. Until such a program is available, no definitive guidelines can be offered on how to specify the ground surface flux, except that it is necessary to perform a sensitivity analysis to establish the importance of the surface flux. Such a sensitivity analysis may reveal that the surface flux is not a critical issue, and consequently a reasonable estimate may be adequate. If the sensitivity analysis reveals that the surface flux is critical to the solution, then efforts will have to be directed toward more clearly defining the ground surface flux. SEEP/W provides several options for specifying the ground surface flux boundary. For a steady-state analysis, the ground surface flux boundary can be specified as a constant flux rate (q) or a constant flux quantity (Q). For a transient analysis, the ground surface flux boundary can also be specified as a function of q vs. time or Q vs. time. SEEP/W has a feature that makes it possible to modify the surface flux on the basis of the negative porewater pressures in the ground. This is done by defining a modifier function, such as shown in Figure 7.13. At the beginning of each time step, SEEP/W first computes the surface flux (e.g., from a q vs. time function). Next, SEEP/W establishes the current pore-water pressure at the boundary node and then reduces the surface flux according to the modifier function.

GEO-SLOPE Office 5 275 Figure 7.13 Example of a Modifier Function

Boundary Reviews Boundary Reviews for Potential Seepage Faces For certain types of seepage problems, the boundary conditions on some nodes are unknown function of the flow process. A typical example is where seepage exits on the downstream homogeneous dam. The point where the phreatic surface intersects the dam face is unknown. situation arises after the drawdown of a reservoir (Figure 7.14). Establishing the correct conditions for these situations requires an iterative procedure similar to that required to nonlinear finite element equations.

and are a face of a A similar boundary solve the

Figure 7.14 Typical Location of Review Nodes

SEEP/W allows the modelling of these special boundary conditions with a "review boundary". All nodes on the potential seepage face are initially assigned a flux-type boundary condition. After the heads are computed for all nodes, these nodes are reviewed to ensure that these nodes are either remind unsaturated or at zero water pressure with water leaving the flow system. During a transient analysis, all review nodes are set to a flux type boundary condition at the start of each time step. This includes all nodes that were converted to a head type boundary condition during the previous time step. The applied flux is set to the initial action specified at the review nodes. If the review nodes follow a flux type boundary function, the flux at the review nodes is computed from the function for the start of each time step. Review nodes can be located anywhere along a boundary. For example, the nodes may be located on the downstream seepage face and on the upstream drawdown face at the same time. All nodes are considered in the review procedure. Consequently, the modification may jump from one area to another with each successive iteration. If the review nodes follow a head versus time boundary function, the Q=0 boundary option must be used.

276 SEEP/W This is required to ensure that all nodes with a y coordinate greater than the boundary function head have a condition of flux equal to zero at the start of each time step. It is important to remember that nodes that need to be reviewed must have a flux type boundary at the start of the time step. Nodes with a specified head boundary condition cannot be reviewed.

Handling Convergence Difficulties The solutions to unsaturated seepage problems can be highly nonlinear due to the variability in conductivity and in the rate at which water is released or retained during a transient process. The degree of nonlinearity is dependent on the steepness of the conductivity function and volumetric water content function. Difficulties with convergence can be encountered when either of these material property functions become relatively steep. The first thing to do when you experience convergence problems is to re-evaluate the relevance of coarse materials, as discussed in the Relevant Materials topic in this chapter. If a coarse material does not contribute to dissipation of the head, then you should try excluding the coarse material from the analysis by setting the K-Fn number to none. This will simplify the problem and assist you in overcoming the convergence difficulties.

The Problem with Steep Functions Coarse-grained materials can sustain a relatively small capillary zone and tend to desaturate almost completely at small negative pore-water pressures. This behavior manifests itself in a very steep hydraulic conductivity function; that is, a function where the hydraulic conductivity varies greatly with small changes in negative pore-water pressure. A typical steep hydraulic conductivity function is shown in Figure 7.16. Figure 7.16 A Typical Steep Hydraulic Conductivity Function

Theoretically, the hydraulic conductivity function approaches a vertical line (infinitely steep) near the zero pressure axis when the material is very coarse. This is the case for sands and gravels that have virtually no capillary zone and are essentially dry above the water table. Very steep hydraulic conductivity functions can create difficulties with convergence. In fact, it may not be possible to obtain convergence when the hydraulic conductivity function approaches a vertical line. The solution will tend to diverge instead of converge and oscillate between two extreme solutions

GEO-SLOPE Office 5 277 represented by the extremities of the hydraulic conductivity function. Consider the function illustrated in Figure 7.16. Assume that for the first iteration all elements are assigned a saturated hydraulic conductivity (ka) corresponding to zero pressure. This hydraulic conductivity will allow for more flow than is required and will result in a highly negative pore-water pressure (Point F). For the next iteration, the hydraulic conductivity will be kf. This value does not allow for enough flow, and the computed pressure will be positive. Once again, the hydraulic conductivity will be set to a value that is too high, resulting in a solution which oscillates between the extremities permitted by the function. In order to obtain a converged solution for steep hydraulic conductivity functions, the change in hydraulic conductivity from one iteration to the next must be controlled. SEEP/W controls this change with three parameters: Max_Change, Rate_of_Change, and Min_Change. Max_Change represents the maximum allowable change in conductivity, Min_Change represents the minimum allowable change in conductivity, and the Rate_of_Change parameter controls the rate of the conductivity change.

Using Convergence Parameters The SEEP/W convergence parameters (i.e., Max_Change, Rate_of_Change, and Min_Change) can be thought of in terms of a circular search region. Max_Change is the radius of the circle within which SEEP/W is allowed to find a new k value. Rate_of_Change is the rate at which the radius of the search circle decreases with successive oscillations. Min_Change is the minimum allowable radius of the search circle. The Max_Change and Min_Change radius search values are expressed in terms of the log of the conductivity. For example, a Max_Change value of 1.0 means that the conductivity can vary by one order of magnitude, while a Max_Change value of 0.5 means the conductivity can vary by one half of an order of magnitude. At each point of reversal in the convergence process, the Max_Change value is decreased by the Rate_of_Change value. For example, assume that the Rate_of_Change value is 1.1 and the starting Max_Change value is 1.0. After the first reversal in the convergence process, Max_Change is reduced to 0.91 (1.0/1.1), then to 0.83 (0.91/1.1) after the next reversal. This process continues until the computed Max_Change value is less than the Min_Change value. Figure 7.17 shows a typical convergence record. Note how the magnitude of the oscillation decreases due to a reduction in Max_Change.

278 SEEP/W Figure 7.17 A Typical Convergence Record

Selecting Convergence Parameters Unfortunately, there are no firm rules for selecting parameters that will lead to convergence. Usually, in difficult convergence cases, it is necessary to try various combinations of parameters until an acceptable solution has been obtained. A reasonable initial value to use for Max_Change is 1.0 (one order of magnitude), and a modest value for the Rate_of_Change, such as 1.1, is a good initial value. A low rate like this may mean that more iterations are required, but there is a better chance of converging to the correct solution. A higher rate may require fewer iterations, but SOLVE may reach the Min_Change value too soon and give you a false impression that the solution has converged. A lower Rate_of_Change value is better, even if it results in more iterations. You must be careful not to make the Min_Change value too low. If this value is too low, the percentage change from one iteration to the next may be less than the convergence tolerance, again giving a false impression that the solution has converged when it really requires more iterations. If the Min_Change parameter value is very low, then the convergence tolerance value must also be very low. In fact, in a difficult convergence problem, it may be necessary to set the convergence tolerance to zero and the number of iterations to a high value so that you can graphically monitor the convergence process over a large number of iterations. You can then click on the Halt Iteration button in the SOLVE window when you decide that the convergence is acceptable. In most cases, a convergence tolerance of 0.01 is adequate and the solution should be converged within 50 iterations. In the case of steep K functions (e.g., KISCH example), allowing a smaller convergence tolerance and a larger number of iterations may be required.

Acceptable Convergence During the iterative process, SEEP/W calculates the residual which represents the total difference in the total head of all nodes between two consecutive iterations. In a fully saturated problem the residual will be zero in the second iterations. This indicates that the solution converges in two iterations, and the total head values of all nodes between the first and second iterations are identical. However, in the case of an unsaturated problem, the residual may be large in the early iterations and gradually reduced to a small number. In general, a convergence tolerance of 0.01 leads to an acceptable solution in many cases. If the solution is highly nonlinear and the convergence process oscillates greatly, you can use the SOLVE

GEO-SLOPE Office 5 279 Graph command to watch the convergence process graphically in order to decide when convergence has been reached. Figure 7.18a presents a typical Residual versus Iteration plot of a converging process, the solution is not converged after 20 iterations. The residual is converging, but the magnitude is still quite high. Figure 7.18b shows the convergence plot when the same problem is run to 100 iteration. The solution is converged. As a broad guideline, in a normal converging situation, the residual would oscillate but also decrease in magnitude. If the residual keeps oscillating without decreasing in magnitude, the problem is not converging, and you must change your model such as refining your mesh or reducing the steepness of the material K functions. In addition to the Residual versus Iteration plot, you may also select to view the K versus Suction plot. In this plot, the estimated unsaturated hydraulic conductivity at each Gauss points of an iteration is compared with the user specified unsaturated K functions. Figure 7.18c illustrates the case when there is major difference between the estimated unsaturated hydraulic conductivity (red dots) and the user specified unsaturated K functions (blue squares). Figure 7.18b illustrates the case of a converged solution, when the estimated unsaturated hydraulic conductivity line up closely with the the user specified unsaturated K functions. With the helps of the two type of convergence plots provided for you during and after run time, you should be able to determine graphically if a problem has achieved an acceptable convergence or not. When the SOLVE Graph window shows that the iteration process has reached a certain limit, you can click on the Halt Iteration button to stop the iteration process. Visually monitoring the convergence is useful during the early stages of an analysis when you are uncertain about what convergence parameters to use. Once you have found a suitable set of parameters, you can do further analyses without continuing to visually monitor the convergence process. Figure 7.18 Using SOLVE to Visually Recognize Convergence a) Residual vs Iterations Plot - Not Converged

280 SEEP/W b) Residual vs Iterations Plot - Converged

c) K vs Suction Plot - Not Converged

d) K vs Suction Plot - Converged

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Effect of the Volumetric Water Content Function The Max_Change, Rate_of_Change, and Min_Change parameters all control the changes in hydraulic conductivity. Variation in the slope of the volumetric water content function, however, can also cause some convergence problems. If you make changes to the convergence parameters but notice no changes in the convergence behavior, then the convergence problem is likely caused by the volumetric water content function. It is important to recognize that problems with convergence due to the volumetric water content function occur only in a transient analysis and never in a steady-state analysis. There are several things that you can do if you determine that convergence problems arise due to the volumetric water content function. Some analyses may have convergence problems in a few time steps, but most of the time steps may converge properly. (It is often most difficult to get convergence in the first or second time steps). In this case, the overall solution may be acceptable even though convergence has not been achieved for all time steps. As long as there is a consistent trend in the migration of the wetting front, the solution is likely reasonable and acceptable. Lack of convergence in one or two time steps does not necessarily mean that the entire solution is unacceptable. Another thing that can be done when the volumetric water content function is causing the convergence problem is to alter the time steps. Smaller time steps can sometimes help to bring about convergence. Refinement of the finite element mesh in areas of steep hydraulic gradients can also help to reduce convergence problems.

Unnatural Boundary Conditions Unnatural boundary conditions can also lead to convergence problems. For example, consider the case of filling a reservoir. Often, the reservoir is assumed to have been filled instantaneously. By modelling it this way, the initial flow gradients are so high that it can be difficult to get a solution. Applying a more realistic boundary condition that fills the reservoir over time can reduce convergence problems. Having unrealistic initial conditions in a transient analysis may also lead to convergence problems. In general, you should not try to model situations that cannot occur in reality.

Transmissivity and Storativity Transmissivity and Storativity Transmissivity, storativity, and specific storage are terms commonly used to describe the characteristics of groundwater aquifers. These terms have a comparable parameter in SEEP/W which makes it possible to use SEEP/W to analyze the behavior of groundwater aquifers. The storativity, (storage coefficient), S is defined as: S = Ss b (7.1) where Ss is the specific storage and b is the thickness of a confined aquifer. The specific storage is defined as: (7.2) where: p = water density

282 SEEP/W g = gravitational constant a = compressibility of the aquifer n = porosity b = compressibility of the water Specific storage is identical to the gwmw term in SEEP/W terminology. (7.3) (7.4) Therefore,

(7.5) In SEEP/W, the term mw is the parameter that represents the compressibility of the system due to a change in pore-water pressure. The transmissivity T of a confined aquifer is defined as:

(7.6) where: b = aquifer thickness K = hydraulic conductivity If the transmissivity and the thickness are known, the appropriate hydraulic conductivity value (K) can be established for a SEEP/W analysis.

Axisymmetric Analysis An axisymmetric analysis can be used to simulate three-dimensional problems with symmetry about a vertical axis of rotation. The problem is defined in two dimensions but for analysis it is as if the section is rotated about a vertical central axis. A typical example of an axisymmetric analysis is the flow into a single pumping well or flow out of a single recharge well into a uniform aquifer. In SEEP/W the vertical symmetric axis of rotation is always at x-coordinate equal to zero. The x coordinates in an axisymmetric finite element mesh must, therefore, all be greater or equal to zero. This affects the simulation of well and casing sizes. The distance from the central axis to the inside vertical edge of the mesh is the well and casing radius, as illustrated in Figure 7.19.

GEO-SLOPE Office 5 283 Figure 7.19 Central axis and x-coordinate definition for axisymmetric analyses

For an axisymmetric analysis, the computed flux is per unit radian if the element thickness is specified as 1.0. If the computed flux is for the entire circumferential area, you must specified the element thickness as 6.2832 (i.e., 2 pi radian). You can change the element thickness for the entire mesh with the Draw Element Properties command. Infinite elements may be used for the outside far field edge of the axisymmetric mesh. However, the application of non-zero q (unit flux) boundary conditions along the infinite elements is not allowed. This is because the nodal contributing area is dependent on the distance of the node from the rotation axis, and since the far nodes of the infinite elements are at infinity, the nodal contributing area becomes undefined. Even though SEEP/W may still compute a solution to the problem in some simple cases, the solution becomes suspect and the use of q-type boundary conditions in this case is therefore not recommended.

Plan View Analysis A plan view analysis views the finite element mesh as lying on its side instead of standing upright in a vertical plane. This makes it possible to model the potentiometric surface changes that result from extracting or injecting fluid into an aquifer. However, the analysis is limited to a perfectly flat hydraulic conductivity function (that is, the hydraulic conductivity cannot be a function of the pore-water pressure). The limitation is not serious in the case of confined aquifers where the water pressure remains positive at all locations and at all times. However, it may be a serious limitation in the case of an unconfined aquifer. Therefore, the plan view analysis type is intended for confined aquifer only, and application to unconfined problems must be conducted with caution. The position of the potentiometric surface as computed for unconfined aquifers should be viewed only as a rough approximation. For a plan view analysis, you can define the z coordinate (elevation) for each node and the thickness of the elements. If the z-coordinate is not specifically specified, it is taken to be zero by default. Similarly, if the thickness is not specifically specified, the thickness of the element is set to 1.0. The plan view elevation and thickness can be set after you have defined the x- and y coordinates of the plan view problem with the KeyIn Generate Plan View command. The elevation (z-coordinate) and thickness are generated on a planar basis by defining the x-, y- and z coordinates as well as the thickness at three points. The thickness of the elements influences the computed flux quantity across a flux section. Therefore, when you are interpreting the flow across a flux section you must take into account the aquifer thickness at the location of the flux section. If you have not specifically specified the element thickness, then the

284 SEEP/W thickness is by default unity (1.0). The z-coordinate can be thought of as the depth down to the top of the aquifer. Adopting this definition helps with interpreting the results. The pore-water pressure in a plan view analysis is computed as total head (H) minus the elevation (Z). This means that when the water pressure is positive, the water table is above the top of the aquifer and the aquifer remains saturated. When the water pressure is negative, the water table is below the top of the aquifer and the aquifer in part has desaturated. To maintain a positive water pressure in the aquifer, the specified and computed head must be greater than the z coordinate. You can specify a rate of infiltration or evaporation on the ground surface of a plan view analysis using the q (unit flux) boundary condition. SEEP/W computes the contributing surface area for each node to get the nodal flux required for solving the finite element equations. You can use infinite elements in a Plan View analysis. However, the application of a non-zero q (unit flux) to infinite elements is not recommended. The outer edge of infinite elements is theoretically projected to infinity and consequently the contributing areas for the outer edge nodes are not well defined. The resulting heads may or may not be reasonable. If you are going to apply a surface flux to infinite elements, you will have to make a careful assessment of the results to make sure they are reasonable. You can apply H and Q type boundaries without difficulty.

Element Addition and Removal Any element can be considered to be nonexistent by assigning the conductivity function number a value of zero. This feature makes it possible to simulate the construction of embankments and excavations. It is necessary at the start of the problem to define the elements you anticipate adding or removing. Defining the complete mesh at the beginning of an analysis will maintain compatibility between files. The total number of elements and number of nodes must not change as you progress from one stage of the analysis to another. If the number of nodes or elements changes, it is no longer possible to use previously computed results as initial conditions for a subsequent step because the files will be incompatible. The Draw Element Properties command in DEFINE is useful for applying a null material type to specific elements as you are simulating the construction of embankments or excavations. A null material type may be defined by using the KeyIn Material Properties command to create a material type with a KFunction of zero.

The Use of Infinite Elements Near field boundary conditions can sometimes create difficulties, as discussed in Boundary Conditions in this chapter. Some of these difficulties can be overcome with the use of infinite elements.

