Laboratory 4 - Rock Slope Stability

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : PLOTTING POLES AND CONTOURING OF STRUCTURAL GEOLOGY DATA ( LAB 4a )

NO. OF PAGES: EDITION: NO. OF CHECKING:

1/5 LAB 4a

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

1.0 OBJECTIVE

To plot poles and carry out contouring of the structural geology data.

2.0 LEARNING OUTCOMES

a) b) c) d)

Students should able to use the geological compass. Students should able to measures the dip and dip direction of any planes. Students should able to plot poles of the structural geology data. Students should able to plot contour from the structural geology data.

3.0 THEORY

Analysis of the orientation of structural structural geology data involves; involves; 

Plotting poles representing the dip and dip direction of of each discontinuity. This plot will help help to identify discontinuity discontinuity sets, se ts, for which both the average orientation and the scatter (dispersion) can be calculated.



The second step in the analysis is to plot great circles circles representing the average orientation of each set, major discontinuities such as faults, and the dip and dip direction of the cut face.

4.0 EQUIMENT AND MATERIALS     

Equal-area for plotting poles and great circles (Appendix C) Equal-area polar net (Appendix D) Kalsbeek counting net (Appendix E) Tracing paper Pencil

5.0 PROCEDURE 

Poles can can be plotted on the polar stereonet on which the dip direction is indicated indicated on the periphery of the circle, and and the dip is measured along radial lines with zero degrees at the center.



The procedure for plotting poles is to lay a sheet of tracing paper on the the printed polar net and mark the north direction and each quadrant position around the edge of the outer circle. A mark is then made to show the pole that represents the orientation of each discontinuity as defined by its dip and dip direction. Poles for shallow dipping discontinuities lie close to the center of the circle, and poles of steeply dipping discontinuities lie close to the periphery of the circle.



Concentrations of pole orientations can be identified using using Kalsbeek Kalsbeek counting net. The Kalsbeek net is made made up of mutually overlapping hexagons, each with an area of 1/100 of the full area of the stereonet.



Contouring is performed by overlaying overlaying the counting net on the pole and counting the the number of poles in each hexagon; this number is marked on the net. These numbers of poles are converted into percentages by dividing each by the total number of poles and multiplying by 100. Once a percentage is written in each hexagon, contours can be developed by interpolation.

Prepared by

:

Lecturer

Name

:

Aziman Bin Madun / Mohd Hazreek Bin Zainal Abidin

Signature

:

Date

:

8 January 2007

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : PLOTTING POLES AND CONTOURING OF STRUCTURAL GEOLOGY DATA (LAB 4a)


2/5 LAB 4a

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

6.0 RESULT AND ANALYSIS 

Discontinuities pattern.



Equal-area equatorial net for plotting poles and great circles.

7.0 QUESTION AND DISCUSSION

(1) Give two (2) methods to draw the structural geology data and discuss based on what situation we choose that method (each method). (2) Explain the type of geological structure plotted in the stereonet with the aid of diagram. (3) Explain the methodology to determine the discontinuities survey data.

8.0 CONCLUSION

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : PLOTTING POLES AND CONTOURING OF STRUCTURAL GEOLOGY DATA (LAB 4a) TABLE 1

No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

Distance m 0.0 0.5 1.5 1.9 3.0 3.5 3.8 4.1 0.3 6.7 7.0 8.2 9.0 9.5 9.9 10.3 10.8 11.9 12.4 12.8 13.9 14.2 15.5 15.8 16.0 16.9 17.7 18.5 19.8 20.6 21.0 22.5 22.7 23.1 23.8 24.3 24.8 25.0 26.0 27.6 28.0 28.7 29.2 30.0 31.6 32.0 32.7 33.7 34.0 35.2


3/5 LAB 4a

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

ORIENTATION AND PHYSICAL CHARACTERISTICS OF DISCONTINUITIES

Type 1 1 1 1 3 1 1 1 1 1 1 1 1 3 1 1 3 1 4 4 1 3 1 3 1 1 1 4 3 1 3 1 1 1 4 1 3 1 1 3 1 3 1 1 3 1 1 1 1 1

