EXPLORATION GUIDE
····n:L~i···· ,,";~)i:,'-~Si:
MEMORANDUM
ConverseWard DavIs Dixon ;'
Date
February 9, 1980
Project No. _ _ _ _ _ _ _ _ _ _ _ _ __
To
All Employees, Grades I thru IX and T-l thru T-IV Technicians
Subject
From
Schaefer J. Dixon
5
Explorat jon Gll ide
Herewith is your working draft copy of the CWDD Exploration Guide. This document is for your use while you are employed by CWDD and if employment is terminated, it shoulCl be returned to your supervisor. The Guide is for use within CWDD and should not be reproduced in whole or part for external distribution. , The Exploration Guide is intended to help provide a basis for company-wide consistency in exploration praotices. It provides information and data on techniques and tests mOst commonly used in exploration work performed by CWDD. It WaS not intended to include discussion of every exploration tool and technique available, all of the many in situ tests performed in soil and rock, construction inspection and testing methods, and laboratory testing, all of which will be the s1,lbject matter of future pUblications. This working draft is· for us!" through the remainder of 1980 and until a final copy is issued. We would like your comments on /~how the dQcument can be improved. Instructions for submitting comments are given on page 1-1. Comments to be considered in preparation of the final copy must be submitted by December 31, 1980. If you find errors or believe something should be changed in this working draft, do not hesitate to submit your comments as soon as possible. i
\
.,
{\
Converse Ward Davis Dixon, Inc,
TABLE OF CONTENTS
i
\.
Page No. 1.
INTRODUCTION .
.
1-1
2.
EXPLORATION PLANNING
2-1
2.1
2-1
• .
SOURCES OF PROJECT INFORMATION 2.1.1 Prior Projects 2.1.2 Published Sources
•
2-1 2-2
•
2.1.2.1 Publications of the U.S. Geo1goica1 Surve¥ • • . 2.1.2.2 Geologic Quadrangle Maps • 2.1.2.3 State Geological Survey Maps and Reports . . • • 2.1.2.4 Soil Conservation Service (SCS) Reports 2.1.3 Additional Mapping 2.1.4 Aerial Photography 2.2
(
2-3 2-3 '2-3
•
2-4
Right of Entry Documentation Site Access . . • . Si te Mobility • . . . . Support Operations • • Geotechnical Conditions • • Previous Construction
•
..
•
• • •
Selection of Exploration Methods. Selection of Contractor Permits and Clearances Materials and Equipment 2.. 3.4.1 2.3.4.2 2.3.4.3 2.3.4.4 2.3.4.5
2-5 2-5 2-6 2-7 2-8 2-8 2-9
EXPLORATION PROGRAM • • • • 2.3.1 2.. 3.2 2.3.3 2.3.4
3.
2-3
PRELIMINARY SITE Rl]:CONNhISSANCE 2.2.1 2.2.2 2.2.3 2.2.4 2 • .2.5 2 • .2.6
2.3
2-2 2-2
•
•
2-9 2-10 2-11 2-12
Fault Investigation Trenches Diamond Core Logging. • • Soils Sampling & Logging. Soil Ex~loration Test Pit Permeab~lity Testing.
2-13 2-14 2-14 2-15 2-15
FIELD OPERATIONS
3-1
3.1
CONTACTS
3-1
3.1.1 3.1.2 3.1.3 3.1.4
3-1 3-2 3-3 3-4
Client Contact Project Manager Contact Contractor Contact General Public Contact
·
.
.1
Page No. 3.2 3.3 3.4 3.5
4.
SAFETY . . . . . . • . CONTRACTOR'S EQUIPMENT DOCUMENTATION . . . . SUPPLEMENTAL RECONNAISSANCE
3-5 3-8 3-10 3-11
3.5.1 Studies in Urban Areas 3.5.2 Studies in Undeveloped Areas
3-l3
3-15
EXPLORATION METHODS AND EQUIPMENT
4-1
4.1
GEOPHYSICAL METHODS
4-2
4.1.1 Onshore Geophysical Methods 4.1.2 Offshore Geophysical Methods
4-2 4-2
MECHANICAL PROBING AND SOUNDING OPEN SUBSURFACE EXPLORATION
4-2 4-4
4.3.1 Hand Excavated Test pits and Shafts. 4.3.2 Backhoe Excavated Test pits an¢! Trenches • • . 4.3.3 Drilled Shafts.. ...•. 4.3.4' Dozer Cuts . . • . .•.•• 4.3.5 Trenches for Fault Investigation
4-6
DEEP EXPLORATION.
4-14
4.4.1 Auger Borings
4-17
4.2 4.3
4.4
4-18 4-18
4.4.1.1 Hand Augers 4.4.1.2 Power Augers 4.4.2 Wash Borings . • . • 4.4.3 Percussion and Churn Borings
•
•
4.4.3.1 Percussion Drills . . 4.4.3.1.1 Downhole Percussion unit 4.4.3.1.2 Becker Hammer Drill.
4-19 4-20 4-21 4-22 4-23
4.4.3.2 Churn Drill
4-24
4.4.4 Rotary Borings . .
4-25
4.4.4.1 Truck-Mounted Rotary Drills 4.4.4.2 Skid-Mounted Rotary Drills. 5.
4-7 4-9 4-10 4-11
4-25 4-27
SOIL SAMPLING AND FIELD TESTS
5-1
5.1 5.2 5.3
PREPARATION FOR SAMPLING METHODS OF ADVANCING SAMPLER UNDISTURBED SAMPLES
5-2 5-4 5-6
5.3.1 Sampling Equipment and Methods
5-8
• , '
~".'
Page NQ. 5.3.1.1 5.3.1.2 5.3.1.3 5.3.1.4 5.3.1.5
/
5.4
Shelby Tube Sampler . • • Stationary Piston Samnler Hydraulic Piston Sampler Double Tube Core Barrel Hand Trimmed Samples
.
DISTURBED SAMPLES
..
·.
,
5-15 5-15
5.4.1 Sampling Equipment and Methods. 5.4.1.1 5.4.1.2 5.4.1.3 5.4.1.4 5.5
Split Barrel Sampler • . • Converse Sampler • • . • Retractable Plug Sampler Bulk Samples • • • •
..
SAMPLING OPERATIONS 5.5.1 Undisturbed 5.5.2 Disturbed
5.6
• •
PREVENTING LOSS OF SAMPLES
5.7
SAMPLE SIZES
.
5-20 5-22 5-23 5-23 5-28
•
'
•
•
•
5-28, 5-28 5-29 5-30 5..,31
PRESERVATION AND SHIPMENT OF SAMPLES.
.. ..
5-31
5.8.1.1 Marking of Samples. 5.8.1.2 Packing and Shipment
5-33 5-33
5.8.2 Disturbed . . . . . • • . "
5-34
5.8.1 Undisturbed .
.
.
.
5.8.2.1 Marking of containers. 5.8.2.2 Packing and Shipment 5.9
• •
•
5.7.1 Identification Tests 5.7.2 Compaction Tests 5.7. 3 Other Tes ts . . . • 5.8
• •
• • •
5 .. 15 5-16 5-17 5-17 5-18
• •
5.6.1 Undisturbed 5.6.2 Disturbed
5-8 5-9 5-11 5-12 5-14
·
.
5-35 5-35
IN SITU TESTS . . . . • . . . •
5-35
5.9.1 5.9.2 5.9.3 5.9.4
5-36 5-37 5-39 5-41
Standrad Penetration Test (SPT) Cone Penetrometer Tests Menard Pressuremeter Vane Shear Test • . . .
Page No. 5.10 SUBMARINE SAMPLERS . . 5.10.1 5.10.2 5.10.3 5.10.4 5.10.5 6.
Petersen Dredge Open Barrel Gravity Corer Phleger Corer . . Piston Gravity Corer. Vibratory Corer
5-42 5-43 5-44 5-45 5-46
ROCK SAMPLING TECHNIQUES
6-1
6.1
BULK SAMPLING
6-1
6.1.1 Surface Bulk Samples 6.1.2 Subsurface Bulk Samples
6-1 6-2
CORE DRILLING
6-3
6.2.1 Field Coordination 6.2.2 Core Drilling Operations
6-3 6-5
6.2
6.2.2.1 6.2.2.2 6.2.2.3 6.2.2.4
Overburden Drilling Depth Measurements cutting of the Core Grinding of Core
6;2.3 Core Recovery and Extraction 6.2.3.1 Core Boxes and Labelling 6.2.3.2 Transportation and Storage 6.3
6-5 6-6 6-'7 6-8 6-8 6-9 6-9
CORE DRILLING AND SAMPLING EQUIPMENT
6-10
6.3.1 Rock Drilling Bits.
6-10
6.3.1.1 Diamond Core Barrels 7.
5-42
6-11
SOIL BORING LOGS
7-1
7.1
CLASSIFICATION SYSTEMS
7-1
7.1.1 Unified Soil Classification System
7-3
7.1.1.1 Soil Groups and Symbols. .
7-4
7.1.1.1.1 Coarse-grained Soils 7.1.1.1.2 Fine-grained Soils.
7-4 7-5
7. 2 7.3
7.1.2 Burmister Soil Identification System 7.1.3 Additional Classification Systems 7.1.4 Additional Components of Soil Identification . . . . • . . . . 7.1.5 Examples of Field Classification and Identification
7-6 7-7
LOG HEADING DATA THE LOG
7-11 7-13
7-7 7-9
/
Page No. 8.
ROCK BORING LOGS . 8.1 8.2 8.3 8.4
9.
8-3 8-3 8-5 8-5
8.4.1 Lithologic Classification and Description . . . . • . . . . . • 8.4.2 Description of Physical Condition
8-6 8-9
Degree of Weathering Discontinuities Rock Hardness ..• Order of Descriptive Terms
,
WATER PRESSURE T,EST REMARKS . . . . . CORE PHOTOGRAPHY
8-9 8-9 8-13 8-13
.
8-14 8-14 8-14
• •
LOGS FOR OPEN SUBSURFACE EXPLORATIONS
9-1
9.1' OPEN EXCAVATIONS FOR ENGINEERING PURPOSES.
9-2
9.2
10.
8-1
BORING DEPTH, ELEVATION, AND SIZE PERCENT CORE RECOVERY/ROCK QUALITY DESIGNATION GRAPHIC LOG . . . . . . . . . . . . . CLASSIFICATION AND PHYSICAL CONDITION. . . .
8.4.2.1 8.4.2.2 8.4.2.3 8.4.2.4 8.5 8.6 8.7
. . . . . . . . . .
9.1.1 Basic Required Data 9.1. 2 Graphic Sketch 9.1. 3 Descriptions
9-2 9-3 9-4
FAULT INVESTIGATION TRENCH LOGS
9-4
9.2.1 9.2.2 9.2.3 9.2.4 9.2.5
9-4 9-5 9-10 9-11 9-12
Basic Required Data . . Trench Mapping Methods Trench Photography Displacement Evaluation Techniques Age Evaluation Techniques
FIELD PERMEABILITY TESTS
..
10-1
10.1 EVALUATING THE BEST TYPE OF TEST 10.2 PRE-TEST PROCEDURES . . . . 10.2.1 Drilling and Casing 10.2.2 Boring Cleaning 10.2.3 Test Section Isolation 10.3 PERMEABILITY TEST PROCEDURES 10.3.1 Equipment . • . . . 10.3.2 Data to be Recorded 10.3.3 Types of Tests . . •
10-2 10-6 •
•
10-7 10-9 10-11
10-15 10-15 10-16 10-17
Page No. 10.3.3.1 10.3.3.2 10.3.3.3 10.3.3.4
10-17 10-18 10-20 10-21
Rising Head Tests . . . Constant Head Tests . . Falling Head Tests Pressure (Packer) Tests
10.3.3.4.1 Setup . • . 10.3.3.4.2 Pressures To Be Used In Testing . . . . 10.3.3.4.3 Length of Time for Tests 10.3.3.4.4 Calibration and Detection of Leaks 10.3.3.4.5 Test Procedure 10.3.3.5 Well-Pumping Tests 10.4 PERCOLATION TEST PROCEDURE 10.5 INSTALLATION OF PIEZOMETERS 10.6 BACKFILLING BORINGS . . • • REFERENCES INDEX • . .
..
...
•
10-21 10-24 10-25 10-26 10-26 10-27 10-33 10-34 10-36 R-l thru R-5 I-I thru I-5
(,
Tables
,I
(
,
4-1 4-2 4-3
Onshore Geophysics for Engineering Purposes Offshore Geophysical Methods Use, Capabilities, and Limitations of Exploration Methods
5-1 5-2
Common Samplers Common Submarine Samplers
7-1 7-2 7-3 7-4 7-5 7-6 7-7 7-8
USCS Grain Size Ranges USCS Soil Symbols Burmister System Terms CWDD Color Abbreviations CWDD Soil Moisture Terminology CWDD Guide For Compactness of Coarse-Grained Soils CWDD Guide for Consistency of Fine-Grained Soils CWDD Sampling Symbols Used on Logs
8-1 8-2 8-3 8-4 8-5 8-6
Degree of Weathering Discontinuity Spacing Separation of Fracture Walls Fracture Filling Surface Roughness Rock Hardness
9-1 9-2
Summary of Quaternary Dating Methods Soil Profile Description '
Figures
2-1
Site Reconnaissance Report
4-1 4-2
Test pit Sheeting Shored Trench Backhoe Trenching Techniques Augers Large Auger Types Continuous Flight Auger Large Helical Auger Bucket Auger Wash Boring Percussion Drills Becker Hammer Drill Rotary Drill Equipment Skid Mounted Rotary Drill
4-3 4-4 4-5 4-6 4-7 4-8
4-9 4-10 4-11 4-12 4-13
5-15 5-16 5-17 5-18 5-19 5-20
Typical Flight Auger Setup Drill Setup for Drive Sampling Clean-Out Auger Shelby Tube Sampler Stationary Piston Sampler Hydraulic Piston Sampler Retractable Plug Sampler Dennison Sampler pitcher Sampler Converse Sampler Split Barrel Sampler Cone Penetration Test Cone Penetrometers Menard Pressuremeter Equipment Vane Shear Test Arrangement Petersen Dredge Gravity Corer Phleger Corer Ewing Piston Corer Vibratory Corer in Sampling position
6-1 6-2 6-3 6-4 6-5 6-6
Suggested Drill Site Dimensions Sample Daily Report Core Size Nomenclature Nominal Sizes of Standard Coring Bits and Pipe Casing Typical Diamond Core Barrels Wire Line Core Barrels
7-1 7-2
Example Field Log of Boring Unified Soil Classification System
5-1
5-2 5-3 5-4 5-5 5-6 5-7 5-8 5-9 5-10 5-11
5-12 5-13 5-14
Figures (Cont'd)
8-1 8-2 8- 3 8-4
Rock Boring Log Rock Symbols Grain Size 'l'ypical Core Photograph
9-1 9-2 9-3 9-4 9-5
Example Test Pit Log Example Dozer Trench Log Example Test Shaft Log Fault Investigation Trench Log Trench Photo Log
10-1
Typical Boring Development Devices Packer Arrangements Test Zone Isolation Methods Falling/Rising Head Test Data Sheet Constant Head Test Data Sheet Pressure Test Data Sheet Determining Adequate Dur.<'ltion of Test Pressure Test Setup Average Friction Losses in Drill Rods, Pipe, and Hose Packer Leakage Analysis Aquifer Test Data Sheet Estimating Rate of Flow from Pipe Discharge Open Standpipe PiezCDmeters
10-2
10-3 10-4 10-5
10-6 10-7 10-8
10-9 10-10
10-11 10-12 10-13
( \
APPENDICES
Appendix A.
ASTM D 653-77a. "Standard Definitions of Terms and Symbols Relating to Soil and Rock Mechanics"
Appendi!K B.
"O.S.H.A. Sa;Eety Requirements for Excavations, Trenches and Shoring"
Appendix c.
ASTM D 1586-67. "Standard Method for Penetration Test and Split Barrel Sampling of Soils"
Appendix D.
Unified Soil Classification System 1. ASTM D 2487-69. "StanQard Test Method for Classifica tiOll!Zfil!Soils for Engineering. purposes" 2. ASTM D 2488 .. 69. "S'tandard Recommended Practicefor'Descr'lption of Soill;! (Visual-Manual proc",Qure)"
I
l
EXPLORATION GUIDF:
February 1980
1
INTRODUCTION
Field explorations are the basis, or foundation, of a geotechnical study and must be performed with care, with a thorough knowledge of the techniques and tools available, as well as with a complete understanding of the intended purpose of the exploration.
The contract with the client,
which provides a scope of work, should be utilized as a basis for proceeding with the work.
Well-planned and well-
executed field explorations are needed to provide good basic data and enhance the opportunity for an excellent end-product.
Converse Ward Davis Dixon
s~rives
for excellence in work
performed for clients and it is with this intent that this Exploration Guide has been prepared.
Recognizing that it
would be impracticable to prepare a manual encompassing discussions of teqhniques and equipment for all contingencies and conditions, this Guide concentrates on providing information for use in the most common types of explorations.
The loose
leaf notebook form has been chosen so that new information may be added as necessary and so that the enclosed data may be updated conveniently.
Your written suggestions regarding
data which needs revision, or data which should be added to this Guide, should be forwarded
~hrough
your Office Manager
to Chairman, Technical Activities Committee.
1-1
Since soil and rock conditions vary in different geographical areas, it is expected that explorations for similar types of projects may be performed by differing methods throughout the company.
Hence, it is not the intent that rigid standards
by established in this Guide, but that information is provided to enhance care and diligence in planning and executing professional services.
This Guide is provided for the use of all CWDD personnel, but is aimed predominantly at personnel: 1)
who are new to CWDD field work, or to particular phases of such work;
2)
who have not been to the field recently or not . handled a particular type of exploration recently;
3)
who have been transferred from one office to another, temporarily or permanently, and therefore have not been exposed to the type of exploration tools and methods used in the new area, and
4)
who are planning an investigation.
1-2
2
EXPLORATION PLANNING
(
Office preparation for field exploration falls into various categories:
the planning by the Project Manager, based on
the size and type of project involved; the planning of the exploration program in general; and the planning by the fietdrepresentative fOr the actual work.
Before a
vi~it
to the site, it is necessary that the field
representative have a clear understanding of the requirements of the project, and as much advance information on the site conditions as possible.
2,1
SOURCES OF PROJECT INFORMATION
A certain amount of judgement is needed in evaluating how I'lxtensivea search for information is required.
Some of the
sources listed melow may be inappropriate considering the size of the project.
The Project Manager should set the
requirements before the search is started.
2.1.1
Prior Projects
The files should be checked for other projects performed by CWDD on the project site or on nearby sites.
Logs and
rl'lports from previous projects can be a source of information not only on geologic conditions, but also on local drilling
2-1
and excavating contractors, surveyors, and aerial photographers who may have coverage of the area.
Many times inquiries to
local, State, or Federal agencies, will disclose valuable data.
The fact that a prior report by another company is available may not be mentioned in the early discussion of the project. At least inquire, as such a source of information may be extremely important.
A call to a contractor active in the area
may elicit considerable information about the particular region. If you intend to use this contractor on the project, he may wish to meet at the site to observe accessibility and he may be able to provide advice on appropriate equipment for the work.
( 2.1.2
Published Sources
2.1.2.1
publications of the U.S. Geological Survey.
Indices
are available of all USGS publications by state and county listing.
Many of those listed may be out-of-print, but they
may be available or abstracted at university libraries or the United Engineering Center.
2.1.2.2
Geologic Quadrangle Maps.
Many of these are listed
in the publications of the U.S. Geological Survey, but may be out-of-print; however, as they are a very valuable source of information, they should be searched out if the project warrants the time and expense.
2-2
2.1.2.3
State Geological Survey Maps and Reports.
by state universities and colleges are valuable.
Publications Some
states are active and have extensive coverage of large areas.
Other states have done little work and information
is limited.
2.1.2.4
Soil Conservation Service (SCS) Reports.
These
reports are pUblishe¢1 on a county or township format and deal with only the shallow surficial soils; however, they indicate the drainage characteristics of the soil., and provide an agricultvral soil desoription of the surficial soils that may be translated into the Unified Soil. Classification System.
2.1.3
AdditionalMapping
Other :(orm$
of top 0 9raphic mapping may be available for the
site, from the county, the client or from other sources. 'rhese maps may be at 'a more detailed scale than quadrangle maps and their availability should be ascertained.
2.1.4
Aerial Photography
photography companies or the U.S. Dept. of Agriculture may be contacted for sources of stereo coverage of the site, if such photos are not available in-house.
If more than one source of
photographs is available, or more than one series, the Project
(
Manager may consider acquiring both the most recent and the
oldest available to evaluate changes, such as conditions existing prior to placement of fill, etc. 1"
A photo scale of
= 1000 ft. or larger is most useful in both field
reconnaissance and in photo interpretation.
Obtain coverage
of the area surrounding the site, overlapping by from 50% to 100% where possible.
2.2
PRELIMINARY SITE RECONNAISSANCE
At the earliest stages of any project, i t is often necessary. or desirable for a brief preliminary reconnaissance of .the site to be performed as an aid in planning the field operations and in developing a budget for the project.
The preliminary
visit provides an overview of surficial conditions that may affect the progress of the exploration •.
The preliminary reconnaissance deals mainly with problems to be expected in the exploration phase of the project, and, to a lesser degree, an evaluation of geological and geotechnical conditions to be found at the site.
A field report of the
reconnaissance should be submitted.
The Site Reconnaissance
Report form, Fig. 2-1, when properly completed, would ordinarily serve the purpose of a field report.
Each site and project
has its own peculiarities, however, and the field report should cover the important aspects regardles~ of whether or not there is a space to be filled in on a form such as Fig. 2-].
The following paragraphs represent a guide as to what
2-4
to look for, and to what should be included, if applicable, in a complete field report.
2.2.1
Right of Entry Documentation
There must be a clear understanding of who actually owns the property, and that perrniss!on has been given for access onto the grounds.
If nothing else, a letter from the Client or
owner to CWDD authorizing entry shC)tt'l.d be obta!ned and carried. In addition the client or owner ahould be requested to give advanced notice to tenants.on the property.
2.2.2
Site Access
For a large rural site, travel around the perimeter on public rQllds allows evaluation of all possible means of access to the property.
The following questions may help
the C\ccess evaluat.ion. 1)
Is access by paved or unpaved roads?
Of what
width? 2)
Are the drives fenced off, and are the gates locked?
If so, who hC\s the key?
How wide is the
gate? 3)
Are the drives all-weather roC\ds, or will storms cause problems in use?
2-5
4)
If there are no drives into the site, is area isolated by ditches, or fences? crossed?
Can they be
By what type of equipment?
A sketch of suitable access paths will assist the next person to visit the site.
2.2.3
Site Mobility
The use of topographic maps or airphotos may assist the evaluation of:
1)
Areas that are readily accessible by most equipment.
2)
streams or ditches that isolate portions of the
site.
Areas that are too steep, or too heavily
wooded, to permi.t access with truck-mounted equipment. 3)
Areas that are swampy, poorly drained, or subject to flooding.
4)
Fences, including internal ones, that limit access.
5)
Areas containing livestock.
6)
Areas with crops that may be damaged.
7)
Utilities, overhead or underground, that may affect mobility and/or progress on the site.
The following questions should be answered during a preliminary site reconnaissance.
2-6
(
I}
(
If underground utilities are present, to whom do they belong and who should be contacted for field locations?
2)
If overhead utilities are present, is there clearance at planned boring locations?
3}
What appear to be the easiest methods of overcoming access problems?
A diagram of the site, noting abrupt changes in elevation and areas inaccessible (or with difficult access) to some, if not all, equipment should be made.
2.2.4
SupportOperatiOriS
, r
smoother field operations will be possible with the answers to the following questions. I}
What are the sources of drilling water?
2)
Will water have to be trucked, or can hoses or pipe reach a nearby water source?
3}
Can boring locations be established by topographic features or by detail shown on airphotos?
4}
Can equipment be safely left on the site overnight, or will vandalism or theft be a risk?
5}
What permits are likely to be needed for borings?
6}
Will normal exploration procedures create a fire hazard?
I \
2-7
It should be reported to all concerned if the client has special requirements on operations and cleanup, or has restrictions on types of equipment allowed on the site.
2,2.5
Geotechnical Conditions
The level of knowledge about geotechnical condi t.ions at the site prior to a visit may be solely a function of the extent of information that could be attained from the published data and the client.
As part of the preliminary reconnaissance,
SOme cursory mapping of the observed conditions should be made as time will permit.
A brief written report should be
prepared of the apparent surficial and shallow subsurface conditions.
General view photographs should be taken, along
with photos of rock outcrops, on-site structures, and soil and rock exposures in road cuts or erosion channels, either on the site or nearby.
(Paragraph 3.5 provides information on
areas of concern in later supplemental reconnaissance.)
2.2.6
Previous Construction
Observations should be made as to whether or not there is any evidence of existing or previous construction at the site; and/or if there is evidence of fill. be made to show important features.
2-8
A sketch should
"
2.3
2.3.1
EXPLORATION PROGRAM
Selection of Exploration Methods
In planning the exploration for the project, a great many factors should be considered in developing an appropriate program.
The primary considerations are the requirements of the
project, the client's level of commitment to the project, and the level of knowledge appropriate at the particular stage of development.
The level of technical ability of the
available subcontractors and the relative ease of access onto the property may cause the "ideal" program to be modified.
For example, planning an expioration program for a client who has an option on some property which he is considering as a shopping center may produce the following considerations: The client's main concern may be with traffic patterns and demographic studies being carried out by another consultant, and the geotechnical investigation may be merely for the purpose of avoiding gross problems with soil conditions or of meeting local requirements if he decides to go ahead with development at some future date.
He may be understandably
upset if faced with an extensive study that promises detailed answers to unposed questions.
2-9
On the other hand, an exploration program of widely scattered, shallow borings may be questioned by a client nearing the final stages of planning for a power plant.
The difficulty
of gaining access with proper equipment to conduct an extensive program may not be an acceptable reason for a limited program.
2.3.2
Selection of Contractor
Before finally developing an exploration program, it is appropriate to hold at least preliminary discussions with one or more potential contractors.
The scope of the program
may be beyond the capabilities of the local firms, and thus contractors may have to be brought in from outside the area, and/or additional specialized equipment may have to be purchased in order to perform the work.
Local practices
or procedures may cause modifications of the proposed investigation, or may lead to misunderstandings in the field, if not discussed initially.
The level of formality of selection is dependent on the requirements of the client and the relative size of the project.
The selection process can consist of an informal
negotiation or bidding by one or more contractors, or a formal submission of bids by those qualified to perform the work, complete with full project specifications on performance and/or procedures.
(
2-10
The contract for contractor services has many forms and
(
may depend on the type and magnitude of the work to be performed.
A written agreement or contract should form the
basis for any services to be performed.
Each Managing Officer
has a form outlining general requirements for contractors and stating the required insurance limits for compliance with CWDD's insurance carriers recommendations.
In most cases
such forms should be signed and certificates of insurance should be furnished by the contractor prior to performing work for CWDD.
2.3.3
Permits and Clearances
The various permits and clearances needed will vary from project to project and from area to area.
Listed below are
some of those that may be needed, and who is apt to be responsible. 1)
Permission from owner and/or tenant.
Client
should supply. 2)
Clearance from utilities.
Either CWDD or the
contractor should be assigned the responsibility for notifying all utilities, even if they are in the general area but not believed to cross the site. (In some areas, the local utility companies have a joint service for checking on underground services. In New Jersey, for example, someone at the phone
(
number 800-272-1000 will alert all companies who are members of the service of the proposed work) •
2-11
3)
Local Municipal Licenses.