The Implications of Infinite Elements Infinite elements can be useful for analyzing unbounded problems where the boundary conditions are unknown at the point of engineering interest (the near field) and are only known at some far-off distance (the far field). The geometric shape of infinite elements are displayed the same way as other ordinary elements, but for computational purposes, the outer edge is deemed to be at infinity. In the example shown in Figure 7.20, the right edge of the problem is actually at infinity, even though it is shown on the drawing. Since the displayed shape of the infinite elements does not represent the actual condition used in the finite element calculations, the resulting contours within an infinite element usually are sharply bent upwards or downwards, as illustrated in Figure 7.21. If the right boundary was sketched to infinity (as in

GEO-SLOPE Office 5 285 the calculations), the water table contours would continue on a smooth, near-horizontal line. In summary, it is important to recognize that the outer edge of the problem is actually a long distance away from the displayed edge of the mesh when you are using infinite elements. Figure 7.20 Example Problem Using Finite and Infinite Elements

Figure 7.21 Axisymmetric Flow to a Pumping Well Using Infinite Elements

The Pole Position The pole is used to compute the nodal position of the infinite elements and it must be specified whenever you use infinite elements. In general, the pole should be near the source of the seepage (e.g., a reservoir) or at the discharge point, (e.g., a pumping well). The pole should also be near the opposite end of the mesh from where the infinite elements are located. If infinite elements are located at both ends of the mesh, the pole should be near the center of the mesh. The pole cannot be located within an infinite element or within the direction of infinity of any infinite element. For example, if an infinite element has a negative x-infinity, the pole must be located to the right of the infinite element. If the pole is located to the left of this infinite element, SEEP/W will compute a negative element area and will be unable to find a solution. SEEP/W DEFINE, by default, places the pole at the center of the mesh when you specify the first infinite element. If necessary, you should reposition the pole near the source or discharge point. Fortunately, the solution with infinite elements is not very sensitive to the exact pole position. The pole

286 SEEP/W position can affect the solution particularly within the infinite elements, however, this effect is not significant if the pole is in a reasonable, approximate position.

Infinite Flux Boundaries The specification of non-zero q (unit flux) boundary conditions along infinite elements is not recommended. To use a q boundary, SEEP/W needs to compute the nodal contributing area. Since the outer edge of an infinite element is deemed to be at infinity, the computation of nodal contributing areas becomes suspect. In fact, for an axisymmetric analysis, the nodal contributing area of an infinite element becomes undefined. When non-zero q (unit flux) boundary conditions are specified along infinite elements, SEEP/W may still give a solution to the problem in most cases. However, the solution becomes suspect and you will have to make a careful assessment of the results to make sure they are reasonable.

Flow Paths SEEP/W can draw a flow path by clicking on a point within the flow domain. The path is drawn strictly on the basis of the velocity vectors within each element. The path is projected forwards and backwards incrementally within each element until the path encounters a boundary The flow path is simply a graphical representation of the route a molecule of water would have traveled under steady-state conditions from the entrance to exit point within the flow regime. The SEEP/W flow paths are not intended to replicate the flow or stream lines within a traditional flow net. In many cases the SEEP/W flow path will be the same or very close to a flow line. Slight variations between a flow path and a flow line should not be of concern because they are computed in entirely different ways. At best, the SEEP/W flow path should be viewed as a reasonable approximation of the flow lines within a flow net. The flow paths will always be the most realistic in saturated zones where there is significant velocity. In zones where there is little or no flow, the SEEP/W flow paths may not be realistic. Several cases are illustrated in Figure 7.22. In the upstream toe area where there is little flow, the flow path ends along the bottom boundary. This is not physically correct and therefore is not a realistic flow path. Within the unsaturated zone in Figure 7.22 there is a flow path that ends within the dam section. The reason for this is that the path has reached an area where there is essentially no flow. Once again, such a flow path has no meaning. Since it is possible to click in an area with relatively no seepage and create an unrealistic flow path, some judgment is required by you when drawing flow paths. You should discard flow paths that you judge to be unrealistic. Figure 7 22 Illustrative flow paths

Another important point is that in a saturated/unsaturated SEEP/W flow analysis, the phreatic line is not a flow line. It is simply a line of zero water pressure. Since water can flow from the saturated to the

GEO-SLOPE Office 5 287 unsaturated zone, and vice versa, flow can take place across the phreatic surface. Consequently, a flow path may cross the phreatic surface as illustrated in Figure 7.22. This is acceptable and realistic. Flow paths can only be drawn for steady-state conditions. Flow paths based on velocity vectors at an instant in time during a transient process have no physical meaning. For this reason, SEEP/W does not permit you to draw flow paths for transient conditions

Flow Lines For totally saturated steady-state conditions, it is possible to compute flow or stream lines such that the discharge between each of the lines is the same. These lines are the exact flow lines within a flow net. You can trick SEEP/W into computing flow lines by reversing the H and Q boundary conditions along the perimeter of the problem. Consider the case presented in Figure 7.23 and 7.24. To compute the equipotential lines it is necessary to specify the head (H) along the reservoir-ground contact and along the ground surface beyond the downstream toe of the dam. Along the remainder of the perimeter the boundary condition is set to zero flux, (Q = 0). Figure 7.23 Boundary conditions for computing equipotential lines

Now to compute flow lines, the boundary types must be reversed. Along the left and right vertical boundaries, and along the base of the mesh the head is specified as zero (H = 0). Along the base of the dam and the cutoff wall the head is, for example, specified as H = 10. Along the reservoir-ground contact and along the ground surface beyond the downstream toe of the dam, the boundary type now is Q = 0. The result will be as illustrated in Figure 7.24. The H difference of 10 produces 10 flow channels. A higher H difference would result in more flow channels and vise versa. Figure 7.24 Boundary conditions for computing flow lines

The flow lines next to the left and right boundaries become near vertical. This is a reflection of the

288 SEEP/W infinite elements. The flow lines would remain curved if the infinite elements were drawn at the true scale. The compressed representation of the infinite elements causes the break in the flow lines. Tricking SEEP/W into drawing flow or stream lines has its limitations. It works best for saturated homogeneous confined flow problems such as presented in Figure 7 24. Applying the technique to unconfined or heterogeneous or unsaturated problems may give reasonable results but you have to assure yourself through your own assessment as to the validity of those results. Tricking SEEP/W into computing flow lines should only be done when Q = 0. If the boundary flux is non-zero, the technique breaks down and should not be used. The results shown in Figure 7.24 were produced using the example problem called CUTOFF, included with the software. You can modify the included CUTOFF.SEP file to duplicate this example if you wish.

Chapter 8 Theory Introduction This chapter presents the methods, equations, procedures, and techniques used in the formulation and development of the SEEP/W SOLVE function. It is of value to be familiar with this information in order to use the software. An understanding of these concepts will be of great benefit in applying the software, resolving difficulties, and judging the acceptability of the results.

Volumetric Water Content Functions Fundamental to the formulation of a general seepage analysis is an understanding of the relationship between pore-water pressure and water content. As water flows through soil, certain amounts of water are stored or retained within the soil structure. The amount of water stored or retained is a function of the pore-water pressure and the characteristics of the soil structure. For a seepage analysis, it is convenient to specify the stored portion of the water flow as a ratio of the total volume. This ratio is know as the volumetric water content. In equation form: (8.1) where: = volumetric water content Vw = volume of water V = total volume The volumetric water content ( ) is dependent on the pore-water pressure. Figure 8.1 illustrates this relationship, which is also known as the soil-water characteristic function, (see Fredlund, D.G. and Rahardjo, H., 1993, pp. 136-140).

290 SEEP/W Figure 8.1 General Form of Volumetric Water Content Function

When the degree of saturation is 100%, the volumetric water content is equivalent to the soil porosity, which is defined as the volume of voids divided by the total volume. Consider a completely saturated soil where the pore-water pressure is near zero, and the total external load on the soil remains constant. As the pore-water pressure becomes more positive, the effective stress will decrease. This causes the soil to swell and results in an increase in its water content. As the pore-water pressure becomes negative, the soil begins to desaturate and the water content decreases. Ultimately, the soil becomes completely desaturated, and the water content no longer changes with a further decrease in pore-water pressure. The slope of the soil-water characteristic curve (designated as mw) represents the rate of change in the amount of water retained by the soil in response to a change in pore-water pressure. When the pore-water pressure is positive, mw is equivalent to mv, the coefficient of compressibility for one-dimensional consolidation. The parameter mw is required in a transient seepage analysis. Soil-water characteristic functions for fine-grained (clay) soils may be relatively flat, while for coarse-grained soils (sand) the function may be quite steep. Figure 8.2 presents actual volumetric water content curves obtained by Ho, 1979, for fine sand, silt, and clay. The variation in these curves demonstrates the effect that the soil properties have on the characteristic functions. Appendix A presents guidelines for establishing these functions in the laboratory; it also contains more typical published functions.

GEO-SLOPE Office 5 291 Figure 8.2 Actual Vol. Water Content Functions for Fine Sand, Silt, and Clay

Hydraulic Conductivity Functions Water in liquid form can be considered to flow along a web of interconnected but continuous conduits. Decreasing the water content has the effect of decreasing the size and number of conduits, thereby reducing the capacity to conduct water through the soil. Ultimately, when the soil is dry, the capacity to conduct water along continuous water-filled conduits disappears. When the soil is saturated, all of the available conduits are utilized, and the water hydraulic conductivity capacity is at a maximum. The capacity of soil to conduct water can be viewed in terms of hydraulic conductivity (or the coefficient of permeability). In this context, the hydraulic conductivity is dependent on the water content. Since the water content is a function of pore-water pressure and the hydraulic conductivity is a function of water content, it follows that hydraulic conductivity is also a function of pore-water pressure. Figure 8.3 presents a curve showing a typical relationship between hydraulic conductivity and pore-water pressure.

292 SEEP/W Figure 8.3 A Hydraulic Conductivity Function

Techniques have been developed for predicting the hydraulic conductivity function from a soilwater characteristic function. Establishing the characteristic function is generally not as complicated as conducting laboratory tests to measure the conductivity function. SEEP/W uses the Green and Corey, 1971, procedure for estimating the conductivity function from a soil-water characteristic function. The details of this predictive method and some typical hydraulic conductivity functions are presented in Appendix A. Defining the hydraulic conductivity for negative pore-water pressure regions makes it possible to analyze problems involving unsaturated flow as well as saturated flow.

Flow Law SEEP/W is formulated on the basis that the flow of water through both saturated and unsaturated soil follows Darcy's Law which states that: q = ki (8.2) where: q = specific discharge k = hydraulic conductivity i = gradient of fluid head or potential Darcy's Law was originally derived for saturated soil, but later research has shown that it can

GEO-SLOPE Office 5 293 also be applied to the flow of water through unsaturated soil (see Richards, 1931 and Childs & Collins-George, 1950). The only difference is that under conditions of unsaturated flow the hydraulic conductivity is no longer a constant but varies with changes in water content and indirectly varies with changes in pore-water pressure. Darcy's Law is often written as: v = ki (8.3) where v is known as the Darcian velocity. The actual average velocity at which water moves through the soil is the Darcian velocity divided by the porosity of the soil. SEEP/W computes and presents only the Darcian velocity.

Governing Equations The governing differential equation used in the formulation of SEEP/W is:

(8.4) where: H = total head kx = hydraulic conductivity in the x-direction ky = hydraulic conductivity in the y-direction Q = applied boundary flux = volumetric water content t = time This equation states that the difference between the flow (flux) entering and leaving an elemental volume at a point in time is equal to the change in the volumetric water content. More fundamentally, it states that the sum of the rates of change of flows in the x- and y directions plus the external applied flux is equal to the rate of change of the volumetric water content with respect to time.

294 SEEP/W Under steady-state conditions, the flux entering and leaving an elemental volume is the same at all times. The right side of the equation consequently vanishes and the equation reduces to:

(8.5) Changes in volumetric water content are dependent on changes in the stress state and the properties of the soil. The stress state for both saturated and unsaturated conditions can be described by two state variables (see Fredlund and Morgenstern, 1976 and Fredlund and Morgenstern, 1977). These stress state variables are ( - ua) and (ua - uw) where is the total stress, ua is the pore-air pressure, and uw is the pore-water pressure. SEEP/W is formulated for conditions of constant total stress; that is, there is no loading or unloading of the soil mass. The second assumption is that the pore-air pressure remains constant at atmospheric pressure during transient processes. This means that (s - ua) remains constant and has no effect on the change in volumetric water content. Changes in volumetric water content are consequently dependent only on changes in the (ua - uw) stress state variable, and with ua remaining constant, the change in volumetric water content is a function only of porewater pressure changes. A change in volumetric water content can be related to a change in pore-water pressure by the equation: (8.6) where mw is the slope of the storage curve. The total hydraulic head is defined as:

(8.7) where: uw = pore-water pressure = unit weight of water y = elevation

GEO-SLOPE Office 5 295 Equation 8.7 can be rearranged as: uw = (H - y) (8.8) Substituting Equation 8.8 into 8.6 gives the following equation: (8.9) Now can be substituted into Equation 8.4, leading to the following expression:

(8.10) Since the elevation is a constant, the derivative of y with respect to time disappears, leaving the following governing differential equation: (8.11)

Coordinate Systems The global coordinate system used in the formulation of SEEP/W is the first quadrant of a conventional x y Cartesian system. The local coordinate system used in the formulation of element matrices is presented in Figure 8.4. Presented as well in Figure 8.4 is the local element node numbering system. The local coordinates for each of the nodes are given in Table 8.1.

296 SEEP/W Table 8.1 Local Element Node Numbering System Element Type Quadrilateral

Triangular

Node

r

s

1

+1

+1

2

-1

+1

3

-1

-1

4

+1

-1

5

0

+1

6

-1

0

7

0

-1

8

1

0

1

0

0

2

1

0

3

1

1

4

–

–

5

½

0

6

½

½

7

0

½

8

–

–

SEEP/W uses the fourth node to distinguish between triangular and quadrilateral elements. If the fourth node number is zero, the element is triangular. If the fourth node number is not zero, the element is quadrilateral. In the case of quadrilateral elements, Nodes 5, 6, 7, and 8 are secondary nodes. In the case of triangular elements, Nodes 5, 6, and 7 are secondary nodes. The local and global coordinate systems are related by a set of interpolation functions. SEEP/W uses the same functions for relating the coordinate systems as for describing the variation of the field variable (head) within the element. The elements are consequently isoparametric elements.

GEO-SLOPE Office 5 297 Figure 8.4 Global and Local Coordinate Systems

The x and y coordinates anywhere in the element are related to the local coordinates and to the x y coordinates of the nodes by the following equations: x = {X} (8.12) y = {Y} (8.13) where is a vector of interpolating shape functions and {X} and {Y} are the global x y coordinates of the element nodes. The interpolating functions are expressed in terms of local coordinates. Therefore, once a set of local coordinates (r,s) have been specified, the corresponding global coordinates can be determined by Equation 8.12 and Equation 8.13.

Interpolating Functions SEEP/W uses a general set of interpolating functions presented by Bathe, 1982, pp. 200, 230.

298 SEEP/W These general functions are suitable for elements which have none, some, or all of the secondary nodes defined. This allows for considerable versatility in the types of elements that can be used. The interpolating functions in terms of local coordinates r and s for quadrilateral and triangular elements are given in Tables 8.2 and 8.3, respectively. Table 8.2 Interpolation Functions for Quadrilateral Elements Function

Include in function if node is present 5

6

7

8

N1 = ¼(1+r)(1+s)

-½N5

—

—

-½N8

N2 = ¼(1-r)(1+s)

-½N5

-½N6

—

—

N3 = ¼(1-r)(1-s)

—

-½N6

-½N7

—

N4 = ¼(1+r)(1-s)

—

—

-½N7

-½N8

N5 = ½(1-r2)(1+s)

—

—

—

—

N6 = ½(1-s2)(1-r)

—

—

—

—

N7 = ½(1-r2)(1-s)

—

—

—

—

N8 = ½(1-s2)(1+r)

—

—

—

—

Table 8.3 Interpolation Functions for Triangular Elements Function

Include in function if node is present 5

6

7

N1= 1-r-s

-½N5

—

-½N7

N2 = r

-½N5

-½N6

—

N3 = s

—

-½N6

-½N7

N5 = 4r (1-s)

—

—

—

N6 = 4rs

—

—

—

N7 = 4s(1-r-s)

—

—

—

The functions represent a linear equation when the secondary nodes are missing and a quadratic (nonlinear) equation when the secondary nodes are included.

GEO-SLOPE Office 5 299

Field Variable Model To formulate a finite element analysis it is necessary to adopt a model for the distribution of the field variable within the element. Since the field variable in the seepage analysis is the total head (H), it is necessary to adopt a model for the distribution of H within the element. SEEP/W assumes that the head distribution within the element follows the adopted interpolating functions. This means that the head distribution is linear when the secondary nodes are missing, and the head distribution is nonlinear when the secondary nodes are present. In equation form the head distribution model is: h = {H} (8.14) where: h = head at any local coordinate = vector of interpolation function {H} = vector of heads at the nodes

Interpolation Function Derivatives The constitutive relationship for a seepage analysis is Darcy's Law. The equation is: q = k i (8.15) The gradient i is one of the key parameters required in the finite element formulation. The following presents the procedure used by SEEP/W to compute the gradient. From the adopted head distribution model, the head at any point within the element in terms of the nodal heads is: h = {H} (8.16) The gradients in the x and y directions are:

(8.17)

(8.18)

300 SEEP/W The interpolating functions are written in terms of r and s and not in terms of x and y. The derivatives must consequently be determined by the chain rule of differentiation, as follows:

(8.19)

(8.20) This can be written as:

(8.21) where [J] is the Jacobian matrix and is defined as:

(8.22) The derivative of the interpolation function with respect to x and y is called the B matrix and can be determined by inverting the Jacobian matrix and rewriting the equations as:

(8.23) Recall from Equation 8.12 and 8.13 that: x = {X} y = {Y}

GEO-SLOPE Office 5 301

Substituting these values into Equation 8.22, the Jacobian matrix becomes:

(8.24) The derivatives of the interpolation functions with respect to r and s are required to compute the Jacobian matrix (Equation 8.24) and to compute the flow gradients (Equations 8.17, 8.18, and 8.23). The derivatives of the interpolation functions with respect to r and s used by SEEP/W for quadrilateral and triangular elements are given in Tables 8.4 and 8.5, respectively.