Dip Direction Dip Persistence Aperture Infilling degree degree m 212 70 20 1 2 160 85 20 1 2 138 86 20 1 2 147 85 20 1 2 105 46 20 1 2 150 78 20 1 4 260 65 20 1 4 200 64 20 1 4 262 65 20 1 4 205 75 20 1 2 262 52 20 1 2 145 75 20 2 2 128 75 20 2 2 70 40 20 1 3 320 74 20 1 3 215 74 20 1 3 95 38 20 1 3 168 85 20 1 3 310 35 20 2 4 190 40 20 3 2 352 64 20 1 2 88 62 20 1 2 213 60 20 1 2 80 48 20 1 2 200 58 20 1 2 205 60 20 1 2 165 88 20 1 2 206 54 20 2 2 85 42 20 1 2 205 55 20 1 2 90 42 20 1 2 235 60 20 1 2 310 36 20 1 2 200 58 20 1 2 350 60 20 1 6 212 76 20 1 2 98 50 20 1 2 310 50 20 1 2 205 62 20 1 2 98 48 20 1 2 354 86 20 1 2 94 50 20 1 2 194 75 20 1 2 275 44 20 1 2 95 46 20 1 2 210 75 20 1 2 303 25 20 1 2 355 80 20 1 2 207 75 20 1 2 260 50 20 1 2

Roughness

water

5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 5 3 5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 5 3 5 3 3 3 3 3 3

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1



4/5 LAB 4a

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

CONT’D :-

51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

36.0 37.1 37.4 38.1 38.9 39.0 40.2 40.5 41.2 42.0 43.0 43.5 44.1 44.5 44.9 50.6 50.9 51.6 51.9 53.0 54.2 55.0 55.8 56.2 57.0 58.0 58.9 59.5 60.0 60.2 60.9 61.3 61.9 62.4 62.9 63.8 64.0 65.2 66.0 66.7 68.0 69.8 70.0 71.9 72.0 73.1 73.9 74.3 75.0 76.2

3 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 3 1 1 1 1 1 1 1 3 1 1 3 1 1 1 3 1 1 1 1 3 1 1 1 1 3 1 1 1

95 185 94 353 260 192 193 288 200 215 295 206 308 330 204 214 90 205 306 210 298 100 204 307 210 214 290 212 215 100 255 205 90 342 210 265 100 172 262 10 206 100 208 190 320 210 95 220 300 348

42 80 38 80 60 55 74 52 62 80 56 60 50 70 60 60 45 55 30 68 24 58 65 30 60 65 60 62 62 56 50 62 50 85 55 45 52 88 48 88 75 55 56 80 88 60 52 58 45 88

20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

2 2 2 2 6 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

3 3 3 3 3 3 3 3 3 3 5 5 3 5 3 3 3 3 3 3 3 3 3 3 3 3 5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 5 3 3 3

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 3 2 3 2 2 2 3 2 2 2 2 2 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1



5/5 LAB 4a

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

CONT’D :-

101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

77.3 78.0 79.0 80.6 82.0 84.0 85.8 86.0 87.0 89.5 90.0 90.8 91.3 92.0 92.9 94.0 95.5 97.0 98.6 100.0

1 1 1 3 1 1 1 1 3 1 3 1 1 3 1 1 1 3 1 1

210 348 336 93 180 320 205 312 102 205 90 314 210 95 216 320 207 95 204 298

60 84 78 38 80 36 62 39 44 60 45 36 62 46 82 38 70 48 60 42

20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

4 4 4 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

2 2 2 3 3 3 3 4 3 4 4 3 3 3 4 4 5 3 3 3

1 1 2 3 3 3 3 3 2 2 2 2 3 3 3 2 2 2 1 1

Type

Aperture

Infilling Materials

Roughness

Water

1) 2) 3) 4) 5)

1) 2) 3) 4) 5) 6)

1) 2) 3) 4) 5) 6) 7) 8)

1) 2) 3) 4) 5) 6)

1) Dry 2) W et 3) Flow

Joint Bedding Foliation Fault Others

Very narrow ( <2mm) Narrow (2-6mm) Moderately narrow (6-20mm) Moderately wide (20-60mm) Wide (60-200mm) Very wide ( >200mm)

Clean Surface staining Cemented Cohesive Noncohesive Chlorite + talc Calsite Others

Polish Slikensisded Smooth Rough Define ridges Very rough

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : DETERMINE THE DISCONTINUITIES SETS AND MODES OF FAILURES OF STRUCTURAL GEOLOGY DATA DUE TO SLOPE (LAB 4b)


1/3 LAB 4b

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

1.0 OBJECTIVE

To identify the major and minor discontinuities set, plot the great circle of discontinuities and analyze the failure modes.


a) b)

Students should able to plot the great circles. Students should able to analyze the potential failures modes.