Contractors should
know if this is needed, and be responsible. 4)
Hydrant Opening.
Contractor's responsibility.
5)
Insurance Requirements.
Many clients have specific
requirements that may be in excess of CWDD requirements of contractors.
A certificate of
insurance should be requested and obtained in the amount required by CWDD and the client and, when necessary, a copy should be provided to the client prior to start of field work. 6)
Special Permits.
Frequently needed for work in
existing power plants, refineries, or other ongoing operations.
2.3.4
Materials and Equipment
rhe following checklists contain some of the more common equipment which may be needed to successfully perform explorations.
Each project is different and has its own
special requirements.
Depending on the conditions and the
equipment or test being conducted, some or all of the following materials and equipment may be needed, with modifications as appropriate for special conditions.
The
field representative should plan the equipment needs with knowledge of the project requirements using the following checklists as a guide only.
2-12
2.3.4.1
Fault Investigation Trenches. Equipment
Materials (per trench)
1. 2. 3.
4. 5. 6.
7. 8.
9. 10 .. 11. 12. 13. 14. 15. 16.
200'-400' heavy nylon string 25-50, 6" long nails or spikes 2-3 rolls flagging 2-3 marking pens 4-5 DayGlo aerosol paint cans (survey marking paint preferred) 2 or more 2"x12"xlO' wood planks 1 roll 36"-wide fade-out blue g:dd mylar 2, 2'x3' masonite mapping boards 2-3 wire reinforcing mats with 6" squares, cut to 4' x6' si z:e pencils, erasers, pens rags dilute HCL masking tape sample bags trench photo log forms graph paper
1. 2. 3. 4. 5.
6. 7. 8. 9.
10. 11. 12. 13 . 14. 15. 16. 17. 18. 19. 20. 21. 22.
2-13
hard hat carpenter's rule, wood 6-foot plumb bob 200' fiberglass tape 10' steel tape whisk broom small trowel hand level extending ladder (aluminum) mapping vest (optional) clip boards hand lens (15x) transit Brunton, w/case geologic pick broad-bladed pick shovel (folding) wire cutters gloves string bubble level Philadelphia rod hydraulic shores with pump, release tool, and extra fluid. scales/protractor
2.3.4.2
Diamond Core Logging. Equipment
Materials
1. 2. 3. 4. 5. 6. 7. 8. 9, 10. 11, ~2.
log forms Daily Reports (drilling and contract items) notebooks pencils, erasers, etc. keel rags paraffin dilute HCL core boxes (if not contract item) sample tubes sample jars permeability test data sheets
1. 2. 3.
4. 5. 6. 7.
B. 9. 10. 11. 12. 13. 14. 15. 16.
2.3.4.3
Soils Sampling & Logging. Equipment
Materials
1.
2. 3. 4. 5. 6. 7. 8. 9. 10.
tape, steel, 10-foot carpenter's rule, wood 6-foot transit, Brunton, w/ case flashlight screwdriver pliers geologic pick hand level scale/protractor hand lens (15x) steel dies, 1 set each of alphabet and numbers hard hat bucket shovel stove handscreens and sieves
site plan soil boring logs graph paper Daily Reports (drilling and contract items) pencils and marking pens (permanent type) erasers sa11lple tubes paraffin plastic bags and tags water
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
2-14
samplers w/proper adaptors to driller's equipment extra sampler cutting shoes CWDD sampler ring ejector & push handle rings or liners ring containers & shipping boxes ring bags gum labels trim knife wire brush (clean sampler threads) WD-40 or equivalent 2 pipe wrenches (for sampler breakdown) bucket and scrub brush (wash sampler), pick and shovel stove clean-out auger penetrometer (pocket) hand level
18. 19. 20. 21. 22. 23. 24. 25. 2.3.4.4
Soil Exploration Test pit. Materials
1. 2. 3. 4. 5. 6. 7. 8.
Equipment
site plan test pit logs graph paper Daily Report forms pencils, eraser, permanent ink marking pen plastic sample bags, sample jars sample tags
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
2.3.4.5
4.
5.
hard hat hand level tape, steel, 10-foot 100-ft. tape scale pick and shovel small trowel and/or knife clip board penetrometer (pocket) optional - tape recorder optional - camera and film hydraulic shores with pump, release tool, extra fluid torvane (pocket)
Permeability Testing.
~quipment
Materials 1. 2. 3.
100-foot measuring chain or tape hard hat scales clip board wire saw optional - camera, film, site photos torvane (pocket) tape, steel, 10-foot
Daily Reports 1. pencils graph paper (arithmetic and semi-log) 2. boring sealing materials: cement and bentonite (l,z"diameter commercial compressed bentonite pellets should be 3. available in most areas) if not contract item pea gravel if not contract item
2-15
small folding rules or tapes for taking near surface measurements 200-foot cloth tape with float and or weight or "popper" (l-inch concaveupward metal disk) watch with a sweep second hand or digital second readout
6. 7. 8.
sand filter cloth or burlap permeability test data sheets
4.
5. 6. 7.
8.
2-16
two 350-foot electrical well-sounders tamping rod tremie pipe small-diameter PVC, reusable pipes for taking water level measurements or injecting water during constant head tests bailer or surge block. If no bailer, alternate water removal device (air-lift, small submersible pump)
CONVERSE WARD DAVIS DIXON SITE RECONNAISSANCE REPOR1' PART I - PROJECT DATA Date:
JQb Name :_~_ _ _ _ _ _ _ _ _ _ _ _ _ _l?roject No. _ _ _ __ Recan By: _ _ _ _ _ _ _ _ _ _ _ _ _Project Mgr: ____________ Address or adjoining houses
-----------------------(no)): -------------
Directions to site (Map attached (yes)
P~anned
Exploratory Program (Site, plan, layout attached (yes) (no)) : ________________--------------------------___
PART 11- PRELIMINARY RECONNAISSANCE (To be completed on site) I.
TO):'OGRAPHY (plains, rolling hills, mountains, relief} _________________________________________
Site Relief (slopes) ______________________
II.
III.
VEGETATION (weeded - light, med, heavy, forested - density and size of trees, plowed, planted, brush, open-field)
EXPOSED SOILS (sand, clay, gravel, glacial, fluvial (stream), marine (beach), residual) _________________
Fig. 2-1
IV.
V. VI.
ESTIMATED DEPTH TO ROCK & BASIS OF ESTlMATE _____________
TOPSOIL
(thickn~ss)
_____________________________________
ROCK OUTCROPS (number and location)
ROCK ID (shale, sandstone, limestone, granite, trap) ____
ROCK STRUCTURES (bedding, fOlds, faults, joints, massive, dips, strikes) ______________________________ __________ ~
V);I.
VIII.
WATER (streams, ponds, lakes, swamps, seepage, springs) (drainage, direction", system, size, flooding) _ _ _ _ __
PRESENT LAND USE (farm, light industrial, residential, dUmps, :enls)
IX.
EXISTING STRUCTURES (buildings, foundations, size, type, condi tion, cracks) ______________________________
X.
SLOPES & EMBANKMENTS (excavations or cuts, depth, size, exposed soils or rock, slopes stability) ____________
Xl.
UTILITIES (gas, electric, telephone, sewers, water) _____
Fia. 2-1 (con '
XII.
LOCAL ROADWAYS (type, lanes, U.S., State, County, concrete, asphalt, dirt, condition) _______________________
XIII.
EXPLORATION EQUIPMENT ACCESS (roads, gates, drilling unit recommended - truck, skid, ATV, portable equipment)
(utilities - overhead, underground) _______________________
XIV.
XV.
XVI.
XVII.
XVIII.
WATER SOURCES (available on-site (yes) (no), location, type) ___________________________________________________
IS SURVEYOR NEEDED (reference points)
SPECIAL EQUIPMENT (bulldozer, floating equipment, flagman, axes, power saws, water pump (lift), extra hose, transit)
PH.OTOGRAPHS (locations, special features) ________________
OTHER OBSERVATIONS (any information important to the project that is not listed above) _______________________
USE BACK OF SHEETS FOR SKETCH AND ANY ADDITIONAL NOTES. Fig. 2-1 (cont'd)
SECTION 3 '
3
3.1
FIELD OPERATIONS
CONTACTS
Field representatives playa key role in Qreating the image of CWDD.
In many cases the field representative has more
contact with the client, Qontraqtor, and general public than anyone else in the firm. CWDD staff cpnduct
It is, therefore, important that
t~emselves
in an exemplary manner, being
courteous, knowledgeable, and sensitive t9 the client's need for information and for confidentiality of an investigation.
3.1.1
c~ient
Contact
In dealing with the client there should be open communication regarding work in progress.
pie1d representatives should be
cautious to avoid making interpretations of partial data which might mislead the Qlient.
Interpretations often
require knowledge of many pieces of information including geologic mapping, boring data, laborat'ory data, etc., and, therefore, questions requiring interpretations should be directed to the Project Manager, as
3-1
~hould
most other questions.
A description of the client is well-stated by the following: 1)
He is the mos't important person in our business.
2)
He is not dependent on me--I depend on him.
3)
He is not an interruption--He is the purpose of my work.
4)
He does me a favor when he calls--I am not doing him a favor when I serve him.
5)
He is a part of my business--He is not an outsider.
6)
He is not a statistic--He is flesh and blood, with feelings and emotions as I have.
7)
He is an individual--He is not a face with a number.
8)
He is not someone to argue; or match wits, with.
9)
He is a person who brings me his wants--It's my job to fill those wants.
10)
He is the life-blood of my buSiness.
11)
He is the person who buys my service, pays the salaries, and goes to the polls and votes.
12)
Therefore:
The CLIENT deserves the most courteous
and attentive treatment I can give him!
3.1.2
project Manager Contact
For most jobs it is important that the Project Manager be aware of daily field activities.
Each project Manager will
establish a schedule for the field representative to contact the office.
Daily Reports dealing with the progress, the
3-2
costs, and the contractor's activities should be sent periodically to the office.
Telephonic reports of progress
may also be required, the frequency of which may be controlled by the remoteness of the project area and the available communication facilities.
A telephonic report
does not absolve the field representative of the responsibility of cpmpl~ting acyur~te DailyRepo~ts nor of transmitting them to the office as required.
The project Manager will define the limits within which the field representatives can chose alternatives regarding sampling, boring locations, added borings, etc.
As the field work proceeds, conditions may be found that differ from those anticipayed in developing the e~ploration program.
Changes in the procedures should not be made by
the field representative witho~t discussion with, and approval by, the project Manager, regardless of the pressures applied by the Contractor, Client, or others in the field.
3.1.3
Contractor Contact
As a representative of the contractor, the job Of the drill operator is to advance the boring.
The job of the field
representative is to establish the order of sampling, to evaluate the adequacy of the samples for the purpose,
3-3
to monitor the drilling and sampling procedures, and to provide a complete record of each boring.
It is important
that an adversary relationship between the drill operator and the field representative not be allowed to develop. There is, however, opportunity for conflict and misunderstanding.
The driller ultimately wants to do the boring as
fast, and with as little effort, as possible while the field representative has to maintain certain standards of operations that usually conflict with the driller's progress. Further, the field representative has to constantly check the work being performed.
If done officiously or obtrusively, res~nted
the necessary checking can be
by the driller,
perhaps not even consciously, and can affect the work being done.
Time should be takent6~expla:l.nyour actions and the
need for your checkingl ,the 'dommunications should go two ways.
3.1.4' General Public Contact
Public curiosity is invariably provoked by the arrival of drill rigs, excavating equipment, or even just strangers reconnoitering in a populated area.
Many projects on which
CWDD consults are confidential as to their exact nature and it is important that the client's confidentiality is not violated by CWDD personnel.
There are also many sensitive
projects on which premature release of data could have adverse effects and/or could cost the client immeasurably in terms of time and money.
In all dealings with the public,
it is of utmost importance that CWDD personnel remain
3-4
courteous, even when a member of the public becomes (
antagonistic.
The field representatives should avoid
discussing any project with. the public.
In particular,
results of investigations, such as boring data or trench mapping should not be discussed.
When questions regarding
any part of a project which is not public knowledge are asked, it is proper to refer the questioner to the Project Manager.
It is generally proper to refer all questions to
the Project Manager, thus negating the possibility of inadvertently revealing information which
mi~ht
be taken
out of context and used adversely.
3.2
SAFETY
carelessness of any kind, whether it endangers the person performing the act or others, should be firmly discouraged. Field exploration has inherent hazards of which each field representative should be aware.
When exploration work, such
as drilling or pit excavation, is in progress, the contractor is responsible for.safety practices.
Unsafe equipment or
practices furnished or performed under contract to CWDD should be reported to the contractor or his agents.
The
unsafe condition should also be reported to the Project Manager concurrent with the notification to the contractor. A notation of the reports to the contractor and the Project Manager should be included in the Daily Report.
To not
report unsafe Gonditions may incur liability for a contractor's safety practices.
3-5
The safety practices used ip excavations may be a function of the local codes, the OSHA regulations, and the contractor's insurance more than they are a function of the soil or rock conditions encountered. fully aware of the
The field representative should be
requirem~nts
for shoring and/or bracing
in a narrow excavation.
Hazards of working around drill rigs are similar to those encountered when working around most other types of machinery, including hazards presented by moving parts and falling objects.
The operators of the equipI1)i;)~'l:; ire aocustomed to
operating and handling the equipme,ntinvolved,apd are
toge#W~;t' as"~',t.~~~.
acoustomed to working
It is CWDD policy
that a field representatiV'~.d.~'·prohi.~ited from "assisting" the crew by handling-rods .-
,{tJll.:>,,~~iji;~ea~ - - -'--~,
., -- -::,
--'
equipment, or other
-, ,
work tlla,\:may only 1l1?S<;1t thf,'!"·:normal routine. C"U$e .
Assistance may
serious injury not:.~\)nly t.o the field representative, .
but also to members of the contractor's crew.
Neither CWDD's
nor the contractor's insurance will cover this condition and thus the field representative may be found personally r<;1sponsible.
Small tools of various types are used by the
crew and the hazards connected therewith are present.
Hard
hats are mandatory and th<;1 use of gloves and other protective apparel is encouraged.
3-6
Vlorking on a barge or over water presents special hazards. Life jackets should be worn at all times.
Equipment being used should have necessary safety devices (covers over accessible belt or chain drives, safety chains on high pressure water or air lines, etc.).
Each field
representative should know how to disengage or stop equipment being used on the job in case of emergency.
Other types of moving equipment such as dozers and backhoes present different types of hazards to field representatives. If logging or sampling is being done during
e~cavation,
particular care should be taken to remain clear of the operating equipment and to tell the operator where other personnel will be located. severe hazard.
Deep backhoe trenches present a
No one should enter deep 'trenches for
mapping, sampling, or testing without the trenches being adequately shored, braced, or sloped.
Explorations not involving equipment also have safety hazards.
Adequate clothing and boots should be worn for the
climatic conditions at the site of the work.
Safety equipment
such as glasses, snake-bit kits, survival kits, etc. should be available where such equipment might be needed and the personnel involved should be knowledgeable about their use.
3-7
Field explorations often extend over periods when the contractor and the field representative will not be at the site.
Precautions must' be
ta~en
to protect the general
public against holes left open temporarily, unattended operating machinery, unmarked projecting pipes, etc., at any time personnel leave the exploration site.
Furthermore, at
the conclusion of the exploration, the site should be left in a safe condition, making certain all exploration openings are properly covered and/or baQkfilled, and no Objects or debris are left to trip over or otherwisep<:>f&h'tially injure persons visiting the site at borings is further discussed inp~¥.~gr
'-_0
I f the field representativ~ isgilling>ailone to a job site, ,.-.,-
and particularly i f to/a remotJ;i;;rit~,it is essential that the itirterarY be knowrl]::Jy s;;'iile responsible l?erson.
A
specific time should beset fOr a cont&ct, either perlOonal or telephoniC, following the visit.
(This is for the field
representative's protection and safety in the event of ' injury or other reason necessitating
3.3
help~)
CONTRACTOR'S EQUIPMENT
When working with a contractor performing exploration, the field representative has the task of providing field administration of the contract.
3-8
Therefore, the field
representative must be familiar with terms of the contract and must keep records of pay and other pertinent items.
The
project Manager will furnish forms and instructions for this record-keeping function.
When the contractor's equipment arrives at the site, a cursory examination should be made to evaluate the capabilities of the equipment. 1)
Is it the type required? (truck-mounted or conventional wheeled, etc.)
2)
Will it be mobile on thiScl!!:ilite? (t.oo heavy, mast too t.all, etc.)
3)
Can it do the work effioiently? (bits too worn, bits of the right type)
If there are any deficiencies, discuss how quickly they can be rectified and how they will affect the work.
Serious
deficiencies should be resolved prior to the start of any explorat.ion work.
The field representative should discuss in detail with the operator the planned work, and learn if he is prepared with: the proper connections for the different samplers to be used; proper materials to be used, such as drilling additives; pressure test equipment; . and a proper hammer for the SPT test, if appropriate.
3-9
The drilling equipment and samplers are discussed in later sections of this Guide and references are given for even greater detail.
The field representative should be fully
aware of the equipment to be used, both its proper use and its limitations.
3.4
DOCUMENTATION
A written daily report Or reports must be
prepar~d. -<-"~
Each
report should be limited to factual informst:f!';ii&n, and should ,_.{_?
':;_~;:?i)'---~
never contain personal feelings or,Q~';ij;j)fkons .'otl\;i.s record should report on the day' s
progr~~'~:';~~4,':,in
add1t.ion contain
the following, as applicabl~i" 1)
headings to conta,:i.n
'2)
the, field representative's time of arrival and departure;
3)
contractor's start and finish time; verify overtime hours for the drillers in field. (get signature in field, if possible);
4)
contractor personnel and equipment inventorY (to document time and material contracts);
5)
interruptions in work, listed by item, time of shutdown and restart, and detailed information on cause;
6)
accidents - full details (call office and so inform) ;
3-10
7)
visitors - name of company, name of person, time of arrival and departure, purpose of visit;
8)
report salient details of conversations;
9)
report in detail all suggestions or instructions given to contractor that affect or alter normal or previously followed procedures.
A written copy of
any such instructions should be given to the contractor (attach copy to field report); 10)
report program alterations directed by the Project Manager;
11)
discuss in detail any problems that develop, and method(s) used to resolve;
12)
report in detail anything out of the ordinary; and
13)
prepare sketches shqwing salient details of . operations.
Reports should be prepared in dark pencil to facilitate reproduction.
3.5
SUPPLEMENTAL RECONNAISSANCE
On some projects, the field representative is the only member of CWDD to visit the site.
Thus the extent and
accuracy of field observations will have an extensive effect on the quality of the report that is finally prepared and submitted to the client.
3-11
When a preliminary reconnaissance has been made, it can provide a starting point for a reconnaissance performed as part of the exploration.
The field representative
should be familiar with the earlier work and should expand and/or amend the previous data.
The Project Manager should
brief the field representative on the extent of data needed, including additional areas of interest not covered in the Site Reconnaissance Report form (Fig. 2-1) (cost factors, local design practice, special problems, etc.).
Often the field representative can find till\e;during the field operations to perform a moreccl!!lpiete fie:;U;1 reconnaissance; as the rigs are during breakdowns, etc. __ .
DUring such:J;;ime the representative -.'---.
.-:-- c_
_-_->',
may conduct a more :"C9ml?leterecoritlais!f~tlce of the site without the pressure of alsb -
-
lllort:it6iing
the f·ield operations.
--.-,
Re. can map 'Surface conditions', take photographs, make informed guesses as,\to the subsurface conditions existing between borings or pits, and search for off-site information. (If therenas not been sufficient time during the field operations, then .the representative should remain on the site until the needed data have been recorded.)
The extent of the reconnaissance should be defined by the Project Manager prior to the start of field operations.
If
project confidentiality has been imposed by the client, no contact with outside parties may be permissible, thus severely limiting the sources of data.
3-12
The sources of outside data
discussed below assume no limitations due to project confidentiality.
3.5.1
Studies in Urban Areas
If the site being studied has been cleared, try to learn the size, extent, and use of the previous structure(s).
The
client may have provided the data, even if there are good records available, check further.
If good records are not
available, or if the information is vague, i.e. "a couple factories got torn down years ago," then the field representative should obtain additional information.
There
may have been even earlier structures on the site that predate the reported conditipns.
City tax records and/or
drawings filed with the Tax Assessors office or the City Engineer, mayor may not be available.
The local library or
historical society may have photographs or old tax maps.
A
cautious approach to local residents or neighboring businesses may give some general information, but a contact should not be made without the approval of the Project Manager.
Each
possible source will probably yield other sources to try. This approach is useful, whether done during preliminary reconnaissance, on arrival at the site to start exploration, during field operations when time allows, or after completion of the actual exploration.
3-13
If there are structures still on the site, carefully map the (
locations and relative elevations of lowest slabs, or check the accuracy of mapping that has been provided. of walls or slabs that can be found.
Map remains
Contact local utility
companies regarding services leading into the property.
Old
service leading to the property but not presently used may indicate even older structures than presently shown.
Report
age and condition of pavements, on the site and nearby.
Examine the conditions of all structures on.the property and <
adjacent to the site and estimate tl),~~~,,;a:g~. '~l::!port on
p:J~~~;:.S;imple
sketches of
Estimateloadirtgon slabs.
Inquire as
cracking of slabs and walls and any crack pattern.
to the nature of the foundations .fortile structures, and any problems that have been experienceci';This is especially importartt;fo:t:' allY struqturethat immediately abuts the proposed construction. "'6btain elevations of lowest slabs, and,if possible, foundation drawings.
Contact the water company to learn when water and sewer service were provided into the site.
If the service post-
dates the indicated age of the structures on site, then there may be wells and/or cesspools on the property.
Prepare a written description of:
surface conditions on
site, slopes, areas of fill, existing structures, surrounding boundaries, using the form of a general description.
3-14
,I
3.5.2
Studies in Undeveloped Areas
It may be necessary during the exploration phase of the project to prepare surface geology maps of the site and closely surrounding areas.
The map should include areas of
fill, outcrops, and areas that appear to be subject to flooding.
Spring emergences, intermittent streams, steep
slopes, sinkholes, landslides and apparent unstable slopes, alluvial fans, and any other geologic conditions that can be observed or inferred should be reported.
As the exploration proceeds, simple cross-seotions should be prepared, incorporating surface observations.
It may
become apparent that additional borings may be needed to clarify apparent discrepancies and anomalies.
Information
from road cuts or erosion channels should be incorporated, where possible, in the cross-sections.
Prepare a description of topographic and surface conditions, reporting on areas under cultivation, woods, and swamps. Characterize the topography:
hilly, flat, rolling?
on the extent and effectiveness of drainage.
Report
Describe and
map prominent features, existing structures and ruins, roads, rivers and streams, and rock outcrops.
(
3-15
Photographs are inexpensive and are an effective tool to assist others in visualizing the site and conditions. Photograph anything that may be pertinent.
Identify the
photograph and define the purpose of each shot.
Have photos
processed as soon as possible, including partial rolls. photo still in the camera is useless.
3-16
A
SECTION 4
4
EXPLORATION METHODS AND EQUIPMENT
Methods and equipment commonly used in exploration for engineering purposes vary with location.
A company operat-
ing in a variety of geographical areas relies on experienced, flexible personnel that are familiar with equipment capabilities and limitations of all operating areas, as well as various field methods.
Knowledge of field techniques will
greatly increase the quality of information gathered and minimize outside contract costs.
Basically, exploration for engineering purposes can be divided into two categories:
indirect and direct methods.
Indirect methods includegeop,hysical surveys and mechanical probing or sounding.
The common direct methods include near-
surface exploration by test pits, dozer cuts, and backhoe trenches, and deeper exploration by drilling.
The reliability
of the subsurfac.e information obtained from these methods various as do the costs.
Consequently, the method or com-
bination of methods selected is based on which will result in the most accurate portrayal of the subsurface conditions with the least cost to the client.
In addition to the two main categories of subsurface exploration, the procedures can be subdivided into onshore and offshore operations.
4-1
4.1
GEOPHYSICAL METHODS
4.1.1
Onshore Geophysical Methods
Onshore geophysical methods commonly used for geologic or engineering purposes are seismic, electrical, magnetic, and gravity.
Table 4-1, Onshore Geophysics For Engineering
Purposes, summarizes the four methods and their applications.
4.1.2
Offshore Geophysical Methods
The primary offshore geophysical exploration methods consist of depth recorders, sub-bottom seismic reflection profilers, and side scan sonar.
There is a great variety of seismic
reflection equipment, each suited for specific bottom conditions, water depths, and exploration requirements.
Table
4-2, Offshore Geophysical Methods, lists some of the common equipment used:
their purposes, characteristics, and capabi-
lities.
4.2
HECHANICAL PROBING AND SOUNDING
Table 4-3 summarizes the general use, capabilities and limitations of mechanical probing and sounding.
Soil sounding or probing
consists of forcing a rod, a rod encased in a sleeve pipe, or a wire and resistor body into the soil and observing the
4-2
penetration or withdrawal resistance.
Variations in the
/
resistance indicate dissimilar soil layers, and the numerical values of the resistance permit an estimate of some of the physical properties of the stratum.
Soil sounding can,
therefore, be considered as a method of both exploration and field testing.
Similar estimations may be obtained by
observation of the penetration resistance of a sampler which is driven (Section 5).
Soundings are generally considerably faster and less expensive than borings.
In case of erratic soil conditions, it may be
advantageous to replace a number, but not all,·of the borings with a greater number of soundings an.d thereby obtain more complete data on variations in the soil profile.
Sounding profiles give indications of the in situ consis·tency of cohesive soils and of the compactness of cohesionless soils.
Consistency and/or compactness information is very
valuable when undisturbed samples are difficult and/or expensive to obtain, as in saturated cohesionless soils.
In general, both small and large areas can be explored rapidly and economically by soil sounding methods, especially when the depth of exploration is moderate and the soils penetrated are soft or loose.
Soundings furnish data which
supplement data obtained from borings.
4-3
However, soundings
alone cannot provide sufficient data for the final design, especially of important or unusual foundation and earth structures; nor when consolidation, seepage, earth pressures, or groundwater pressures must be taken into consideration.
The oldest and simplest form of soil sounding consists of pushing or driving a rod into the ground by repeated blows of a drop hammer.
Driving rods, as well as water jet probing,
must be used with prudence.
Erroneous results can be obtained
when probes meet resistance or refusal on cobbles, boulders, or hard soil layers.
Soundings can be made by jet probing the subsurface soils with water and a chopping bit.
The advantage of jet probing is
that it is a relatively inexpensive,and quick method of obtaining limited information on subsurface conditions.
(A
portable gas-powered water pump can usually be rented near the job site.)
The major disadvantage is a depth limitation of
about 20 feet. explorations.
Jet probing is ,rarely used in foundation For more information on probing, refer to
Ref. 1.
4.3
OPEN SUBSURFACE EXPLORATION
Near-surface explorations are accessible test pits, test trenches, shafts, adits, and drifts large enough to permit entrance of a man for inspection and sampling of subsurface
4-4
materials in situ.
Table 4-3 summarizes the general use,
capabilities and limitations of open subsurface explorations. The minimum dimensions are usually determined by the space required for efficient work rather than by accessibility.
Of all methods, open subsurface explorations provide the most reliable and detailed information on soil and rock conditions along a specific vertical, inclined, or horizontal line.
They make it possible to examine, sample, and perform
field tests on the material in situ.
Furthetaltc,re, the ve,ry
act of advancing such an exploratiol).gives valuable information on the difficulties to be encountered in, and the probable costs of, excavation for'the proposed structure.