302 SEEP/W Table 8.4 Interpolation Function Derivatives for Quadrilateral Elements Derivative of Function

Include in derivative if node is present 5

6

7

8

N1,r = ¼(1+s)

-½(N5,r)

—

—

`

N2,r = -¼(1+s)

-½(N5,r)

-½(N6,r)

—

—

N3,r = -¼(1-s)

—

-½(N6,r)

-½(N7,r)

—

N4,r = ¼(1-s)

—

—

-½(N7,r)

-½(N8,r)

N5,r = -½(2r+2sr)

—

—

—

—

N6,r = -½(1-s2)

—

—

—

—

N7,r = -½(2r-2sr)

—

—

—

—

N8,r = ½(1-s2)

—

—

—

—

N1,s = ¼(1+r)

- ½(N5,s)

—

—

-½(N8,s)

N2,s = ¼(1-r)

-½(N5,s)

-½(N6,s)

—

—

N3,s = -¼(1-r)

—

-½(N6,s)

-½(N7,s)

—

N4,s = -¼(1+r)

—

—

-½(N7,s)

-½(N8,s)

N5,s = ½(1-r2)

—

—

—

—

N6,s = -½(2s-2sr)

—

—

—

—

N7,s = -½(1-r2)

—

—

—

—

N8,s = -½(2s+2sr)

—

—

—

—

Table 8.5 Interpolation Function Derivatives for Triangular Elements Derivative of Function

Include in derivative if node is present 5

6

7

N1,r = -1.0

-½(N5,r)

—

—

N2,r = 1.0

-½(N5,r)

-½(N6,r)

—

N3,r = 0.0

—

-½(N6,r)

-½(N7,r)

N5,r = (4-8r-4s)

—

—

—

N6,r = 4s

—

—

—

N7,r = -4s

—

—

—

GEO-SLOPE Office 5 303

N1,s = -1.0

-½(N5,s)

—

—

N2,s = 0.0

-½(N5,s)

-½(N6,s)

—

N3,s = 1.0

—

-½(N6,s)

-½(N7,s)

N5,s = -4r

—

—

—

N6,s = 4r

—

—

—

N7,s = (4-4r-8s)

—

—

—

The following notation is used in the preceding tables:

The Jacobian matrix is a 2x2 matrix:

(8.25) The inverse of [J] is:

(8.26) The determinant of [J] is: det[J] = (J11 x J22 - J21 x J12) (8.27)

Finite Element Equations The finite element equation that follows from applying the Galerkin method of weighed residual to the governing differential equation (Equation 8.11) is:

(8.28)

304 SEEP/W where: [B] = gradient matrix [C] = element hydraulic conductivity matrix {H} = vector of nodal heads = T = [M] = mass matrix

{H},t =

= change in head with time

q = unit flux across the side of an element = vector of interpolating function For a SEEP/W two-dimensional analysis the thickness of the element is considered to be constant over the entire element. The finite element equation can consequently be written as:

(8.29)

where t is the element thickness. When t is a constant the integral over the volume becomes the integral over the area and the integral over the area becomes the integral over the length from corner node to corner node. In an axisymmetric analysis the equivalent element thickness is the circumferential distance radian times R. Since about the symmetric axis. The complete circumferential distance is SEEP/W is formulated for one radian, the equivalent thickness is R. The finite element equation for the axisymmetric case is:

(8.30)

GEO-SLOPE Office 5 305 The radial distance R is not a constant as is the thickness t for a two-dimensional analysis within an element; consequently, R is a variable in the integration. In abbreviated form, the finite element equation is: [K] {H} + [M] {H},t = {Q} (8.31) where: [K] = element characteristic matrix

=

[M] = mass matrix

{Q} = applied flux vector

Equation 8.31 is the general finite element equation for a transient seepage analysis. For a steady-state analysis, the head is not a function of time and consequently the term [M] {H},t vanishes, reducing the finite element equation to: [K] {H} = {Q} (8.32)

306 SEEP/W

Time Integration The finite element solution for a transient analysis is a function of time as indicated by the {H},t term in the finite element equation. The time integration can be performed by a finite difference approximation scheme. Writing the finite element equation in terms of finite differences leads to the following equation (see Segerlind, 1984, pp. 183-185): (8.33) where: t

= time increment = a ratio between 0 and 1

{H1} = head at end of time increment {H0} = head at start of time increment {Q1} = nodal flux at end of time increment {Q0} = nodal flux at start of time increment [K] = element characteristic matrix [M] = element mass matrix SEEP/W uses the Backward Difference Method, a method that sets The transient finite equation for

to 1.0.

equal to 1.0 is: (8.34)

As indicated by this equation, in order to solve for the new head at the end of the time increment, it is necessary to know the head at the start of the increment. Stated in general terms, the initial conditions must be known in order to perform a transient analysis.

Numerical Integration SEEP/W uses Gauss numerical integration to form the element characteristic matrix [K] and the

GEO-SLOPE Office 5 307 mass matrix [M]. The integrals are sampled at specifically defined points in the elements and then summed for all the points. The following integral (from Equation 8.31):

can be replaced by:

(8.35) where: j = integration point n = number of integration points det|Jj | = determinant of the Jacobian matrix W1j, W2j = weighting factors The number of sample (integration) points required in an element depends on the number of nodes and the shape of the elements.

308 SEEP/W Tables 8.6 to 8.9 contain the number and location of sampling points that are used by SEEP/W. Table 8.6 Sample Point Locations and Weightings for Four Point Quadrilateral Element: Point

r

s

w2

w1

1

+0.57735

+0.57735

1.0

1.0

2

-0.57735

+0.57735

1.0

1.0

3

-0.57735

-0.57735

1.0

1.0

4

+0.57735

-0.57735

1.0

1.0

Table 8.7 Sample Point Locations and Weightings for Nine Point Quadrilateral Element Point

r

s

w2

w1

1

+0.77459

+0.77459

5/9

5/9

2

-0.77459

+0.77459

5/9

5/9

3

-0.77459

-0.77459

5/9

5/9

4

+0.77459

-0.77459

5/9

5/9

5

0.00000

+0.77459

8/9

5/9

6

-0.77459

0.00000

5/9

8/9

7

0.00000

-0.77459

8/9

5/9

8

+0.77459

0.00000

5/9

8/9

9

0.00000

0.00000

8/9

8/9

Table 8.8 Sample Point Location and Weighting for One Point Triangular Element Point 1

r 0.33333

s

w1

0.33333

w2

1.0

0.5

Table 8.9 Sample Point Locations and Weightings for Three Point Triangular Element Point

r

s

w1

w2

GEO-SLOPE Office 5 309

1

0.16666

0.16666

1/3

1/2

2

0.66666

0.16666

1/3

1/2

3

0.16666

0.66666

1/3

1/2

One-point integration for a triangular element results in a constant gradient throughout the element. The number of integration points is denoted as the integration order. The appropriate integration order is a function of the presence of secondary nodes. When secondary nodes are present, the interpolating functions are nonlinear and consequently a higher integration order is required. Table 8.10 gives the acceptable integration orders. Table 8.10 Acceptable Element Integration Orders Element Type

Secondary Nodes

Integration Order

Quadrilateral

no

4

Quadrilateral

yes

9

Triangular

no

1

Triangular

yes

3

It is also acceptable to use four-point integration for quadrilateral elements which have secondary nodes. This is called a reduced integration order (see Bathe, 1982, p. 282). Acceptable results can be obtained with reduced integration. For example, reduced integration is useful in saturated zones where the hydraulic gradient is low and the hydraulic conductivity is constant. Selective use of reduced integration can greatly reduce the required number of computations. It is also possible to use three-point and nine-point integration with elements that have no secondary nodes. However, the benefits of this are marginal, particularly for quadrilateral elements. Nine point integration for quadrilateral elements involves substantially more computing than four point integration, and there is little to be gained from the additional computations. As a general rule, quadrilateral elements should have secondary nodes to achieve significant benefits from the nine point integration. The situation is slightly different for triangular elements. One-point integration means the material properties and flow gradients are constant within the element. This can lead to poor performance of the element, particularly if the element is in an unsaturated zone where the hydraulic conductivity varies sharply with changes in pore-water pressure. Using three point integration, even without using secondary nodes, can improve the performance, since material properties and gradients within the elements are distributed in a more realistic manner. The use

310 SEEP/W of three point integration in triangular elements with no secondary nodes is considered acceptable for triangular elements in a mesh that has predominantly quadrilateral elements. This approach is not recommended if the mesh consists primarily of triangular elements with no secondary nodes. In general, it is sufficient to use three-point integration for triangular elements and four-point integration for quadrilateral elements. In situations where there is unsaturated zone with hydraulic conductivity varies sharply within an element, it is best to use quadrilateral elements with secondary nodes together with a nine-point integration.

Hydraulic Conductivity Matrix The general form of the SEEP/W hydraulic conductivity matrix is:

(8.36) where: C11 = kx cos2

+ ky sin2

C22 = kx sin2

+ky cos2

C12 = kx cos

sin

- ky sin cos

C21 = C12 The parameters kx, ky, and are defined in Figure 8.5.

GEO-SLOPE Office 5 311 Figure 8.5 Definition of Hydraulic Conductivity Matrix Parameters

When is zero, [C] reduces to: (8.37) The parametric kx is always determined from the hydraulic conductivity function. Parameter ky is then computed as kx multiplied by K-Ratio. In equation form, (8.38)

Mass Matrix As first presented in Equation 8.31, the element mass (or storage) matrix for a two-dimensional analysis is defined as:

and for an axisymmetric analysis as:

where: = mw = slope of storage curve

312 SEEP/W

= unit weight of water t = element thickness R = radial distance from the symmetric axis to the integration point = vector of interpolating functions. SEEP/W uses a lumped formulation, to establish the mass matrix. The details of this formulation is given by Segerlind, 1984, pp. 178-182. The mass matrix is formed by numeric integration as discussed in Numerical Integration in this chapter. This has the advantage of making it possible for the parameter mw to vary throughout the element. SEEP/W obtains an mw value from the storage function for each integration point. SEEP/W computes mw from the slope of a straight line between the old and new pore-water pressures at a Gauss point, as illustrated in Figure 8.6. The slope of this straight line can be viewed as the average rate of change during one increment of time. This is considered to be a more realistic value than taking the derivative of the function at a specific point. An exception to this procedure is when the old and new pore-water pressures are nearly identical. In this case, SEEP/W computes mw by calculating the derivative of the function at the average of the old and new pore-water pressures. Figure 8.6 Computation of Mw

GEO-SLOPE Office 5 313

Flux Boundary The nodal boundary flux (Q) for a two-dimensional analysis is defined as:

(8.39) for an axisymmetric analysis as:

(8.40) and for a plan view analysis as:

(8.41) where: {Q} = vector of nodal flux q = unit flux across the side of an element t = element thickness A = area of the element R = radial distance from the symmetric axis to the element corner nodes = vector of interpolating function Solutions to the integrals are dependent on the analysis type and on the presence of secondary nodes. For two-dimensional (i.e., vertical section) and axisymmetric analyses, the integrals are solved by close form solutions as illustrated in Figures 8.7 and 8.8 respectively. However, for plan view analysis, the contributing area of a node is computed by numerical integration in the same way as forming the mass matrix. Two types of flux boundaries may be specified in SEEP/W namely: a nodal flux boundary (Q) and a unit flux boundary (q). A nodal flux boundary (Q) can be specified directly on the boundary nodes. A unit flux boundary (q) must be specified along the boundary edges of the elements, except for a plan view analysis. DEFINE allows you to identify the edges of the elements across which a q boundary should be applied. Based on this specific element edge information, SOLVE performs the integration and determine the applied flux Q at the nodes. SOLVE needs Q, not q, to solve the finite element equations.

314 SEEP/W For two-dimensional (i.e., vertical section) and axisymmetric analyses, the nodal flux Q computed by SOLVE is dependent on the specified element thickness. For plan view analysis, since the surface area is independent of the element thickness, the nodal flux Q is also independent of the element thickness. Figure 8.7 Contributing Areas for Vertical Two-Dimensional Elements with Width Equal to 1 Unit

GEO-SLOPE Office 5 315 Figure 8.8 Contributing Areas for Axisymmetric Elements Over 1 Radian

Assembly of Global Equations and Equation Solver The element matrix for each element in the discretized finite element mesh can be formed and assembled into a global system of simultaneous equations. The finite element solution requires the solving of the system of simultaneous equations. SEEP/W stores the coefficients of the global system equations using a Compressed Row Storage

316 SEEP/W scheme (Barrett et. al, 1994). This is a general scheme that make no assumptions about the sparsity structure of the matrix. Instead of a full matrix with many zero elements, the Compressed Row Storage scheme stores the matrix with 3 vectors: one for the non-zero elements, one for the column index and one for the row pointers. As a result, it provides significant saving in storage memory particularly in large finite element meshes. SEEP/W utilizes a preconditioned Bi-Conjugate Gradient (BiCG) iterative solver in solving the system equations. The BiCG solver is adopted from IML++ (Iterative Methods Library) made available freely by the National Institute of Standards and Technology, Oak Ridge National Laboratory, University of Tennessee, Knoxville, U.S.A. The BiCG solver works effectively with the compressed row storage scheme and is suitable for both symmetric and unsymmetric system of equations. The equation solver can accommodate missing elements in the array. This feature makes it possible to add and delete elements from a finite element mesh without renumbering the nodes and elements. Unlike the Gauss elimination solver used in previous versions of SEEP/W, sorting the node number vertically or horizontally will have no effect to the computational time and accuracy of the solution with this improved iterative solver. As a result of the iterative solver, the solution of the system of simultaneous equations is to a large degree dependent on the convergence tolerance and the number of iterations. In most cases, the default tolerance and number of iterations will be adequate for a solution.

Iteration Scheme The objective of solving the finite element equations is to compute the total head at each node. For linear analyses when the material properties are constant, the nodal total head can be computed directly. However, in the cases of nonlinear analyses, when the material hydraulic conductivity is a function of total head, the correct material properties are not known at the start of the analysis; consequently, an iterative scheme is required to solve the equations. SEEP/W uses a repeated substitution technique in the iterative process. For the first iteration, the user-specified initial heads are used to define the material properties. The material properties are updated in subsequent iteration using the computed head from the previous iteration. For transient analyses, the head at the mid-point of the time interval is used to define the material properties; that is, the material properties are defined at the average of the past and current computed heads. The iterative process continues until the iteration number reaches the maximum number specified or until the results satisfy the convergence criteria.

GEO-SLOPE Office 5 317

SEEP/W uses the Euclidean norm of the change of total head vectors {Dh} between consecutive iterations as a measure of convergence. The vector norm of the changes is called residual and is defined as:

(8.42) where: R = residual n = total number of nodes j = node number Dh = nodal total head difference between two consecutive iterations The residual is a measure of the size of the total head difference between iterations. In a normal convergence process, the residual will be decreasing and approaching a zero value. The solution is deemed to have converged when the residual is less than a user-specified convergence tolerance. When analyzing problems with potential seepage boundaries, a converged solution is reviewed to check if a seepage face has developed on potential seepage boundaries. As a result, boundary conditions on potential seepage boundaries may be adjusted, and the iteration process may be repeated until all potential seepage boundaries satisfy the adaptive iteration.

Gradients and Velocities Once the solution has converged and the nodal heads are known, SEEP/W computes the hydraulic gradients and Darcian flow velocities at each of the integration points within each element. The gradient at each Gauss or integration point is computed from the equation:

(8.43) where: ix = gradient in x direction iy = gradient in y direction

318 SEEP/W [B] = gradient matrix as defined in Finite Element Equations {H} = vector of total head at the nodes The Darcian velocities at each Gauss point are computed from the equation:

(8.44) where: vx = velocity in x direction vy = velocity in y direction [C] = hydraulic conductivity matrix SEEP/W stores in an array the hydraulic conductivity at each Gauss point used in the formulation of the finite element equations. The same hydraulic conductivity values are later used to compute the velocities. The SEEP/W velocity is actually the specific discharge, which is the total flux Q divided by the full cross-sectional area (voids and solids alike); it is not the actual speed with which the water moves between the soil particles. The actual microscopic velocity is:

(8.45) where: v = average linear velocity q = specific discharge n = porosity SEEP/W does not compute the actual pore-channel velocity.

Flow Quantities SEEP/W has the ability to compute the seepage quantity that flows across a user-defined section. This quantity can be computed from the nodal heads and the coefficients of the finite element equation.

GEO-SLOPE Office 5 319 For example, consider a mesh with only one element, as illustrated in Figure 8.10. The objective is to compute the total flow across a vertical section of the element. Figure 8.10 Illustration of a Flux Section

Equation 8.34 can be rewritten as:

(8.46)

In a steady-state analysis, the storage term reduced to: (8.47)

becomes zero, and the equation can be

320 SEEP/W The global set of finite equations for one element is as follows:

(8.48) From Darcy’s Law (Equation 8.2), the total flow between two points is:

(8.49)

The coefficients c in Equation 8.48 are a representation of flow from Node i to Node j is:

in Equation 8.48. Therefore, the

(8.50) In a transient analysis, because of material storage, the calculation of the total flow quantity must include the storage effect. The change in flow quantity due to the storage term can be expressed as:

(8.51) where DH1, DH2, DH3, and DH4 are the changes of total head at the various nodes between the start and the end of a time step. In general, the average change of total head from Node i to Node j can be expressed as:

(8.52)

GEO-SLOPE Office 5 321 Therefore, the change in flow quantity from Node i to Node j due to a change in storage is:

(8.53) The total flow quantity from Node i to Node j for a transient analysis then becomes:

(8.54) The total flow quantity through the flux section shown in Figure 8.10 is: (8.55) The imaginary flow lines from one side of the section to the other side are known as subsections. SEEP/W identifies all subsections across a user-defined flux section, computes the flow for each subsection, and then sums the subsection flows to obtain the total flow across the flux section.

Material Functions SEEP/W uses spline interpolation techniques to create smooth, continuous conductivity, and volumetric water content (or storage) functions.

Weighted Splines Smooth curves were produced in the past using mechanical means. This involved the use of a thin, flexible strip of wood or metal held in place with weights. The flexible strip would bend in such a way that the internal energy due to bending was at a minimum (see Lancaster and Salkauskas, 1986, pp. 101-106). Such a curve can be described mathematically by defining the x-y coordinates of the points (weights) and then computing the curvature at the points that minimizes the internal energy term in the equations. Mathematically, this is referred to as a natural spline (see Lancaster and Salkauskas, 1986, pp. 101-106). A natural spline can have many undesirable humps and hollows when the data points are not near the natural maximum curvature positions. Figure 8.11a illustrates this behavior. Salkauskas, 1974, and Lancaster and Salkauskas, 1986, (pp. 101-106), have developed a procedure for controlling the undesirable humps and hollows. They called the resulting curve a weighted spline. Figure 8.11b illustrates the effect on the shape of the curve using the weighted spline interpolation technique.