3.1 THEORY

Mode of rock slope failures.

Prepared by

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Lecturer

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Signature

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Date

:

8 January 2007

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : DETERMINE THE DISCONTINUITIES SETS AND MODES OF FAILURES OF STRUCTURAL GEOLOGY DATA DUE TO SLOPE (LAB 4b)


2/3 LAB 4b

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

3.2 THEORY

Mode of slope failures based on discontinuities sets plot.

Modes of failure

Criteria

Circular

i. Very weak material, highly jointed or fractured or weak soil ii. Homogenous soil

Planar

i. Dip direction lie within ± 20 from the “design slope” dip direction. ii. ψf > ψp >  j (slope angle>plane angle>friction angle) iii. Release surfaces must be present to define the lateral boundaries of the slide.

Wedge

i. ψf > ψi >  j (slope angle>intersection of 2 plane angle>friction angle) ii. driving force due to the weight of wedge must exceed the frictional resistance of the planes.

0

Toppling

i. The discontinuities dip direction must lie between ±10° of slope dip direction (opposite direction). (900  f )   j   p ii.

4.0 EQUIMENT AND MATERIALS  

Equal-area equatorial net (Appendix C) Tracing paper

Prepared by

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Signature

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Date

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8 January 2007

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING

NO. OF PAGES:

3/3

DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : DETERMINE THE DISCONTINUITIES SETS AND MODES OF FAILURES OF STRUCTURAL GEOLOGY DATA DUE TO SLOPE (LAB 4b)

EDITION: NO. OF CHECKING:

LAB 4b

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

5.0 PROCEDURE

Plotting great circles:-

Great circles are plotted on the equatorial net, but they cannot be plotted directly on this net because the true dip can only be scaled off the h orizontal axis. The plotting procedure for great circles consists of the following steps:

1. Lay a piece of tracing paper on the net with a thumbtack through the center point so that the tracing paper can be rotated on the net.

2. Mark the north direction of the net on the tracing paper.

3. Locate the dip direction of the plane on the scale around the circumference of the net and mark this point on th e tracing paper. Note that the dip direction scale on the equatorial net for plotting great circles starts at the north point at the top of the circle and increases in a clockwise direction. o

4. Rotate the tracing paper until the dip direction mark coincides with one of the horizontal axes of the net, that is, the 90 o

or 180 points of the dip direction scale.

5. Locate the arc on the net corresponding to the dip of the plane and trace this arc into the paper. Note that a horizontal plane has a great circle at the circumference of the net, and a vertical plane is represented by a straight line passing through the center of the net.

6. Rotate the tracing paper so that the two north points coincide and the great circle is oriented correctly.

The slope data was given as 90° (dip direction) and 60° (dip angle)

6.0 RESULT AND ANALYSIS 

Major and minor discontinuities sets marks as J1,J2……..Jn



Potential modes of failures


(1) Explain the mode of failure for rock slope for each type. (2) Identify which discontinuities sets that have some potential to fail and what are their failure modes. (3) What are the others criteria that must be met in order to promote the slope failure?

8.0 CONCLUSION

FACULTY : CIVIL & ENVIRONMENTAL ENGINEERING DEPARTMENT : GEOTECHNICAL & TRANSPORTATION ENGINEERING LABORATORY : ENGINEERING GEOLOGY & GEOPHYSIC LABORATORY TOPIC : PLANE AND WEDGE FACTOR OF SAFTEY (LAB 4c)


1/1 LAB 4c

EFECTIVE DATE :

8/1/2007

AMENDMENT DATE:

8/1/2007

1.0 OBJECTIVE

To identify which discontinuities are potential to fail and calculate the factor of safety.


a) b)

Students should able to calculate the safety factor for plane failure. Students should able to calculate the safety factor for wedge failure.