In open s,ubsurface explorations Clne can obtain larger and usually less disturbed samples than in borings of relatively small diameter, but certain causes of disturbance should be recognized and proper measures taken to ascertain and reduce their influence on the condition of the samples obtained.
stress changes in the soil below the bottom of an
ordinary boring can be reduced by filling the opening with water or drilling fluid, but open subsurface explorations must be kept dry.
There is, therefore, greater danger that
a slow plastic flow and consequent disturbance of the soil may occur in the vicinity of the bottom of a deep test pit, of the bottom of a drilled shaft, or at the face of an adit.
4-5
4.3.1
Hand-Excavated Test pits and Shafts
Often test pits are excavated using hand methods.
Deeper
shafts may also be excavated by hand, using air hammers when rock is encountered.
Square or circular pits or shafts with the least dimension of about 4 feet, or unsheeted, shallow rectangular pits, 3 by 5 feet, are often used; however, a rectangular crosssection of 4 by 6 feet permits easier, and often less expensive" excavation.
This rectangular section is the minimum required
when vertical sheeting is driven ahead of the excavation and large undisturbed samples are to be taken.
The dimensions
are net dimensions at the bottom of ,the pit and do not include the space required for sheeting, wales, nor special arrangements for drainage.
Starting dimensions at the
ground surface may be much larger for deep test pits, which require several offsets or lifts.
Shallow (less than five feet deep) test pits in fairly firm ground can generally be excavated without any support of the pit walls, but sheeting is required in unstable ground, for deep pits and shafts, and wherever else codes may require.
Arch action in the surrounding soil will materially
decrease the earth pressure acting on the sheeting, at least when dimensions of the pit are small and when material displacements in the surrounding soil are avoided during the
4-6
excavation and the short period of actual use of the pit. The size of the sheeting is, in such cases, based on practical experience or codes rather than on theoretical earth pressures.
The lumber sizes shown in Fig. 4-1 are
adequate only under favorable conditions, such as firm soils; they should be modified when the pit is larger, when the soil is soft, when hydrostatic pressures are to be resisted, and when there is danger of soil movement (rough methods of excavation, vibration, etc.).
There are various methods of supporti.llg and excavating test pits and shafts.
For a detailed discussion see Ref. 1.
Extreme care must be taken in,control of ground water, especially when a pit is advanced through soils with little or no cohesion.
Cohesionless soils should be under capillary
tension when undisturbed samples are to be taken; that is, the groundwater level in the central part of the pit should be depressed below the bottom elevation of the samples. Dewatering by means of well points is the safest method of control; it should be used when pits in cohesionless soils are extended any appreciable depth below the groundwater level.
4.3.2
Backhoe Excavated Test pits and Trenches
For many engineering investigations, backhoe equipment is used for excavation.
The investigations are normally con-
4-7
cerned with material groundwater rate.
level,
classification, depth of bedrock,
in situ testing, and/or excavation
The ideal minimum bottom width of backhoe test pits
and trenches is 30 to 36 inches, but a width of 24 inches is sometimes used.
The narrower trench restricts movement of
personnel and sampling or testing equipment.
Small backhoe
equipment, such as Case 580 C or John DeareHD-4, can reach maximum depths of about 13 feet in soil, without extenders. Larger backhoes, such as Hopto 550 or Hein-Werner C-148 are capable of excavating to a depth of about 22 feet.
Extenders
on the larger backhoes can be used to qi;!epen test;. pits to about 30 feet in soil.
Specifications for large hydraulic
backhoes can be found in Ref. 3.
Although larger backhoes are generally more expensive, they are able to move material faster and thus may become more cost-effective than smaller ones, particularly when excavating weathered rock. a number of variables:
The rate of trenching depends on depth and width of the trench;
bucket size and efficiency; cycle time of the backhoe; digging quality of the soil or rock; obstacles and hazards, both below and above ground; shoring or fencing requirements; and the need of separating topsoil.
Field representatives should develop an understanding of the potential efficiency for various backhoes.
Because backhoe
work is usually contracted on an hourly basis, field
4-8
representatives should be able to evaluate whether apparent inefficiency results from physical limitations of the equipment, subsurface conditions, or operator inexperience.
If ·the
latter occurs, the Project Manager may wish to ask the Contractor to replace the operator with a more experienced person.
All equipment requires a two- to four-hour break-in
period for an experienced operator to become familiar with the controls and hydraulic response of different backhoes. Excavation rates, cycle time, and production estimates should be recorded for use in estimating costs· of future work and documenting contractor efficiency.
4.3.3
Drilled Shafts
Drilled shafts with a steel orconcr€te shell are occasionally preferred to sheeted test pits, particularly when the shafts can be used as a part of the proposed foundation structure. 30
i~ches,
'rhepractical minimum bottom diameter is about but a diameter of four feet or more is generally
used.
A boring with a diameter of 30 inches is generally accessible, but a larger diameter is preferable.
Borings up to 6
feet in diameter have been drilled for special field tests. Shafts in soil and very soft rock are drilled with poweroperated augers of various types, usually bucket augers,
4-9
especially designed for pre-excavation for piles and shafts. Rock or frozen soils must be drilled with calyx type rigs using steel shot at the cutting edge or steel-toothed, single tube core barrels.
When appropriate drilling rigs and core barrels are available, accessible borings can often be made in a fraction of the time required for sinking test pits in soil and shafts in rock by hand methods.
A rate of progress of 25 feet per
hour can be attained in soil under favorable conditions, but acceptable work can be as slow as 5 teet per hour. Borings to be entered, may require support, thus restricting visual observation of the boring walls.
Inspection slots or
openings may be provided.
4.3.4
Dozer Cuts
Dozer cuts or scrape-'downs provide valuable subsurface information at a relatively low cost.
Usually an equivalent
Caterpil1er D-4 size (International Harvester TD-lSB) or larger is used.
Exploration dozer cuts or scrape-downs
allow evaluation of: 1)
bedrock hardness, fracture spacing, and degree of weathering;
2)
depth of bedrock/ground water;
3)
equipment performance; and
4)
excavation ease/difficulty (rippability).
4-10
Also dozers can be effectively used to: 1)
remove weathered materials or overburden;
2)
increase depth capabilities. of backhoe trenches; and
3)
provide level work area for other exploration equipment.
Sidehill dozer cuts for roads provide valuable exposures for detailed geologic mapping.
Dozer production varies more than tha,t. of other excavators. For examples of production rate$.{see Ref. 3.
Trenches for Fault InV'~;stig~tion
4. 3.5
,-
-
-. -
-~-->
-,
-_-:_.;-'-i.
The purpose of fault investigation trenches is to expose the I
subsurface materials tda depth sufficient to enable experienced geologists
to make a detailed inspection and evaluation
of the excavation walls to appraise fault features that may influence the project.
Trenches for fault investigation
differ from test trenches excavated for engineering purposes. The following factors set fault investigation trenches apart from other trenches: 1)
they are usually deeper and longer than other test trenches;
2)
their sidewalls are carefully cleaned by hand chipping, washing, or air blowing, prior to inspection and logging;
4-11
3)
they are logged in much greater detail than other trenches and care is taken to accurately record the geometry and dimensions of structural features;
4)
they often require extensive shoring even in bedrock, as the materials in fault zones are weak;
5)
their logging is time-consuming and often several people familiar with fault trench logging techniques will review the field work requiring the trenches to be open for long periods; and
6)
these trenches often require fencing or protective covers during the logging and review process.
The upper weathered zone, whether in soil, alluvium, glacial deposits ·or bedrock, obscures the subtle features associated with active faulting.
In some areas, excavation depths of
30 to 40 feet are required because of deep weathering profiles, thus requiring large backhoes.
Alternatively,
upper level cuts, to depths of 20 feet, can be made with a dozer and a backhoe used to complete the deeper excavation. Normally the dozer cut is logged in detail from the top down in maximum eight-foot high lifts.
Because bracing is not
used, the sidewall of the dozer cut is often laid back at an appropriate angle for safety, resulting in an inclined surface to be logged as opposed to a vertical trench wall. The trench excavation should extend appreciably beyond the fault zone and at least one short verification trench should be excavated across the strike extension of the fault.
4-12
The excavation should be safe.
Compliance with local,
state, and federal safety requirements and permits is mandatory.
Appendix B includes a copy of OSHA safety
requirements.
The safety requirements in Appendix Bare
considered a minimum standard for trench operations.
Most
hydraulic shoring suppliers offer one-day training courses on shoring requirements and installations.
Fig. 4-2 shows a
properly shored trench.
The following field procedures have proven satisfactory for excavation of trenches for fault investig~ti6fi~.
1)
The excavation, or (usually at least
segmel'lt3'/Qf;~~~'~xcavation 50:\\~\~;o;t),
For
(If this is
nO{d~~~";';a daWg~i:~~~"'~\T~~~ang
on the uphill side
trench wall will,;resultas shown on Fig. 4-3.) In trenchesa'::ross recent ground ruptures, the o • • ---:,'
._<__
__
weight of the backhoe may close the ground cracks; therefore, the excavation should start at the ground rupture and proceed in a direction away from it as opposed to crossing over the ruptures (l'ig. 4-3). 2)
Adequate safety measures are taken, as outlined in Appendix B.
Generally, if hydraulic, aluminum
shores are used, they are set on four-foot centers. A ladder should be available for all trenches.
If
livestock, wildlife, or people frequent the area,
4-13
the trenches should be fenced or alternatively, covered with at least 3/4-inch plywood sheets. Construction zone signs and appropriate barriers should be installed.
The walls of the trench are cleaned prior to logging.
Often
during excavation in alluvial materials, the walls are disturbed and smeared with a layer of clay and silt. Likewise, in bedrock areas, the walls are coated with dust and loose soil after excavation.
There are several ways to
clean trench walls as outlined in Section 9.
4.4
DEEP EXPLORATION
Most deep explorations for geotechnical
Table 4- 3 sununarizes. the general use, capabilities
and limitations of the various methods of deep exploration by borings.
The average depth of borings for engineering
purposes is much shallower than drilling for oil, geothermal sources, or most mineral exploration.
In normal foundation
explorations, the average drilling depth may be 50 feet whereas in an exploration for dams, power plants, or nuclear reactors, drilling depths up to several hundred feet may be required.
Rarely does goetechnical exploration for civil engineering
investigations extend more than 500 feet below the ground surface.
4-14
The commonly used drilling methods for onshore geotechnical exploration may be classified in the following groups:
1)
auger;
2)
wash;
3)
percussion and churn;
4)
rotary, skid- or truck-mounted.
The efficiency of the various drilling methods varies greatly with the character of the material ..t(:{'lYe penetrated
thiJaBbf...lW9'; several .
and with the diameter and depth of
-
-
methods are often used in advanpi'rtg a singlepP+,ing. -_ct_,
In
selecting the drilling IlIe,,"hod to.;);l.E!;llsE;d, consideration should be given to: '_:_-i~;;c
I)
the'.material
__
-_
eri<:li:)Ur:¥~·ked and
the relative efficiency
. of the various me;thods, 2)
the facility and accuracy with which changes in the soi3: and groundwater conditions can be recognized, and
3)
the possible disturbance of material to be sampled.
The essential equipment consists of: 1)
the actual drilling or sampling tools and cleanout equipment;
2)
the drill rods or cables connecting the tools to the operating equipment at the ground surface;
4-15
3)
the casing, when required, to stabilize the boring and a drop hammer for driving the casing;
4)
the motors and winches for lowering, operating, and withdrawing drilling tools, drill rods, and casing;
5)
a tripod or mast of wood or pipe sections to permit handling of reasonably long sections of drill rods and casing; and
6)
a pump, when required, for circulation of water or drilling fluid to remove cuttings from
The operating machinery and the
p~mp.lnay
~he
boring.
be used as inde-
pendent units, but they are often aSseIllbled in a single drilling rig which may be mounted on skids or on a truck, on which a collapsible mast also may·be erected.
Drilling rigs
are often mounted on trucks to increase their mobility and to reduce the time required for setting up and dismantling the equipment; however, skid-mounted drilling rigs or independent units must be used when locations are inaccessible by motor vehicles.
Drilling rigs are generally designed for
one particular boring method and examples' of such rigs will be given in the following paragraphs.
However, some drill
rigs may be used for several boring methods and for the operation of samplers.
For exploration of water-covered areas, the drilling equipment may be erected on a platform supported by piles; on a raft consisting of a platform supported by small boats, pontoons,
4-16
or empty oil drums; or on a barge or drill boat.
The raft
or barge is generally provided with a well in the center through which boring operations are performed. used, at least through the open water.
Casing is
The raft or barge
must be securely anchored and in such a manner that it can rise or fall with changing water levels.
A method of recording
the actual drilling depths must be maintained (tidal gage) as measuring the drill rods is totally inaccurate during changing water levels.
For more accurate work, a permanent reference and
surveying techniques may be required. extremely time-consuming in case of and drilling operations from a rafj;.
The operations may be
great,,;tfa~f:' fluctuations,
.~~,.i;;;'~g~;inay
. 'F'
-
become
-
impossible in the case of swif£t¢tltreI1 j;.s and/a:l." considerable wave action.
4.4.1 -. ~- >--
,-~--:--
Ariauger
-----,-.. /:>~->->-}.
B(jrin~'il3 advahced by rotating a soil auger while ~:-->
----:
pressing intJ thEi"'soil and later withdrawing and emptying -f
the soil"'laden auger.
Soil augers are used in subsurface
exploration for three purposes: 1)
general exploration and obtaining of representative disturbed samples;
2)
advancing and cleaning borings between depths at which samples are to be taken; and
3)
drilling large accessible borings which permit direct inspection of the soil in situ.
{
\
4-17
Augers are also used for various construction purposes, such as drilling drainage wells, pre-excavation for piles, and excavation for piers.
Types of small augers are shown on Fig.
4-4 and types or large augers on Fig. 4-5. 4.4.1.1
Hand Augers.
Hand augers are generally small
helical augers, Fig. 4-4, and posthole or Iwan type augers. Hand augers are used primarily in dry soils to depths not exceeding 10 feet.
The rate of progress is slow, but the
method is employed extensively in shallow subsurface exploration as for highways, railroads, and airfields. simple, light, and inexpensive.
The equipment is
The limitations of hand
augers are the depth and resistance of materials encountered. In stiff or dense soils, hand augers cannot be used.
Hand
augers operate best in loose, or moderately cohesive, moist soils.
4.4.1.2
Power Augers.
portable powered hand augers are
slightly faster than hand depth capacity.
~ugers,
but have very little added
Machine-powered augers are used at depths
up to 100 feet and are often operated so that a great rate of progress is obtained.
Large helical or worm type
augers, spoon augers, and hinged augers, in many different forms, are used.
4-18
Auger borings are kept dry, as far as possible, since water in the boring increases the danger of losing the soil in the auger, as well as the soil-laden auger acts as a piston and tends to force water above it and out of the boring. Casing is required for auger borings in unstable soil and when the boring is extended below the groundwater surface.
Machine driven augers are of three types:
continuous
helical flight augers 3 to 16 inches in diameter; disc augers up to 42 inches in diameter; and 48 inchee in diameter. illustrates the basic augers.
hollow
augers up to
Larger augers0-" ai'eavailable. -_
difference:s;$hll~fween >yu-:.:::,·-.--
Figs. 4-6, 4-7 '0 ,and
augers in operation.
buc~51t,
Fig. 4-5
the three types of
4}'~~\§J~p~3'the diff~t;ent types of
d~~l:~~prbe~~t~.amples may be obtained from
st;emoSl~ti\a~qJ;?+e-t~j~i{f~~9ai!~#:Ugers.
Typically, a plug is
maintained i~, the hale wli.iidfg;ct:~tiiing the auger.
The plug is re-
",,'--~
moV'ed,the sa~piE:Jf.is'l9~eted, and the auger acts as the casing.
4.4.2
Wash Borings
A wash boring is advanced partly by a chopping and twisting action of a light bit and partly by jetting with water which is pumped through the hollow drill rod and bit (Fig. 4-9). Cuttings are removed from the boring by the circulating fluid.
The drill rod and bit are moved up and down, by
pulling and slackening the rope, and concurrently rotated back and forth by means of the tiller.
4-19
The operation, as
well as the pumping, may be performed entirely by hand, but a small motor-driven winch and pump are generally used.
The
(
water may be pumped from a river or pond or taken directly from local water supply lines, when such sources are near the boring, but a closed circulating system is generally preferable.
In the latter case, water is pumped from a
small sump or a tub, and the soil-laden water from the boring is discharged into the same reservoir, where the coarse material settles out and from which a wet sample can be secured.
Wash borings are not often used for foundation
investigations, particularly if the site is accessible to truck mounted .rotary rigs.
A complete description of the method and
equipment is found in Ref. 1. 4.4.3
Percussion and Churn Borings
Pneumatic percussion drills range in size from hand-held jackhammers to track-mounted tower drills.
The larger
pneumatic percussion drills are useful for making borings in geotechnical exploration for the following reasons: 1)
fast, efficient way to penetrate rock to a desired depth for sampling;
2)
effectively drill through cobb ley alluvium and glacial deposits to bedrock, sometimes the only way; and
3)
efficient for drilling holes to a)
install rock anchors
b)
drill blast holes
c)
drill grout nipple holes.
4-20
,(
Sampling is possible with some of the pneumatic percussion 'f
\
drills.
However, usually only dust and rock chips 1/8 to
1/4 inch in diameter are recovered.
The greatest limitation
to all pneumatic percussion drills is the presence of ground water.
Excessive ground moisture causes jamming and slows
drilling considerably (with some rigs, water may stop drilling entirely).
4.4.3.1
Percussion Drills.
Percussion rock bits chip or
crush rock with hammer blows. impact with each blow.
Rotation ch&nqe$ the area of
Compressed a;i,r, .or a,;I.'.r and water, -~-
supplied through the center paSSl.!i\qe in the roct, and through {-:;:~-,\
one or more holes in the
-:,-- ----~:---'-
--
rock away from ·the bit ancto~t.of·t~1;l boring.
Bits are usually made of deep-hardened alloy steel.
They
may have inserts;of tun'lfsten carbide at impact areas.
Most
bits can be restored by grinding when worn.
As the bit reduces rock to chips, sand, and dust, the particles must be removed promptly or a layer will form that will prevent the bit from striking the rock.
The basic method of
removal is by a current of compressed air, entering the hollow rod at the drill, and emerging from the bit in holes at the front or bottom (one) and sides (none to four).
In
a properly balanced rig, the air that cleans cuttings from
(
4-21
the bottom of the boring has sufficient volume and velocity to carry the cuttings up and out the top of the boring.
At
the top, the chips and coarse sand will pile in a ring around the boring, fine sand will go a little farther away, and dust will drift with the wind.
A crawler percussion drill (air-track) has a pair of tracks; a body and turret mounted between the tracks; a boom that is based on the turret and can be raised, lowered, and swung in a part circle; a mast on a universal mounting at the boom point; and a percussion drifter drill that can be moved along the mast by a power feed.
fig. 4-10 shows a typical
crawler drill and shows the range in/Oize of track ....mounted drills.
The larger drills would only be used on large
construction or quarry work.
Percussion drilling is an
inherently dusty and noisy operation.
The dust is a nuisance,
is unhealthy to breathe and, in some environments, its suppression may be required by law.
4.4.3.1.1
Downhole Percussion Unit:
A downhole percussion
unit is a simple, heavy pneumatic unit in which the piston blow is delivered against the bit shank, without any steel or rod between. inserts.
Drill bits are usually fitted with carbide
The drill is very slender in proportion to its
weight and strength. itself.
It has no rotation mechanism in
Air is exhausted through the bit and carries chips
to the surface, around the outside of the rods.
4-22
The downhole unit is used for making borings of 5 to inches in diameter in hard and medium rock.
7~
Since none of
the striking force is absorbed by the drill rod, the working depth is limited only by the ability of the air stream to keep cuttings blown out of the boring, and by the capacity of the rotary bearings to carry the weight of a long string of rods.
Rigs built primarily for downhole percussion drilling can usually be changed to use rotary bits.
HoweV'&r, rotation
may not be as rapid nor the down preS'sure as' great as in -, --
machines that are built primarily for rotary 'drilling.
A principal disadvantage ofdqwnhole percussion drilling is the danger of losing, a whole driLl as a result of a rock fall, Or of the formation of mud collars. drilling may not be
pr~dent
Percussion
in badly fractured formations,
or in wet shale, or in other muddy strata.
4.4.3.1.2
Becker Hammer Drill:
This equipment is particularly
useful for rapid penetration of sand, gravel, and boulder deposits.
with the Becker Hammer Method, a double-wall
drive pipe is driven by a diesel-operated pile hammer, while air or water, under pressure, is forced down the annulus of the drive pipe (Fig. 4-11).
The material cut by the drill
bit is rapidly transported to the surface through the inside pipe by the drilling fluid.
The discharged materials.can be
accumulated in suitable containers as they emerge from a
4-23
cyclone and samples bagged at specified intervals.
As the
center of the drive pipe is always clear and the bit always remains on the bottom of the boring, standard penetration tests (paragraph 5.9.1) or undisturbed samples can be taken at any desired interval.
Upon reaching bedrock, a rotary drill
unit can be moved over the boring, and the drive pipe then can be used as the overburden casing and conventional drilling methods may proceed for the coring of bedrock.
4.4.3.2 drill.
Churn Drill.
The churn drill is a type of percussion
until a few years ago the churn drill was in the
4- to 12-inch diameter range; now up to 25-inch.diameter drills are available.
A churn drill boring is advanced by alternatively
raising and dropping a heavy drillil1it, usually attached to a cable.
The method is also called· cable tool drilling.
The chopping action of the bit against soil or rock causes a slurry to J;>e formed in the boring.
(When drilling above the
water level a small amount of water must be added.)
The
cuttings in the slurry are removed by a bailer or sandpump. Ordinarily casing is installed as the boring is advanced.
The churn drill has many advantages.
It is rugged and
dependable; the principle of operation is simple; and, with suitable adaptions in the drill column and winches, it can drill any material to great depths.
However, progress is
only two to ten feet per hour, including bailing and changing time.
Competitive machines can make borings at five to ten
times that rate.
As a result, labor costs per foot of depth
4-24
are high, and several times as many machines and shifts may be needed to do a job with a churn drill as with other equipment.
Churn drills continue to be used extensively for
water well drilling. exploration purposes.
They are infrequently used for foundation It may be expedient to use a churn drill
for a boring through coarse cobbley material to locate suitable foundation materials or to start a boring for core drilling of foundation rock.
Sampling is not recommended with a
churn drill as only a crude log of the material encountered can be made from an examination of the cuttings, and the material deeper than the actual drill bit is usually too disturbed to allow undisturbed sampling and even Standard Penetration Tests will not have much validity.
4.4.4
Rotary Borings
Rotary drill equipment for geotechnical exploration is highly flexible in mobility, in size of boring obtained, and in depth of penetration.
Rotary drills may be truck-
or skid-mounted.
4.4.4.1
Truck-Mounted Rotary Drills.
The truck-mounted
rotary drill is used for both soil and rock exploration where accessibility is not a problem.
The rotary drill may
be operated with a variety of bits, Fig. 4-12.
The types of
bits used are dependent on the character of the material to be penetrated.
Fish tail. bits, and two-bladed bits are used in
4-25
relatively soft soils and three- or four-bladed bits in firmer soils and soft rock.
The cutting edges are surfaced
with tungsten carbide alloys or formed by special hard metal inserts.
The bits usually used in rock and some gravel and
cobble formations all have several rollers with hard-surfaced teeth.
The two-cone bits are used in soft or broken formations,
whereas the tricone and roller bits provide smoother operation and are more efficient in harder rocks.
The number of
rollers as well as the number and shape of the teeth are variable and are used in accordance with thechar~cter of _c--:-
the rock being drilled.
In soft
_, __
0 __ --
_
roc~,'rela.tively
large and
few teeth are used and the teeth~reinterfitte2t;so that the bit will be self-cleaning .'):'):J.e te~e):J.:I:'ri ~ll bits 'are flushed by drilling fluid flowing ou.to$ vel).t$';in the base of the bit.
In most soils and rocks the rate of progress is greater than can be obtained by other methods.
However, rotary drilling
may not be well suited for use in deposits containing very coarse gravel, numerous stones, boulders, or chert nod·ules; or in badly fractured or cavernous rock; or very porous deposits where water or drilling fluid losses occur.
Accessories for a drill rig are a cathead winch and derrick for driving casing and for hoisting and lowering the drill rods; a pump for circulating water or drilling fluid (mud) to the bit and for flushing and water testing the boring; a water meter; and the necessary driving weights, bits, drill
4-26
rods, and core barrels.
Support for borings is usually
required except when drilling through solid rock or stiff cohesive soils.
A short collar pipe is commonly used at
the top of the boring.
The use of drilling fluids, including
stabilizer compounds, often avoids the need of casing in soil; however, when such fluids are used, permeability tests in the boring may not give accurate results.
At least two driving weights should be available, a 140pound weight for Standard Penetration Tests and a 250- to 400-pound weight for driving and remQving casing.
The
weights are raised by pulling.t;i:ght on an attached rope threaded through a
sh",~v:e>at
the 't6pof the derrick and
wound two times on therElVolvingc.a.thead winch. Sudden loosening of theropepermit:s the weight to drop on the driving head attached to the casing.
Various types of
chopping bits are used to facilitate the driving of casing through soils containing. cobbles and boulders.
Large
boulders must be either blasted with explosives or drilled with a diamond bit or a roller rock bit.
The casing is
raised several feet prior to blasting operations.
4.4.4.2
Skid-Mounted Rotary Drills.
Usually used in steep
terrain or other places where access is limited (physically or by other constraints - as environmental), these drill rigs are portable and lightweight. position by dozer or by helicopter. of a skid-mounted rig.
4-27
They may be placed in Fig; 4-13 is a schematic
Skid-mounted rigs are extensively used for exploration work and most are specifically made for diamond core drilling. The rigs may have a detachable mast or portable tripods may be used.
Generally the hoist arrangement is capable of ten-
foot pulls . . The machines are equipped with a hoist drum which can also be used as a winch in moving the machine. under its own power.
Catheads are often attached, which
gives more flexibility in driving casing or even in taking samples in soft zones.
The power unit is typically an
automobile type four- or six-cylinder engin~"~" .. Jk>tation is achieved through the drill head and
tll!;J/~{lpEi!ed<9!fi
rotation is
controlled by the engine speed. set in any position, makin,lltiiAt.: horizontal borings ,or -,;
tion.
pos~l.~M~)'io drill~~9le
eveh.I~~~ticai'l;i?~;rings ~'-;-<'-_-__
--,-~-:-((--
borings,
in an upward direc-
\ni~l.'
Feed meolrarii sm$i·inc rii~e.lilci-~~", ~f'hydra ulic feeds.
For
most exploration work the hydt'aulic feed is desirable since the operator hasoomplete;~Control of the rate of feed and .
.
the pressureo£" the''bi t face against the rock.
Screw feeds,
on the6ther hand, generally give the operator a choice of four rates of feed.
The lighter weight air-operated machines
are generally equipped with screw feed.
Skid-mounted rigs can be moved about in difficult terrain. The rigs can be moved by towing or they can be moved by winching on their own power.
Long moves by winching are
usually not economical and should be avoided in planning a drilling program.
4-28
Skid rigs are more adaptable to core drilling than to soil sampling.
Some of the larger skid-mounted rigs can do
certain types of soil sampling, however, skid-mounted rigs are not recommended for extensive soil sampling projects.