322 SEEP/W SEEP/W utilizes the weighted spline technique to create smooth conductivity, volumetric water content, boundary, and modifier functions. In addition to defining a continuous and smooth function, spline interpolation also provides first derivatives of the curve at any point. This is a useful feature for establishing the slope of the soil-water characteristic curve (mw) at any porewater pressure. Figure 8.11 Natural Spline and Weighted Spline

Best-Fit Splines Since all functions are approximations of real-world behavior, it is often convenient to use measured data values for the definition of a function. These values, however, usually do not lie along a smooth, continuous curve. A spline function that is fit to these values will appear jagged and will not accurately reflect the measured data. To overcome this problem, SEEP/W allows you to define a "best-fit" spline through the data points, as illustrated in Figure 8.12. The DEFINE KeyIn Functions commands provide a means of controlling how the spline curve is fit to the data points. For each function, you can assign a "Fit Curve to Data percentage" and a "Curve Segments percentage" between 0% and 100%. When the curve is fit exactly (100%) to the data points, the spline passes through each data point. As the curve fitting is reduced, the spline shape approaches a straight line that passes

GEO-SLOPE Office 5 323 close to each data point. This is useful when you want to approximate a spline through laboratory-measured data points without moving any of the data points. When the curve segments are curved (100%) between data points, the curve is defined as a natural spline. As the curve segments are made straighter, the curve segments approach a straight line between data points. Straightening the curve segments helps to prevent "spline overshoot" (extreme peaks or valleys in the spline). It also allows you to define "step" functions that have straight line segments between each data point. When specifying a best-fit percentage, it is best to experiment with different values until you obtain a smooth spline that still passes close to the data points. Figure 8.12 Interpolation of Data Points using Best-Fit Splines (a) Fit Curve to Data Using a Value of 30%

324 SEEP/W (b) Curve Segments Using a Value of 30%

Infinite Elements Many seepage problems can be classified as unbounded. Consider the case illustrated in Figure 8.13. The condition along the right vertical boundary cannot be correctly defined as a head boundary or as a flux boundary. The problem is said to be unbounded on the right. The correct boundary condition is only known at some large (i.e., infinite) distance to the right of the problem. These types of unbounded problems can be analyzed with infinite elements. SEEP/W follows the infinite element formulation presented by Bettess, 1992, pp. 53-85. SEEP/W is formulated only for eight-noded quadrilateral elements.

GEO-SLOPE Office 5 325 Figure 8.13 An Unbounded Flow Problem

Mapping Functions For standard elements, SEEP/W uses the same interpolating functions both to describe the distribution of the field variable within an element and to relate the local and global coordinate system (i.e., the elements are isoparametric). For infinite elements, the relationship between the local and global coordinate system must be described by a special set of shape functions. The interpolating functions for describing the field variable distribution is the same for all elements, but the geometric shape functions are different. SEEP/W uses the "serendipity" family of mapping functions presented by Bettess, 1992, pp. 5385, to relate the local and global coordinate systems for infinite elements. The unique feature about these functions is that they are zero at the nodes deemed to be at infinity. Figure 8.14 Node Numbering Scheme for Infinite Elements

Figure 8.14 presents the different types of elements which extend to infinity. The mapping or

326 SEEP/W shape functions for one-directional and two-directional, (corner), infinite elements are given in Table 8.11. In the table, r and s are the local coordinates within the element and M1 through M8 are the mapping functions for infinite elements shown in Figure 8.14. The derivatives of the mapping functions are required to compute the Jacobian matrix and the flow gradients for infinite elements. The derivatives of the mapping functions for onedirectional and two-directional infinite elements with respect to r and s are given in Tables 8.12 and 8.13, respectively. Table 8.11 Mapping Functions for Infinite Elements 1-D Infinite Element

2-D Infinite Element

M1 = 0

M1 = 0

M2 =

M2 = 0

M3 =

M3 =

M4= 0

M4 = 0

M5 =

M5 = 0

M6 =

M6 =

M7 =

M7 =

M8 =0

M8 = 0

Table 8.12 Derivatives of Mapping Functions for One-Directional Infinite Elements Derivative in r-Direction

Derivative in s-Direction

M1,r = 0

M1,s = 0

M2,r =

M2,s =

M3,r =

M3,s =

M4,r = 0

M4,s = 0

M5,r =

M5,s =

M6,r =

M6,s =

M7,r =

M7,s =

M8,r = 0

M8,s = 0

Table 8.13 Derivatives of Mapping Functions for Two-Directional Elements

GEO-SLOPE Office 5 327

Derivative in r-Direction

Derivative in s-Direction

M1,r = 0

M1,s = 0

M2,r = 0

M2,s = 0

M3,r =

M3,s =

M4,r = 0

M4,s = 0

M5,r = 0

M5,s = 0

M6,r =

M6,s =

M7,r =

M7,s =

M8,r = 0

M8,s = 0

Once these shape functions and derivatives have been defined, the numerical integration scheme used to form the element characteristic matrix for the infinite elements is the same as for the standard elements. These special shape functions must also be used when formulating the mass matrix and nodal action (i.e., flux) vector for axisymmetric cases.

Pole Definition In order to project the outer edge of the infinite element to infinity, it is necessary to define a pole position. This is simply a point at some position on the opposite side of the infinite edge of the element. Figure 8.14 shows the infinite element pole at the center of the finite element mesh. For a one-directional infinite element, the nodes on the infinite edge are taken to be at infinity. Secondary Nodes 5 and 7 must be extended out towards infinity. SEEP/W does this according to Equations 8.55, 8.56, and 8.57. For infinity in the x-direction only: x5 = x2 + (x2 - xp) (8.56) x7 = x3 + (x3 - xp) For infinity in the y-direction only: y5 = y2 + (y2 - yp) (8.57) y7 = y3 + (y3 - yp)

328 SEEP/W If the x- and y-directions of infinity are both positive or both negative, there is no adjustment to x6 and y7. However, x7 = x3 + (x3 - xp) (8.58) y6 = y3 + (y3 - yp) If one direction of infinity is positive and the other is negative, there is no adjustment to x7 and y6. However, x6 = x3 + (x3 - xp) (8.59) y7 = y3 + (y3 - yp) Generally, the SEEP/W solutions are not sensitive to the position of the pole, provided the pole is in a reasonable position. As a broad guideline, the pole must either be positioned at the origin of the flow as it migrates towards infinity or positioned at the exit point of the flow if the flow originates at infinity. Further guidelines on selecting the pole position are presented in The Pole Position in Chapter 7.

Density-Dependent Flow SEEP/W may be used together with CTRAN/W to perform density dependent contaminant transport analyses. For density-dependent analyses, a instance of SEEP/W SOLVE is started and controlled by CTRAN/W SOLVE so that the groundwater flow equation can be solved simultaneously with the contaminant transport equation at each time step. The simultaneous solution of the groundwater flow equation and the contaminant transport equation is required for density-dependent flow problems because the groundwater flow velocities are dependent on the contaminant densities which in turn are dependent on the contaminant concentrations. The formulation used in SEEP/W for density-dependent flow was proposed by Frind, 1982. To accommodate density-dependent flow analyses, a density body force term is added to the governing groundwater flow equation. After discretizing the problem domain into finite elements, the density body force term becomes a body force vector, [G], which is added to each finite element’s governing flow equation in SEEP/W. In matrix form, the body force vector can be expressed as:

(8.60) where: = element density body force vector

GEO-SLOPE Office 5 329

= element average hydraulic conductivity in the y direction = element average contaminant concentration = contaminant density contrast = contaminant relative density at reference concentration = element gradient matrix in the y direction Note from Equation 8.60 that if the contaminant relative density is 1.0 at the reference concentration, (indicating zero density contrast between contaminated water and freshwater), then and the density body force vector [G] is also zero. Equation 8.60 also shows that the body force vector is a function of the element average contaminant concentration which is also is a function of the seepage results. For more information about density dependent analyses, see Density-Dependent Flow in Chapter 8 of the CTRAN/W User’s Guide.

Chapter 9 Verification Introduction This chapter presents the analyses of some common problems for which there are closed form or published solutions. The purpose of presenting these analyses is to: ·

Provide benchmark references which can be used to verify that the software is functioning properly.

·

Illustrate the use of SEEP/W and demonstrate that the software simulates a specific problem.

The data input files and computed output files for each problem are included with the SEEP/W software. The files can be used to re-run each analysis and to verify that you can obtain the same results as presented in this chapter.

Dam Foundation Cutoff Figure 9.1a presents a flow net solution for seepage flow in the foundation of a concrete dam with a cutoff wall as presented by Lambe and Whitman, 1969, p. 272. The hydraulic conductivity of the homogeneous foundation material is 1x10-3 feet/min and the dimensions of the problem are as shown in Figure 9.1b. Figure 9.1 Foundation Cutoff Problem

Based on the flow net solution, the seepage under the dam is 5.76x10-3 ft3/min/ft, the uplift pressure at

332 SEEP/W the downstream toe, (Point A), is 7.1 feet, and the exit gradient is 0.34. The steady state seepage of the foundation cutoff problem is analyzed using SEEP/W. The finite element mesh used for the analysis is shown in Figure 9.2. Note the use of infinite elements on the left and right vertical boundaries. The associated files are named CUTOFF. The boundary nodes of the upstream and downstream surfaces are designed as head boundaries with total head equals to 60 feet and 40 feet respectively. Default boundary conditions (no flow) are assumed for all other boundaries. Figure 9.2 SEEP/W Mesh for Dam Foundation Cutoff

Figure 9.3 SEEP/W Computed Head Distribution and Flow Vectors for Dam Foundation Cutoff

Figure 9.3 presents the SEEP/W computed head distribution and flow vectors. There are 15 contours at intervals of 1.429, beginning at a minimum value of 40. The number of contours is the same as the number of equipotential lines in the flow net, (Figure 9.1a). The equipotential lines and SEEP/W head contours are essentially the same. Table 9.1 compares the flow net and SEEP/W results.

GEO-SLOPE Office 5 333 Table 9.1 Comparison of Flow Net and SEEP/W Results Item

Flow Net

SEEP/W

Total Seepage (ft3/min/ft)

5.76x10-3

5.81x10-3

Uplift Pressure Head at A (ft)

7.1

6.91

Exit Gradient at Downstream Toe

0.34

0.35

The uplift pressure head at Point A (Node 219) is computed as: Total Head - Elevation = Pressure Head (9.1) 41.91 - 35.00 = 6.91 The exit gradient can be viewed with the CONTOUR View Element Information command and clicking in the Gauss region nearest to the downstream ground surface and nearest to the dam. In other words, the upper left Gauss region of element number 168. For all practical purposes, the results can be considered to be the same.

Unconfined Dam Seepage Figure 9.4a shows the flow net for seepage through a homogeneous earth dam with a rock toe drain as published by Lambe and Whitman, 1969, p. 273. The hydraulic conductivity is 5x10-4 ft3/sec. The dimensions of the problem are as shown in Figure 9.4b. Figure 9.4 Dam Seepage Analysis

The steady state seepage through the unconfined earth dam is analyzed using SEEP/W. The finite element mesh used for the analysis is shown in Figure 9.5, and the associated files are named DAM. The mesh includes higher-order eight-noded elements near the toe. The upstream boundary nodes are

334 SEEP/W designated as head boundaries with total head equals to the water level in the reservoir (40 feet). The bottom node along the contact between the dam and toe drain is designed as a zero pressure head boundary. The other nodes along the contact are designated as review nodes (by elevation), since the seepage exit point is unknown. Default boundary conditions (no flow) are assumed for all other boundaries. The mesh includes two flux sections. One section passes through the entire dam and the other section is near the downstream face of the dam. The second short flux section is included to estimate how much of the total seepage flows through the unsaturated zone. Figure 9.5 SEEP/W Mesh for Unconfined Dam Seepage

The saturated hydraulic conductivity is 5x10-4 feet/sec, which is the value used by Lambe and Whitman. An approximate conductivity function is adopted for the unsaturated soil region. The data points are given in Table 9.2 and graphed by SEEP/W in Figure 9.6.

GEO-SLOPE Office 5 335 Table 9.2 Approximate Conductivity Function Point

Pressure (psf)

Conductivity (feet/sec)

1

-835.42

5.00x10-8

2

-584.70

1.00x10-7

3

-383.38

6.00x10-7

4

-271.51

9.00x10-6

5

-208.85

9.03x10-5

6

-100.00

3.95x10-4

7

0.00

5.00x10-4

Figure 9.6 Approximate Conductivity Function

Figure 9.6a shows the SEEP/W results with contours of equal head, while Figure 9.6b shows the resulting flow vectors. There are 10 contours at intervals of 4.445 and beginning at a minimum value of 0. The number of contours in Figure 9.6a is the same as the number of equipotential lines in the flow net, and the head loss in both cases is 4.445 (40/9) feet per contour. The shape and location of the flow net equipotential lines and the SEEP/W contours are quite similar. The total SEEP/W seepage flux is computed to be 6.72x10-3 ft3/sec/ft. This is higher than 5.9x103 3 ft /sec/ft, the value obtained from the flow net. The difference is largely because SEEP/W allows for the unsaturated flow. It is not possible to completely separate the saturated and unsaturated flow, however, the short flux section (Section 2) near the downstream face can provide an estimate of the unsaturated flow. The Section 2 flux is approximately 0.58x10-3 ft3/sec/ft. Subtracting this value from the total Section 1 flux results in an estimated saturated flow of 6.14x10-3 ft3/sec/ft, which is within 4 percent of the flow net value of 5.9x10-3 ft3/sec/ft.

336 SEEP/W Figure 9.6 SEEP/W Computed Head Distribution and Flow Vectors for Unconfined Dam Seepage (a) Computed Head Distribution

(b) Computed Flow Vectors

Slope Infiltration Rulon and Freeze, 1985, pp. 347 356, have studied the development of multiple seepage faces on earth slopes due to a layered soil system. To verify their theory, a physical model was constructed in the laboratory. Figure 9.7 shows a schematic diagram of the physical model. Water was sprinkled on the upper flat part to simulate rain, and instruments were installed to measure the pore-water pressure distribution and to measure the total seepage outflow. In addition, Rulon used a finite element analysis to predict the model performance. Figure 9.8 summarizes the results. The model developed two seepage exit points on the slope. The observed results compared favorably with the predicted performance.

GEO-SLOPE Office 5 337 Figure 9.7 Schematic Diagram of Rulon and Freeze Model

Figure 9.8 Experimental and Finite Element Results Obtained by Rulon and Freeze

Rulon used laboratory tests to establish the hydraulic conductivity function for a medium sand. A summary of the results is shown in Figure 9.9. The function was then moved vertically to match a desired saturated hydraulic conductivity. Laboratory tests were conducted to measure the saturated hydraulic conductivity for the medium and fine sands used in the physical model. The best-fit values were found to be 1.4X10 3 m/sec for the medium sand and 5.5X10 5 m/sec for the fine sand. Figure 9.9 shows the corresponding hydraulic conductivity functions used in the SEEP/W analysis.

338 SEEP/W Figure 9.9 Hydraulic Conductivity Functions

Results of the physical model testing revealed that a simulated rainfall rate of 1.26 cm/min (2.1x10m/sec) produced a steady state water table as shown in Figure 9.8 with an observed seepage flow of 996 cm3/min. (1.66x10-5 m3/sec).

4

A steady state SEEP/W analysis of the Rulon and Freeze model leads to essentially the same results as observed in the laboratory and predicted by the Rulon and Freeze finite element analysis. Figure 9.10 illustrates the finite element mesh used to analyze the Rulon and Freeze model. Head boundary conditions are specified at the toe of the slope to simulate the standing water at a level of 0.3m. The nodes along the rest of the slope are specified as review nodes (by maximum pressure). The nodes along the top of the slope are specified as flux boundary equals to the infiltration rate. Default boundary conditions (no flow) are assumed for all other boundaries. Two flux sections are specified. Section 1 immediately beneath the upper flat part was included to compare the computed flux with the specified infiltration rate. Section 2 was included to compute the total outflow. The associated files are named SANDBOX. Of significance with respect to using SEEP/W in this example is the combination of element types, the nonzero specified boundary flux and the thickness of 0.1m.

GEO-SLOPE Office 5 339 Figure 9.10 SEEP/W Mesh for Slope Infiltration

Figure 9.11a shows the SEEP/W computed water table and equipotential lines. There are 14 contours at intervals of 0.05 and beginning at a minimum value of 0.35. Figure 9.11b shows the water table together with the flow vectors. Comparison of these figures with Figure 9.8 reveals that the position of the water table as predicted by SEEP/W is the same as in Rulon's physical model. The length of the upper flat part of the model is 0.84m (2.44m - 1.60m) and the width is 0.1m. The surface area is 0.084 m2. The rainfall rate is 2.1x10-4 m/sec. This rate multiplied by the area is 1.764x10-5 m3/sec, which is equal to the computed value for Flux Section 1, as displayed on the CONTOUR drawing. Because this is a steady-state analysis, the outflow must equal the inflow. The computed outflow as per Flux Section 2 is 1.764x10-3 m3/sec which is the same as the specified inflow. Figure 9.11 SEEP/W Computed Head Distribution and Flow Vectors for Slope Infiltration (a) Computed Head Distribution

340 SEEP/W (b) Computed Flow Vectors

Radial Flow to a Well Closed form solutions are available for predicting the drawdown of the piezometric surfaces resulting from flow to a well in a horizontal confined aquifer (see Freeze and Cherry, 1979, pp. 316 318). If the aquifer properties T (transmissivity), S (storativity), and Q (pumping rate) are known, it is possible to predict the drawdown at any distance from the well at any time after the start of pumping. Comparing such a solution with a SEEP/W analysis makes it possible to verify the axisymmetric and transient features of the software. The drawdown (h0-h) is defined by the following equations, known as the Theis Solution:

(9.2a)

(9.2b) where: Q = pumping rate T = transmissivity W(u) = well function r = distance from well axis t = pumping time S = storativity Figure 9.12 illustrates the problem selected for this verification example. The aquifer is 5m thick and the total hydraulic head in the aquifer is 16m. The aquifer has a storativity of 0.05 and a transmissivity of 0.010m2/sec. The well screen is 0.3m in diameter (0.15m radius) and extends over the entire depth of the aquifer. The pumping rate Q is assumed to be 0.125 m3/sec.