3.0 THEORY

To obtain the factor of safety for planar is much simple rather than wedge. For plane, consideration on one discontinuity, besides wedge two discontinuities (sets). Two (2) conditions need to exam, wet and dry conditions.

4.0 EQUIMENT AND MATERIALS  

Equal-area equatorial net (Appendix C) Tracing paper

5.0 PROCEDURE   

Determine the mode of failures Used appropriate formula of planar or wedge given in APPENDIX A and B The other information/properties from the site study and laboratory works are given as following:3 i. Rock unit weight, r = 25 kN/m ii. Rock friction angle,    =  b = 30° 3 iii. Water unit weight, w = 9.81 kN/m iv. Cohesion of discontinuities, Ca = Cb = 50 kPa v. Height of slope = Height of wedge = Height of plane, H = 50 m vi. Tension crack depth, Z = Tension crack height, Zw = 1 meter vii. Upper slope data = 100° (dip direction) and 20° (dip angle) Inclined angle of anchor (Ω) = (ψ T) = 20° viii. ix. Bars for Y25 = 10 ton = 100 kN a

6.0 RESULT AND ANALYSIS   

Factor of safety of plane failure in wet and dry condition No of bars required to reinforced the plane failure Factor of safety of wedge failure in wet and dry condition


(1) For some cases, give the recommended value of safety factors for the rock slope in civil engineering / construction industry with some justifications. (2) Describe and explain the rock slope stabilization method. (3) Explain the main differences about the assessment of the Rock Slope and Soil Slope.

8.0 CONCLUSION

Prepared by

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Lecturer

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Signature

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Date

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8 January 2007

APPENDIX A SEMESTER/SESSION : SUBJECT :

GEOLOGI KEJURUTERAAN

COURSE CODE

Z

V

: :

3BFC BFC 3013

Zw

T Ω

U

H

W

β

α

Given: FOS =

cA + (W cosβ - U - V sinβ + T sin (Ω+β)) tan  W sinβ + V cosβ - T cos (Ω+β)

A = failure plane area c = cohesion W = weight of failure block β = failure plane angle H = height of plane T = tension of anchor γr = unit weight of rock

 = friction angle U = vertical water pressure V = horizontal water pressure α = slope angle Z = tensional cracks Ω = inclined angle of anchor γw = unit weight of water

A = (H-Z).cosec β W = ½ r . H² [(1-(Z/H) ²)cot β – cot α] U = ½ w.Zw .(H-Z).cosec β V = ½ w.Zw cosec = 1/sin

sec=1/cos

cot=1/tan

APPENDIX B SEMESTER/SESSION : SUBJECT :


COURSE CODE

: :

3BFC BFC 3013

Given:

Fos 

3

 H

(C a. X  C b.Y )  ( A 

 w 2

. X )Tan a  ( B 

 w 2

.Y )Tan b

t

C a = Cohesion Ht = height of wedge ψ b = dip angle for plane b γ = unit weight of rock

 b = Friction angle ψa = dip angle for plane a ψ5= dip angle for wedge intersection γw = unit weight of water

X, Y, A, B is factor which depend upon the geometry of wedge X  B 

Sin 24 Sin 45Cos 2.na

Y 

Sin 13 Sin 35Cos 1.nb

Cos b  Cos aCos na.nb Sin

5.

2

Sin  na.nb

A 

Cos a  Cos bCos na.nb 2

Sin 5. Sin  na.nb

APPENDIX C SEMESTER/SESSION : SUBJECT :


COURSE CODE

: :

3BFC BFC 3013

Equal-area equatorial net for plotting poles and great circles (DO NOT CHANGE THE SIZE)

APPENDIX D SEMESTER/SESSION : SUBJECT :


COURSE CODE

: :

Equal-area polar net for plotting poles (DO NOT CHANGE THE SIZE)

3BFC BFC 3013

APPENDIX E SEMESTER/SESSION : SUBJECT :


COURSE CODE

: :

3BFC BFC 3013

Kalsbeek counting net for contouring pole concentrations (DO NOT CHANGE THE SIZE)

Laboratory 4 - Rock Slope Stability

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