4-29
TABLE ~-l ONSHORE GEOPHYSICS FOR ENGINEERING PURPOSES ~AHE
OF InHOC
pnemunE on PRIt:CIPLE UTILIZEC
APPLI ct,", I LI TY
SEISMIC METHODS REFRACTION
HIGH RESOLUTION
BASED ON TIME REQUIRED FOR SEISMIC WAVES TO TRAVEl FROM SOURCE OF BLAST TO POINTS ON GROUND SURFACE) AS MEASURED BY GEOPHONES SPACED AT INTERVALS ON A LINE AT THE SURFACE. REFRACTION OF SEISMIC WAVES AT THE INTERFACE BETWEEN DIFFERENT STRATA GIVES A PATTERN OF ARRIVAl TIMES VS. DISTANCE AT A LINE OF GEOPHONES.
UTILIZED TO DETERMINE DEPTH TO ROCK OR OTHER LOWER STRATUM SUBSTANTIALLY DIFFERENT IN WAVE VELOCITY THAN THE OVERLYING MATERIALJ RIPABILITY AND FAULTING, GENERALLY LIMITED TO DEPTHS UP TO IUu FT. OF A SINGlE STRATUM. USED ONLY WHERE WAVE VELOCITY IN SUCCESSIVE LAYERS BECOMES GREATER WITH DEPTH.
REFLECTION
ARRIVAL OF SEISMIC WAVES REFLECTED FROM THE INTERFACE OF ADJOINING STRATA.
GEOPHONES RECORD TRAVEL TIME FOR THE
SUITABLE FOR DETERMINING DEPTHS TO DEEP ROCK STRATA. GENERALLY APPLIES TO DEPTHS OF A FEW THOUSAND FEET. REFLECTED IMPULSES ARE WEAK AND EASILY OBSCURED BY THE DIRECT SURFACE AND SHALLOW REFRACTlQN IMPULSES.
CONTINUOUS VIBRATION
THE TRAVEL TIME OF TRANSVERSE OR SHEAR WAVES GENERATED BY A MECHANICAL VIBRATOR CONSISTING OF A PAIR OF ECCENTRICALLY WEIGHTED DISKS IS RECORDED BY SEI$MIC DETECTORS PLACED AT SPECIFIC DISTANCES FROM THE VIBRATOR.
VELOCITY OF WAVE TRAVEL AND NATURAL PERIOD OF VIBRATION GIVES SOME INDICATION OF SOIL TYPE. TRAVEL TIME PLOTTED AS A FUNCTION OF DISTANCE INDICATES DEPTHS OR THICKNESSES OF SURFACE STRATA. USEFUl IN DETERMINING DYNAMIC MODULUS OF SUBGRADE REACTION AND OBTAINING INFORMATION ON THE NATURAL PERIOD OF VIBRATION FOR THE DESIGN OF FOUNDATIONS OF VIBRATING STRUCTURES.
RESISTIVITY
BASED ON THE DIFFERENCE IN ELECTRICM. CONDUCTIVITY OR RESISTIVITY OF STRATA. RESISTIVITY OF SUBSOilS AT VARIOUS DEPTHS IS DETERMINED BY MEASURING THE POTENTIAl DROP AND CURRENT FLOWING BETWEEN TWO CURRENT AND TWO POTENTIAL ELECTRODES FROM A BATTERY SOURCE. RESISTiViTY IS CORRELATED TO MATERIAL TYPE.
USED TO DETERMl~E HORIZONTAL EXTENT AND DEPTHS UP TO IOU FEET OF SUBSURFACE STRATA. PRINCIPAL APPLICATIONS FOR INVESTIGATING FOUNDATIONS OF DAMS AND OTHER LARGE STRUCTURES} PARTICULARLY IN EXPLORING GRANULAR RIVER CHANNEL DEPOSITS OR BEDROCK SURFACES.
DROP IN POTENTIAl
BASED ON THE DETERMINATION QF THE RATIO OF POTENTIAl DROPS BETWEEN j POTENTIAL ELECTRODES ~S A FUNCTION OF THE CURRENT IMPOSED ON Z CURRENT ELECTRODES.
SIMIlAR TO RESISTIVITY METHODS BUT GIVES SHARPER INDICATION OF VERTICAL OR STEEPLY INCLINED BOUNDARIES AND MORE ACCURATE DEPTH DETERMINATIONS. MORE SUSCEPTIBLE THAN RESISTIVITY METHOD TO SURFACE INTERFERENCE AND MINOR IRREGUlARITIES IN SURFACE SOilS.
E-lOGS
BASED ON DIFFERENCES IN RESISTIVITY AND CONDUCTIVITY MEASURED IN BORINGS AS THE PROBE IS LOWERED OR RAISED.
USEFUL IN CORRELATING UNITS BETWEEN BORINGS 1 HAS BEEN USED TO CORRELATE MATERIALS HAVING SIMILAR SEISMIC VELOCITIES. GENERAlLY NOT SUITED TO CIVIL ENGINEERING EXPLORATION BUT VALUABLE IN GEOLOGIC INVESTIGATIONS.
t·IAGNETIC MEASURHIENTS
HIGHLY SENSITIVE PROTON MAGNETOMETER IS USED TO MEASURE THE EARTH'S MAGNETIC FIELD AT CLOSELY SPACED STATIONS ALONG A TRAVERSE,
DIFFICULT TO INTERPRET IN QUANTITATIVE TERMS BUT INDICATES THE OUTliNE OF FAULTS, BEDROCK} BURIED UTILITIES,
GRAVITY flEASUREI1ENTS
BASED ON DIFFERENCES IN DENSITY OF SUB-
USEFUL IN TRACING BOUNDARIES OF STEEPLY INCLINED SUBSURFACE IRREGULARITIES SUCH AS FAULTS} INTRUSIONS} OR DOMES, METHODS NOT SUITABLE FOR SHALLOW DEPTH DETERMINATION BUT USEFUL IN REGIONAL STUDIES, SOME APPLICATION IN LOCATING LIMESTONE CAVERNS,
ELECTRICAL tlETHODS
SURFACE MATERIAlS AS INDICATED BY THE VERTICAl INTENSITY OR THE CURVATURE AND GRAVATIONAL FIELD AT VARIOUS POINTS BEING INVESTIGATED.
MODIFIED FROM NAVFAC DM-7,1971
TABLE 4-2 OFFSHORE GEOPHYS! CAL
,/
1'~ETfIOCS
CAPA3! L1T1ES
PURPOSE
CHARACTERISTICS
PRECISION DEPTH RECORDING DETERMINING BATHYMETRY.
MOST RECOROIN~ SOUNDERS OPtRATE AT tOU KHZ, PIPE MOUNTED TRANSDUCER. LITTLE SUBBOTTOM PENETRATION.
FOUR DEPTH RANGES COVER 0-205 FEET; RANGE DOUBLING SWITCH P,RMITS BOTTOM TRACKING 10 410 FEET; ACCURACY OF O,)l OF INDICATED DEPTH.
STRATASONOE ACOUSTIC HYPACS
SEISMIC PROFILING (SHALLOW) - CHARACTERISTICS OF SURFACE MATERIALS.
LOW-FREQUENCY SotIAR-TYPE TRANSDUCER PBOEILING SYSTEM; OPERATES AT 5.0 AND 7 KHZ FREQUENCY; HIGH RESOLUTION DUE TO SHORT PULSE LENGTH AND HIGH REPETITION RATE.
RESOLVE R~FLECTtNG LAYERS WITHIN 3-4 FEET OF THE BOTTOM ~oNETRATION CAPABILITIES OF jU FEET OR LESS.
ACOUSTIPULSE BOOMER
SEISMIC PROFILING (INTERMEDIATE) - CHARACTERISTICS OF SURFACE ANP SUBSURFACE MATERIALS.
ELECTROMECHANICAL TRANSDUCER; SHORT DURATION, HIGH POWER ELECTRICAL PULSE DISCHARGES FROM AN ENERGY SOURCE INTO AN ELECTROMAGNETIC cOI.GONTROLLED METAL PLATE, B~"ERA TING A REPEATASLE·$OUND PULSE; MOUNTED I N A IiMAMAllAN SLED TOWED BYVES.aiLJ BO~BD8~~ND ACOUSTIC PUJ.SE IN oUU- UU ttz RE.GION • .---
9EEBAIES IN WATER DEPTH FROM
SEISMIC PROFILING (OE£P)GEOLOGIC STRUCTURE OF BEOROCK
LOW-FREQUENCY, HIGH ENERGY SOUND GENERATED BY RAPID DISCHARGE OF·ELECTRICAl ENERGY.BETWEENEI.ECTRODES AND A SURROUNDING FRAME; A PLAS.~A BUBijLE I S FORMED11~ REQUEHCY RANG'E OF UU. ZOANDENERGY DISCHARGES "0 U JOULES.
OPEBATES IN WATER DEPTHS OF 4U-lUUU FEET, RE~8LUrION CAPABILITIES OF J -~U FEET WITH PENETRATION DEPTHS OF HUNDREDS TO THOUSANDS OF FEET
EQU! PI·iENT DEPTH RECORDERS FATHOMETER
SElSr1IC REFLECTION PROFILERS
SPARKER
~8~ ~
S IDE SCAN SONAR
. BOTTOM SURFACE FEATURES
MARK
lB;
SOIiAR IMAGE OF OCEAN UP TO 50U METERS ON EACH SID'OOF TOW FISH; OPERATES AT 1 ? KHZ FREQUENCY; NEW SAFETY RELEASE HARNESS AllOWS RECOVERY OPTOW FISH . WHEN OBSTRUCTION IS ENCOUNTERED) ACOUSTIC REFLECTORS, (ROCKS J METAL OBJECTS) SAND RIPPLES) ARE SHOWN BY DARK AREAS) DEPRESSIONS ARE SHOWN BY LIGHT AREAS. BO~TOM
,1.U:..60U FEETJ PROVIDES MODERATE
RESOlUT ION WITH MODoRATE PENETRATION UP TO ,UU FEET OR MORE FOR GEOLOGIC AND ENGINEERING INVESTIGATION.
DEPENDING UPON ENERGY SELEC-
TION • HIGH RESOLUTION SCANNING CAN DIFFERENTIATE VARIOUS BOTTOM MATERIALS} LOCATE HAZARDS OR OBSTRUCTIONS (SUBMERGED HULKS} OUTCROPS).
TABLE 4-3 USE, CAPABILITIES AND LHiITATIONS OF EXPLORATION
11ETHO~S
EXPLORATION METHOD
GENEP.Al USE
CAPABI LITIES
LHHTATIONS
MACHINE PROBING AND SOUNDING
SOIL CONSISTENCY AND COMPACTNESS,
RAPID, RELATIVELY INEXPENSIVE,
WITH BORINGS) NO SAMPLES TAKEN,
HAND-EXCAVATED TEST PITS AND SHAFTS
BULK SAMPLING, INSITU TESTING, VISUAL INSPECTION,
PROVIDES DATA IN INACCESSIBLE AREAS, LESS MECHANICAL DISTURBANCE OF SURROUNDING GROUND,
LIMITED TO DEPTHS ABOVE' GROUNDWATER LEVEL,
BACKHOE EXCAVATED TEST PITS AND TRENCHES
BULK SAMPLING, IN-SITU TESTING, VISUAL INSPECTION, EXCAVATION RATES, DEPTH OF BEDROCK AND GROUNDWATER,
FAST, ECONOMICAL, GENERALLY LESS THAN 15 EEET DEEP, CAN BE UP TO 50 FEET DEEP,
EQUIPMENT ACCESS, GENERALLY LIMITEO TO DEPTHS ABOVE GROUNDWATER LEVEL, LIMITED UNDISTURBED SAMPLING,
DRILLED SHAFTS
PRE-EXCAVATION FOR PILES FAST, MORE ECONOMICAL AND SHAFTS I LANDS~JDE THAN HAND EXCAVATED, INVESTIGATIONS) MIN, 3U INCHES DIAJ MAX. DRAINAGE WELLS, b FEET DIA,
EQUIPMENT ACCESS J DIFFICULT TO OBTAIN UNDISTURBED SAMPLES 1 CASING OBSCURES VISUAL INSPEC-
DOZER CUTS
BEDROCK CHARACTERISTICS RELATIVELY LOW COST, DEPTH OF BEDROCK AND EXPOSURES FOR GEOLOGIC GROUNDWATER LEVEL, RIP- MAPPING, PABILITY, INCREASE DEPTH CAPABILiTY OF BACKHOES, LEVEL AREA FOR OTHER EXPLORATION EQUIPMENT,
EXPLORATION LIMITED TO DEPTH AMvE GROUNDWATER LEVEL,
TRENCHES FOR FAULT INVEST IGAT IONS
EVALUATION OF PRESENCE DEFINitiVE LOCATION OF AND ACTIVITY OF FAULTING FAUlnN~, SUSSURFA~' ANO SOMETIMES LANDSLIDE OBSERVATIONUP"TO 50 FEET,' ' PEATURES,
TIME-CONSUMING, REQUIRE SHORING, ONLY USEFUL WHERl:DATABLE MATERIALS ARE PRESENT, DEPTH LIMITED TO ZONE ABOVE GROUNDWATER LEVEL,
OPE~:
NEED TO BE CLOSELY CALIBRATED
SUr-FACE EXPLOnATION EXPENSIVE 1 TIME CONSUMING 1
TION,
~OSTlY,
DEEP EXPLORATIONS AUG!;R BORINqs
HAND AUGERS POWER AUGERS
__ -,_".:.>,-_~-,--
-:,_0 ___ --
:: ,-,.,,:
~ENERAL Ex!>LidRATION;,J.o'R c 'sl~p"~.lIGHT INEXPEN-
,REPRESENTATIVE DISTURutltstVE, SAMPLES,- - -' ' , --
AD';~NCiN~AIlDCkEANING BORI~Gs, DRll~JNG
BORINGS, DRAINM' WELLS, PREEXCAVATION FOR PILES OR PIERS, 'NOT OFTEN USED FOR FOUNDATION INVESTIGATIONS, DRILLING COBBLY ALLUVIUM OR GLACIAL DEPOSITS, INSTALL ROCK ANCHORS, DRILL BLAST HOLES, DRILL GROUT NIPPLE HOLES, ACC~$SIBLE
WASH BORINGS PERCUSSION DRILLS
CHURN DRILL
FAST, CAN REACH DEPTHS UP TO lOU FEET,
SLOW BATE OF PROGRESS J LESS
THAN 10 FEET DEPTH, CANNOT BE USED IN STIFF OR DENSE SOILS, CASING IS REQUIRED IN UNSTABLE SOILS AND BELOW GROUNDWATER LEVELS, DIFFICULT TO IDENTIFY LOCATION OF SOIL CHANGES, DISTURBED SAMPLES,
FAST, PROBING TO BEDROCK
DISTURBES MATERIAL, LIMITED SAMPLING,
EFFICIENT METHOD TO PENETRATE ROCK, ALLUVIUM OR GLACIAL MATERIALS,
EXCESSIVE GROUND MOISTURE cAUSES
RUGGED) DEPENDABLE) WATER WELL DRILLING, DRILLING COBBLY ALLUVIUM SIMPLE OPERATION CAN OR GLACIAL MATERIAL, ORILL TO GREAT VEPTllS, NOT AFFECTED BY GROUNDWATER LEVEL,
JAMMING AND MAY STOP DRILLING J
OIFFICULT TO LOG AND SAMPLE MATERIALS,
SLOW PROGRESS 1 SAMPLING NOT
RECOMMENDED BECAUSE OF DIS-
TURBANCE} DIFFICULT TO LOG,
ROTARY DRILLS TRUCK MOUNTED
SKID-MOUNTED
ALL SOIL AND ROCK EXPLORATION,
ROCK CORING
MOBILE, FAST, EFFICIENT, ALLOWS CONTINUOUS SAMPLING EASE OF IDENTIFYING SOIL AND ROCK CHANGES, WIDE VARIETY OF SAMPLING TECHNIQUES, LIGHT-WEIGHT J
PORTABLE~
CAN BE MOVED ABOUT IN OIFFICULT TERRAIN,
LIMITED TO ROAD ACCESS, LEVEL
DRILLING AREAJ DIFFICULT TO
DRILL ALLUVIUM OR GLACIAL DEPOSITS OR WHERE WATER LOSS OCCURS, MORE ADAPTABLE TO CORE DRILLING
THAN SOIL SAMPLING,
(
I r I I
(
!
~
t--UEATS
'-r 4· ··1&"
OR
::J
~"
CLE,o.T
·-~-lOCT:;::
f
11
PRENTIS L WHIT~. ltNOERPI>lN'tlC;, I~~'. p.
A - SPACERS
.tiQTCHED BOX SHEETING
BOX SHEETING WITH CLEATS BOX SHEETING WITH LOUVERS
,.
WALE
i
.;
,~[ i I"'-WQOD
S~~ET
OR
6.
B - SLOTS
A-INCLINED BOARDS
'--'-
,
STE£~
,. ..........
h ..
'
hi
,
I'I~'NG.
B-VERTICAL BOARDS
POLING BOARDS
,
"
~
'
,.
.. : ,
"""'-
..
'.
0:
..
'li
~
:
g
-
1; ~ :
/WELI.. POINlS
I
I
I
I
(,
,
:
I
,
,"
TEST PIT AT FRANKLIN FALLS DAM VERTICAL SHEETING - ONE LIFT
VERTICAL SHEETING- TWO LIFTS
VERTICAL SHEETING-THREE LIFTS-WELL POINTS
Modified from Hvorslev, 1965
TEST PIT SHEETING Figure 4-1
SHORED TRENCH
Figure 4-2
SIDE HILL TRENCHING Spoil
=l
INCORRECT
CORRECT
NOTE; When the backhoe is tilted on sidehills, the spoil is dumped on the uphill side for stability; with a level pad, downhill dumping is possible.
TO AYOID CLOSING GROUND CRACKS Ground Cracks !Ruptures or Projected Fault Zone
(
Backhoe Arm Reach .............-Backhoe Weight -
I-- 15' - 25'
_ 0_0_0_0_0_0_0-0_0_0
-Backhoe
/
Trenching Direction For Second Segment
~
I /
0.........
~\
Weight-~·~
Trenching Direction For • First Segment
____ _ Fault Zone
I
BACKHOE TRENCHING TECHNIQUES Figure 4-3
\
SMALL HELICAL AUGER
POSTHOLE OR IWAN AUGER
LARGE HELICAL OR WORM TYPE AUGERS
~..
V
SPRAGUE &. HENWOOD SPOON AUGER
VICKSBURG HINGED AUGER
BARR_~L
AUGERS
BUDA CONTINUOUS HELICAL AUGE RS
ModiFied from Hvorslevr 1965
AUGERS Figure 4-4
CLEARANCE CUTT
---. -HELIX
TOOTHEO CUTTER LIP-
(a) HELICAL
-
___ SHUTTER PLATE
CLEARANCE CUTTER·
_-HAND TRIP FOR UNLOADING
' ,'.
,
,
,i
-",;
•
1 1 ·
ROCK BUCKET
CHOPPING
BIT
HINGED BOTTOM
CUTTER
CUTTER (c) BARREL Earth Manual, U5BM, 1974
LARGE AUGER TYPES Figure 4-5
Acker Drill Company
CONTINOUS FLIGHT AUGER
Figure 4-6
LARGE HELICAL AUGER
Figure 4-7
BUCKET AUGER Figure 4-8
SI~OU
(101
()QU~.[ CRQW~ ~[.ve· H()o~
~UUlPlE ~UX;KS
FOR
I'V,LI~O
FOR
OF CJ.MNO
., (:~SIN(jC!lllPUNfi
'J
n .' 11
DRilL IWO
(:O~PLlNO
:1
i
::
DRI~E5I1Oo-
I:
FOR SIlPfOllT Of DRILL ROD OIITSIOE C01lPlIN(l5
WlT~
DIlILL BIT
Wash Boring
o Fork
Hoisting Plug
11
Ii!
! I!
..: ··i, ~
!
:~
i
OFfSET CRilL
:: ~
I
Drill Rod
Wash Boring Bits Mod1fled from Hvorslev, 1965
WASH BORING Figure 4-9
1.
.....
S. L1ft. awJ.ng, aDd tUt
2. Roller feed clala
..
•
Slldlng cOIle
Hydraullc nlnl cyllPder
S. Drilling 'IaUOII ~ullc
feed !notor
TUt ey)J.Q.del
•• Gra"ler track 10. Lift cylmder 11. Lubricator p.unp
12. IJQom iJWlng cyl1ndor 13. Trammtng control,
l<. DetelJ«l.t lalllt
(:'Qlut,syof Ch/cagrJ Pntumatlc Tool COmpany
J'
.,:,,.;
• ',I,· .1'1\,. -•• ~
" .,j.'
PERCUSSION DRILLS Figure 4-10
DIESEl. PILE DRIVER ANVIL AIR COMPRESSOR
AIR IN
'4/~
OUr
~o
_I
_
HAMMER IMPACT
Q)
JOINT DOlJBLE-WALL DRIVE PIPE
,.
,•
DISCHARGE
NOZZLE FOR CORE MATERIAL
Bf;lckor Drilling (Alborta) LTD.
BECKER HAMMER DRILL Figure 4-11
~ - DRILL RODS
TWO~CONE
TRI-CONE
BIT
FIG.
44 ~
BIT
ROCK
ROL.L.ER
AND
COUPLINGS
BIT
BITS.
FIG.4S - SAFETY
CLAMP
FIG.46 -SpiDER AND SLIPS
MO(flrled from Hvorslev, 1965
,,
,
ROTARY DRILLING EQUIPMENT
FIgure 4-12
BOLT B. CLEVIS DOUBLE SHEAVE
4- LEG DERRICK"'..,.
WATER SWIVEL
ROO
ORILL
HOCK
------
DIAMOND Ct,SING . ORILI. RorJ COllPLING /ORILL ROD
BED RUCK
CORE BARREL .
r~EAMEf~
Acker Drill Company
SKID-MOUNTED ROTARY DRILL
Figure 4-13
S,ECTION 5
5
SOIL SAMPLING & FIELD TESTS
Sampling is usually the prime objective of exploratory excavation Or drilling, regardless of whether or not the sample is retained.
For some projects in situ field testing
may be the objective.
Often both operations are included
in the same exploration program.
When
s~mpling,
every pre-
caution should be taken to obtain representative and uncontaminated samples; to see that the samples are adequately and correctly identified as to location, ma:terial, and properties; and to protect the samples from damage from the time they are removed from,the sampler to the time they are used for field logging and/or deli",i;i:ped to the laboratory. wi thout the information' gained frolJl sampling and field testing, much of the information r~quired to formulat,e reasonable design criteria is missing.
Furthermore, i f 1)
the·information is not representative, 2) the sample is disturbedI;;;Y miE:ibandling or improper preparation, or 3) the sample is contaminated, the erroneous data gained from such samples may result in costly overdesign or disastrous underdesign.
Basically, there are two types of samples, undisturbed and disturbed.
The types may be broken down into subtypes,
based to a large degree on the method of obtaining the sample.
Ideally, the type of testing to be performed will
5-1
be the chief factor in deciding the methods used for sampling.
Practically, the equipment available for the job (Section 4 covers equipment in
may be a governing factor. some detail.)
5.1
PREPARATION FOR SAMPLING
Section 4 of this Guide discusses the various methods used in advancing the boring to the desired depth for sampling. All methods have in common that the boring is opened, and kept open long enough to permit sampling.
The method chosen
for advancing the boring should not cause a significant disturbance of the underlying soil to be sampled.
In bucke:t auger work, disturbance of the sample material is limi ted generally to the depth of the cutting teeth.
Bulk
samples are representative of the stratum cut in that particular zone.
In wash borings, considerable disturbance below the bottom of the boring can be caused by careless handling of the bit and by excess erosion when the flow of the wash water is not properly, controlled.
Coarse, segregated materials
tend to collect at the bottom of the boring, and sticky soils may adhere to the casing instead of being removed by the wash water.
Careful cleaning of the boring is therefore
required before samples are taken.
5-2
The choice of washing bit depends on the nature of the (
material being penetrated.
It is important in selecting a
bit that the water flow is restricted, and not applied in a heavy stream against the bottom of the boring.
using an
open-ended rod without a bit should never be allowed, nor should a sampler be used without the check valve.
The coarse
material that collects in the boring is very difficult to remove.
Methods that can be tried to clean the boring include
2 or 3 drive samples between desired sampling depths, and pushing a Shelby tube just for the purpose of removing the material.
cuttings may also be removed, just prior to
taking an undisturbed sample, with a clean-out auger (Fig. 5-3).
Bulk samples cannot be obtained from wash borings.
The cuttings from the wash can be retained (they are sometimes called "wet samples"), but they are not representative, as the fines are in suspension and the coarser sizes are broken up or remain at the bottom of the boring.
Rotary drilling methods are usually effective in cleaning the boring right to the top of the sample, as the drilling fluid, if properly mixed, can transport all but the largest gravel sizes.
Bits used in rotary drilling disperse the
drilling fluid so that erosion into the soil to be sampled is limited.
The fluid passageways are also designed to
protect the sample.
If the boring is starting to squeeze
closed, material can be inadvertently scraped off the sides in lowering the sampler, partially filling it or the boring with materia], from another s·tratum.
Careful cleaning of
the boring is required when that condition exists.
5-3
Disturbance of the soil at sampling depth can be quite extensive with the hollow stem auger.
The rate at which the
auger is· rotated and advanced, the choice of teeth on the auger, the depth below the groundwater level, and the character of the soil are all factors in the extent and seriousness of the degree of disturbance.
Sampling from the flight auger is limited to bulk samples. It is difficult to define the depth from which the soil, discharged by the auger, was excavated.
Fig. 5-1 schematically
shows atypical flight auger se.tup.
5.2
METHODS OF ADVANCING SAMPLER
Sample tubes or barrels are normally advanced into the soil by three basic methods:
pushing, hammering, or rotating.
Of the three methods, pushing is usually preferred for undisturbed sampling.
However, in firmer materials, it often
becomes necessary to hammer or rotate.
The means by which
the sampling device is forced into the soil has a pronounced effect on the quality of the "undisturbed" sample.
It is
obvious that the method used should be such that it will cause the least disturbance to the soil. pushing.
pushing is accomplished by exerting a steady
continuous pressure to force the sampler into the soil. pressure is usually supplied by hydraulic means.
The
pushing
has been found to be the most satisfactory mechanical method
5-4
of taking undisturbed samples.
Experience has indicated
that the soils must be relatively soft to prevent excessive pushing pressures from occurring.
The gage pressure should
not exceed 250 psi when pushing thin wall brass tubes, or 500 psi when using steel tubes, or deformation of the tubes may occur. Hammering.
Hammering is accomplished by repeated blows of a
drop hammer.
This causes the sampler to penetrate the soil
intermittently, or in pulses.
Such motion sometimes results
in objectionable disturbance of the sample.
Vibrations
caused by hammering may also result in serious disturbance. In general, the hammer method should only be used when the sampler cannot be advanced by pushing or when the "blow count" data are especially needed.
A discussion of "blow
count" data is presented under the heading Standard Penetration Test, paragraph 5.9.1.
Fig. 5-2 shows a rotary drill setup
wherein blow count data can be obtained when driving a split barrel sampler. Rotating.
Rotating indicates the sampler is advanced by
rotation, together with the application of hydraulic pressure. The Denison Sampler and the Pitcher Sampler are examples of samplers used with this method of obtaining a sample.
5-5
5.3
UNDISTURBED SAMPLES
As a broad definition, undisturbed samples are ones in which the materials have been subjected to so little disturbance that they are suitable for all laboratory tests, and will yield reasonable values for strength, consolidation, and permeability characteristics of the material as it exists in situ.
Care should always be taken in obtaining a sample;
however, there will always be some degree of disturbance. The disturbances that can affect the samples can be classified as follows.
1)
Changes in stress conditions - There is not a great deal that can be done to prevent changes during the sampling process, as it involves the changes that occur in removing a sample from the confinement and pressures acting on it in the ground and exposing it to atmospheric pressures.