GEO-SLOPE Office 5 341 SEEP/W uses the term mw which is the slope of the volumetric water content curve (or the soil-moisture characteristic curve) to represent the storativity of a material. The value of mw (slope of the storage curve) corresponding to a storativity S of 0.05 can be calculated as below: Ss = S / b (9.3) Ss= 0.05 / 5 = 0.01 m-1 (9.4) mw = 0.01 / 9.81 = 0.001 kPA-1 SEEP/W uses hydraulic conductivity rather than transmissivity. The hydraulic conductivity corresponding to a transmissivity of 0.010m2/sec in a 5m thick aquifer can be calculated as below: k = T / b (9.5) k = 0.010 / 5 = 0.002 m/sec The finite element mesh used for the analysis consists of one row of eight-noded elements with an infinite element at the right end of the mesh. The initial water table is assumed to be 16.0 m above the bottom of the aquifer. The initial condition is established by running a steady-state analysis with all nodes specified with a total head of 16.0 m. This will generate a uniform total head distribution of 16.0 throughout the entire aquifer. The files for this part of the analysis are named WELL_I. The time step sequence starts with an increment of 10 seconds and increases with an expansion factor of 2 up to a maximum time step of 900 seconds. Figure 9.12 Pumping from a Confined Aquifer

The files for this transient analysis are named WELL. Figure 9.13 shows the SEEP/W computed drawdown curves (displayed using the CONTOUR Draw Graph command) at times of 30, 150, 630, and

342 SEEP/W 3970 seconds after the start of pumping. Figure 9.13 SEEP/W Drawdown Curves at Different Times

Table 9.3 compares the total head values as predicted by the Theis solution and the SEEP/W analysis. Table 9.3 Comparison of Theis Solution and SEEP/W Results Elapsed Time

(seconds)

Head 4m from Well

Head 20m from Well

Head 4m from Well

Head 20m from Well

Theis

SEEP/W

Theis

SEEP/W

10

15.9

15.89

16.0

16.0

30

15.7

15.59

16.0

16.0

70

15.1

15.12

16.0

16.0

150

14.6

14.54

16.0

15.98

310

13.9

13.91

15.9

15.90

630

13.1

13.24

15.7

15.69

1270

12.5

12.58

15.3

15.37

2170

11.9

12.10

14.9

15.08

3070

11.7

11.82

14.6

14.89

3970

11.3

11.67

14.3

14.77

The agreement between the SEEP/W and closed form solution is very good, especially considering the limited accuracy with which the well function values W(u) can be ascertained from tables. This example illustrates that SEEP/W can be used to analyze radial flow to a well in terms of the water

GEO-SLOPE Office 5 343 well industry parameters of transmissivity and storativity.

Consolidation Analysis It is possible to use SEEP/W to perform a consolidation analysis, since the Terzaghi consolidation equation is fundamentally identical to the SEEP/W governing differential equation. Moreover, since closed form solutions are available for the consolidation equation, it is also possible to check the transient capability of SEEP/W by comparing hand-computed results for a one-dimensional consolidation problem with SEEP/W results. Figure 9.14 shows the setup and material properties for a one-dimensional consolidation analysis. Figure 9.14 Consolidation Analysis Parameters

Drainage is allowed only at the top of the soil layer. In accordance with the Terzaghi theory of consolidation, the dimensionless time factor T and the real time t can be related as follows:

(9.6) where: H = maximum drainage path T = non-dimensional time factor cv = coefficient of consolidation Using Equation 9.6 and commonly available graphical charts, (see Lambe and Whitman, 1969, p. 408), the time t required to reach a certain degree of consolidation can be computed for a given time factor T. Also, the hydraulic conductivity (or coefficient of permeability) of the material can be calculated as: k = cv mw (9.7) where mw is the coefficient of volume change or, in SEEP/W terminology, the slope of the soil-water

344 SEEP/W characteristic curve. The above one-dimensional consolidation process is simulated with SEEP/W. The associated files are named CONSOL. The initial excess pore-water pressure head is assumed to be 100m through out entire column. The initial condition is obtained by doing a steady state analysis of the column with total head boundary conditions of 101 m on the top nodes and 100 m on the bottom nodes of the column. The associated files of the initial steady state run are named CONSOL_I. Table 9.4 presents the resulting excess head at mid-height and at the bottom of the layer as determined by hand-calculation and by SEEP/W. Table 9.4 Comparison of Hand Calculation and SEEP/W Results T

t (hours)

Head at Mid-Height Graph

SEEP/W

Head at Bottom Graph

SEEP/W

0.05

100

88

87.87

99

97.52

0.10

200

74

75.49

95

92.09

0.15

300

64

65.39

86

84.99

0.20

400

55

57.25

77

77.33

0.30

600

42

45.42

60

63.22

0.40

800

33

36.35

47

51.27

0.50

1000

26

29.22

37

41.47

0.60

1200

20

23.54

29

33.54

0.70

1400

15

18.99

22

27.14

Figure 9.15 shows the form of the excess head dissipation curves as determined by SEEP/W. The form of the curves is the same as commonly published graphical solutions for Terzaghi's equation. A close agreement can be observed between the SEEP/W and the closed-form solution. Figure 9.15 Consolidation Analysis Results

GEO-SLOPE Office 5 345

Reservoir Clay Liner A common technique for reducing the seepage loss from a reservoir is to line the reservoir with a clay blanket. The problem is challenging to analyze because of the sharp contrast in the saturated hydraulic conductivity of the clay blanket and that of the underlying material; as well, the underlying material is often sandy with a very steep hydraulic conductivity function. Kisch, 1959, (pp. 9 21), studied this problem and developed closed form solutions. Hydraulic conductivity data was obtained for a Yalo Light Clay and for a Superstition Sand. These functions are presented in Figure 9.16. Kisch's work indicated that the pore-water pressure distribution in the clay blanket and in the underlying sand is as illustrated in Figure 9.17. When the water level in the pond is at the surface of the clay blanket, the flow through the system is in an unsaturated state down to a water table in the sand. The pore-water pressure decreases sharply at the clay-sand contact and remains at a constant value down to the capillary zone in the sand. SEEP/W is capable of computing the negative pore-water pressure distribution as predicted by Kisch. The data files for this verification example are named KISCH. To obtain a solution to this highly non-linear problem, it is necessary to use many iterations and control the change in hydraulic conductivity from one iteration to the next iteration. The iteration scheme incorporated in SEEP/W allows you specify how the hydraulic conductivity should be changed. Table 9.5 gives the convergence parameter values specified for this example. Table 9.5 Specified Convergence Parameters Convergence Parameter

Value

Maximum number of iterations

300

Convergence tolerance

0.001

Maximum conductivity change (orders of magnitude)

1.0

Rate of conductivity change

1.1

Minimum conductivity change (orders of magnitude)

0.0001

Figure 9.18 shows the results of the SEEP/W analysis. The form and shape of the pore-water pressure distribution is the same as the closed-form solution predicted by Kisch (Figure 9.17). The SEEP/W distribution is slightly more gradual in the transition zone between the clay and sand interface than Kisch’s prediction. This difference is minor, however, considering the extreme non-linearity of the flow system due to the steep hydraulic conductivity function of the sand. Figures 9.19 shows a plot of the residual versus iteration number for all iterations as displayed by the SOLVE Graph command. It reveals that the residual gradually decreases with the number of iterations. The residual oscillation is much reduced after 100 iterations. A solution to the problem is obtained after 135 iterations, at which point the residual is less than the specified convergence tolerance. Figures 9.20 shows a plot of the K versus suction for the iteration as displayed by the SOLVE Graph command. The plot presents a comparison of the estimated hydraulic conductive used in the computation (red dots) and the user specified hydraulic conductivity function (blue squares). The plot reveals that when the solution is converged the estimated hydraulic conductive line up with the user specified hydraulic conductivity function. This example shows that SEEP/W can be used to analyze unsaturated flow in materials with extremely steep hydraulic conductivity functions. However, the analysis requires a fine mesh with higher-order elements and a large number of iterations.

346 SEEP/W Figure 9.16 Hydraulic Conductivity Functions for Yalo Light Clay and Superstition Sand

Figure 9.17 The Kisch Negative Pore-Water Pressure Distribution Beneath a ClayBlanketed Reservoir

GEO-SLOPE Office 5 347 Figure 9.18 The SEEP/W Computed Negative Pore-Water Pressure Distribution

Figure 9.19 Residual vs. Iteration Number Plot for all Iterations

348 SEEP/W Figure 9.20 K vs. Suction Plot for the Last Iteration

Reservoir Filling Analysis A reservoir filling example is included with SEEP/W to illustrate the transient migration of the wetting front within an homogeneous embankment. The geometry and the finite element mesh is shown in Figure 9.21. Figure 9.21 Geometry and Finite Element Mesh of the Embankment

The embankment is assumed to be a pervious material with a hydraulic conductivity function and a volumetric water content (storage) function as shown in Figures 9.22 and 9.23 respectively.

GEO-SLOPE Office 5 349 Figure 9.22 Hydraulic Conductivity Function

Figure 9.23 Volumetric Water Content Function

For analysis purposes, it is assumed that the reservoir was filled instantaneously. This means that the total head on the upstream face is a constant 11 m during the entire transient process. The data and output files for this example are named FILL. The initial condition is defined by a steady state analysis with water table at the base of the dam. The data file for the initial condition run is named FILL_I. Figure 9.24 shows the resulting migration of the wetting front, or the position of the water table at different times. Figure 9.25 illustrates the flow vectors at time step 2.

350 SEEP/W Figure 9.24 Changes in Water Table Position at Different Time Steps Due to Filling of the Reservoir

Figure 9.25 Flow Vectors and Water Table Position at Time Step 2

The migration of the wetting front appears to have been computed correctly, since the migration is gradual and is in the correct direction, and the wetting front has a sensible shape. From this perspective, the solution appears correct and reasonable. However, the distribution of other parameters (e.g., porewater pressure and volumetric water content) may be irregular in the unsaturated zone just above the water table, particularly in the early time steps when the influx gradient is large. This example therefore illustrates some of the secondary effects that can occur during a transient analysis. Figure 9.26 shows the pore-water pressure distribution at Time Step 2. Note that the pressure contours at -40, -60 and -80 are not smooth. This is likely due to numerical difficulties when the gradients within one element become excessive.

GEO-SLOPE Office 5 351 Figure 9.26 Pore-Water Pressure Distribution at Time Step 2

The irregularity in the pore-water pressure means there is also irregularity in variables such as the volumetric water content. Figure 9.27 shows the volumetric water content distribution for the same time step. The water content at Nodes 77 and 90 is smaller than the minimum value of 0.05 on the volumetric water content function. The reason for this anomaly is the very sharp variation in the water content within Elements 65, 66, 77 and 78. Projecting the Gauss point values in these elements to the nodes for contouring results in over-shoot at the nodes (see Draw Contours in Chapter 6 for a discussion of the over-shoot problem) . This kind of irregularity is commonly observed in early time steps when boundary conditions are changed rapidly. A refined mesh, a gradual change in boundary conditions and a smaller convergence tolerance would improve the situations in most cases. Figure 9.27 Volumetric Water Content Distribution at Time Step 2

Resolving this problem requires you to spend more time refining the mesh, resulting in a larger problem

352 SEEP/W that requires more computation time. Whether or not this extra effort is necessary must be decided in light of your analysis objective. Overall, the distribution of variables in the unsaturated zone is good; the irregularities only occur along a band in the unsaturated zone near the wetting front. This may be acceptable to you if your primary objective is to follow the position of the wetting front with time. If, however, you wish to improve the distribution of variables in the unsaturated zone for each time step, then you would have to spend more time on the discretization and computing. In other words, there needs to be a balance between the level of time and effort devoted to the analysis and the objectives of the analysis.

Rapid Drawdown Analysis The same embankment of the reservoir filling example is also used to illustrate how to do a rapid drawdown analysis. The example also shows how to use a boundary function and demonstrates the effect of a review boundary. The data and output files for this example are named RAPID. The initial conditions are given by a steady state analysis with water level equals to 11 m. The associated files for the initial condition are RAPID_I. Nodes along the upstream face are specified with a boundary function of Total Head versus time (Figure 9.28). Furthermore, the nodes above the specified total head are assumed to be no flow with review boundary. The boundary function used in the analysis models the drawdown of the reservoir from a high of 11 m to a low of 1 m over a period of 30 days. Thereafter, for all remaining time steps, the reservoir is at an elevation of 1 m. Figure 9.28 Upstream Face Boundary Function Showing Total Head As a Function of Time

The drawdown process are simulated for 12 time steps. Figure 9.29 shows the resulting positions of the water table as the excess pore-water pressure dissipates at different time steps after reservoir drawdown. Figure 9.30 illustrates the flow vectors and total head contours (equipotential lines) at time step 9.

GEO-SLOPE Office 5 353 Figure 9.29 Changes in Water Table Position due to Rapid Drawdown of the Reservoir

Figure 9.30 Flow Vectors and Total Head Contours at Time step 9

Appendix A Unsaturated Hydraulic Conductivity Introduction Analyzing saturated-unsaturated seepage processes requires establishing the hydraulic conductivity versus pore-water pressure relationship. In the case of a transient analysis, the volumetric water content function must also be defined. Both of these functions can be either measured directly in the laboratory or predicted using a variety of methods. The volumetric water content function can be predicted from the grain-size distribution curve and the hydraulic conductivity function can be predicted using the volumetric water content function and the measured saturated hydraulic conductivity. In SEEP/W Version 5, several published and verified methods have been incorporated into the program to aid in the determination of these functions. In addition a comprehensive library has been added that provides measured grain-size curves, measured volumetric water content functions and predicted hydraulic conductivity functions using measured saturated hydraulic conductivities for a wide range of materials. The purpose of this Appendix is to introduce the SEEP/W user to published information on each of the predictive methods, to describe how volumetric water content functions may be obtained in a laboratory and to present the materials included in the function library.

Direct Measurement of the Hydraulic Conductivity Function The hydraulic conductivity versus pore-water pressure relationship can be established directly from laboratory measurements. This involves measuring the hydraulic conductivity of soil samples at various negative pore-water pressure levels. The techniques for measuring unsaturated hydraulic conductivity have been documented by Klute, 1965, pp. 253 261. This document describes the fundamentals of the equipment and procedures involved. Another paper on the subject has been presented by Corey, 1957, pp. 710. Hillel, 1990, discusses the measurement of unsaturated hydraulic conductivity in situ. Making measurements of unsaturated hydraulic conductivity is a fairly complex and involved task. Difficulties associated with the measurements have been discussed by Brooks and Corey, 1966, and Green and Corey, 1971, pp. 3 8. The difficulties are generally related to problems with air diffusion and measuring small flow quantities.

Hydraulic Conductivity Predictive Methods - Introduction The difficult task of measuring the unsaturated hydraulic conductivity function directly is often overcome by predicting the unsaturated hydraulic conductivity from either a measured or predicted volumetric water content function, such as the one illustrated in Figure A.1. Consequently, this is the preferred approach if a suitable predictive model is available.

356 SEEP/W Figure A.1 Water Content vs. Pore-Water Pressure

SEEP/W has three separate methods built into the model that can be used to predict unsaturated hydraulic conductivity functions using either a measured or estimated volumetric water content function and a saturated hydraulic conductivity. All three predictive methods have been verified in the literature and are referenced as follows: Fredlund, D.G., Anqing Xing, and Shangyan Huang. 1994. Predicting the permeability function for unsaturated soils using the soil-water characteristic curve. Canadian Geotechnical Journal, Vol. 31, pp. 533-546. Green, R.E. and Corey, J.C., 1971. Calculation of Hydraulic Conductivity: A Further Evaluation of Some Predictive Methods.. Soil Science Society of America Proceedings, Vol. 35, pp. 3-8. van Genuchten, M. Th. 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. Vol. 44 pp. 892-898. NOTE: It is important to realize that prediction techniques such as predicting the volumetric water content function from grain-size distributions or estimating an unsaturated hydraulic conductivity function from a volumetric water content function are only ESTIMATES. The estimation techniques generally work better for fine granular soils than they do for clayey soils. In addition, there is no way to incorporate important information such as what compactive effort was used to place the material or to include the influence of secondary structures such as fissures on the flow system. It is up to you, as the user of this software, to judge the applicability of the estimation techniques and sample functions provided to the situation and soils you are trying to model.

Hydraulic Conductivity Predictive Method (Fredlund et al, 1994) One of the three methods available to predict the unsaturated hydraulic conductivity function from a volumetric water content function is that proposed by Fredlund et al.,1994. This method consists of developing the unsaturated hydraulic conductivity function by integrating along the entire curve of the volumetric water content function. If the volumetric water content function has been curve-fit using the method proposed by Fredlund and Xing, 1994, then the hydraulic conductivity function can be predicted over the entire suction range (i.e., from 0 to 106 kPa), which removes the need to determine the residual water content, which is usually required for other predictive methods. In SEEP/W, we have made an assumption that the residual water content is 10% of the saturated water content (porosity) and the resulting curve is developed only over the negative pore-water pressure range identified by the modeler.

GEO-SLOPE Office 5 357 The Fredlund et al. method is generally more accurate for sandy soils than it is for finer grained materials such as clay. The governing equation is:

where: kw = is the calculated conductivity for a specified water content or negative pore-water pressure, (m/s) ks = the measured saturated conductivity, (m/s) q = the volumetric water content e = the natural number, 2.71828 y = a dummy variable of integration representing the logarithm of negative pore-water pressure i = the interval between the range of j to N j = the least negative pore-water pressure to be described by the final function N = the maximum negative pore-water pressure to be described by the final function y = is the suction corresponding to the jth interval q' = is the first derivative of

where: a = is approximately the air-entry value of the soil n = is a parameter that controls the slope at the inflection point in the volumetric water content function m = is a parameter that is related to the residual water content C(y) = is a correcting function defined as

358 SEEP/W where: Cr = is a constant related to the matric suction corresponding to the residual water content. A typical value is about 1500 kPa.

Hydraulic Conductivity Predictive Method (Green and Corey, 1971) A method for predicting unsaturated hydraulic conductivity from soil-water characteristic functions has been presented by Green and Corey, 1971, pp. 3-8. Green and Corey concluded that their method is sufficiently accurate for most field applications. Elzeftawy and Cartwright, 1981 compared measured unsaturated coefficients of permeabilities for various soils with predicted values using the Green and Corey method and reached the same conclusion. The Green and Corey equation is:

(A.1) where: = the calculated conductivity for a specified water content or negative pore-water pressure (cm/min)

= the matching factor (measured saturated conductivity / calculated saturated conductivity) i = the last water content class on the wet end. e.g. i=1 identifies the pore class corresponding to the lowest water content, and i=m identifies the pore class corresponding to the saturated water content hi = negative pore-water pressure head for a given class of water-filled pores (cm of water) n = total number of pore classes between i and m = water content (cm3/cm3) = lowest water content on the experimental curve = saturated water content (cm3/cm3) T = surface tension of water (Dyn/cm) = water-saturated porosity h = viscosity of water (g/cm •s-1) g = the gravitational constant (cm/s-1)

GEO-SLOPE Office 5 359

m = density of water (g/cm3) p = a parameter that accounts for the interaction of pore classes The following are some suggested values of p given by various authors: Author

p

Marshall, 1958

2.0

Millington and Quirk, 1961, pp. 1200 1207

1.3

Kunze, Vehara and Graham, 1968

1.0

The shape of the conductivity function is controlled by the term

in

Equation A.1. The term is a constant for a particular function and can be taken to be 1.0 when determining the shape of the hydraulic conductivity function. This is the assumption made in SEEP/W. SEEP/W first computes the hydraulic conductivity at the zero pressure value using the equation,

(A.2) The saturated conductivity ks is a user-defined value in SEEP/W. When ks is specified, the entire conductivity function is moved up or down by a constant ratio of ks /ksc. In summary, SEEP/W uses the Green and Corey equation to estimate the shape of the conductivity function and then moves the curve up or down so that the function passes through the user-specified value of ks.

Hydraulic Conductivity Predictive Method (van Genuchten, 1980) Van Genuchten (1980) proposed the following closed form equation to describe the hydraulic conductivity of a soil as a function of matric suction.

360 SEEP/W where: ks - saturated hydraulic conductivity a,n,m = curve fitting parameters n = 1/(1-m) y = required suction range From the above equations, the hydraulic conductivity function of a soil can be estimated once the saturated conductivity and the two curve fitting parameters, a and m are known. Van Genuchten (1980) showed that the curve fitting parameters can be estimated graphically based on the volumetric water content function of the soil. According to van Genuchten, the best point to evaluate the curve fitting parameters is the halfway point between the residual and saturated water content of the volumetric water content function. Let qp be the volumetric water content at the halfway point of the volumetric water content function, and yp be the matric suction at the same point. Then the slope Sp of the function can be calculated as:

Van Genuchten (1980) proposed the following formula to estimate the parameters m and a when Sp is calculated:

for Sp between 0 and 1

for Sp > 1

Direct Measurement of Water Content Function The water content of soil at a particular negative pore-water pressure can be measured with a commercially available apparatus known as a TEMPE Pressure Cell. This cell is manufactured and marketed by Soilmoisture Equipment Corp. in Santa Barbara, California, USA. Figure A.2 shows a schematic diagram of the cell.

GEO-SLOPE Office 5 361 Figure A.2 Schematic Cross Section View of a TEMPE Pressure Cell

It is important that the soil sample is placed in direct contact with a porous ceramic plate located on the bottom of the inner chamber. The ceramic plate acts like a semi-permeable membrane between the soil sample and the water filled reservoir at the bottom of the cell. Positive air pressure is applied to the top of the cell and increases the air pressure in the chamber. The increase in air-pressure causes pore-water from the soil sample to be pushed out through the ceramic plate and air enters the previously water-filled pores in the soil sample. It is very important that the air entering the soil is only from the air chamber and not a result of diffusion through the ceramic plate at the bottom of the cell. This is achieved by using a high air-entry plate, which will allow water to readily flow through the plate but restrict the flow of air up to a certain maximum pressure. Each incremental increase in air pressure results in an incremental decrease in water content within the soil sample. Equilibrium conditions must be established following each incremental increase in air pressure, then the entire cell is weighed and the change in weight is recorded. At the end of the test, the changes in cell weight are used together with the final dry weight of the sample to compute the water content of the sample that existed at each of the various applied pressures. In this manner the volumetric water content versus negative pore-air pressure relationship can be developed.

Volumetric Water Content Predictive Methods Introduction It is not especially difficult to obtain a direct measurement of a volumetric water content function in a laboratory, but it does require time and it requires finding a geo-technical laboratory that performs the service. It is, however, standard practice to obtain a grain-size distribution curve and many companies have the capability and facilities to develop their own curves. The development of the grain-size distribution curve is inexpensive and can be quickly accomplished. One of the required input parameters for a transient analysis is the volumetric water content function. Since it can sometimes be difficult or time consuming to obtain a volumetric water content function, it may be of benefit to be able to get a develop an estimation of the volumetric water content function using either a closed-form solution that requires user-specified curve-fitting parameters, or to use a predictive method that uses a measured grain-size distribution curve. SEEP/W has four methods available to develop a volumetric water content function. The four methods are: Arya, L.M., and J. F. Paris. 1981. A physicoempirical model to predict the soil moisture characteristic from particle-size distribution and bulk density data. Soil Science Society of America Journal, Vol 45. pp: 1023-1030.

362 SEEP/W Aubertin, M. Mbonimpa, B. Bussiere, and R. P. Chapuis. 2001. A physically-based model to predict the water retention curve from basic geotechnical properties. Submitted to the Journal of Geotechnical and Geoenvironmental Engineering. Fredlund, D. G., and Anqing Xing. 1994. Equations for the soil-water characteristic curve. Canadian Geotechnical Journal. Vol. 31, pp: 521-532. van Genuchten, M. Th. 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, Vol. 44, pp:892-898. The governing equations and summaries of all four methods are described in the following sections. NOTE: It is important to realize that prediction techniques such as predicting the volumetric water content function from grain-size distributions or estimating an unsaturated hydraulic conductivity function from a volumetric water content function are only ESTIMATES. The estimation techniques generally work better for fine granular soils than they do for clayey soils. In addition, there is no way to incorporate important information such as what compactive effort was used to place the material or to include the influence of secondary structures such as fissures on the flow system. It is up to you, as the user of this software, to judge the applicability of the estimation techniques and sample functions provided to the situation and soils you are trying to model.

Volumetric Water Content Predictive Methods (Arya and Paris, 1981) Arya & Paris (1981) proposed a physico-empirical approach to predict the volumetric water content function of a soil based on its grain size distribution and bulk density. The grain size function is divided into a number of segments. Recognizing that the volumetric water content function is essentially a poresize distribution curve, the model involves finding a pore volume and a representative pore radius corresponding to each grain size segments. The following is a summary of the proposed method. The soil mass in each segment is assumed to form a uniform matrix with a bulk density equal to that of a natural-structure sample. For a unit of sample mass, an equivalent pore volume for each segment is computed from:

where: Vi = the pore volume per unit mass of a segment Wi = the solid mass per unit mass of a segment rp = the particle density of the soil e = the void ratio of the soil The pore volumes calculated from each grain size fraction can be integrated progressively to give the volumetric water content at a segment:

GEO-SLOPE Office 5 363 It is assumed that the solid mass in a particle-segment Wi can be represented by many individual spherical particles having the same radius, Ri , then the number of particle, ni, in a unit mass of soil can be calculated as:

Arya & Paris (1981) proposed that the pore radius of each segment can estimated as below:

Where a is a particle shape constant, an empirical constant equal to 1.38. Once the pore radii are obtained, the equivalent soil matrix suction, yi can be obtained from the equation of capillarity:

Where T is the surface tension of the water and b is the contact angle. At 25oC, T is equal to 72.8 dyn/cm (0.074256 g/cm) and b is about zero. The volumetric water content and the matrix suction at each segment of the grain size function can be calculated using the above equations to produce the complete function. Arya & Paris’s method works very well with granular material when the entire grain-size function is well defined. In most cases, the predicted volumetric water content functions are in close agreement with the measured data.

Volumetric Water Content Predictive Methods (MK Modified Kovacs Method) Aubertin et al, 2001, presented a method to predict the volumetric water content function which is modified from the method proposed by Kovacs, 1981 (Seepage Hydraulics, Elsevier Science Publishers, Amsterdam.) The modifications were made to Kovac's method to better represent materials such as tailings from hard-rock mines. A further modification extended the method for clay type soils. The Aubertin et al. method predicts the volumetric water content function using basic material properties which can be useful, particularly for preliminary analysis. It should be cautioned that, especially for clay type materials, it is critical to base final design on measured material properties. The function is initially determined as a degree of saturation function and then is later converted to a volumetric water content function. The function is developed by defining the degree of saturation for two main components. The first component contributes to the amount of water that is stored in a soil by capillary forces (Sc) that exist at relatively small negative pore-water pressures . The second component contributes to the volumetric water content function at large negative pore-water pressures where the amount of water that exists in the soil is primarily a function of adhesion (Sa). Both of these components (Sc and Sa ) can be evaluated from the negative pore-water pressure and material property information such as particle-size, the shape of the particles and the porosity. The degree of saturation (Sr) as determined based on the capillary ( Sc) and adhesive (Sa) components is

364 SEEP/W as follows:

where: Sr = degree of saturation qw = volumetric water content n = porosity Sc = degree of saturation due to capillary forces Sa* = bounded value of degree of saturation due to adhesion (Sa) where:

The adhesive component is a bounded value since it is possible at low suctions for the value Sa to be greater than 1. The bounded value ensures that for a Sa greater or equal to 1, Sa* = 1 and if Sa is less than 1, then Sa* = Sa. The adhesion component (Sa) is associated with the thin film of water that covers the surface of the soil grain and depends on basic material properties such as the negative pore-water pressure in the soil and the particle-size, shape coefficient and porosity of the soil. It is determined by the following equation:

where: a = a curve fitting parameter Y = negative pore-water pressure or suction Yn = suction term introduced to ensure dimensionless components e = void ratio hco = the mean capillary rise, determined by the following equation: for capillary type soils:

GEO-SLOPE Office 5 365

or, for cohesion type soils:

D10 = the particle diameter (in cm) corresponding to 10% passing on a grain-size distribution curve

Cu = the coefficient of uniformity WL = the liquid limit (%) z  = a constant approximately equal to 402.2 cm2 CY = is a correction coefficient that allows a progressive decrease in water content at high suctions, forcing the function through qw = 0 at Yo = 106 kPa, and was initially proposed by Fredlund and Xing (1994) and described by the following equation:

Yr = suction corresponding to the residual water content (qr) representing the point where further increases in suction will not effectively remove further water from the soil.

The capillary saturation, which depends essentially on the pore diameter and the pore size distribution provided is given by:

where: m = a fitting parameter that takes into account the pore size distribution and controls the shape and position of the volumetric water content function in the capillary zone For plastic-cohesive soils considered here, with hco,P both the value of parameters m and a can be taken as constants with m=3x10-5 and a=7x10-4 in the predictive applications. For the capillary based soils, m and a can be taken as 1 and 0.01 respectively.

366 SEEP/W

Volumetric Water Content Predictive Methods (Fredlund and Xing, 1994) The Fredlund and Xing, 1994 method is a closed-form solution that can be used to develop a volumetric water content function based on the user's knowledge of a group of three parameters. The governing equation is as follows:

or if the function is predicted out to qw = 0 at 106 kPa. where: qw = the volumetric water content qr = the residual volumetric water content qs = the saturated volumetric water content e = the natural number, 2.71828 y = is negative pore-water pressure a, n, m = curve fitting parameters The 'a' parameter, which has units of kPa, is the inflection point of the volumetric water content function. It is generally slightly larger than the air-entry value. The parameter n controls the slope of the volumetric water content function and the m parameter controls the residual water content. The three parameters a, n, and m are determined as follows:

where: yi = the negative pore water pressure corresponding to the volumetric water content of qi occurring at the inflection point (yi, qi) s = the slope of the line tangent to the volumetric water content function that passes through the inflection point

where: yp is the intercept of the tangent line and the negative pore-water pressure axis The Fredlund and Xing, 1994 method is only functional if you know values of a, n and m. It is not

GEO-SLOPE Office 5 367 intended to predict a volumetric water content function from grain-size curves, but was developed to obtain a smooth function over the complete range of negative pore-water pressure values (0 to 106 kPa).

Volumetric Water Content Predictive Methods (van Genuchten, 1980) In 1980, van Genuchten proposed a four-parameter equation as a closed form solution for predicting the volumetric water content function. The governing equation is as follows:

where: qw = the volumetric water content qr = the residual volumetric water content qs = the saturated volumetric water content y = is negative pore-water pressure a, n, m = curve fitting parameters Although the terminology of the a, n and m parameters are similar to those of Fredlund and Xing, 1994, the definitions are slightly different. The 'a' parameter in particular can not be estimated by the air-entry value, but instead is a pivot point about which the 'n' parameter changes the slope of the function. The parameter 'm' effects the sharpness of the sloping portion of the curve as it enters the lower plateau. The 'a' parameter can be expressed as a function of the other two parameters in the following manner:

where:

In summary, the van Genuchten closed form solution can only be used when the a, n and m parameters are known.

Example Material Property Functions It can sometimes be difficult to obtain the appropriate input parameters or functions that are required for seepage analyses. SEEP/W has various function estimation techniques built into the software and also has a file, which is included in the examples folder, that contains soil property functions for twenty-four different soils. The sample functions and estimation techniques are provided to help you get started using the software and to help you understand the significance of material property functions in seepage analysis. If you are unfamiliar with these types of functions, looking through the example file will help

368 SEEP/W you learn what an appropriately shaped function looks like and comparison of the functions will give some insight as to how the functions can vary for different types of materials. Utilizing the estimation techniques and sample functions can be very useful during the early stages of analysis when you are trying to understand the flow processes for your project and to identify critical issues and areas within a flow regime. If it appears that the analysis is going to be very sensitive to the material property functions, then it may be necessary to more accurately quantify the soil that is being modeled. It may also become necessary to conduct a sensitivity analysis to ensure that your understanding of the material property functions is sufficient to analyze the results. A function library describing twenty-four different soils ranging from uniform sand to clayey silt has been included with your purchase of SEEP/W and can be found in the examples folder under the file names FN_METRE.SEP and FN_FEET.SEP, which present the functions in terms of metric (SI) units and imperial (English) units respectively. The information provided for the first seventeen soils include measured grain-size distribution curves, measured volumetric water content functions and predicted hydraulic conductivity functions developed using a measured saturated hydraulic conductivity and one of the three predictive methods built into SEEP/W. The last seven functions (18-24 inclusive) do not have grain-size distributions available, but are described by volumetric water content functions taken from published literature. The hydraulic conductivity functions for these materials have also been predicted using a measured saturated hydraulic conductivity value. In some cases, the hydraulic conductivity functions were adjusted slightly from the estimated data points in order to create a smooth function. The functions presented in these files can be imported into your own project files and then modified as necessary to suit your given situation. For example, you can import a function that has properties similar to the soils you are trying to model. The functions can then be adjusted as necessary to increase their applicability to your situation. Another benefit of the function library is the ability you now have to compare your grain-size distribution curves to those in the function library and thereby select material property functions that may represent soils found on site. These example functions are provided to help you define functions when you do not have any other data. As discussed in Chapter 7, using an approximate function leads to more realistic results than using a single-value function when the problem includes unsaturated flow. The following sections present the information that describe each of the twenty-four soils in the function library. Both the metric and imperial versions of the material property functions are presented in this section. Grain-size distributions are only presented in SI units.

GEO-SLOPE Office 5 369 A summary listing of the 24 soils contained in the function library Function #

Soil Name

K-sat (m/s)

Porosity

1

Uniform Fine Sand #1

2.15E-5

0.30

2

Uniform Fine Sand #2

1.13E-6

0.38

3

Sandy Loam

5.83E-06

0.38

4

Very Fine Sand

2.00E-08

0.42

5

Sandy Silt (Coarse Tails)

4.80E-07

0.45

6

Silty Sand

5.00E-07

0.51

7

Well-graded #1

1.00E-07

0.41

8

Well-graded #2

1.50E-08

0.40

9

Silt #2

1.00E-06

0.44

10

Glacial Till (Uncompacted)

5.00E-06

0.30

11

Glacial Till (Compacted)

1.00E-07

0.23

12

Silt Loam

7.00E-07

0.45

13

Sandy Silty Clay

1.40E-07

0.42

14

Silty Clay (Fine Tails)

3.00E-08

0.50

15

Uniform Silt

1.00E-08

0.49

16

Clay/Silt

2.50E-08

0.38

17

Well-graded #3 (high clay)

7.00E-10

0.35

18

Uniform Sand

1.00E-04

0.35

19

Sand

5.40E-05

0.39

20

Fine Sand

4.30E-06

0.35

21

Silt

2.50E-07

0.38

22

Silt (Tailings)

5.80E-08

0.39

23

Sandy Clayey Silt

1.50E-08

0.35

24

Clayey Silt

8.40E-09

0.41

Uniform Fine Sand #1 - Function #1 (Metric and Imperial)

370 SEEP/W

Reference:

Staple, W. J. (1969)

Saturated Conductivity:

2.15 x 10-5 m/sec 7.05 x 10-5 ft/sec

Porosity:

0.30

Air Entry Value

2 kPa 42 psf

D60

0.4 mm

D10

0.18 mm

Conductivity Estimation

Fredlund & Xing

Metric

GEO-SLOPE Office 5 371 Imperial

Uniform Fine Sand #2 - Function #2 (Metric and Imperial)

372 SEEP/W

Reference:

Becher, (1970)

Saturated Conductivity:

1.13 x 10-6 m/sec 3.71 x 10-6 ft/sec

Porosity:

0.38

Air Entry Value

1 kPa 21 psf

D60

0.4 mm

D10

0.07 mm

Conductivity Estimation

Fredlund & Xing

Metric

GEO-SLOPE Office 5 373 Imperial

374 SEEP/W

Sandy Loam - Function #3 (Metric and Imperial) Reference:

Topp,G. C. (1969)

Saturated Conductivity:

5.83 x 10-6 m/sec 1.91 x 10-5 ft/s

Porosity:

0.38

Air Entry Value

6 kPa 125 psf

D60

0.3 mm

D10

0.06 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 375 Imperial

Very Fine Sand - Function #4 (Metric and Imperial)

376 SEEP/W

Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

2.00 x 10-8 m/sec 6.56 x 10-8 ft/sec

Porosity:

0.42

Air Entry Value

3 kPa 63 psf

D60

0.15 mm

D10

0.06 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 377 Imperial

Sandy Silt (Coarse Tailings) - Function #5 (Metric and Imperial)

378 SEEP/W

Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

4.80 x 10-7 m/sec 1.57 x 10-6 ft/sec

Porosity:

0.45

Air Entry Value

10 kPa 208 psf

D60

0.09 mm

D10

0.001 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 379 Imperial

380 SEEP/W

Silty Sand - Function #6 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

5.00 x 10-7 m/sec 1.64 x 10-6 ft/sec

Porosity:

0.51

Air Entry Value

12 kPa 251 psf

D60

0.07 mm

D10

0.008 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 381 Imperial

Well-Graded #1 - Function #7 (Metric and Imperial)

382 SEEP/W

Reference:

O'Kane Consultants Inc.