2)
Changes in water content and void ratio - Some uncontrollable changes do occur during sampling. Properly and promptly sealing the sample, avoiding prolonged exposure, avoiding shocks and vibrations in handling, and arranging for prompt testing will minimize these changes.
3)
Changes in the soil structure - The choice of sampling method and the degree of care exercised in handling the sample will influence these changes.
5-6
Protecting all samples from freezing and high heat, taking proper care in preparation for sampling, minimizing the damage done in washing or drilling to the sample depth, and removing the waste material from the boring just prior to sampling will minimize these changes.
When possible,
the use of a thin-walled sampler (e.g. a Shelby Tube sampler) to minimize soil remolding, and pressing the sampler smoothly will produce a better sample.
4)
Chemical changes - There can be chemical changes resulting from the drilling fluid heing in contact wi th the sample, or from ·the exposure of the sample to the air.
Once a sample is obtained,
oxidation or corrosion can occur between the sample and the container.
Brass sample tubes or
rings are used or the inside of steel samplers are lacquered to minimize the effect.
The condition
of lacquering should be checked before using steel tubes.
The sample should be sealed to be airtight
and watertight.
The disturbances listed and briefly discussed above should be reduced to an absolute minimum; certain procedures (discussed in following paragraphs) have been established, based on experience, to reduce the effects.
It is the responsibility
of the field representative to see that the procedures are followed.
5-7
If excessive disturbance does occur, it mayor may not be detected in laboratory testing and examination.
If not
detected, then the data are potentially misleading.
If the
disturbance is detected, it may be necessary to obtain replacement samples at an unnecessary additional cost and delay to the project.
5.3.1
5.3.1.1
Sampling Equipment and Methods
Shelby Tube Sampler.
The Shelby tube sampler,
Fig. 5-4, is the simplest undisturbed sampler and, with care, excellent samples of fine-grained or soft soils can be obtained. There are, however, many ways in which the sample can be disturbed or lost.
A small chamber for disturbed soil is provided above the sample tube.
This is necessary as the lower end of the
sampler is not closed and 1) soil can be scraped off the walls of the boring as the sampler is lowered or 2) soil cuttings from the bottom of the boring may partially or completely fill the sampler prior to its arrival at the planned sample depth.
Some of the disturbed soil can vent
through the ball check into the rods, but then the vacuum may be lost when the sampler is withdrawn.
Without vacuum there
is a strong likelihood that the sample will be partially or completely lost.
5-8
\
In sampling, the rods are clamped in the drill chuck, and the sampler pressed for a predetermined distance into the formation.
After a pause of 2 to 3 minutes to allow the
soil to expand slightly in the sampler, the rods (and therefore the sampler) are rotated clockwise to shear the soil sample at the bottom of the sampler.
The sample is
then withdrawn to the surface.
5.3.1.2
St.ationary Piston Sampler.
The stationary piston
sampler, Fig. 5-5, is an improved, but more complicated sampler which eliminates most of the drawbacks, of the Shelby tube sampler.
The piston assembly at the end of the
sample prevents entry of disturbed soil during insertion to the sampling level.
After sampling, the assembly maintains
a vacuum above the sample.
The piston rod (also called actuating rod) extends to the surface through the center of the drill rods.
Thus, to take
each sample, it is necessary to thread lengths of piston rod inside the drill rods, and connect the piston rods together as the sampler is lowered into the boring.
Recovering the
sampler, and sample, is equally complicated and slow.
A piston rod lock is provided preventing the piston rod from sliding out below the bottom of the sample tube, but allowing the piston assembly to move freely up.
During insertion to
the sampling level, the piston rod is clamped to the drill rods at the surface to prevent the upward movement of the piston assembly.
5-9
Once the sampler is in place, the piston rod is unclamped and the drill rods are pressed downward for a predetermined distance. 1)
The operation is as follows: Before inserting the sampler into the boring, determine the length of piston rod that will stick up above the top of the drill rods.
2)
Once the sampler is in place at sampling depth, and the piston rod is unclamped and free to move, measure the length sticking up above the drill rods.
Technically, the length should be the same
as determined prior to insertion.
As a practical
matter, the rod will often be 1 too 3 inches higher than at the start, indicating that the piston has been pushed up a like distance, or that the sampler has moved down that distance.
Thus the space
remaining inside the sampler has also been reduced by the same length. 3)
The sample should ,be pressed 24 inches less the distance that the piston rod has risen to prevent compressing a larger sample into the available space.
While pressing the sampler in one continuous, steady stroke (at a rate of about 1 inch/sec.), the piston rod should not move down along with the drill rods.
If the piston rod
moves downward with the drill rods, the pressing should be stopped immediately and a check made ,to see that the rod has been unclamped, i.e. is free to move.
5-10
After completing the press a pause of 2 to 3 minutes should be made.
Then, 1) the drill rod should be twisted through 1
or 2 complete revolutions (to shear the soil off at the end of the sampler), 2) the piston rod should be clamped to the drill rods, and 3) the sampler should be slowly withdrawn.
This sampler is suitable for use in soft to medium clays, and should no·t be used in sandy soils.
A heavy rig with a
hydraulic drill head is required to press the sampler.
No
piston sampler should be advanced by hammering.
5.3.1.3
Hydraulic Piston Sampler.
The hydraulic piston
sampler, Fig. 5-6, is an improv(:lment over the stationary piston sampler in that the activating rods are eliminated, and the sampling can be done with light, portable drilling equipment.
Compressed air, water, or other drilling fluids,
under high pressure are pumped through the drill rods to press the sampler into the formation.
In operation the sampler is lowered to sampling depth after cleaning the boring of all debris and cuttings.
The bottom
of the sample tube should be flush with the fixed piston at the start of sampling.
The drill rods are clamped to the
drill chuck or the casing to resist reverse pressure.
Water
or compressed air is pumped through the drill rods to build up pressure in the chamber between the head and the sample
5-11
tube carrier, forcing the carrier and the sample tube into the formation.
Once the tube is fully extended, the excess
pressure is vented into the boring.
On extraction, the
fixed piston is in immediate contact with the top of the sample and a vacuum is developed that helps to prevent loss of the sample.
This sampler, as with the stationary piston sampler, is suitable for use in soft to medium clays, and should not be used in sandy soils.
It can be operated with a light drill rig equipped with
a high pressure pump.
The sampler should not be advanced by
hammering.
5.3.1.4
Double Tube Core Barrel.
The double tube core barrel
may be used successfully to obtain relatively undisturbed samples of sand and silt above the water level, stiff to hard clays, soft shale, and soft and friable sandstone.
sampling combines drilling and undisturbed soil sampling techniques.
The outer tube is provided with cutting teeth
and is rotated to cut away the surrounding soil.
The inner
barrel does not rotate, and is pushed ahead as the outer barrel rotates.
5-12
A core retainer consisting of very thin and overlapping springs is placed in the joint between the shoe and the inner tube.
The inner tube has a liner in which the core is
preserved during shipment and storage.
The inner tube of
the core barrel has a shoe with a sharp cutting edge.
In the Denison Sampler, Fig. 5-8, the extension of the cutting edge below the outer barrel bit can be varied from zero to about 3 inches by means of interchangeable coring bits of various lengths.
The maximum extension is used in
relatively soft or loose soils, and a cutting edge flush with the coring bit is used in very stiff, in dense, and in brittle soils.
The operation of the Pitcher Sampler, Fig. 5-9, is quite similar to the Denison Sampler.
The major difference is
that the extension of the inner barrel beyond the cutting edge is not pre.set as in the Denison, but can vary, depending on the downward pressure on the rods and on the spring tension.
As a result, there is a constant pressure on the
cutting edge.
Thus in soft zones, the inner barrel may move
further ahead of the core teeth; in a harder layer the tube is forced back even with the teeth.
5-13
5.3.1.5
Hand Trimmed Samples.
Hand trimmed samples may be
obtained in test pits, in test trenches, or in surface exposures.
Samples so obtained are potentially the least
disturbed of all types of samples.
The basic procedure
consists of trimming out a column of soil the same size or slightly smaller than the container to be used in transportation, sliding the container over the sample, and surrounding the sample with wax.
Tight, stiff containers
that can be sealed, and are not readily distorted, should be used.
The actual method used will depend on the soil.
In very
soft or cohesionless, dry soils, it is probably best to press a cylinder with a sharp cutt,in g edge over the soil without much trimming.
If the material exhibits significant
cohesion, or is firm and without gravel sizes, then the sample may be trimmed to a size just slightly larger than a container with a sharp cutting edge.
The container can then
be slid over the sample, using the cutting edge to remove the excess.
If gravel is present, or if the material is
only slightly cohesive, the sample can be disturbed by forcing the container over it; therefore, the sample should be trimmed so that there is
~
inch to
~
inch of clearance on
all sides inside the container and the void between the sample and container filled with wax.
5-14
5.4
DISTURBED SAMPLES
A disturbed sample is one in which the strength and structure of the material are not necessarily preserved in sampling. The purpose of such samples is to obtain representative examples of a stratum for examination, identification, and testing.
Such samples may be obtained from test pits or
test trenches, auger borings, or from conventional borings in split or solid barrel samplers.
5.4.1
Sampling Equipment and Methods
5.4.1.1
Split Barrel Sampler.
The split barrel sampler,
Fig. 5-11, is simple in design, and can take considerable punishment without damage.
It is normally driven with a
standard weight hammer as part of the Standard Penetration Test, discussed in paragraph 5.9.1.
In its standard form, the split barrel sampler is 2.0 inches in outside diameter, and 1 3/8 inches in inside diameter.
Length varies, but preferably is 24 inches from
the tip of the drive shoe to the upper end of the split barrel (Appendix C).
Larger size split barrel samplers are
used, some being fitted with inner sampling tubes or rings. Under certain soil conditions samples obtained in tubes or
5-15
rings are considered undisturbed samples and may be suitable for laboratory testing to evaluate strength parameters.
When
the sampler is equipped with tubes or rings, it is not used with the flap valve illustrated in Fig. 5-11 but it may be equipped with a spring core retainer.
Core retainers often
cause sample disturbance and the field representative should carefully inspect the samples to observe the extent of disturbance and decide if the retainer should be removed.
The sampler is lowered to sampling depth and driven for an 18- or 24-inch distance, or until an excess of 100 blows are required for the sampler to penetrate 6 inches or less using a l40-pound or heavier hammer.
After sampling, it
is disassembled, the sample removed, and a representative sample is usually preserved in sealed glass jars.
5.4.1.2
Converse Sampler.
The Converse Sampler, Fig. 5-10,
i
is a simple and rugged device which can be used to obtain representative samples of the stratum and under certain conditions may be used to obtain relatively undisturbed samples of dense soils that cannot be obtained with a thin walled sampler.
It may be pressed or hammered into the
ground without damage to the sampler.
The samples are
retained in brass liners which may be extruded in the field for classification and logging or they may be stored in plastic cans for laboratory testing.
The sampler is
driven with the kelly bar of a bucket auger or by whatever
5-16
drive hammer is available.
'fhe drive energy may be converted
by formula to ft.-kips/ft.
The sampler has been used for
many years in Southern California and extensive drive energy data have been accumulated for correlation purposes.
The
field representative should record the kelly bar or hammer weight and drop distance used, and the number of blows per 6 inches of penetration of the sampler.
5.4.1.3
Retractable Plug Sampler.
The Retractable Plug
pr Porter Sampler, Fig. 5-7, is useful in obtaining samples of soft soils not accessible to conventional drilling equipment. It consists of an outer tube and an inner rod made up in sections depending on desired length.
The sampler plug is
held in the forward position preventing any material from entering the sampler.
At the desired depth, the plug is
withdrawn, and the sampler is driven forward. should be avoided.
Hard driving
When the sampler is withdrawn, the tubes
are removed and the sampl.es may be extruded for field classification or the tubes may be capped and sealed and sent to the laboratory.
The sampler is recomnended for
recovering silts, clays, and fine loose sands only; the samples obtained are not suitable for strength testing.
5.4.1.4
Bulk Samples.
Disturbed samples obtained by hand
from the ground surface, road cuts, pits, or trenches are ordinarily called bulk or grab samples.
5-17
Also included in
this category, however, might be those samples obtained from equipment operations such as backhoe, dragline, and flight or bucket augers.
Bulk samples can be taken in a variety of
containers ranging from small plastic bags to barrels.
The
size of sample required depends upon the type of testing to be done on the material. in paragraph 5.5.
A discussion of sample size follows
If natural moisture is a factor to be
considered at least a small portion of the sample should be placed in an airtight container.
It is important that all bulk
samples be taken in an orderly sequence, that accurate records or logs be made of each sampling location and that those samples are as representative as possible of the total soil deposit being explored.
5.5
SAMPLING OPERATIONS
It is important that the field representative keep current as to exactly what is occurring in the drilling operations. A close count should be kept on the number of rods in the drill stem, the length of the sampler, the length of the drilling
bit, or the length of auger bucket being used.
The field representative should know the length of casing in place or the depth of boring at any time to the nearest inch.
Most drill rods and casing used are in even lengths,
drill rods are usually in lengths of 1, 2, 5, or 10 feet and flush joint casing is in lengths of 2 or 5 feet.
(There
are some metric sizes in use that are near, but not the same as the convention.al rods.)
Some rods and casing may have
5-18
been cut down and rethreaded.
,
\
Drive shoes on casing can add
a length that is readily forgotten.
Sampler and chopping
bits come in all sizes.
One good field rule is to measure and check everything to be used at the very beginning of field operations.
If the rods
and casing are all the same, then the problem of control is reduced.
For example, one rod 6 inches shorter than the
rest, or a forgotten drive shoe 6 inches long, can mean that sample depths being recorded are inaccurate by 6 inches. If the field representative observes that there has been driven, for example, five lengths of casing, each 5 feet long, plus a 6-inch drive shoe, and that the casing is sticking 6 inches above the ground, then the bottom of the casing is exactly at the 25-foot depth.
However, if the driller then
lowers a 30-inch long- sampler down the boring on a string of rods made up of two 10-foot lengths and a 5-foot length, the rod should not stick anything other than 30 inches above the ground, or 24 inches above the casing.
If the measurements
are not as calculated, the field representative should find out what is wrong before the sampling operation proceeds. The check is easy wi-th one quick measurement and a little mental arithmetic.
Each field representative will evolve the
best method of keeping current as to the exact depth of the boring and/or sample depth, tailored to the particular drilling assemblage in use,
5-19
5.5.1
Undisturbed
Unless certain simple precautions are observed, even though the sampler is properly designed and the boring properly stabilized and carefully cleaned, non representative samples may be obtained.
Samples may be disturbed, incomplete, or
even lost when improper methods are used to force the sampler into the soils.
The following guidance applies to sampling
operations in which difficul·ties are not normally encountered.
Preparations.--The sampler should be carefully cleaned and vents, check valves, piston packing, clamps, and other parts checked for proper function.
Tubing or liners with the
appropriate length for the sampler being used and cutting edges or shoes with the proper clearances for the soil conditions should be selected.
The lengths of the drill
rods in operating position should be checked.
(The
cumulative effect of small deviations from the nominal length may be considerable for deep borings.)
Number of Samples.--The number of samples'required from a boring depends on the purpose of the boring and the type of project.
Prior to initiation of the exploration program the
Project Manager should specify the sampling requirements.
A
common method is to sample every 5 feet and at changes of lithology; however, that frequency may be more than required for some projects or less than required for others.
5-20
Initial penetration.--The penetration of an open sampler under its own weight and that of the drill rod should be assessed.
A piston sampler should be forced through the zone
of disturbed soil before the piston is released and the actual sampling is started.
It is desirable to assess the penetration
of the closed sampler below the bottom of the boring.
The actual sampling.--Whenever possible, the sampler should be forced into the soil by fast, uninterrupted pushing.
A
single blow of a heavy drop hammer will produce equally good results provided the sampler has sufficiently large and streamlined vents and provided the material to be sampled does not have a sensitive structure;
There should be no
rotation of the sampler during the downward movement. Interruptions of the movement t.o reset hydraulic cylinders, blocking, tackle, etc., will often cause a drop in the recovery ratio and increase the penetration resistance.
Rest period.--After completion of the drive, it is advisable to wait 2 to 3 minutes before starting the actual separation and withdrawal operation to allow full development of adhesion and friction between the sample and the sample tube.
Separation of sample from subsoil.--Before starting the actual withdrawal, a moderate pull should be exerted on the drill rod while it is rotated through 2 or 3 full revolutions to be certain that the rotation is transmitted to the sampler
5-21
and not merely taken up in the joints of the drill rod. The initial pull should facilitate separation of the sample from from the subsoil, but it should not be so great as to cause an upward movement of the drill rod before the sampler has been rotated.
Withdrawal of the sampler.--After rotation, the sampler should be withdrawn slowly and at uniform speed; great acceleration, shocks, and vibrations should be avoided, especially in sampling of soft or cohesionless soils.
The sample is often lost at the
moment the sampler is raised above the surface of water or drilling fluid in the boring.
The fluid surface sinks as the
drill rod and sampler are withdrawn, and it is advisable to keep the boring filled during the,withdrawal, except in a dry boring.
5.5.2
Disturbed
Disturbed samples obtained with any of the samplers are taken in much the same manner as previously described.
Bulk samples,
on the other hand, are usually transferred from the sampling location to the container by shovel.
It is important that representative samples be obtained.
In
sampling open banks such as road cuts or trenches, an excellent technique is to take a "channel sample" where a channel about 12 inches i.n width is delineated from top to bottom of the bank. Shovel samples are obtained systematically with depth and at
5-22
changes in lithology of the soil.
A composite sample would
be a representative mixture of material from the top to the bottom of the channel.
Sampling from a flight auger is done by grabbing samples as the soil rises to the top of the flights.
The field
representative should be aware of the lag in time from when the auger bit bores into the soil and when it reaches the top (Fig. 5-1) and should account for this lag when recording the depth of sample.
Sampling requirements vary, but,
samples are often taken systematically such as at 5-foot intervals and at changes of material.
sampling from helical, disc and bucket augers (Fig. 4-5) is similar in that Samples are obtained directly from the auger or from the disposal pile after dumping.
Determining
depth of sample from these augers is much easier than with flight augers.
Sampling is done systematically as previously
described for flight
5.6
5.6.1
auger~.
PREVENTING LOSS OF SAMPLES
Undisturbed
The greatest danger of loss occurs at the start of the withdrawal and until the cutting edge of the sampler is above the bottom of the boring.
The principal causes of loss of samples
are the following:
5-23
1)
excessive air or water pressure on top of the sample, caused by fluid in the drill rod; air between the top of the sample and a check valve; and leakage around check valves or pistons, through joints in the liner, or between the tubing and the sampler head;
2)
improper clearance ratio between cutting tip and sample tubes;
3)
insufficient development of friction and adhesion between sample and sampling tube or liner;
4)
insufficient length of sample to transmit the required total forces from the sample tube or liner to the sample;
5)
great tensile strength of the soils, or adhesion between the subsoil and bottom of a sample;
6)
development of a partial vacuum'or a decrease in hydrostatic pressure below the sample;
7)
progressive internal failure of soil with little or no cohesion, caused by its dead weight and/or a downward flow of fluid through the sample, or due to turbulence in, and erosion by, fluid below the sampler during rapid withdrawal; and
5-24
exces!?ive aocelerationapd speed, s.hocks, and /
vibrations during withdrawal of the. sampler.
The total friction and adhesion between sample apd sampler . . increases with increasing length of sample, whereas the differenoe between the forces aoting on the top and bottom of the sample.ispraotioal)..y
indep~ndent q£
the length but
incrE;lat;les with increasing. cross-sE)otionalarea Or with the square 9f the diameter of the sample.
Likewise, the danger
Of pJ;Cogressive internal failure of the soil,inc;t;eases rapidly with inc;t;easing diameter of.thflsamPle.
In general,
the difficulties in retaining the Sample dll;t;ing withdrawal deGrease with increasing length and'.increaaewith increaEling diameter of the sample.
When precautions. are taken,. saniplE;ls up to .3 inohes I
;2
inohes, and often
in diameteJ;' , oan usually be r.etained without
difficulty, at least whE;Jn samplers with a piston are use9-' When diffioulties are enoountered in r.staining samples of small diameter, it is generally suffioientto malee minor modifications in the sampling.procedure and equipment.
Suoh
modifications may also suffice to retain large-diameter. samples of many soils, but special methods and equipnv;mt are often rE;Jqvired to prevent lOSEl of large-diameter samples of soft or oohesionless soils.
5-25
Before making any massive changes in sampling procedures, the sampler should be thoroughly inspected to ascertain that its various parts are in proper working condition.
Defective
p'arts should be cleaned, repaired, or replaced as may be' requ'ired.
The ball check valves are easily fouled by dirt, and should be cleaned p'rior to each sampling.
Leakage through' the
joint between a sample tube and the adapter, between the top of a liner and the sampler head, and through, tti!fJoints in a split' barrel may decrease or destroy t~¥l£fe¢t:ivEmess of check valves and cause loss of sayl~":fg~,especia'11y in cohesionless' soil . .-, ,.'" -'-' -,. :->~\!:r> One of the most;, wfdely
samples of soLE.Consists of :~t~vidi~g core springs, flap valves, or 61jlter}t.ypes·oi"'.core retainers in the sampler -
shoe •
--',
The me'tnbdfgi. simple in operation and generally
successfu.}·iIiretaining samples of stiff soils, but it is not always effective when the sample consists of very soft soil or loose cohesionless soils.
The core 'retainer may cause
disturbance of such soil samples and may not be effective in retaining the samples.
A small increase in the length of the rest period between completion of the drive and start of the withdrawal will, in many cases, increase the adhesion and friction between the sample and the sampler.
This may also increase the strength
5-26
of the thin layer of disturbed soil at the surface of the sample, especially in soils which are very sensitive to remolding.
(The increase in strength of the disturbed
surface layer is, in part, caused by dissipation of excess porewater pressures and consequent consoU,.dat:i.on and, in part, by thixotropic processes.)
On the other hand, an excessively
long rest period may permit appreciable consolidat:i.on or 1iwe),.ling of the whole sample and/or an increase in outside friction and adhesion such that the sampler cannot be rotated without breaking or distorting. the joipts in the drill r<;ld, the joint between the adapter and thin-walled sample tube, Or the t1.11;>e itself.
Short samples are often lost because the total inside fr:i.ction and adhesion is insufficient to transmit the forces required to separate the sample from the. subsoil by a direct pull, or by combined pull and. rotation.
An increase in length of
sample may, in such cases, be sufficient to prevent loss of aample.
Actua),. overdriving is one of the oldest and most effective methods for preventing loss of samples of cohesion less or partially saturated soils.
Although it may cause compaction
of the samples (an undesirable disturbapce), it increasea the inside wall friction and the strength of the soil.
Therefore,
overd:r:iving should be used only when a disturbed sample is acceptable.
5-27
5.6.2
Disturbed
Much of the foregoing discussion concerning undisturbed samples applies to disturbed samples when using samplers. /
Even when a sample will not be used for strength testing, it is 'very important that it be obtained in a form so that logging of the lithology and structure can be confidently accomplished.
Loss of samples from auger operations is generally not a problem.
When it occurs it is usually due to poor condition
of equipment (e.g. worn cutting teeth) or the wrong equipment for the work.
5.7
SAMPLE SIZES
The size of sample will vary depending on the grada'tion of the material and on'ttie intended use of the sample.
Only a
few ounces are needed for a visual identification of a finegrained soil, while a pound or more might be necessary for a proper laboratory identification of a coarse-grained soil. The following is a guide to the minimum quantities required for laboratory testing.
5.7.1
Identification Tests
Samples for laboratory identification testing will depend on the size of the coarse fraction:
5-28
Fine-grained soils (silts, clays, sand/silt combinations wit~out
gravel
si~es)
- minimum of 350 grams-say
~
pint.
Coarse-grained soils (sand-silt-gravel mixtures).
Size
dependent on diameter of largest size.
Diameter of largest gravel
5.7.2
Minimum Weight (Air-Dry) (pounds)
3/8"
1
3/4"
2~
1 "
5
2 "
10
Compaction Tests
If l&rge:;;tpaJ;'ticle size does not pass t):le #4 sieve, then a minimum of 16 pounds of air-dry soil is needed for each point on the GUrVe; thus, the sample should be between 80 and 100 pounds, with an absolute minimum of 50 pounds.
If larger size particles are present, then the larger sizes have to be sieved ou·t in the lab, and replaced with material between the 3/4" sieve and the #4 sieve.
A larger sample
consequently is needed, on the order of 25 to 30 pounds for each point on the curve, or at least 100 pounds, and preferably 150 pounds.
5-29
5.7.3
Other Tests
Permeabi l i ty A.
Disturbed 1. 2. 3.
B.
Minus No. 4 Soil Minus 3/4" Material Minus 2" Material
7 to 10 Ibs 20 Ibs 200 Ibs one 6-inch tube
Undisturbed
Direct Shear A.
Disturbed
SIbs
B.
Undisturbed
Minimum of 6 inches of material in a thinwalled sample tube or liner. Preier full 24inch recovery for full cycle of tests.
consolidation A.
Disturbed
5 Ibs
B.
Undisturbed
Minimum of 6 inches of material in thinwalled sample tube or liner.
Triaxial Compression A.
Disturbed
10 Ibs
B.
Undisturbed
Preferably full 24-inch recovery of undisturbed material in a thin walled sample tube. Minimum of 10 inches required for single test.
5-30
5.8
5.8.1
PRESERVATION AND SHIPMENT OF SAMPLES
Undisturbed
The dismantling of the sampler upon its withdrawal from the boring should be performed without shocks and blows which would cause disturbance of the sample.
The gross length of
soil samples should be estimated after eliminating any wash. If the lower part of a sample is lost, the length of the lost part should be estimated and the probable cause of the loss recorded.
Undisturbed soil samples should be preserved
in the sample tube or in liners to minimize disturbances caused by removal and handling of the unprotected sample under adverse conditions in,the field.
When the samples are
obtained by block sampling methods, they are usually given a coating Of, or encased in, wax.
Seriously disturbed parts of the sample should be separated from the undisturbed parts and discarded.
The possibility
of migration of porewater from the disturbed to the undisturbed parts of a sample is thus minimized.
When carefully performed, satisfactory protection of the sample can be obtained by sealing in wax, but difficulties and defective sealing are often encountered in practical applications.
The wax used in sealing is subject to con-
siderable shrinkage during congealing and shrinkage, especially
5-31
at joints where melted wax has been poured on top of congealed and relatively cool wax.
Samples in long, thin-wall sample tubes or in long liners may be sealed with a plug of paraffin and beeswax at least 3/4-inch ·thick.
The wax should be applied at a temperature
as close as possible to its congealing temperature. The physical properties of the wax can be improved to some extent by mixing several grades of paraffin having different melting and congealing temperatures and also by admixtures of ceresine, carnaubawax. or beeswax.
Beeswax does not
shrink as much as paraffin and has stronger adhesion to metal, but it is not as airtight as paraffin and should not be used when the samples are to be stored for protracted periods.
When samples are to be stored for short periods,
reusable expansible plugls are sometimes preferred in lieu of wax.
Short liner sections are sealed with caps, which should be of the same metal as the liner or of electrically inactive materials in order to avoid electrolysis and chemical changes of the soil.
It is advisable to cover the top and
bottom of samples of relatively impervious soils with a thin layer of paraffin and to place the cap while the paraffin is still liquid.
The joint between the cap and the liner
should be sealed with adhesive tape and by dipping in paraffin or sealing compound.
5-32
The joint may also be sealed
with a rubber band when the samples are to be tested within 24 hours after sampling.