Saturated Conductivity:

1.00 x 10-7 m/sec 3.28 x 10-7 ft/sec

Porosity:

0.41

Air Entry Value

15 kPa 313 psf

D60

16 mm

D10

0.005 mm

Conductivity Estimation

Fredlund & Xing

Metric

GEO-SLOPE Office 5 383 Imperial

384 SEEP/W

Well-Graded #2 - Function #8 (Metric and Imperial) Reference:

O'Kane Consultants Inc.

Saturated Conductivity:

1.50 x 10-8 m/sec 4.90 x 10-8 ft/sec

Porosity:

0.40

Air Entry Value

50 kPa 1045 psf

D60

6.7 mm

D10

n/a

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 385

Imperial

386 SEEP/W

Silt #2 - Function #9 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

1.00 x 10-6 m/sec 3.28 x 10-6 ft/sec

Porosity:

0.44

Air Entry Value

15 kPa 209 psf

D60

0.05 mm

D10

0.006 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 387

Imperial

388 SEEP/W

Glacial Till (Uncompacted) - Function #10 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

5.00 x 10-6 m/sec 1.64 x 10-5 ft/sec

Porosity:

0.30

Air Entry Value

8 kPa 167 psf

D60

0.07 mm

D10

0.002 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 389

Imperial

390 SEEP/W

Glacial Till (Compacted) - Function #11 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

1.00 x 10-7 m/sec 3.28 x 10-7 ft/sec

Porosity:

0.23

Air Entry Value

20 kPa 418 psf

D60

0.07 mm

D10

0.002 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 391

Imperial

392 SEEP/W

Silt Loam - Function #12 (Metric and Imperial) This material is a silica flour Reference:

Newman, G.P., (1995)

Saturated Conductivity:

7.00 x 10-7 m/sec 2.30 x 10-6 ft/sec

Porosity:

0.45

Air Entry Value

15 kPa 313 psf

D60

0.026 mm

D10

0.002 mm (estimated)

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 393

Imperial

394 SEEP/W

Sandy Silty Clay - Function #13 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

1.40 x 10-7 m/sec 4.59 x 10-7 ft/sec

Porosity:

0.42

Air Entry Value

50 kPa 1045 psf

D60

0.026 mm

D10

0.002 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 395

Imperial

396 SEEP/W

Silty Clay (Fine Tailings) - Function #14 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

3.00 x 10-8 m/sec 9.84 x 10-8 ft/sec

Porosity:

0.50

Air Entry Value

40 kPa 836 psf

D60

0.015 mm

D10

0.001 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 397

Imperial

398 SEEP/W

Uniform Silt - Function #15 (Metric and Imperial) Reference:

Civil Engineering Dept, Univ. of Saskatchewan

Saturated Conductivity:

1.00 x 10-8 m/sec 3.28 x 10-8 ft/sec

Porosity:

0.50

Air Entry Value

80 kPa 167 psf

D60

0.013 mm

D10

0.003 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 399

Imperial

400 SEEP/W

Clay Silt - Function #16 (Metric and Imperial) Reference:

O'Kane Consults Inc.

Saturated Conductivity:

2.50 x 10-8 m/sec 8.20 x 10-8 ft/sec

Porosity:

0.38

Air Entry Value

10 kPa 209 psf

D60

0.01 mm

D10

>0.001 mm

Conductivity Estimation

Fredlund & Xing

Metric

GEO-SLOPE Office 5 401

Imperial

402 SEEP/W

Well-Graded #3 (high clay) - Function #17 (Metric and Imperial) Reference:

O'Kane Consultants Inc.

Saturated Conductivity:

7.00 x 10-10 m/sec 2.30 x 10-9 ft/sec

Porosity:

0.34

Air Entry Value

45 kPa 898 psf

D60

0.30 mm

D10

>0.001 mm

Conductivity Estimation

Van Genuchten

Metric

GEO-SLOPE Office 5 403

Imperial

404 SEEP/W

Uniform Sand - Function #18 (Metric and Imperial) Reference:

Swanson, 1991

Saturated Conductivity:

1.00 x 10-4 m/sec 3.28 x 10-4 ft/sec

Porosity:

0.35

Air Entry Value

3 kPa 63 psf

D60

n/a

D10

0.1 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 405

Imperial

A grain-size distribution is not available for this material

406 SEEP/W

Sand - Function #19 (Metric and Imperial) Reference:

Ho, 1979

Saturated Conductivity:

5.4 x 10-5 m/sec 1.77 x 10-4 ft/sec

Porosity:

0.39

Air Entry Value

6 kPa 125 psf

D60

n/a

D10

n/a

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 407 Imperial

A grain-size distribution is not available for this material

Fine Sand - Function #20 (Metric and Imperial)

408 SEEP/W

Reference:

Bruch, 1993

Saturated Conductivity:

4.30 x 10-6 m/sec 1.41 x 10-5 ft/sec

Porosity:

0.35

Air Entry Value

4 kPa 84 psf

D60

n/a

D10

0.093 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 409 Imperial

A grain-size distribution is not available for this material

Silt - Function #21 (Metric and Imperial)

410 SEEP/W

Reference:

Ho, 1979

Saturated Conductivity:

2.50 x 10-7 m/sec 8.20 x 10-7 ft/sec

Porosity:

0.38

Air Entry Value

20 kPa 418 psf

D60

n/a

D10

n/a

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 411 Imperial

A grain-size distribution is not available for this material

Silt (Tailings) - Function #22 (Metric and Imperial)

412 SEEP/W

Reference:

Gonzalez and Adams, 1980

Saturated Conductivity:

5.80 x10-8 m/sec 1.90 x 10-7 ft/sec

Porosity:

0.30

Air Entry Value

10 kPa 209 psf

D60

n/a

D10

n/a

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 413 Imperial

A grain-size distribution is not available for this material

Sandy Clayey Silt - Function #23 (Metric and Imperial)

414 SEEP/W

Reference:

Huang, 1994

Saturated Conductivity:

1.50 x 10-8 m/sec 4.92 x 10-8 ft/sec

Porosity:

0.35

Air Entry Value

15 kPa 313 psf

D60

n/a

D10

n/a

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 415 Imperial

A grain-size distribution not available for this material

Clayey Silt - Function #24 (Metric and Imperial)

416 SEEP/W

Reference:

Bruch, 1993

Saturated Conductivity:

8.40 x 10-9 m/sec 2.76 x 10-8 ft/sec

Porosity:

0.41

Air Entry Value

25 kPa 522 psf

D60

n/a

D10

0.003 mm

Conductivity Estimation

Green & Corey

Metric

GEO-SLOPE Office 5 417 Imperial

A grain-size distribution not available for this material

Appendix B DEFINE Data File Description Introduction SEEP/W DEFINE creates a data file with the extension SEP that contains the definition of the flow problem and which is read by SEEP/W SOLVE. The data in the SEP file is structured using a series of keywords. In the following sections, the keywords and the data associated with each are documented. An understanding of the SEP data file may be useful in some situations. However, it is strongly recommended that users not attempt to modify the data file with a text editor. Modifications to the problem definition should be conducted using SEEP/W DEFINE.

File Keyword FILEINFO Keyword Format Keyword Program-Name Version Description Keyword

= the keyword FILEINFO

Program-Name

= the name of the program - SEEPW

Version

= the version of the program

Example FILEINFO SEEPW 5.00

Comments The information is used by SEEP/W for data file identification and file conversion in order to maintain upward compatibility of the data file between versions. Both the program name and the version number are generated automatically by SEEP/W DEFINE.

TITLE Keyword Format Keyword Project-Title Comments Date Time

420 SEEP/W Description Keyword

= the keyword TITLE

Project-Title

= the title of the project

Comments

= the comments or description of the problem

Date

= the project data file creation date

Time

= the project data file creation time

Example TITLE SEEP/W User's Guide Example 1-D Consolidation DATESTAMP 8/18/01 TIMESTAMP 8:28:08PM

Comments The title information is created using the KeyIn Analysis Settings command in Chapter 4. This information serves as an identifying header in all output files created by SEEP/W SOLVE. If no information is specified, the four lines under the TITLE keyword will be blank.

ANALYSIS Keyword Format Keyword Problem-Type Problem-View Water-Weight Precision Sort-Direction Description Keyword

= the keyword ANALYSIS

Problem-Type

= the type of the flow problem

Problem-View

= the view of the flow problem

Water-Weight

= the unit weight of water

Precision

= the type of precision used in the computation

Sort-Direction

= the sorting direction of the finite element mesh

Example ANALYSIS 1 1 +9.8070e+000 1 0

Comments The analysis information is created using the KeyIn Analysis Control command in DEFINE. SEEP/W allows the simulation of the following types of problems, (Problem-Type):

GEO-SLOPE Office 5 421

Type

Type of Problem

1

steady state analysis

2

transient analysis

3

SIGMA/W consolidation analysis

4

CTRAN/W density-dependent analysis

SEEP/W allows the simulation of the following problem views (Problem-View): View

View of Problem

1

two-dimensional vertical sectional flow problem

2

axisymmetric flow problem

3

plan flow problem

The unit weight of water, (Water-Weight), must be in units that are consistent with the dimension of the flow problem. Typically, the value is 9.807 when the problem is defined in meters and 62.4 when the problem is defined in feet. SEEP/W Version 4 always solves the problem in double precision (i.e., Precision = 1). The finite element mesh may be sorted either in the vertical direction (Sort-Direction = 0) ,or in the horizontal direction (Sort-Direction = 1). The finite element mesh sorting is only performed in SEEP/W DEFINE.

CONVERGE Keyword Format Keyword Max-Iteration Tolerance Max-Change Rate-Change Min-Change Max-Solver Iteration Tolerance-Solver Max-Review Iteration

422 SEEP/W Description Keyword

= the keyword CONVERGE

Max-Iteration

= the maximum number of iterations per time step

Tolerance

= the convergence tolerance

Max-Change

= the maximum change in hydraulic conductivity between iterations

Rate-Change

= the rate at which Max-Change diminishes with each oscillation reversal

Min-Change

= the minimum change in hydraulic conductivity between iterations

Max-Solver Iteration

= the maximum number of iterations for the iterative solver

Tolerance-

= the convergence tolerance for the iterative solver

Solver Max-Review Iteration

= the maximum number of iterations for the review boundary per time step

Example CONVERGE 20 +1.0000e+000 +1.0000e+001 +1.0000e+000 +1.0000e-004 500 +1.0000e008 10

Comments These parameters control the iteration process of a flow problem. For most problems, the default values of the convergence parameters are adequate in obtaining a solution. However, for flow problems that involve surface infiltration into a large unsaturated zone with steep conductivity functions, the solution may require careful adjustments to the convergence parameters. For more information about the convergence parameters, see KeyIn Analysis Settings in Chapter 4. An iteration process will stop either when the maximum number of iterations per time step has been reached or when the iterative solution has achieved the convergence tolerance.

TIME Keyword Format Keyword TSSel TSStart IncInit IncMax SaveMult Adaptive %Change TS# TS-Increment Elapsed-Time Save-Flag

IncFactor

TSGen

SaveStart

GEO-SLOPE Office 5 423 Description Keyword

= the keyword TIME

TSSel

= the total number of time steps selected for analysis

TSStart

= the starting time of the analysis

IncInit

= the initial time step increment size

IncMax

= the maximum time step increment size

IncFactor

= the time step increment expansion factor

TSGen

= the total number of time steps generated

SaveStart

= the starting time step to save computed results

SaveMult

= the time step multiple to save computed results

Adaptive

= the flag indicating if adaptive time step should be used

%Change

= the maximum % head change to activate time step reduction and the % reduction of time step.

TS#

= the time step number

TS-Increment

= the time step increment

Elapsed-

= the total elapsed time

Time Save-Flag

= the flag indicating if results should be saved

Example TIME 8 +0.0000e+000 +1.0000e+002 +1.0000e+005 +1.0000e+000 10 2 2 0 +2.5000e+001 1 +1.0000e+002 +1.0000e+002 0 2 +1.0000e+002 +2.0000e+002 1 3 +1.0000e+002 +3.0000e+002 0 4 +1.0000e+002 +4.0000e+002 1 5 +1.0000e+002 +5.0000e+002 0 6 +1.0000e+002 +6.0000e+002 1 7 +1.0000e+002 +7.0000e+002 0 8 +1.0000e+002 +8.0000e+002 1

Comments The time step numbers, (TS#), must be in ascending order, and the total number of lines describing the time steps must be the same as the total number of time steps selected for analysis, (TSSel). The parameters starting from TSStart to SaveMult are only used by SEEP/W DEFINE for time step generation purposes. Since the generated time steps can be modified, the total number of time steps selected for the analysis, (TSSel), may not be the same as the total number of time steps generated. Save-Flag = 1 specifies that the computed results of the time step will be saved, while Save-Flag = 0 indicates that the results will not be saved. Time step information is not required for a steady state analysis. For more information about the time step parameters, see the KeyIn Analysis Settings command in Chapter 4.

424 SEEP/W

MATERIAL Keyword Format Keyword Number Material# K-fn W.C.fn K-Ratio K-Direction Description Keyword

= the keyword MATERIAL

Number

= the total number of materials specified in the problem

Material#

= the material number

K-fn

= the hydraulic conductivity function number

W.C.fn

= the volumetric water content function number

K-Ratio

= the hydraulic conductivity ratio

K-Direction

= the hydraulic conductivity direction

Example MATERIAL 2 1 1 0 +1.0000e+000 +0.0000e+000 2 2 0 +1.0000e+000 +0.0000e+000

Comments The material numbers, (Material#), must be in ascending order and the total number of file lines describing the materials must be the same as the total number of materials, (Number). The hydraulic conductivity function number, (K-fn), and the volumetric water content function number do not need to be the same as the material number, (Material#). When a material has a zero hydraulic conductivity function number, the material is considered as a NULL material. A volumetric water content function number must be specified for a transient analysis. The hydraulic conductivity ratio, (K-Ratio), and the hydraulic conductivity direction, (K-Direction), can be used to model anisotropic conditions of the material For more information about the matierial properties, see the KeyIn Material Properties command in Chapter 4.

KFUNCTION Keyword Format Keyword Number Function# Points Smooth Tension Points-Est Pres-Min Pres-Max W.C-Fn# K-Sat Log-Suction Method Fn-Description Pressure Conductivity Description 1 20 +0.0000e+000 +1.5300e+000 20 -1.0000e+002 +2.0000e+001 1 8.6007e-003 0 2

GEO-SLOPE Office 5 425

Keyword

= the keyword KFUNCTION

Number

= the total number of conductivity functions

Function#

= the function number

Points

= the number of data points in the function

Smooth

= the smoothing factor for the function

Tension

= the tension factor for the function

Points-Est

= the number of data points used in the function estimation

Pres-Min

= the minimum pressure used in the function estimation

Pres-Max

= the maximum pressure used in the function estimation

W.C-Fn#

= the Vol. W.C. function number used in the function estimation

K-Sat

= the saturated conductivity

Log-Suction

= the flag to indicate if suction is presented in Log scale

Method

= the estimation method

Fn-Description

= the description of the function

Pressure

= the pressure data points of the function

Conductivity

= the conductivity data points of the function

Example KFUNCTION 2 1 5 +0.0000e+000 +1.5000e+000 0 +0.0000e+000 +0.0000e+000 0 4.3000e006 0 1 Fine sand Ks=4.3e-06m/s -1.0000e+002 +2.3331e-011 -7.3431e+001 +5.3573e-011 -2.9335e+001 +3.4708e-009 -9.6555e+000 +8.3502e-007 +0.0000e+000 +4.3000e-006 2 5 +0.0000e+000 +0.0000e+000 0 +0.0000e+000 +0.0000e+000 0 1.5000e008 0 1 Sandy clayey silt ks=1.5e-08m/s -1.0000e+002 +8.7178e-013 -7.3245e+001 +6.3589e-012 -4.8742e+001 +1.5049e-010 -1.7895e+001 +9.0541e-009 +0.0000e+000 +1.5000e-008

Comments The conductivity function numbers, (Function#), must be in ascending order and the number of functions described in the data file must be the same as the total number of conductivity functions, (Number). Furthermore, the number of file lines describing each function must be the same as the number of data points in the function, (Points). Each conductivity function is specified by a series of data points, (Pressure and Conductivity). The values of the data points must be in ascending order. The Smooth and Tension values are used by SEEP/W DEFINE to control how the fit of the conductivity

426 SEEP/W function to the data points. The parameters starting from Points-Est to W.C-Fn# are only used by SEEP/W to provide an estimation of the conductivity function based on a volumetric water content function. In the cases when the conductivity function is not estimated from a volumetric water content function, the values of all estimation parameters will be zero. To specify conductivity functions, use the KeyIn Functions Conductivity command in SEEP/W DEFINE.

SFUNCTION Keyword Format Keyword Number Function# Points Smooth Tension Method a n m Fn-Description LiquidLimit Pressure Vol-W.C.

grain-size

WC-Sat

M2W

Log-Suction

Description Keyword

= the keyword SFUNCTION

Number

= the total number of volumetric water content functions

Function#

= the function number

Points

= the number of data points in the function

Smooth

= the smoothing factor for the function

Tension

= the tension factor for the function

grain-size

= the grain-size function number if used

WC-Sat

= the saturated water content

M2W

= the coefficient of volumetric compressibility

Log-Suction

= the flag to indicate if suction is presented is Log scale

Method

= the estimation method

a

= the parameter "a" in a closed form estimation method

n

= the parameter "n" in a closed form estimation method

m

= the parameter "m" in a closed form estimation method

Fn-Description

= the description of the function

Pressure

= the pressure data points of the function

Vol. W.C.