However, planned testing may be
superceded and the samples stored for much longer periods; thus, the best practical seal should be obtained in the field.
When the sample consists of swelling soils, the caps
should be secured in such a manner that expansion of the sample is prevented.
5.8.1.1
Marking of Samples.
All samples and containers
should be clearly marked with the number of the project, boring and sample number, and top and bottom of the sample. Other information such as date of sampling, depths between which the sample is taken, type of material, method of sampling, gross and net
len~ths,
and recovery ratios may be
included.
5.8.1.2
Packing and Shipment.
Undisturbed samples should
be protected, as far as possible, against vibrations and shocks.
Where possible, they should be transported in
private vehicles and placed in upright position in padded crates or on a mattress.
When undisturbed samples are to be
shipped by common carriers, they should be packed in strong wooden boxes and surrounded with excelsior or sawdust.
The
samples should at all times be protected against freezing.
Undisturbed samples of loose cohesion less soils are particularly sensitive to vibrations, and they cannot be shipped by common carriers without suffering some compaction
5-33
and disturbance of the soil structure.
When such samples
are intended for accurate laboratory tests, they should be transported in private and carefully driven vehicles .
. 5.8.2
Disturbed
The sampler should be dismantled and the gross length of sample estimated after eliminating all waste.
If sample is
missing, the length of lost part should be estimated and probable cause of loss recorded.
If samples are in tubes
they can be sealed in much the same fashion as undisturbed samples for detailed logging, classification, and moisture tests in the laboratory. logged in the field.
Samples can also be extruded and
The extruded sample can then be
preserved in containers, e.g. glass jars' with screw lids and gaskets, or if there is a reason to preserve the soil structure for later examination, the extruded cores can be wrapped in foil and dipped in wax.
Split barrel samples, if
recovered during 8PT are generally preserved in glass jars with a screw top and gasket.
Bulk samples are generally preserved in plastic or canvas bags. If samples are to be stored for any length of time, it is unlikely that natural moisture can be retained, therefore, if moisture is important, a small sample should be placed in a sealed container such as a glass jar with screw cap and gasket.
5-34
5.8.2.1
Marking of Containers.
Containers should be clearly
marked with the number of the project, sample location or boring, depth interval, and sample number.
Where there is
a chance of an outside identification tag being torn off, or the information obliterated, a duplicate tag should be placed inside the container.
5.8.2.2
Packing and Shipment.
Samples should be packed for
shipment in such a manner that the containers are protected against breakage and also against excessive moisture which may cause deterioration of labels and tags.
A form of packing
and shipment where samples are not exposed to the elements is preferred.
5.9
IN SITU TESTS
other paragraphs of this section 'have dealt in some detail with the equipment and ,techniques that are encountered in exploration.
The most commonly used in situ test, Standard
Penetration Test (SPT), is explained in some detail herein while the remaining paragraphs are devoted to providing brief descriptions of unusual exploration procedures, or of tests that are not commonly performed by CWDD.
The information
contained herein is insufficient to actually monitor the performance of such tests, but provides an idea of their use and usefulness.
5-35
5.9.1
Standard Penetration Test (SPT)
The purpose of the Standard Penetration Test is to provide some means of evaluating the strength and relative density of the soils.
Correlations have been establsihed between
N-value (blows per foot of penetration) and consistency and unconfined compressive strength in clays, and of compactness in sands.
These correlations, given in Tables 7-6 and 7-7,
must be used with extreme caution.
The location of the test
relative to the location of the groundwater level can be important, and requires an adjustment in N-value, especially in fine sands.
Depth, rod diameter,. and material penetrated
must all be considered in the anlaysis.
Sources 0·£ further
reading are provided in Refs. 16 and 29.
This test is performed with the standard 2 inch O.D. split barrel sampler, driven bya 140-pound hammer dropping 30 inches in free fall.
The test should be performed in accordance with
ASTM Standard D 1586-67 (Appendix C).
The procedure is generalized as follows: 1)
clean the boring of all loose material, and material disturbed by drilling, before inserting sampler;
2)
administer a few light taps with the hammer to seat sampler;
5-36
3)
drive the sampler at least 18 inches, or until normal maximum resistance (refusal) is reached, using the standard hammer and drop (Refusal can be defined as a penetration of less than 6 inches for 100 hammer blows) ;
4)
count and record the blows required to drive each 6 inches of penetration; and
5)
obtain a consistent 3D-inch free-fall drop of the hammer with two wraps of a rope around the cathead on the drill rig.
(Cables attached to the hoisting
drum should not be used since it is difficult to obtain a free fAll.)
5.9.2
Cone Penetrometer Tests
The purpose of the cone penetrometer test is to evaluate the resistance of the soil.
This test, Fig. 5-12, simply involves
forcing a cone into the ground and measuring the rate or pressure needed for each increment of penetration.
Commonly
used penetrometers are illustrated in Fig. 5-13.
The resistance to penetration is the sum of point resistance and frictional resistance on the sides of the shaft.
The
more sophisticated systems can differentiate between the point and frictional components of the resistance, and the ratio between frictional and point resistance is one aid in differentiating between various soil types.
5-37
Clean sands
generally exhibit very low ratios (low friction component in comparison to point resistance), while an increase in clay content will usually result in a higher ratio, more often the result of a reduction in point resistance rather than a change in frictional component.
In most cone penetrometer systems, regardless of the sophistication, the apparatus is located in position and soil reaction anchors installed.
The cone is forced into
the ground at a constant rate and a plot of pressure vs. depth is prepared. gages.
The system is provided with pressure
Loading pressures of 1750 tons/ft 2 are commonly
available, with up to 1000 tons/ft 2 usable with small portable equipment.
When frictional resistance is measured, the system consists of two or sometimes three concentric pipes, with the inner pipe connected to the point, and the outer (or middle) pipe to a sleeve located just above the point. a 3-pipe system functions as a casing.
The outer pipe in
The rods can be
advanced separately or together, depending on the parameters being measured.
The point used in the most common test, the Dutch Cone, has a point angle of 60 degrees and a projected end area of 10cm2 (Fig. 5-13).
The penetration rate used lies
5-38
between 2 and 4 feet per minute. The inner rods are advanced first, advancing the point.
After a short distance, 1.5
inches, the outer sleeve also starts to move, giving a reading for the combined resistance.
Finally, the outer rod
is pushed alone, giving a measure of only the frictional resistance.
The pressures that are measured during penetration can be converted readily into strength values of the soils.
Some
correlations have also been made with compressibility parameters.
The static cone test can be used as a partial replacement for conventional borings.
'rhe speed of operations allows
considerable data to be obtained in a short period of time. The data requires careful and cautious interpretation.
5.9.3
Menard Pressuremeter
The pressuremeter can be used to estimate the deformation modulus of any soil or soft rock with a modulus not exceeding one million pounds per square inch, but is most effective in soils that can be drilled without erosion or without collapse of the sidewalls of the boring.
A close fit between the probe
and the sidewalls of the boring is necessary for accurate results.
5-39.
The basic idea behind the pressuremeter test is the measurement of the expansion of a cylindrical cavity, formed in situ, to provide a relationship between pressure and deformation of the soil.
In practice, a boring is made to
the level at which the test is to be performed; a length of the boring forms the cylindrical cavity.
The pressuremeter
probe is inserted and then inflated to expand the cavity, while a record is kept of the resulting volume change.
The
probe is designed so the length of the cavity does not change; the increase in volume is due only to radial expansion of the cavity.
Fig. 5-14 presents a schematic
drawing showing the arrangement of equipment.
The pressuremeter consists of three parts; the probe, the control unit, and the concentric tubing.
Water is used to
pressurize the probe and thUS. measure the resulting volume change.
The probe consists of three flexible, impervious rubber cells that can be expanded against the sidewall of the boring.
The upper and lower cells are inflated with gas
to seal the boring and prevent the central measuring cell from expanding other than laterally.
The function of the control unit is to apply a given pressure to the probe and to measure the volume change in the central measuring cell.
The tubing connects the probe and
the control unit.
5-40
5.~.4
Vane Shear Test
The .Vane Shear Test is frequently used to measure the undisturbed and remolded shearing resistance of cohesive soils (Fig. 5-15).
A standard 4-inch boring is made, and
when the casing has advanced to the desired test depth,
a
3-inch wide steel vane on a ;,-inch rod is lowered to the bottom of the casing.
Guides are spaced at 30-foot intervals
in the casing to center the ;,-inch rod.
The vane is then
pushed to a depth 2;' feet below the casing and a torsion applied at a constant rate. casing.
The torsion head is set on the
Ball bearings wi,thin the head and the intermediate
guides in the casing provide friction-free movement.
The shearing resistance is measured on a proving ring located on the torsion head.
When failure occurs, torsion
is stopped and the sample is allowed to "set" momentarily. The test is then rerun and the remolded shearing resistance is measured.
A measure of the "sensitivity" of the soil is
obtained by comparing the remolded values with the undisturbed values.
Correlations with shear strengths computed for actual failure cases suggest that the vane shear test may be the most reliable method of evaluating the in situ shear strength of soft to firm cohesive soils.
5-41
5.10
SUBMARINE SAMPLERS
Many types of samplers are available for offshore exploration. In selecting the type of sampler to be used, consideration must be given to numerous factors including:
depth of water
where samples are to be taken; type of sediment or formation anticipated; type of sample required, grab or tube samples; etc.
The following paragraphs briefly discuss the most
common samplers used in CWDD offshore work.
A thorough
discussion of offshore samplers and exploration techniques for shallow sampling are found in Refs. 48, 49, and 50.
5.10.1
Petersen Dredge
The Petersen Dredge is a versatile and reliable grab sampler (Fig. 5-16).
With the Petersen Dredge, one can obtain grab
samples of submarine surface sediments at numerous locations within a relatively short period of time.
The dredge weighs
approximately 100 pounds and has a capacity of approximately
0.4 cubic foot. The sampler is effective to water depths of 200 feet or more when additional weight is added.
If the
dredge is in good condition with jaws that precisely mate, the retrieved sample may be relatively intact and stratification of the top four inches of the sediment surface may be visually observed.
5-42
5.10.2
Open Barrel Gravity Corer
This sampler is rather simple in design and is available in a wide range of weights and sizes (Fig. 5-17).
Corebarrel
lengths range from 6 to 30 feet and have diameters from 2.5 to 6 inches.
Corer weights may correspondingly range from
100 pounds to 2000 pounds.
Most corers contain plastic
liners but are not equipped with a check valve.
open barrel gravity corers are generally operated by letting the sampler spool freely off the winch drum from the water surface to the sediment surface.
Ordinarily about 35 feet
of water is required to obtain satisfactory samples,
There
is no maximum water depth at which samples can be taken although more weight, line, and larger vessels become necessary with greater depths.
The weight of the sampler,
which can be varied, is relied upon to produce the driving force for the desired penetration.
Retrieved sediment
samples are usually not suitable for strength testing unless short, large diameter samples are obtained with minimal core shortening.
5-43
5.10.3
Phleger Corer
The Phleger Corer, Fig. 5-18a, is a small, relatively lightweight, gravity corer that may be used to obtain samples of the upper 1 to 3 feet of underwater surface sediments.
With
a weight of less than 60 pounds and easily handled by two people, it can be used to obtain samples in the 25- to 200foot water depth range.
It is hydrodynamically designed
with stabilizer fins to enhance vertical penetration of the sediments.
The corer has a built-in check valve which
permits flow of water through the corer during descent but prevents water from entering and disturbing the sample during the retrieval process.
Core barrels are approximately
1.5 inches in diameter and are available in 12-, 24- and 36inch lengths.
Clear plastic liners are housed inside the
barrels for retainment of the ~amples.
A core cutter and
optional core catcher are attached to the end of the core barrel.
Plastic caps are available for sealing the ends of
the core liners.
The clear plastic liners facilitate the
classification and recording of the sediment materials and stratification.
A release (trigger)
level is available to provide free
fall of the corer (Fig. 5-18b).
Free fall is usually obtained
if the trip arm is activated 10 to 20 feet above the bottom. Trial and error can be used to ascertain the optimum free fall height required to obtain the maximum penetration.
5-44
A quantitative measure of the penetration resistance of the sediments may be obtained by measuring the depth of penetration following free fall.
The depth of penetration may be
indicated by the mud line observed on the retrieved core barrel or by the use of vaseline or grease spread along the side of the core barrel.
The degree of sample disturbance
may be evaluated by comparing the depth of core barrel penetration with the length of recovered sample.
5.10.4
Piston Gravity Corer
The piston gravity corer is capable of obtaining relativelY undisturbed samples that are suitable for strength tests if an experienced sampling crew, uses proper procedures.
The
water depths for sampling are similar to those of the open barrel gravity corer.
Although piston corers are avail1;tble
in a variety of sizes, the standard Ewing piston corer weighs approximately 200 pounds and comes with a 2.5-inch diameter core barrel, 10 feet in length (Fig. 5-19a). Additional weights and 10-foot sections of core barrel can be added.
Core catchers may also be used.
The sediment
samples are retained in clear plastic liners.
Plastic end
caps are available for sealing the sample in preparation for shipment.
The piston corer is used with a release (trigger) lever to attain free fall conditions and to prevent the piston from
5-45
penetrating the sediment surface (Fig. 5-19b).
The slack in
the winch wire line below the trigger lever is adjusted so that at the end of the free fall the piston remains stationary at the sediment surface while the core barrel penetrates the bottom sediments.
It is imperative that at the moment the
trigger lever is activated, the descent of the winch wire line is also stopped.
Hence, the necessity for a trained
and experienced crew.
The amount of core shortening should be evaluated so that the degree of sample disturbance can be judged.
Therefore,
the depth of core barrel penetration· should be measured and compared to the length of the recovered sample.
If the two
are approximately the same, then1;:he sample should be relatively undisturbed and suitable for conducting strength tests.
Strength tests should be conducted as soon as possible
after the sediment samples are retrieved.
Pocket pene·trometers
or Torvanes may be used before the samples are sealed for shipment.
If at all possible, all core samples should be
stored in a vertical position so that the sediment stratification is not disturbed during transit.
5.10.5
Vibratory Corer
The vibratory corer is an ocean bottom platform sampler which is operated from a surface support vessel.
There are
pneumatically and hydraulically driven models available, but,
5-46
most experience in CWDD has been with the corer which consists of a pneumatic impacting vibratory hammer mounted on top of a core barrel four inches in diameter.
The core barrel is
normally 20 feet long but may be extended to 40 feet.
The
vibratory hammer and barrel are attached to a guide beam, which is, in turn, supported by a four-legged base platform (Fig. 5-20).
A 3.5 inch-diameter plastic liner is housed in
the core barrel to contain the sampled sediments.
A check
valve at the top of the core barrel and a spring leaf core retainer at the bottom are used to retain the sediment sample during the withdrawal and recovery of the corer.
The
vibratory corer is normally handled by a crane mounted on a ship or barge.
The draft of the support vessel limits the
minimum water depth at which: the corer can be operated. maximum water depth is normally 200 feet.
The
An umbilical
conduit carries compressed air into the vibratory hammer, provides exhaust to the atmosphere, and allows transmission of the measured penetration rates to the support vessel. Coarse gravel or cobble layers may restrict penetration by the vibratory corer but jetting alternatives may be available for finer grained, resistant layers.
Although the retrieved
sediment samples are disturbed during the vibratory penetration, all of the sediment profile may be recovered.
The penetration rates are measured by a potentiometer and are recorded on a strip chart on the support vessel.
The
strip chart records feet of penetration vs. time in seconds.
5-47
A penetration resistance curve can be obtained if the data are plotted in the form of time in seconds required to penetrate one foot vs. the depth in feet penetrated.
The
penetration resistance curves are very useful in determining location of resistant layers.
Also, there have been attempts
in the published literature to correlate the vibratory penetration resistance curves with the standard SPT blow counts (Ref. 48).
5-48
TABLE 5-1 Cm1MON SAMPLERS
~MPLER
DIMENSIONS
FOR UNDISTURBED SHELBY TUBE
METHOD OF PENETRATION
POSSIBLE CAUSES OF DISTURBANCE
FOR COHESIVE FINE-GRAINED OR SOFT SOILS. GRAVELLY SOILS WILL CRIMP THE
PRESSING WITH FAST, SMOOTH STROKE. CAN BE CAREFULLY HAM-
ERRATIC PRESSURE APPLIED DURING SAMPLING.
REMARKS
SA~IPLES
3" OD -2.875 ID
MOST COMMON ~AILABLE fROM TO 5" Ou.
~LENGTH 0" SAMPLER IS STANDARD
STATIONARY PISTON
BEST RESULTS IN SOIL TYPES
3"OD-2. 875 ID MOST COMMON.
AY,A+~A~~Eot~OM
~O" SAMPLE LENGTH IS
MERED.
TUBE.
FOR SOFT TO
MED I un CLA I SAND
FINE SILTS. NOT FOR SANDY SOILS.
PRESSING WITH CON-
T1NUOUS, STEADY
STROKES.
STANDARD
HYDRAULIC PISTON
HAHHERING J
GRAVEL PARTICLES, CRIKPING TUBE EDGE. IMPROPER SOIL TYPES FOR SAMPLER. ERRATIC PRESSURE DURING SAMPLING. ALLOWING PISTON ROD TO KOVE DURING PRESS. IMPROPER SOIL TYPES FOR SAMPLER.
FOR SILTS-CLAYS AND SOME SANDY. SOILS. --.-.-,.
DENISON
CAN BE USED
IMPROPERl'POPERAT-
AND SANDS WI' SOME PLASTIC
PROCEDURES,
HARD CLAY" SI~~'.~";\;i;~I:DI'AUU
ING SAMPLER I
POOR DRILLING
SIMPLEST SAMPLER FOR UNDISTURBED SAMPLES. BORING SHOULD BE CLEAN BEFORE LOWERING SAMPLER. LITTLE WASTE AREA IN SAMPLER.
PISTON AT END OF SAMPLER PREVENTS ENTRY OF FLUID, AND CONTAMINATING MATERIAL. REQUIRES HEAVY DRILL RIG WITH HYDRAULIC DRILL HEAD GENERALLY LESS DISTURBED SAMPLES THAN SHELBY. NEEDS ONLY STANDARD , DRILL RODS. REQUIRES ADEQUATE HYDRAULIC OR AIR CAPACITY TO ACTIVIATE SAMPLER. GENERALLY LESS DISTURBED SAMPLES THAN SHELBY,
INNER TUBE FACE PROJECTS BEYOND OUTER TUBE WHICH ROTATES. AMOUNT OF PROJECTION CAN BE ADJUSTED.
GENERALLY TAKES GOOD SAMPLES. PITCHER SAMPLER
SAME AS DENISON
DIFFERS FROM DENISON IN THAT INNER TUBE PROJECTION IS SPRING CONTROLLED.
VIBRATION
SPT IS KADE USING
FOR DISTURBED SAMPLES SPLIT BARREL
:Kfi-
2
1.
37sYd
I S STANDARD"'!);'! PENEt~.O. ~.·.EUR'S IZ~S UP To--q-:-.--OD - 3.~" ID AVAILABLE
ALL FINE-GRAINED SOILS IN WHICH SAMPLER CAN BE DRIVEN. GRAVELS INVALIDATE DRIVE DATA.
HAMMER DRIVEN
CONVERSE
SAMPLER 3" aD 5" ~~~PLE SIZE 2. 1<' SAMPLE LENGIH POSS IBLE WITH 1 LINER RINGS
FOR COHESIVE FINE-GRAINED SOILS
HAMMER DRIVEN
HARD OR SANDY SOILS VIBRATION
RETRACTABLE PLUG
I" aD
FOR SILTS, CLAYS AND FINE, LOOSE SANDS.
HAMMER DRIVEN
IMPROPER SOIL TYPES FOR SAMPLER. VIBRATION.
TUBES 6" MAXIMUM OF b TUBES CAN BE FILLED IN SINGLE ~ONG.
PENETRATION.
STANDt~B~PENETROMETER
WITH o~At-1MER FALLING • UNDISTURBED SAMPLES . OFTEN TAKEN WITH LARGE SIZE SAMPLERS EQUIPPED WITH LINERS. SOME SAMPLE DISTURBANCE IS LIKELY. A RUGGED, SIMPLY CONSTRUCTED SAMPLER. SOME SAMPLE DISTURBANCE LIKELY. LIGHT WEIGHT, HIGHLY PORTABLE UNIT CAN BE HAND CARRIED TO JOB. SAMPLE DISTURBANCE IS LIKELY.
TABLE 5-2 COMMON SUBllARINE SAI·iPLERS
AIPLER
SIZE OF SAMPLE
LENG TH OF SAI1PLE
PETERSEN DREDGE
GRAB
± 6/1
OPEN BARREL GRAVITY CORER
PHLEGER CORER
PISTON GRAVITY CORER
STANDARD HAS 2" BARREL COB~R
METHOD OF PENETRATI ON
REMARKS
TO 200' AND MORE WITH ADDITIONAL WEIGHT
CLAM SHELL JAW
RELIABLE GRAB SAMPLER, INTACT SAMPLES MAY BE OBTAINED WITH JAWS THAT PRECISELY MATE,
cORE BARRELS LENQIH FROM 6'
ABOUT 35' WATER REQUIRED TO OPERATE SAMPLER, NO LIMIT ON DEPTH BUT REQUIRED WEIGHT, AMOUNT OF LINE, OR SIZE OF VESSEL MAY CONTROL,
SPOOLED FREELY OFF THE WINCH DRUM
SIMPLE IN DESIGN AND AVAILABLE IN LARGE RANGE OF WEIGHTS AND SIZES, SAMPLES NOT USUALLY SU ITABLE FOR STRENGTH TESTS,
CORE BARRELS ~ILBB~E IN ,Zq AND
FROM 25' TO 200' ,
fB~E FA~b FROM 1U TO 2 ' ABOVE BOTTOM
RELATIVELY LIGHTWEIGHT ~ORER FOR UPPER 1 TO 3' OF BOTTOM SEDIMENTS, SAMPLES USUALLY NOT SU !TABLE FOR STRENGTH TESTS,
DEPTH
TO JU'
ABOUT 1.5" DIAMETER
WATER DEPTH 11lllTATlONS
i~
II
LENGTHS
~Wi~'~:iLL
STANDARO BARREL s 10', ADDITIONAL 0' SECTIONS CAN BE ADDED,
FROM
'G~"IBRATED HE I GHT A~Q~~ BOTTOM SUcH
i
TH,II[0RISTON DOES
CAPABLE OF OBTAINING SAMPLES SUITABLE FOR STRENGTH TESTS WITH EXPERIENCED CREWS,
NO':;I~ENETRATE
sEDlJiteNJs,
VIBRATORY CORER
SAMPLE IS 3,5" DIAMETER
J~~~~::'EV PNEUM~:W{~'IMPACT-
H SI
ING VIBRATORY
HAMMER~
SAMPLES NOT SUITABLE FOR STRENGTH TESTING,
PENETRATION RESIS-
TANCE cAN BE MEASURED,
/
ROTARY HEAD
ADAPTER SUB
.
.
~
0
0
0
D
,
o·
..
. , o
o
o
'"
Cl
o
o
D
0 0
D
AUGER ,
0 0
?-«:,(;<
o
0
\) o
0
0
0
o o o
D
o
o
D
o
C
00
0
o
AUGER HEAD
"
WEDGE ~",---BIT
o
o
0
0
a
00
0
0 o
o
o
c
o o
o
0
- 0
o
C\
o
o
-";....
a
o
o
o
•.$:\
0
0
0
0
0
0
6~-
o .o'PR.IVEPIN o o o
o
0
0
o
o
0
0
0
0
o
0
0
o
o
o
Q
o
o
o o
0
0
..
0
0
.
• /}
o
o
=
o
0
o o
C
Longyeor Company
TYPICAL FLIGHT AUGER SETUP
Figure 5-1
DRIVE HAMMER GUIDE
DRIVE HAMMER SAMPLE JARS
JAR.~~~~~~~ COLLAR ,
,
,
,
.
..
. ,TOOL BO~ <>
)
•
0
",
. .
,
'
,
"
,
.
,
'
'
0
0."· ,
0
•
o
o
•
• o
• SPLIT BARREL SAMPLER
o
o Longyeor Company
DRILL SETUP FOR DRIVE SAMPLING Floure 5-2
,
SPIDER
WATER
JET
OPENING
JET Acker Drill Company
CLEAN-OUT AUGER Figura.5-3 .
Sprague & Henwood
SHELBY TUBE SAMPLER Figure 5-4
Sprague & Henwood
STATIONARY PISTON SAMPLER Figure 5-5
Diamond Drill Contracllng Co.
I'IYDRAUIif¢. PISTON SAMPLER Figure 5-6
I.
Sprague & Henwood
RETRACTABLE PLUG SAMPLER Figure 5-7
Outer Tube Bit Inner Tube Shoe Brass Liner
Basket Type Retainer
Sprague & Henwood
DENNISON~MPl..ER
FiS~W:~-8
~
CI
....~
~
~
....~
;;;
'0'~""
.~ ~
~
Pitcher Drilling Company
PITCHER SAMPLER
Figllre 5-9
co NVERSi/!A';.tWi[ER Figu~'~JO
.
SPLIT BARREL SAMPLER Figure 5-11
·..~--...:.--.~. "--',,::,,~;..
CONE PENETRATION TEST Figure 5-12
-,
-----, Casmg
Water Under
~
Sed/i;if-:
x-x
(a)
(d)
"
(e)
,
'.' P~nefrom.t.rs,(a) Original Dutch Cone. (b) and (c) Reflned Dutch Cone wit4 point retracted-;_~while advancing casing and with point extended after measurement of resiS~~_fl~~' (d..)Wash-point penetrometer. (e) Conical drive point.
Ter;wghl and Peck
CONE PENETROMETERS Figure 5-13
PRESSURE GAC;E .....· '
RELIEF
GAS LINE
UNIT PRESSURE VOLUMETER
COMPRESSED
CONCENTRIC TUBING-...........
'-
-":.'
.,.----"..;,t~-'" L:.~EXTEflIOR<~u1~D ZONE OF ~~~~~./ UNDER ST
CELL
ZONE OF BORING UNDER MEASUREMENT
INTERIOR MEASURING CELL
BORING EXPANSION DEVICE (PROBE)
MENARD PRESSUREMETER EQUIPMENT Figure 5-14
GUIDES
?;-CUW," BOREHOLE CASING 6" OIA.
GUIDE
1>;%0- 1/2' OIA.
H.T. STEEL ROD
Hvonlev
VANE SHEAR TEST ARRANGEMENT Figure 5-15
Kohl Scientific In$trument Compony
PETERSEN DREDGE Figure 5-16
ASTM, 1972
GRA VITY CORER Figure 5-17
Kahl.,~.lentlfl;C h,.tiuii\t'nf Compony
(0) PHLEGER CORERa~VICI!
.RELEASE
CORING
HAU INQ
,
TRIGG~R
WEIGHT
US Hyrdographfc Office, 1955
(b) PRINCIPALS OF OPERATION
PHLEGER CORER Figure 5-18
CJRER ARM RELEASE--,
WI~[ CLAMP 0 R[CEASE
\/
-----.<.." ",,!LJ""-l
MECIiA~ISM
\
CORER SUPENOEO-----ON ARM HOOK
/
SAFETY PIN
FINS
.,- W[IGHT LOCK RIN(;
~
L8 LEAD WEIGHTS
PARTIAL PENETRATION
FREE FALL
FULL PENETRATION
HAULING IN
\ 1-TRIGGER WIRE /
LOWERING CABLE
TUSE AllAPTEA
CORER
PI$TQN STOP
MAI~
WillE
,-;:,
(OiliNG TUSE
TRI GER WEIGHT
_PISTON __--PISTCH>j MAIN WIRE tHVIS
TRIGGER LINE 217WMOO
GRAVITY~
CORER
,
tI
J.
cI) SEA BOTTOM
"
CORE CATCHER
CORE CUTTER
Kohl Scientific Instrument CorporatIon
(0) EWING PISTON CORER DEVICE
US Hydrographic Office, 1955
(b) PRINCIPAL OF OPERATION
EWING PISTON CORER
Figure 5-19
VIBRATORY CORER IN SAMPLING POSITION Figure 5-20
SECTION 6
6
ROCK SAMPLING TECHNIQUES
Rock samples are obtained in a number of different ways. The two major methods for obtaining rock samples are by bulk sampling and by core drilling.