= the volumetric water content data points of the function

LiquidLimit

= the liquid limit used in the MK estimation method

Example SFUNCTION 2 1 6 +0.0000e+000 +1.9500e+000 20 -1.0000e+002 +0.0000e+000 0 +3.9000e001 +1.0000e-004 0 2 +1.0000e+002 +2.0000e+000 +1.0000e+000 +1.0000e+000

GEO-SLOPE Office 5 427 Sand -1.0000e+002 +3.2000e-002 -6.5788e+001 +3.9073e-002 -2.6268e+001 +8.3913e-002 -1.3593e+001 +2.2000e-001 -6.5000e+000 +3.7100e-001 +0.0000e+000 +3.9000e-001 2 6 +0.0000e+000 +3.0000e-002 20 -1.0000e+002 +0.0000e+000 0 +4.0000e001 +1.0000e-004 0 2 +1.0000e+002 +2.0000e+000 +1.0000e+000 Clayey silt -1.0000e+002 +2.1209e-001 -8.0000e+001 +2.2051e-001 -6.0000e+001 +2.5209e-001 -3.9999e+001 +3.3672e-001 -1.9558e+001 +3.9470e-001 +0.0000e+000 +4.0000e-001

Comments The volumetric water content function numbers, (Function#), must be in ascending order, and the number of functions described in the data file must be the same as the total number of volumetric water content functions, (Number). Furthermore, the number of lines describing each function must be the same as the number of data points in the function, (Points). Each volumetric water content function is specified by a series of data points, (Pressure and Vol.-W.C.). The values of the data points must be in ascending order. The Smooth and Tension values are used by SEEP/W DEFINE to control the fit of the volumetric water content function to the data points. To specify volumetric water content functions, use the KeyIn Functions Vol. Water Content command described in Chapter 4.

BFUNCTION Keyword Format Keyword Number Function# Points B-Type B-Flag1 Smooth Tension B-Flag2 B-Flag3 Fn-Description Time-Vol Action

428 SEEP/W Description Keyword

= the keyword BFUNCTION

Number

= the total number of boundary functions

Function#

= the function number

Points

= the number of data points in the function

B-Type

= the boundary function type

B-Flag1

= the flag for secondary boundary condition

Smooth

= the smoothing factor for the function

Tension

= the tension factor for the function

B-Flag2

= the flag for cyclic boundary condition

B-Flag3

= the flag for step boundary condition

Fn-Description

= the description of the function

Time-Vol

= the time or volume data points of the function

Action

= the action data points of the function

Example BFUNCTION 2 1 6 3 1 +0.0000e+000 +1.5000e+000 0 Surface Infiltration +0.0000e+000 +1.0000e-009 +2.5496e+003 +3.1348e-009 +4.2780e+003 +5.2634e-009 +6.0168e+003 +4.2649e-009 +8.1519e+003 +6.4591e-009 +9.9695e+003 +6.0944e-009 2 5 1 0 +0.0000e+000 +1.5000e+000 1 Reservoir Drawdown +0.0000e+000 +1.5000e+001 +2.0818e+003 +1.4670e+001 +3.4362e+003 +1.3763e+001 +5.7829e+003 +1.3129e+001 +9.0971e+003 +1.3000e+001

0

0

Comments The boundary function numbers, (Function#), must be in ascending order and the number of functions described in the data file must be the same as the total number of boundary functions, (Number). Furthermore, the number of lines describing each function must be the same as the number of data points in the function, (Points). Each boundary function is specified by a series of data points, (Time-Vol and Action). Depending on the boundary function type, Time-Vol can be time or volume. The values of Time-Vol must be in ascending order. The Smooth and Tension values are used by SEEP/W DEFINE to control the fit of the boundary functions to the data points. SEEP/W provides multiple boundary function types. These boundary function types are represented by

GEO-SLOPE Office 5 429 (B Type) as follows: B-Type

Boundary Function

1

H vs. Time boundary function

2

Q vs. Time boundary function

3

q vs. Time boundary function

6

H vs. Volume boundary function

SEEP/W provides boundary function types 1, 3 and 6 with secondary boundary conditions. The value of, (B Flag1), will be equal to 1 when the secondary condition is applied and 0 when the secondary condition is not applied. If a cyclic boundary function is used, the value of, (B-Flag2), will be equal to 1; otherwise, the value will be 0. If a step function is used, the value of, (B-Flag3), will be equal to 1; otherwise, the value will be 0. Boundary functions are only allowed in transient analyses. When no boundary function is specified, the number of boundary functions, (Number), will be 0. To specify boundary functions, use the KeyIn Functions Boundary command described in Chapter 4.

MFUNCTION Keyword Format Keyword Number Function# Points Smooth Tension Fn-Description Pressure Percentage Description Keyword

= the keyword MFUNCTION

Number

= the total number of modifier functions

Function#

= the function number

Points

= the number of data points in the function

Smooth

= the smoothing factor for the function

Tension

= the tension factor for the function

Fn-Description

= the description of the function

Pressure

= the pressure or X-coordinates of the function data points

Percentage

= the percentage or Y-coordinates of the function data points

Example MFUNCTION 2 1 6 +0.0000e+000 +1.5000e+000

430 SEEP/W Fine sand -1.0000e+001 +2.0000e-001 -9.1585e+000 +5.1136e-001 -8.2740e+000 +6.8425e-001 -6.5658e+000 +8.4048e-001 -4.4103e+000 +9.1421e-001 +0.0000e+000 +1.0000e+000 2 5 +0.0000e+000 +1.5000e+000 Clay -1.0000e+002 +0.0000e+000 -8.3451e+001 +4.6819e-001 -6.2405e+001 +7.6220e-001 -2.9360e+001 +9.4760e-001 +0.0000e+000 +1.0000e+000

Comments The modifier function numbers, (Function#), must be in ascending order, and the number of functions described in the data file must be the same as the total number of modifier functions, (Number). Furthermore, the number of lines describing each function must be the same as the number of data points in the function, (Points). Each modifier function is specified by a series of data points, (Pressure and Percentage). The values of Pressure must be in ascending order. The value of Percentage must be within 0 to 1.0, with 1.0 being 100%. The Smooth and Tension values are used by SEEP/W DEFINE to control the fit of the modifier function to the data points. The modifier function can only be applied to Q vs. Time or q vs. Time boundary functions in transient analyses. When no modifier function is specified, the number of modifier functions, (Number), will be 0. To specify modifier functions, choose the KeyIn Functions Modifier command described in Chapter 4.

NODE Keyword Format Keyword Number Node# X-Coordinate Y-Coordinate Z-Coordinate BC-Action BC-Codes

GEO-SLOPE Office 5 431 Description Keyword

= the keyword NODE

Number

= the total number of nodes in the finite element mesh

Node#

= the node number

X-Coordinate

= the X-coordinate of the node

Y-Coordinate

= the Y-coordinate of the node

Z-Coordinate

= the Z-coordinate of the node

BC-Action

= the boundary condition action specified at the node

BC-Codes

= the boundary condition codes for the node

Example NODE 8 1 2 3 4 5 6 7 8

+3.0000e+000 +3.0000e+000 +3.0000e+000 +3.0000e+000 +3.0000e+000 +3.0000e+000 +3.0000e+000 +4.0000e+000

+3.0000e+000 +4.0000e+000 +5.0000e+000 +6.0000e+000 +7.0000e+000 +8.0000e+000 +9.0000e+000 +3.0000e+000

+0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000

+0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +0.0000e+000 +1.2000e+001 +0.0000e+000

200000 200000 200000 200000 200000 200000 100000 200000

Comments The node number, (Node#), must be in ascending order, and the total number of lines describing the nodes must be the same as the total number of nodes, (Number). In a two-dimensional vertical section or a axisymmetric flow problem, the Z-Coordinate is always presented as zero. However, in a plan flow problem, the Z-Coordinate represents the elevation of the node and may not be zero.

432 SEEP/W The boundary conditions at a node are described by a multiple digit boundary code as follows: Digits

Meaning

1

a single digit code representing the type of boundary condition

2-3

a double digit code representing the boundary function number

4 5-6

a single digit code representing the type of boundary review condition a double digit boundary code representing the modifier function number

SEEP/W allows multiple types of boundary conditions. These boundary conditions are represented by digit 1 of the boundary condition code as follows: Digit 1

Boundary Conditions

0

no flow boundary (by default)

1

constant H, or H vs. Time boundary

2

constant Q, or Q vs. Time boundary

3

constant q, or q vs. Time boundary

4

H vs. Time boundary with secondary condition (if H < elevation, Q = 0)

5

q vs. Time boundary with secondary condition (if q > Ksat, H = elevation)

6

H vs. Volume boundary

7

H vs. Volume boundary with secondary condition (if H < elevation, Q = 0)

8

constant H with P = 0, (i.e., zero pressure boundary, H = elevation)

SEEP/W allows multiple types of boundary review condition. These boundary review conditions are represented by digit 4 of boundary condition code as follows: Digit 4

Boundary Review Conditions

0

no boundary review (by default)

1

review by elevation

2

review by maximum pressure

When a boundary function number is specified, the boundary condition action, (Action), of the node is computed in SEEP/W SOLVE and is therefore presented as zero in the data file. For more information on specifying nodes and boundary conditions, see the Draw Boundary Conditions and Draw Nodes commands in Chapter 4.

ELEMENT Keyword Format Keyword Number Element# N1 N2 N3 N4 N5 N6 N7 N8 Mat I-O Thickness X-Inf Y-Inf

GEO-SLOPE Office 5 433 Description Keyword

= the keyword ELEMENT

Number

= the total number of elements in the finite element mesh

Element#

= the element number

N1

= the first node number of the element

N2

= the second node number of the element

N3

= the third node number of the element

N4

= the fourth node number of the element

N5

= the fifth node number of the element

N6

= the sixth node number of the element

N7

= the seventh node number of the element

N8

= the eighth node number of the element

Mat

= the material number of the element

I-O

= the integration order of the element

Thickness

= the thickness of the element

X-Inf

= the X infinite element direction of the element

Y-Inf

= the Y infinite element direction of the element

Example ELEMENT 6 1 3 1 10 12 2 5 3 12 14 3 6 5 14 15 4 7 6 15 16 5 8 7 16 17 6 9 8 17 18

2 4 0 0 0 0

0 0 0 0 0 0

11 0 1 9 +1.0000e+000 0 0 13 0 1 9 +1.0000e+000 0 0 0 0 1 4 +1.0000e+000 0 0 0 0 1 4 +1.0000e+000 0 0 0 0 1 4 +1.0000e+000 0 0 0 0 1 4 +1.0000e+000 0 0

Comments The element number (Element#) must be in ascending order, and the total number of lines describing the elements must be the same as the total number of elements (Number). The nodes of an element must be input in a counter-clockwise direction, with N1 to N4 being the corner nodes and N5 to N8 being the secondary nodes. SEEP/W allows an element to have a minimum of 3 nodes (a simple triangular element) to a maximum of 8 nodes (a higher order quadrilateral element). A node number of 0 signifies no node.

434 SEEP/W The X and Y infinite element directions, (X-Inf and Y-Inf), are used to define the infinite directions of an infinite element. The values of X-Inf and Y-Inf are either 0, -1 or 1 which produce the following possible combinations for an infinite element: X-Inf

Y-Inf

Infinity Direction

0

0

no infinite direction, not an infinite element

0

1

infinite in the positive Y direction

0

-1

infinite in the negative Y direction

1

0

infinite in the positive X direction

-1

0

infinite in the negative X direction

1

1

infinite in both positive X and Y directions

-1

-1

infinite in both negative X and Y directions

1

-1

infinite in the positive X direction and negative Y direction

-1

1

infinite in the negative X direction and positive Y direction

For more information about infinite elements and infinite directions, see Infinite Elements in Chapter 8. For information on creating elements, see the Draw Multiple Elements and Draw Single Elements commands in Chapter 4.

POLE Keyword Format Keyword Number Position-X Position-Y Description Keyword

= the keyword POLE

Number

= the number of poles in the problem

Position-X

= the X-coordinate of the pole

Position-Y

= the Y-coordinate of the pole

Example POLE 1 +4.5000e+001 +4.0000e+001

Comments The pole is used as a reference point for the infinite elements when their nodes are projected to simulate infinity. SEEP/W allows the specification of only one pole. In problems with no infinite element, the number of poles in the problem, (Number), will be 0.

GEO-SLOPE Office 5 435 For information on creating and moving the infinite element pole, see the Draw Infinite Elements command in Chapter 4.

FLUX Keyword Format Keyword Number Section# Total-Subsection Section# Start-X Start-Y End-X End-Y Description Keyword

= the keyword FLUX

Number

= the total number of flux sections in the flow problem

Section#

= the flux section number

Total-Subsection

= the total number of subsections within the flux section

Start-X

= the starting point X-coordinate of the subsection

Start-Y

= the starting point Y-coordinate of the subsection

End-X

= the ending point X-coordinate of the subsection

End-Y

= the ending point Y-coordinate of the subsection

Example FLUX 2 1 1 1 +1.0488e-001 2 3 2 -5.2033e-002 2 +3.3821e-001 2 +3.8780e-001

+7.7846e-001 +1.2846e-001 +4.6748e-002 +5.6463e-001 +3.3821e-001 +4.4024e-001 +4.4024e-001 +3.8780e-001 +2.3211e-001 +2.3211e-001 +8.0732e-001 +2.1423e-001

Comments The flux section number, (Section#), must be in ascending order and the number of flux sections described in the data file must be the same as the total number of flux sections, (Number). Furthermore, the number of lines describing flux section must be the same as the total number of subsections within the flux section, (Total-Subsection). A flux section must consists of one of more subsections. Each subsection is defined by a starting point, (Start-X and Start-Y), and an ending point, (End-X and End-Y). When no flux section is specified, the number of flux sections in the flow problem, (Number), will be 0. For information on creating flux sections, see the Draw Flux Sections command in Chapter 4.

436 SEEP/W

DENSITY Keyword Format Keyword RefConc RelDens Description Keyword

= the keyword DENSITY

RefConc

= the reference concentration

RelDens

= the relative density

Example DENSITY +1.0000e+000 +1.0250e+000

Comments The relative density is the density of contaminated water, (at a the specified reference concentration), relative to the density of freshwater. The values of reference concentration and relative density define a linear relationship between contaminant concentration and contaminant density relative to water. For information on defining density-dependent analysis input, see the KeyIn Analysis Settings command in Chapter 4.

WATERTABLE Keyword Format Keyword Number Section# Total-Subsection Neg-Pres-Head Section# Start-X Start-Y End-X End-Y

GEO-SLOPE Office 5 437 Description Keyword

= the keyword WATERTABLE

Number

= the number of initial water tables in the problem

Section#

= the initial water table number

Total-Subsection

= the total number of subsections within the initial water table

Neg-Pres-Head

= the maximum negative pressure head allowed in the initial condition

Start-X

= the starting point X-coordinate of the subsection

Start-Y

= the starting point Y-coordinate of the subsection

End-X

= the ending point X-coordinate of the subsection

End-Y

= the ending point Y-coordinate of the subsection

Example WATERTABLE 1 1 2 +1.0000e+000 1 +5.6911e-003 +3.4106e-001 +2.3577e-001 +4.1992e-001 1 +2.3577e-001 +4.1992e-001 +6.1057e-001 +4.2967e-001

Comments The initial water table is used to define the initial condition of a transient analysis. SEEP/W allows the specification of only one initial water table. In problems with no initial water table, the number of initial water table, (Number), will be 0. The number of file lines describing initial water table subsections must be the same as the total number of subsections, (Total-Subsection). In computing the initial condition, a hydrostatic condition is assumed for soils above and below the initial water table. SEEP/W allows you to impose a maximum negative pore-water pressure head by specifying the value of Neg-Pres-Head. The initial water table may consist of one or more subsections. Each subsection is defined by a starting point, (Start-X and Start-Y), and an ending point, (End-X and End-Y). For information on defining an initial water table, see the Draw Initial Water Table command in Chapter 4.

qBOUNDARY Keyword Format Keyword Number Node-1 Node-2 Element-1 Element-2 Action B-Fn# M-Fn#

438 SEEP/W Description Keyword

= the keyword qBOUNDARY

Number

= the total number of element edges specified with q boundary condition

Node-1

= the first node forming the element edge

Node-2

= the second node forming the element edge

Element-1

= the first element sharing the element edge

Element-2

= the second element sharing the element edge

Action

= the boundary action, (q), applied to the element edge

B-Fn#

= the boundary function number of the element edge

M-Fn#

= the modifier function number of the element edge

Example qBOUNDARY 4 129 151 62 0 151 173 72 0 173 195 86 0 195 217 87 0

+2.1000e-004 +2.1000e-004 +2.1000e-004 +2.1000e-004

0 0 0 0

0 0 0 0

Comments An element edge is defined by two corner nodes of the same element. An element edge must be shared by one or two elements. In the case of a boundary edge, Element-2 must be 0. The node number of the first node forming the element edge must be smaller than the node number of the second node. Similarly, the element number of the first element sharing the element edge must be smaller than the element number of the second element, unless the second element is 0 (i.e., a boundary edge). When a boundary function number is specified, the boundary action, (Action), of the element edge is computed in SEEP/W SOLVE and is therefore presented as zero in the data file. The number of file lines describing the element edges must be the same as the total number of element edges, (Number). When no q boundary condition is specified, the total number of element edges is 0.

MATLCOLOR Keyword Format Keyword Number Material# Red Green Blue

GEO-SLOPE Office 5 439 Description Keyword

= the keyword MATLCOLOR

Number

= the number of materials

Material#

= the material number

Red

= the red color value

Green

= the green color value

Blue

= the blue color value

Example MATLCOLOR 2 1 255 0 0 2 225 255 0

Comments The number of materials, (Number), must be the same as the number of material specified in the MATERIAL keyword. The material number, (Material#), must be in ascending order and the total number of lines describing the material color must be the same as the total number of materials, (Number). SEEP/W uses a 24-bit RGB color model in which colors are defined by red, green, and blue color values ranging from 0 to 255, inclusive. The higher the value, the brighter the corresponding color component. In the above example, material 1 is specified as red, and material 2 is specified as yellow by equally combining red and green. For information on defining material colors, see the KeyIn Material Properties command in Chapter 4.