Although both are discussed
herein, diamond core drilling is the more common method used to obtain samples for foundation investigations.
6.1
BULK SAMPLING
Bulk samples for physical propertiiils'testing are obt,ainec;t when diamond core samples areil1
6.1.1
Surface Bulk Samples
The simplest bulk sample to obtain is from rock lying on the surface or from talus slopes.
Care should be taken to obtain
rock samples suitable for the intended.plilrpose.
If a rock
s ample is required to evaluate physicial properties, as for rip rap or aggregate, only fresh rock derived from mechanical weathering processes will be suitable.
If
weathered properties are to be tested, samples of chemically weathered rock will be acceptable.
Care should be taken to
learn the source of loose rock; it is not advisable to
,
6-1
sample rock at a distance from that which it is to represent. Bulk rock samples can be obtained by wedging and baring where joint sets or fractures are properly spaced.
Such
sampling techniques can be time-consuming and are recommended only as a last resort.
Samples must be suitable for the
purpose, especially in terms of the degree of weathering.
A
sketch and description of the location, methods, and rock will make an adequate log.
6.1.2
Subsurface Bulk Samples
When a project is locatedvil}ere prqspect adits or other underground openings exist, these prqvide an opportunity to obtain subsurface bulk samples of fresh rock for testing. The adit location should be shown on a map and a field sketch of the adit and sampling locations should be made.
A
field description of the rock sampled, as well as a description of jointing and other rock defects observed, will complete the field log.
An excellent bulk sample can be obtained from a test quarry. However, unless the job is large or there is a specific purpose, it is unlikely that a test quarry will be available. Test quarries are generally installed to demonstrate the
6-2
suitability of rock for specific purposes. include:
Factors evaluated
blasting patterns, different types of blasting
agents, and rock fragmentation.
When bulk samples
are obtained, a note on the quarry log as to lift elevation or other location identification would suffice, along with a description of the rock.
6.2
6.2.1
CORE DRILLING
Field Coordination
After proper permits and/or landowners permissions, have been obtained, the field representatiVe sho)lld first locate the nearest source of water, i f water supply is not part of the contractor's responsibility.
An adeq,uate water supply
should be located nearby to allow continuous drilling during each shift.
If a nearby water source is not available, the
drilling contraotor should provide an on-site water storage faoility to allow oontinuous drilling.
A quiok appraisal of the drilling oontraotor's equipment and supplies should be made by the field representative.
The
appraisal can be diplomatioally aooomplished by asking the driller a few simple questions and by a oursory look at the
6-3
equipment.
Some basic items that should be noted, to
prevent work delays, particularly in remote areas, are: 1)
general condition of drilling equipment and support vehicles;
2)
type, number, and condition of drill bits;
3)
number and size of drill rods, subs, and casing;
4)
types of core barrels;
5)
capacity of water storage facilities;
6)
type of drilling fluid additives;
7)
types of auxilIary water pumps;
8)
core boxes and accessories (wooden dividers, markers); and
9)
any special equipment needed, as for water pressure testing (Section 10) .
The field representative should arrange or coordinate the drill site preparation, if needed, in accordance with the contractural agreement.
Often, having the clearing/grading con-
tractor work directly with the driller is an efficient method for drill pad or platform preparation.
Some minimal drill site
dimensions for a truck-mounted drill are shown on Fig. 6-1.
Once
the drill sites are prepared, the field representative needs to advise the driller of the location, angle, and direction of the boring. Before work begins, the field representative should remind the drilling contractor's representative of the contractor's responsibility for submitting the drilling reports at the end of each shift, for maintaining a safe site, and for control of drill site litter.
6-4
6.2.2
Core Drilling Operations
During the core drilling operations, the field representative will complete a Daily Report covering at least the following items: 1)
drilling progress;
2)
names of site visitors;
3)
drilling supplies - bits and their condition, and miscellaneous materials used which may affect field costs;
4)
amount of drilling time, standby time, and downtime;
5)
reasons for standby or downtime; and
6)
a summary of geologic conditions.
Daily Reports serve a dual purpose:
1)
contractor charges and/or claims, and 2)
to document drilling to keep the Project
Manager informed uf the progress of the work and resulting costs. desired.
6.2.2.1
Procedural changes may then be made as needed or as An example of a Daily Report is shown on Fig. 6-2.
Overburden Drilling.
At most locations it will be
necessary to drill through soil, or overburden, before coring rock.
Samples from the upper material may be desirable
for general classification.
Depending on the type of drilling
required to penetrate the overburden, it may not be possible to obtain intact samples. In such cases, the cuttings (wet samples) in
6-5
the return fluid should be examined and, based on any data obtained, an accurate description should be developed for the overburden.
6.2.2.2
Depth Measurements.
All depth measurements should
be referred to the ground surface at the location where drilling is started.
This will be 0.0 depth on a log.
The height of casing above the ground should be subtracted from all depth measurements, if the collar is used for the measuring reference.
Also, if the collar is used, frequent
checks should be made to learn if the casing has settled during drilling, thus affecting depth measurements.
Accurate measurements of depth at which each core run is started and stopped are essential:
The drill rods should be
checked for lengths as an occasional rod of differing length invalidates all measurements.
(Checking is easier at one
time, i.e. checking all rods at the site prior to starting the work.)
The capacity, or length, of the inner core barrel
should be checked.
(A so-called
five~foot
does not hold exactly five feet of core.)
core barrel generally Discrepancies
should be recorded in the Daily Reports and suitable allowances made in computing depths.
It may be necessary to measure
the boring itself.
6-6
An accurate record of the length of casing put into the boring, and the length of casing recovered, should be kept in order to determine the length of casing left in the boring.
The distance between the 0.0 depth, or ground
surface elevation, and the top of casing should be measured after completion of the boring, and this measurement entered on the Boring Log.
Measurements from the top of the casing to the water level should be made upon completion of the boring and, if possible, at regular intervals during drilling operations.
6.2.2.3
Cutting of the Core.
Ml)i:;:hpfthe fmJ:l.tive information
is obtained during cu·tti'ng'of the dore. tative should watch. the drilling
The field represen-
car~fullY
and record general
or radical changes made by 'the driller in the operation of the drill, the reasonsfherefor,
and the results therof
(e.g., change in:drilling speed or rotation, unintended changes in drill fluid pressure, etc.).
The field represen-
tative should consult with the driller, as necessary, regarding the reasons for unusual ac:tions of the drill, changes in the operation, etc., and appropriate entries should be recorded in the Daily Report.
It is especially important that the
core barrel be withdrawn when it is blocked.
Observations
mentioned above are an important part of the record, even when 100 percent of the core is recovered, but are especially important when core losses occur.
6-7
6.2.2.4
Grinding of Core.
be prevented.
Grinding of the core should.
Grinding results from continued drilling
after broken core has blocked entry into the core barrel. Heavy vibration of the rods may be a clue.
If the field
representative has reason to believe that core is being ground (indicating that the core barrel is blocked), the core barrel should be pulled.
There is no absolute criterion
for determining when the core barrel is blocked.
Three
common conditions which may indicate blockage are: 1)
the rate of penetration decreases markedly, and is often accompanied by an increase in engine speed;
2)
the drill return fluid may become more heavily loaded with cuttings; and
3)
6.2.3
the circulation fluid pressure rises.
Core Recovery and Extraotion
The field representative should be present when the core barrel is pulled and should generally perform the core extraction and subsequent handling of the core at the drill site.
Once the core barrel is out of the boring, it should
be laid out on a clean area on the drill platform or in a rack and the diamond bit removed.
It is important to avoid
handling the diamond bit with the wrench.
After removal of
the bit, the core retainer, and the inner barrel, the head end should be tipped up and the core slowly removed into a clean core trough or directly into the core box.
6-8
Hammering
or extraction by air or water pressure should be avoided.
A
damp rag or brush is useful for cleaning drilling mud and cuttings from the core.
6.2.3.1
Core Boxes and Labelling.
After the core has been
cleaned and initial observations are completed, the core should be laid in the box in book fashion; that is, with the top of the core to the left in the uppermost row, deeper core to the right.
The uppermost core should be placed next
to the hinge if hinged core boxes are used. placed in successively lower rows.
Core is then
Heavy cardboard or wood
dividers, which are preferable, should be placed between successive coring runs and in in.tervals believed to represent missing core.
The divid'ers shou1
marking pen showing
'.--
- -,-.- -
<'-.
thed.ePt~or d~'l?'th
interval represented.
Properly dimensioned wooden dowels may be used to graphically por1;.raymissingcore intervals.
The project designation,
boring des.ignatioIl, depth interval, and core box number shoUld be marked on the outside of each core box.
6.2.3.2
Transportation and Storage.
Depending on the rock
type, the core may be extremely fragile and/or subject to deterioration with changes in moisture content, or simply on exposure to the atmosphere.
All rock cores should be handled
gently, and packaging material added to particularly fragile cores.
Rock types susceptible to air slaking or dessication
cracking, such as many clay shales, should be protected by \,
6-9
or hard soil where diamonds are not necessary.
The Diamond
Core Drill Manufacturers Association (DCDMA) has developed nomenclature that is used throughout the industry.
Fig. 6-3
shows that nomenclature and Fig. 6-4 presents a graphic picture of the commonly used bit sizes along with standard dimensions of bits and casing, but wire line dimensions are not shown.
The Longyear Q Series is often used for deep
borings since the inner tube containing the core can be retrieved by wire line cable without removing the core barrel.
Nominal dimensions of the Longyear Q Series are: Boring Diameter
C l:-\:lZl"'Jr<7~~ A ~SR-A:(Q.,~
Core Diameter
Inch
~lM
InCh
MM
AQ
2 57/64
48.0
1 1/16
27.0
BQ
2 23/64
60 •. 0
1 7/16
36.5
NQ
2 63/64
75.8
1 7/8
47.6
HQ
3 25/32
96.0
2 1/2
63.5
PQ
4 53/64
122~6
3 11/32
85.0
6.3.1.1
Diamond Core Barrels.
Examples of the principal
types of diamond core barrels are shown in Fig. 6-5.
The
simplest is the single tube diamond core barrel, which is used only in fairly strong, sound, and uniform rock, not subject to erosion by the circulating fluid.
The inside of
the coring bit may be straight, for use in materials which can be retained by dry-blocking, or bevelled to accommodate a split ring core catcher.
It is generally advisable
to use a core catcher since dry-blocking may damage the gage stones on the inside rim of the coring bit.
6-11
Partial protection against blocking of the waterways and against erosion of the core is obtained with double tube, rigid type core barrels, the inner tube of which is rigidly connected to the core barrel head and rotates with the outer tube.
A straight-wall or a bevel-wall bit may be used
according to the character of the rock.
The inner tube is
generally provided with outside vents, and a large number of small holes are drilled through the lower end of the tube. A small amount of water flows through the holes, up along the core, and th:t;ough the outside vents.
Accumuliation of
cuttings, inside friction, and transmission of torsional forces to the core are thereby dec;;re;;tsed; however, in case of outside blocking or excei3sive PWtlpprEtssure, the;re is the .,.- -----> , ---<-
danger that too large a part of theh'.i;rculating fluid may be diverted up through the innertubeali)d cause erosion of the core.
Better protec1::ionOf.the core is obtained with double tube, swivel type core barrels, the inner tube of which does not rotate with the outer tube.
Barrels and bits are made for
discharge of drilling fluid inside, or at the face of, the bit.
A triple tube, swivel type core barrel is similar to the double tube with the addition of an inner, split tube liner to further protect soft rock cOres from damage.
6-12
The best protection of cores of relatively soft and erodible materials is generally obtained with a double tube, swivel type core barrel with a bottom discharge bit, Fig. 6-5.
The water-
ways in the core barrels are generally larger than in other diamond core barrels in order to permit use of a drilling fluid with additives instead of plain water.
Core barrels are furnished in lengths of 5, 10, 15, and 20 feet.
Some single tube core barrels are divided into 5-foot
long sections so that the length can be changed as required by the rock conditions encountered.
Starting barrels or
core barrels with a length of Ito2'feet are used in starting the boring when rock extends tog-round level and the longer core barrels are too long to pass' through the feed screw or the drive rod of the drilling Il\achin~.
Most foundation
exploration work is performed with 5- or 10-foot barrels.
One of the' most' advanced drilling developments in recent years has been the introduction of wire line drill rod and core barrel assemblies, Fig. 6-6, which are especially valuable in deep drilling (~100 feet).
The technique
eliminates trips in and out of the boring with the coring equipment.
with the wire line technique, the core barrel
becomes an integral part of the drill stem.
The drill rod
serves both as a part of the coring device and as casing as it is usually not removed except while making bit changes. Core samples are retrieved by removal of the inner barrel assembly from the core barrel through the drill rod.
This
is accomplished by lowering an overshot or retriever, by 6-13
wire line, through the drill rod to release a locking mechanism built into the inner barrel head.
The core is removed and
the inner barrel returned through the drill rod and the coring process continued.
Clear water is generally preferred as a drilling fluid in operation of diamond core barrels in sound rock.
Water is
cheaper and requires smaller waterways and less pump pressure.
Very high speeds of rotation require dynamically balanced equipment and carefully aligned drillrolis.
As the equipment
becomes worn, it is generally nec$S!ilary to decrease the bit .
speed to avoid excessive the bit with consequent
;;-;>:\~'
-----/<-
v;iiJjl:-~ tion;1,:{wtt'ip,and ----:--',""-.-'-i'-
da~~;'r;tOF
,>-
chattering of
'braaking the core and
damaging the bit.
Drilling operation:;; vary, but in hard rock a high feed pressure genarally not only increases the rate of advance but keepethebit sharp and free cutting, whereas a low feed pressure in the same rock tends to polish the diamonds to a smooth, non-cutting surface.
In other rocks, the best
results may be obtained with relatively low feed pressures.
6-14
Preferable to have bench or trench for water on this side
-_ ...... ---- -\
Min, 5'-~ / (Preferably 6' to 10') I
Water ' or bench ' C t Bench \t,,,..---Prefera bl e to rna k e Pit or u I entire length of one side of drill site
Min, 8' Foot of Stabll ixer (Preferably 20') ~
----r---
'-
i
j
__________________ t~:!'~~~~C~~~~_________ _
I
,
o
1 15'
.IF""")
Foot of Stabi Iixe::r:----- --
,I ,,I
IR~,) ~J
T"""
A_ ... """
----30~-- ---------.. -:1;-----:--20~----- --~t
f--------.. -------1
(17' Minimum)
T ', . .... ,,, l ~"------171~ ...
Optional~t.a
10':
f«rods
I
"
','
. '
..
,
,.
'.'
I
: I
....
...
If can't put areQ for rods at hole area, hove to provide this minimum area somewhere on the drill pad,
NOTE: Make turn-around road (loop), if necessary; also make vechicle turn-around at end of or away from dri II site,
EXAMPlE USED: Truck-mounted rig: International R-160 series truck; 86 UG Type; depth capabil ity 1200',
SUGGESTED DRILL SITE DIMENSIONS Figure 6-1
(
DAILY REPORT
ConverseWardDavlsDlxon Project: _B_E_C_k_-_S_U_L:._:t_A_N_ _ _ _ __
Project No.
Inspector: F. COLE
Day
7 1\ M
Time On Site: From
To
7~-51:t/-51
Date
-ruE'S
I.. I'M ; From
I - 30 - 7"1
To _ _ _ Report No. :l,O
Weather:
LONG'r'MR 34 t 3&'
Equipment In Use:
Work In Progress/Completed: BORING ~olD
CASING
= 3'
"1' - 1:1..' 17-1"/.5
I>lsrURBf£.C> - fI'IosTL'r' Roc../<.
PITc.HER SAMpLfi:. Plrc.HER
SAMPLE
TOT/IL tlOLE
15. '3' 1'0 ?-'3.,,' =&, •.4>'
LOST WATER PRoBLEMs: AT ASOIJT 20 'FT.
PITCHER S,.,/,,\PL/:: ;:1.7'· 2.'1"
GRAY
Ytl/WED c.!,flY TOP,
CoBBLE..
"'1..1.. TE'ETH
1''%,.0
FIELD
E)
13'Ro(.l.>N &RAVe:.U.y SILTY SAND
ON '1>ITcHfi:.R BIT WORN OR BRol
Special Conditions/Corrective Work Required:
:L t3\:1L 01" rUEt.... To AIR COMPRE.SsoR. I)SED /,-t.t. FUEL 81' DAYS END At..JD TooK EMI'TI,J BI3L OUT. MARVIN 'To 'FLY A GA/IV WED. MARVIN 'FLEW
J:VERE,JT sNow
'P£.e>/..U
MADE oNE. PAsS Ai 'RoAP - BRokE.
<7",TE. AND DID NoT REAl-L'r' /tELP RoAD - Too HI6fj St-JolO B ...Nl<:,s At.oNG Ii I. GUESS - Lull-I.. cALL ART
:l.ND
TO
'PLOW
OUT
WED.
Reviewed By:_~Ac::LO:::..-_ _ _ _ _ __
SAMPLE DAILY REPORT Figure 6-2
THREE LETTER NAMES FIRST LETTER
SECOND LETTER
HOLE SIZE
GROUP
Casing, core barrel, die-
Key diameters standardized
--
THIRD LETTER OESIGN
The standardization of other
mond bit. reaming shell and d ri II rods designed
on an integrated group
dimensions, Including thread
basis for progressively
characteristics to permit
to be used together for
reducing hole size with
interchangeability of parts
drilling on approximate
nestmg casings.
mode by different manufacturers.
hole size
I
Letter Inches Millimeters Letters X ond Wore syn- The DESIGN (third) letter I R 2S onymous when used as the designates the specific GROUP (second) letter. 40 design of that particular E It A 2 50 Any DCDMA standard tool tool. It does not IndicB 65 with on X or W as the ate a type of design. 2r N 75 3 GROUP letter belongs In 31. K 90 that DCDMA Integrated 2 H 4 100 group of tools designed P S U
5 6 7
Z
8
125 150 175 200
using nesting casings and
tools of sufficient strength to reach greater depth~ with minimum reductions in core diameter.
TWO LETTER NAMES FIRST LETTER
SECOND LETTER
HOLE SIZE
GROUP AND DESIGN
Approximate hole size, some as in 3 -letter names.
GROUP stondardizoti·on of key diameters for group integration and DESIGN standardization of other dimenSions affecting I ntercho ngeabi Iity
Diamond Core Drill Manufacturers Association
CORE SIZE NOMENCLATURE Figure 6-3
STANDARD DIAMOND CORE BARRELS STANDAIlDS flY NATIONAL ~UREA\J O' STANDARDS DIAMOND CORL DRILL MANU/At TURERS
Hvorslev
IDENTIFICATION SYMBOLS
RX
EX
AX
OX
NX
HX
PX
SX
UX
ZX
"'
EW
"'
AW
"'
OW
"'
NW
"'
HW
"'
PW
"'
SW
"'
UW
"'
ZW
RW
"'
C. BBL. BIT SET I.D. NORMAL
C. BBL. BIT SET 1.0. THINWAlL
C.' BBL. BIT SET 0.0. N. AND TW. C. BBL. SHell SET 0.0. N. AND TW. CASING BIT
SET I.D. CASING BIT AND SHOE SET O.D. CASING SHELL SET 0.0. CASING SHOE SET 1.0.
F.e, CASING 1.0. CASING CPL'G. 1.0.
F.J. CASING
I.D. F.C. AND F.J, CASING 0.0.
Diamond Core Drill Manvfocturerll Awx:lotlon
NOMINAL SIZES OF STANDARD CORING BITS AND PIPE CASING Figure 6-4
SULLIVAN MACHINERY COMPANY
CORE BARREL
E. J, LONGYEAR COMPANY
. SINGLE TUBE DIAMOND CORE BARRELS
E. J. LONG YEAR C()MPANY
SlJl.t.lVAN MACHINERY COMPANY
DOUBLE TUBE RIGID TYPE DIAMOND CORE BARRELS
E J. LONGYEAR COMPANY
TUBE EXTENSION TUBE EXTENSION
SULLIVAN
MACHINERY COMPANY
DOUBLE TUBE SWIVEL TYPE DIAMOND CORE BARRELS
TYPICAL DIAMOND CORE BARRELS
Figure 6-5
Cable bolt
Latch' retainer
t---- Latch Jar
Thrust beari ng Jar rod Outer tube
Inner tube Spring case Spring
Reaming shell
Locking cone Steel balls
Latch spreader Core Barrel Assembly
Retriever Assembly SPRAGUE
WIRE LINE CORE BARRELS Figure 6-6
a
HENWOOD, INC.
7
SOIL BORING LOGS
A number of different log forms are used throughout CWDD. Methods of classification and description of soils may vary according to the purpose of the boring and/or the clien"t' s requests.
There are certain data which should be on a
boring log regardless of the form or system used.
The form
used for the example log, Fig. 7-1, should be used whenever possible.
The guidelines contained herein apply 1:0" field logs. logs should be:
Field
1) filled out legibly lettered (not written) -.,:---,:-.---
--
"
""
;
in soft pencil; 2) suital:l;Lefor r~}'l+ddtiction; and 3) as close to final form as reasonable,thereby:simplifying office pre_f-
paration of final logs .
Field-logs should be completed and
transmitted to the office as soon as possible after completionof a bOring""
All headings used should be consistent
between log~r:abbfJ\riations of client's name or project title, for exa.mple, should be consistent on all logs for a project.
7.1
CLASSIFICATION SYSTEMS
In exploration to obtain data to be used in engineering design and construction, it is essential that the field representative acquire an intimate knowledge of the materials encountered.
The design engineer requires accurate and
7-1
complete data.
An adequate description of the soils in
place, in both borrow and foundation areas, is mandatory. Normally soils are classified and described according to an approved soil description system.
The Unified Soil Classification
System is the principal system to be used in CWDD work, although there may be justification for using other systems in some areas or for some clients.
The quality of the log, to a very large degree, will depend on what has been judged to be the layer or stratum.
Although
representative samples should be taken, the log should not only be a log of the samples.
The description should be made in
terms that convey the exact same meaning to everyone who may use the log.
Accurate field classification of soils requires considerable experience.
Soil description on the basis of visual in-
spection should be confirmed by laboratory testing:
the
extent and frequency of testing is dependent on the field representative's experience, the soil complexity, and the project requirements.
(Samples of each soil 'component may be
taken into the field, for comparison with field samples, until confidence is achieved in visual identification.) The commonly used systems are described in the following subparagraphs, with references for more detailed information.
7-2
7.1.1
Unified Soil Classification System
The Unified Soil Classification System (USCS) is based on the identification of soils by texture and plasticity and their grouping on the basis of engineering performance. Complete discussions of the Unified Soil Classification System can be found in Refs. 9, 21 and 22.
Appendix D
contains a copy of ASTM D 2487 and D 2488 which are standards for classification and description of soils according to the USCS.
The following properties form 1)
the~basis
of classification:
percentages of gravel ,sand, and fines
~(fraction
passing the No. 200 U.S. Standard sieve) ; 2)
shape of the grain-si;~,dfatribution curve; and ,
3)
~
plasticity and compressibility characteristics.
TheUSCS is based Ion classification of the minus 3-inch (75mm) fraction, but all fractions should be included in the description on the boring log according to the grain size ranges as shown on Table 7-1.
For convenience in developing
a wri t·ten description on field logs for CWDD projects, the terms "and", "some", "little", and "trace", as defined by Burmister System Terms, Table 7-3, have been adopted.
7-3
7.1.1.1
Soil Groups and Symbols.
Soils are divided into
two primary groups, coarse-grained, and fine-grained. Course-grained soils are those having 50% or more material larger than the No. 200 sieve and fine-grained soils are those with more than 50% of the material passing the No. 200 sieve.
The soil groups are identifed by letters and
descriptive modifiers as listed in Table 7-2.
The symbols are combined to describe soil types, the first symbol indicates the primary constitutent followed by the modifier.
In the USCS the symbols are all capitalized,
Fig. 7-2.
7.1.1.1.1
Coarse-Grained Soils.
coarse-grained soils are
subdivided into gravels and sands depending on the major coarse-grained constituent.
For purposes of identification,
coarse-grained soils are classed as gravels (G) if the greater percentage of the coarse fraction (retained on No. 200 sieve) is larger than the No. 4 sieve and as sands (S) if the greater portion of the coarse fraction is finer than the No. 4 sieve.
Both the gravel (G) and sand (S) groups
are further subdivided on the basis of uniformity of grading and percentage and plasticity of the fine fraction (minus No. 200 sieve).
7-4
GW and SW soil groups include well-graded gravels and sands with less than 5% non-plastic fines.
GP and SP soil groups
are poorly-graded or skip-graded soils with less than 5% fines.
Gravels and sands containing more than 12% fines may be classified either GM, SM, GC, or SC depending on the plasticity of the minus No. 40 soil fraction.
Silty gravels (GM) and
silty sands (SM) will have liquid limits and plasticity indices which plot below the A-line of the plasticity chart shown on Fig. 7-2.
Clayey gravels (GC) and clayey sands (SC) will have
liquid limits and plasticity indices which plot above the Aline.
(Grading is not a factor when the percentage of fines
is greater than 12%.)
A dual classification symbol (e.g. GC-GP) is used when the minus No. 200 fraction is between 5 and 12% and the soil has characteristics intermediate between two groups.
7.1.1.1.2
Fine-Grained Soils.
The finer-grained soils are
subdivided into silts and clays, based.on their plasticity, and highly organic soils.
To distinguish between silts and
clays the plasticity index vs. the ,liquid limit is plotted, as shown on Fig. 7-2.
Among the inorganic materials, the
clays plot above the A-line and the silts below the A-line. The organic clays fall below the A-line.
Silts and clays
are further subdivided into low (L) and high (H) plasticity based or whether the liquid limit is less than 50% (L) or greater than 50% (H).
7-5
Field techniques for differentiating between silts and clays include manual tests for dry strength, for dilatancy, and for toughness
(Appendix D-2).
The tests are also described
extensively in the previously cited references.
Accurate
identification of silts and clays is primarily a matter of experience and conscientious comparison to laboratory test results.
Highly organic soils are combined into a single classification with the symbol "Pt.", and are characterized by a high organic content, commonly cons~stin'g of leaves, grass, branches, and other fibrous matter;byh;i.gh compressibility; and by relatively low stren.gth.
Typical samples of highly
organic soils are peat, humus, and 'swamp soils.
7.1.2
Burmister Soil Identification System
The Burmister Soil Identification System is described in considerable detail in Refs. 23 and 24. in Appendix E for convenience.
Ref. 24 is included
The Burmister System involves
rather precise soil fraction descriptions utilizing specific terminology and symbols.
Table 7-3 contains the definitions
and symbols used in the Burmister System.
7-6
The Burmister Soil Identification System uses some capital letters as symbols for the components, with lower case letters to indicate proportionality or gradation.
The
proportionality terms, Iland", "some",_ "little", "trace" are
sometimes incorporated into written descriptions in other classification systems.
The Burmister System requires
considerable laboratory and field practice before accurate identifications can be made.
7.1.3
Additional Classification Systems
Several additional soil classification and identification systems are in current use by various agencies and other disciplines.
The systems generally do not lend themselves
to field classification for foundation engineering projects. The more widely used are: The American Association of State Highway and Transportation Officials System. (AASHTO) Ref. 24. U.S. Department of Agriculture Classification System (USDA) Ref. 25. Federal Aviation Agency Classification System, Ref. 28.
7.1.4
(FAA),
Additional Components of Soil Identification
Fundamental to any soil description is color, moisture condition, and consistency (fine-grained soils) or compactness (coarse-grained soils).
7-7
The color of the soil at natural moisture content should be recorded. 7-4.
Standard color abbreviations are listed in Table
Standard soil moisture terminology appears in Table 7-5.
Soil compactness and consistency are frequently described in the field on the basis of the Standard Penetration Test (SPT) and/or by an estimate of the unconfined compressive strength.
Factors affecting penetration resistance include
depth, overburden pressure, soil type and condition, weight of drill rods, drilling fluid, and the presence of disturbed soil at the bottom of the boring.
Due to the interdependence
and complexity of the factors affecting the SPT, relationships of penetration resistance to soil condition, such as those contained in Tables 7-6 and 7-7, are generally only very approximate.
For example, the pen,etration resistance at
shallow depths in sands is generally too low; and thus, corresponding field descriptions may underestimate the compactness of the soil unless corrections are applied to the field data.
A correction formula for field blow counts is given
with Table 7-6 and a chart of the correction formula can be found in Ref. 47.
A complete discussion can be found in
Refs. 29 and 47.
A number of additional soil properties should be recorded such as structure, cementation, grain shape, layering, dry strength, dilatency, toughness, etc.
Appendix D-2 gives information on
visual-manual procedures.
7-8
7.1.5
Examples of Field Classification and Identification
Example 1 Estimated grain-size distribution (volume basis) Gravel
15%
Sand
70%
Fines
15%
Field identification 1.
sand fraction consists of range of sizes from fine to medium, little coarse sand.
2.
Plastic fines.
identification of fines: dry strength:
medium
dilatancy:
very slow
toughness:
medium
Field classification:
(USCS)
clayey sand (Se) little f-c gravel, rounded to sub rounded
Example 2 Estimated grain-size distribution (volume basis): Gravel
o
Sand
15%
Fines
85%
7-9
Field identification: 1.
fine sand only.
2.
identification of fines: dry strength:
very high
dilatancy:
none
toughness:
high
Field classification:
(USCS)
clay (CH) little fine sand sparse fine sand lenses, sparse calcareous nodules
Example 3 Estimated grain-size distribution (volume basis) : Gravel
0%
Sand
20%
Fines
80%
Field identification 1.
predominantly fine sand; slight plasticity
2.
identification of fines: dry strength:
slight
dilatancy:
slow
toughness:
none
7-10
(uses)
Field classification: clayey silt (ML) little fine sand,
desiccated, frequent small root holes
7.2
LOG HEADING DATA
Recording data accurately is very important.
The heading of
each log should be completed with care and in a form that can be transcribed with a minimum of editing.
Fig. 7-1
illustrates a completed heading.
The following information, as a ,minimum, should be include'd on the field log heading. 1)
Project number and project name.
written instructions
from the Project Engineer should establish the exact requirements. 2)
Drilling dates and name(s) of person(s) recording log.
3)
Elevation from survey reference point or from topographic map.
An actual survey elevation is preferred.
Elevation should be to the nearest 'tenth of a foot and the datum should be indicated (MSL or MLL are preferred) . The elevation of borings should also be indicated on the field skiitch or plan.
If no survey is available, a
permanent object (which will not be removed), such
7-11
as top of curb or manhole cover edge should be used and, the reference point shown on the field plan.
If
the elevation is approximate, so indicate. 4)
Brief description of location, such as open field, next to building, etc., with plan dimensions from property line or building.
If boring or test pit
is not made at a pre-staked location a simple sketch with dimensions should be prepared to define the location. 5)
Ground water information is one of the most important parts of the log.
An attempt should be made to access
exactly where the water is coming from, from what stratum, and at what rate.
Ground water information
is an important part of foundation design.
The water
level and time should be recor.ded before work is started in the morning and after lunch breaks.
The
water level should be measured daily or twice weekly for the duration of project, when possible. 6)
Full name of the drilling con'tractor and the driller. The time the setup was started, when drilling commenced, and when the boring was completed should be recorded. Dates should be shown, especially if drilling spans several days.
7)
Description of drilling equipment and size of boring. All spaces provided in the heading for casing size, sampler used, core size and type, and tube sizes for undisturbed samples should be filled in.
Additional
data should be provided in Remarks column and/or in Daily Report. 7-12
8)
The weight of hammer or equipment used, such as kelly bar, inner kelly bar, and stems, should be recorded when samplers are driven.
9)
Make and model of backhoe should be recorded on test pit logs.
7.3
THE LOG
Logs are usually prepared for all types of explorations. Subsurface exploration usually is accomplished with test pits or borings.
The same soil classifications, descriptions,
symbols, etc. should be used for all logs on the same project and preferably throughout all field exploration for the same office.
In general, the same types of data are recorded on all logs. Two basic types of data are available for recording in a log.
These are "permanent" and "fugitive" data.
'fhe
permanent data are of such a nature that time of recording is not critical whereas fugitive data, if not observed and recorded during the drilling or excavation process, are lost forever.
The field identification and classification of soils should be as complete and accurate as possible.
The field representative
should have a substantial understanding·of the subsurface conditions on which to base preliminary evaluations and to
7-13
recommend an effective laboratory testing program.
The
following is a checklist to guide in the preparation of complete field soil descriptions and the recording of relevant subsurface conditions.
(Columns on Fig. 7-1 are identified
as though numbered from left to right.) 1)
The color, moisture, and consistency or compactness of the soil should be described, referring to Tables 7-5 through 7-7.
Descriptions should also
be included of other pertinent properties such as structure, plasticity, cementation, grain shape, lensing, etc. 2)
The blows required to driVe each 6 in6h:es of the standard split barrel sampler should be recorded. (Appendix C).
If> there is any deviation from the
specifications for the standard penetration test (SPT), the deviations should be shown on the log. On the Field Log of Boring, Fig. 7-1, SPT blows are recorded for each 6 inches of drive in column 4. Any other drive test data normally would be recorded in column 2, such as blows required to drive the Converse Sampler or to drive casing. When recording data from a bucket auger boring for conversion to drive energy, care must be taken to record weight of kelly and drill stems and to identify in column 2 which parts are involved in each 6-inch drive.
7-14
3)
The type and location of samples should be recorded according to symbols in Table 7-8.
Bulk
samples are disturbed and should be identified on logs as shown in column 3, Fig. 7-1.
When disturbed
samples are to be retained for later inspection or testing, the type container in which the sample was placed should be recorded according to symbols on Table 7- 8.
Disturbed samples may be retained from any sampling operation, such as an SPT sample or from wash borings, and the samples recorded as shown in Column 3.
Waterproof tags or other permanent
identiiicationshould be placed on all sample containers.
Large bulk samples should have
tags placed both outside and inside the containers.
Numbering and identification of samples
obtained by sampling devices may be accomplished in a number of different ways.
Sample identifica-
tion should be shown similar to that in column 3, Fig 7-1.
Extreme care should be taken that the
correct sample number is placed on each sample container. 4}
The depth of the bottom of the sample (not sampler) is generally recorded as in colunm 3 of Fig. 7-1. Measurement should be in feet with sample depth recorded to nearest tenth.
7-15
5)
The push pressure should be recorded similar to that in column 2 of Fig. 7-1, if a sample is obtained by pushing rather than driving or rotating.
6)
The percentages of gravel - sand - fines are sometimes estimated on field logs similar to column 10 of Fig. 7-1.
The assessment is visual and made on
a volume basis. 7)
The Remarks column on all logs is used to record data which do not naturally fit on other parts of the log.
Remarks column can'!;$; the most important
column on the log in th.i.t>p~rtinent data, not otherwi se logged ,d:m 8)
bef~c6rded.
Soil identifications stiouldb'e indicated for each individual sampleinaJ:lbreviated form as the boring progresses.
Any additional information
concerning the presence of gravel, boulders, roots, organic material, wood, or fill materials such as bricks and concrete, etc. should accompany the soil classification to provide the Office Engineer with as much information as possible concerning the materials encountered.
The log should also indicate layering or stratification of the materials encountered.
The term
"miscellaneous fill" should be used only if a complete description of all the materials encountered in the fill is provided.
7-16
Table 7-1
USCS Grain-Size Ranges
Component
Size Range Millimeters U.S. Standard Sieve Size Above 75 75 to 4.75 75 to 19 19 to 4.75 4.75 to 0.075 4.75 to 2 2 to 0.425 0.425 toU.075 Below, 0;075
Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Medium Fine Fines (silt or clay)
ll'al:Ue.7~2 " .-,-
Above 3 in. 3 in. to No.4 3 in. to 3/4 in. 3/4 in. to No.4 No.4 to No. 200 No.4 to No. 10 No. 10 to No. 40 No. 40 to No. 200 Below No. 200
Us.eS Soil Symbols -
Component or Property
Symbol
Cobble Gravel Sand Clay silt Organic Peat Well-graded Poorly-graded High Plasticity Low Plasticity
None G S C M
o Pt
W P H L
Table 7-3
.~ld t " l I d !
Symbol
lloulLh.!l:"s
Dldr
Burmister System Terms
~ldtlJrial
Cbl
eolJ1J1.us
(,ravel
G
coarse (el met! i.um
f1 nu Sand
S
(In)
(f)
coarse 1lI(~d.i
um
fino SUt
iJ<..!l'inllion
sieve Size
Fraction
~"
tileVU.
3" to 9"
Material passing the 9"
~juvu.
l" to 3" l/B" to 1" No, 10 to 3/8"
Material passing the )" and (ut,1ined 011 the No. sh:vl!.
)0
No. No.
(e) (m) (f)
)0 to No. 60 to No.
ti!UVU
Material pdgsiny the No. 10 Si8VU and retained on the No. 200 sieve.
10 30
No. 200 to No. 6D
Material passinq the No. 200
Passing No. 200 (0.075 mm)
$
retaillt.!d on
sieve th
Organic Silt (OS)
Material passing the No. 200 sieve which exhibi ts P~i~-:--prope:r,~ies within a certain range of moisture content, and has gra_n\l~ and ---- -, organic characteristics.
clayuy S L I,'L' :U.'l'
CLAY
, ,
cy$
CLAY
$ f,C
SlL'I'
C,,$
Silty CLAY l'r,AY
$'tC C
Plasticity
P las u~i.tY_,
Slight (51)
1 to 5
Clay-SoIl
5 to 10
Material p
19W -(L)
10 to 20
Medium (1-1)
High Very
20 to 40
(H)
High
Componont
Written
Principal
CAPI'rALS
Minar
Lower Case
rn~dex
(VII)
erulJ1~
stnm';lll, wh~n air-uril.ld.
40 plus
proportions
*
Symbol
*
Pl.lrC(~ntd':le Hanqe by WI.! i.~Jht ofC
SO or mare and same
little Ll-dce
,.
a.
l. t.
J5 to SO 20 co J5 '[1 to 20 I to 10
¥MinuB 8ign (-) lower limit, plus sign (+) upper limit. no sign middle range. Signs used with proportion., wordS or symbols to indioate lower or upper end of peroentage range.
Table 7-4 CWDD Color Abbreviations
bk
black
gn
green
wh
white
bl
blue
or
orange
yw
yellow
br
brown
rd
red
dk
dark
gy
gray
tn
tan
It
light
standard soil moisture terminology appears in Table 7-5.
Table 7-5 CWDD Soil MoistMtE!;' Terminology
Moisture
Symbol
Characteristic
DrY
D
Makes dust
SlightlY Moist
SM
Below plastic limit
Moist
M
At plastic limit
Very Moist
VM
Above plastic limit Can pump water from silts
Wet
W
Free. water or saturated.
Table 7-6 CWDD Guide for Compactness of Coarse-G'-a!.. ned Soils
Compactness
Symbol
Very Loose
VL
Loose Medium Dense Dense Very Dense
Corrected* SPT Penetration (blows/foot) 0-4
L
4-10
MD
10-30
D
30-50
VD
+50
*Field penetration resistance should bacorrected to a normalized overburden pressure of I-ton/sq.f£. by the multiplication factor C N
where p = effective overburdl?n pra~sure (tons/sq.ft.) at the depth of the s.tandard penetia.tionte~t. Table.7 ..? CWDD Guide for Consistency of Fine-Grained Soils
Consistency Very Soft
Symbol VS
SPT Penetration (blows/foot) 2
Range of Unconfined Compressive Strength tons/sq. ft. 0.25
Soft
S
2-4
0.25-0.50
Medium
M
4-8
0.50-1.00
St
8-15
1. 00-2.00
VSt
15-30
2.00-4.00
Stiff Very Stiff Hard
H
30
4.00
Table 7-8 CWDD Sampling Symbols Used on Logs
First Letter
Second Letter
Type of Sample SPT Split Barrel Brass Liner, Shelby Tube Stationary Piston Dennison Bulk (Loose) Sample Not Recovered
S L
T P D B X
Method of Penetr'ation Driven Pushed Hydraulically
A H
Bulk Sample Container
Bag, Cloth Bag, Plastic Jar Can
B
P J
C
Converse Ward Davis Dixon, Inc. Geotechnical Consvltants FIELD LOG OF BORING
1
Bor'ng N o.
loject A a..nd e, TC>WI:.RS Pro!. No.7';') -1101 ·01 I Sheet 1 of ~ e Client Ace. DEVELO?i"IENT CO Location WW CORNE.R ?RO.,.,S;ED 131..0G-. SE PRoBoring Contr. ?ITC\\ER ORILI.ING CO. Datum M.S.l-. 1g:~ !,;g.. Elev. 'I':l..5 ' Time Date Start {p I:l. 717'1 g:~o AM Boring Method 1>. OTA "''1' 4 'Ys" if!. ,E'RlO-tIIl.{ ".L 1\ "" I<. t. L. Driller Time 11:30 I::!M, Dati EIDilb ('/2,717'1 2.5.0 FT. C. BROlut-J Field ReD. Total Borin DeDth Casing Sample~ Ground Water Core Tube Depth C(J\;"': Type STD. 'l'11'E. CONVEI\S~ Date Time SHE-US" all (p" 7.2.' (P.o' Diameter ID/')..7 hq I~:'i!,o ;l..S " "'_J'~r
-
Weig~t
-
Fall
I~~
:;: r' h
~
w
C>
~ ~
. ii-l5 ~
1 2
~
~
",. .,0
o~~
~Z
r-
,
I
-+-
..
3
A
5.'1
7 -
-i*p$
JO 9
0
0
err
-
PERCENT
~
G. SII.TY CLAY wi~\., rock Ifr"'3ma.nts (FILL)
CL
SII..TY CLAY
CL
REJ.MRKS GR-SA-rINES
I~'O'
IJ> "
BS
5'
CLu~a.r
o..f\:.e~
t0
dYWe,
.s
SM
IY\ M 1-"
I---
r-- ""dkI r-- 'jr
S e
VM
0"0-100
!)om/Z. v(Z.~a.t,,:\:ion
4'-S' '\:.ou,\hne~s: hi'3h df~ stra.n'3\:.I'I; hi~h
\7 W"t~/' .,.
~'1
W
~~-
IV
level 7. Z
6/Z Vi'S
shell fr"'~mq."t.s Sc4tt~reol throu~"'ovt \....~a.r
-
r-I---
-5 5 J
I--- lor
0
SP 0-9\1-:<'
SAN l)
drill c.ho.."''!la. a.t 17.'
flr'l
~
I :to
I---
4>
~ 12~ /B.O
-
~
B.9 --
-
17
120
br
bk
r-\-t I--
15 -
)
".
q
r4 rT
-
13 14 -
18
~
- - I---
11 -
16
(5
-
30"
DESCRIPTION
u
~ It>
-
;.:f. ,~: } l
L
1.9 p
6 -
12
~
2
5
8
0
(')
-+- 1. 13 -.--L
3
4
.e;
".~ ~
~
-
1'10'"
rw r- 9~Dr rr--
ei,..,I\ chM'3
$~NoY
CL
CLlW
low a/1.VV\(l.r'lto.;1; lOr) to\J~h"/1.SS: me<\iu\1) d.~ ~~¢.",\\:'h: medium dil"-"t
r-
I--EXAMPLE FIELD LOG OF BORING Figure
7-1
0-35-("5
I~'
Converse WardDavlsDixon, In<:. Geotechnical Consultants FIELD LOG OF BORING
II 01'In9 N o.
I!mil!it
1\ AND
~Illnt
AcE. OE:v EL.O\>ME.NT co.
~ ~
I-
:;: w 0
"a~
If'~.c o~~
~;:)~
~ ~ ~
~
~.
~
;).z
1..1 r--
.... ~
-7-
22.'
2..5 r--
2./P r-2..1 I - -
"l.S r-"l.q
r-I-I--
r-r-I--
r-r-r-r-I--
~
'--
-
0
0 u
-
'l'l-
-
br
-
61<.
L :2.., r--;sr-=- _A_ -
'-4 r--
~ -rOWE.\<-S
0,'1
w
:,:.
~
'!;,
~
f!~
~
0
-
~
0
DESCRIPTION
~~
~ 1;;
SI\NP'f CLIW (sa-a. S"a.a, t 1)
CL_
SILTY C.I-AY
Cl-
I
PERCENT REMARKS GR-SA-FINES
to Ii '\\ h t W
vs
with
M
IVI•• " ...0
S .......oston<2.
SAN I) SToN E.-
IO-
~o-
"10
va. ....
rr"'lrna.n1:s, 1"''1a.rctd wiH-, .$d.nd'1 c.\~
'3':1
Sh.,t ~ 2f ~ Job No. 7q- 4101- 0
~
w vs
L
(l.ll:
c.l>o.:t\:a. .... ::1.\ • .6 I I
10·40-50
ori 1\ cl\a."'la:
"c."k
Battom of ~f'n~ ;l..S FT.
-
-
--
--
r-r--
-
r-r-r-r-r-EXAMPLE FIELD LOG OF BORING Figure 7~ 1 (continued)
C<.t ~~,o\
r
MAJOR DIVISIONS
/
',tt".',
TYPICAL NAMES
i
Clean gravel, with little or no fin •• 01< oJ"
-"
Ol-
Mor. then half coar •• fraction
w~>
No 4 ,Ia". siz.
O~
o !o.
Z--!
Poorly-Graded Gr."el" Ora"e' . Sand Mlxtur.,
GRAVELS
I, I.rger than
Gra"els with over 12% fine.
Gl
-.!!o
"" JJc.zo.
::~;~,tittle hnd, or no fin ••
SANDS
01
o:~
Uo :Ii
Silty Gra"el., Poorly-Gr.ded Gr ..... ' • Sand Slit Mhctur ••
GM
"g,~----------------------------~--~
>= Clayev Gra"ell, PoorlY-Graded Gravel," Sand~~__-I__C_I_'_V_M __'x_t_U_"_'__________________________________-I
sw
~~~
SP
'J
a
Well-Gradad Sandi, Gravelly Sand,
~
~
Poorly-Graded Sands, Gravelly Sand,
Mor. then half
coarse traction I, smaller than No 4 ,Ie"a size
SM
Sand. with ovar 12% finas
se IJI
Cleyey Sands, Poorlv-Grad.d Sand· Clay Mixtur••
P •• t and Other Highly Organic Solll .
Symbol
COARSE-GRAINED SOilS Fines Symbols ~.• ss than ·5.~ ~"'. GC, GP. ~"'. More than 12% GM, SM. ~p. SC, 5% to 12% Borderline cases require duel "ymbols
C~ 1..1" 10 GW
C .1°30)2 c
0 10
)lt
Gr•• ter than 4
15 60
~
GP
Not meeting all gradation requirements for GW
GM
Atterberg limits below with PI less than 4
GC
Atterberg limits above A-line with PI' nreater than 7
Above A-line with PI between 4 and 7 are borderline cases requiring us. of dual svmbols
.-U60 Cu
010 Greater than 6
SW
Cc • (030)2
SP
Not maeting all gradation requ iremants for SW
SM
Atterberg limits below with PI less'than 4
Atterberg limits above A -line with PI greater than 7
/
~ 30
§ t;
..
CL. 20
:'i
./
0
VOL
1/
v
,,,V
V
.f/ OH 0'
MH
0' ML
o
010 )( 060
SC
CH
w 0 40 Z
CL/ML
Ertwren 1 Wid 3
A- line
50
)(
E1ety,l'en 1 {,nd 3
A-line
FINE GRAINED SOILS
60
.,.
Above
o
10
20
30 40 50 60 70 80 LlOUID LIMIT (%)
A -ilna with
PI between 4 and 7
borderline cases requiring use of dual symbols
PLASTICITY CHART
UNIFIED SOIL CLASSIFICATION SYSTEM
Figure 7-2
90
100
SECTION 8
8
ROCK BORING LOGS
Because of the possibility of damage, deterioration, or loss, accurate on-site description of rock cores is essential.
In addition, fugitive drilling characteristics and
comments by the driller may yield important clues to rock qualities, groundwater conditions, and the location of missing intervals of core.
Thus the observations of the
field representative, properly and timely recorded, often provides valuable insight into geotechnical problems that develop in later design, or even construction, phases.
The most critical rock qualities from the engineering viewpoint are those that affect qverall mass 1) strength and 2) permeability.
The nature and frequency of discontinuities
have a great influence on the engineering properties, although other factors such as degree of weathering and lithology are also important and, in some cases, may be more important.
The terminology and classification parameters evolved by civil engineers do not necessarily coincide with "classical" geologic definitions.
The field representative must record
rock characteristics in terms recognizable to the design engineer, while also recording the sometimes subtle features useful in purely geologic correlations and interpretations. The subtle features may indirectly indicate conditions unforeseen from the boring data alone.
8-1
The following classification systems are designed for broad applicability; however, conditions on individual job sites may require deviations.
The Project Geologist is responsible
for establishing classification systems on the basis of specific project requirements and geologic environments, and may authorize modifications of the systems shown.
When this
is done, the classification scheme used must be clearly understood by the field representative and explicitly stated in the report, as well as the field logs.
A distinction is drawn between a rock b9ring~log>and the core description.
The rock boring>~6g:includesadescrip
tion of relevant data appliqaqle
td';~~hi'i!;aiilling of~·the \';:{;;'.;
boring and to the core recdv~tiWffi••; formats are available for
sEht~):al rock boring log
fi~~(L~:e,~ ;~~:~ardless
of format,
the following data are requir~p for appraisal of rock masses for engineering. purposes and should be recorded on the rock boring 'log : 1)
bOrfing depth, elevation, and size data;
2)
percent core recovery/rock quality designation;
3)
graphic log; and
4)
classification and physical condition of the core.
An example of a rock boring log which contains the aforementioned data is shown on Fig. 8-1.
The specific columns
of information shown on Fig. 8-1 are described below by numerical reference from left to right.
8-2
8.1
BORING DEPTH, ELEVATION, AND SIZE
The angle depth of the core, along with boring size and core box number are shown in column 1.
The scale selected
should be adequate to allow complete and uncrowded descriptions.
This will depend on the variability of geologic
conditions.
If a change in scale becomes necessary after
logging is underway, a note should be made in the left margin at the appropriate point.
Core box depth intervals
are designated by numbered arrows at the left side of the column, boring size in the center, and depth markings on the right.
The core depth may be determined from the length and
number of drill rods.
The field representative should check
lengths of rods actually used.
8.2
PERCENT CORE RECOVERY/ROCK QUALITY DESIGNATION
Pieces of core Should be carefully fitted together as they are removed from the core barrel, and the total length of core recovered measured to the nearest 0.1 foot.
Percent
core recovery is then computed by dividing total length of the core by the length of the core run; however, two points deserve extra attention.
First, is the core barrel empty?
Second, is there a stub remaining?
(Due to the position of
the retainer when the core is broken at the end of a run,
8-3
a stub of varying length may remain.)
Upon re-entering
the boring, the driller will usually have to move the rods by hand to work the bit over the stub and into the original cutting groove.
If less than 100 percent recovery has
occurred without indications of core grinding, ask the driller how much stub remained within the boring before computing percent recovery of the core retrieved.
The Rock Quality Designation (RDQ) is only for NX size core and is computed by summing the lengths of all pieces of core equal to or longer than 4 inches (lOOmm) and dividing by the total length of the coring run.
It is necessary to distinguish
between natural fractures and those caused by the drilling or recovery operations.
The fresh, irregular breaks should
be ignored and the pieces counted as intact lengths.
Depending
on the engineering requirements of the project, breaks induced along highly anisotropic planes, such as foliation or bedding, may be counted as natural fractures.
The Project
Geologist should designate a standard procedure prior to commencement of drilling.
Percent core recovery and RQD should be computed for each coring run and entered in column 2.
Horizontal lines should
be drawn across the column at the appropriate depths to indicate the top and bottom of each run.
8-4
i
8.3
GRAPHIC LOG
The graphic log is drawn using standard symbols as shown on Fig. 8-2, based on the rock's major classification division.
In general, the graphic log should only indicate the major variations in rock or overburden types.
However, the column
is also useful for indicating locations of s:\.gnificant fracturing or shear zones as indicated by the recovery or by assimilation of.fugitive data.
If known, the location of
the groundwater level should .also be log.
indicate~
on the graphic
Particular attention shoulo,.be paid t;o the nature and - ;
.
'.
geometric relationships Qf contaCtS between oiff.eiring lithologies, shear or falllt:;:ones, ·9avi ties, or other major - -f-.
di$continuities.
8.4
CLASS1FICATION ANP ·PHYSICAL CONDITION
Column 4 should contain geologic information of two types: a lithologic (rock-type) classification and a description of the physical condition (fracturing, weathering, etc.). Where the rock type is substantially the same over a continuous zone of the boring, the lithologic description need be given only once, at the top of the zone.
Local variations in
lithology and physical condition generally should be described over shorter zones, and should be separated by short horizontal
8-5
lines at the appropriate depths.
Changes in major lithologic
classification should be indicated by horizontal lines that completely cross columns 3 and 4, although transitional contracts may be indicated by a dashed line on the graphic log portion.
The nature of abrupt or transitional contacts
should be fully described.
8.4.1
Lithologic Classification and Description
The lithologic description serves principally" as a tool for geologic correlation and reference.
Wh'fUe detailed mineralogic
and petrologic features may provid~iittle direct engineering data, they are indispensable ,in prQji;iBt1ng structtrres and stratigraphic features that· maYhave?;iJnportant geotechnical implications.
In some types of invi(;;l,stigations, such as
fault studies, lithology may provide the most important datum of all.
The amount of detailed lithologic description
required should be evaluated for each project.
In general,
the lithologic description should be brief and to the point; complex, lengthy descriptions tend to "clutter" the log and often confuse designers trying to use the log for engineering purposes.
The word "BEDROCK" should be entered where first encountered, followed by the major rock-type, also in capital letters. Standard geologic terminology should be used with minor exceptions.
8-6
1)
Non-layered, indurated, predominantly clay rocks
(
should be classified as claystones, reserving the term "shale" for their fissile or laminated equivalents.
Siltstones also lack the fine
lamination or fissility of shale and have predominantly silt-size particles.
Mudstones are
indurated rocks lacking fissility and containing either equal or indeterminate amounts of clay and silt. 2)
Grain-size ranges for clastic sediments and other granular rocks should be based on . the Unified Soil Classification Systeni(USCS).
uses
A comparison of the
grain size and the Wentworth grade scale,
used in classical st):"atig:raphy, is shown on Fig. 8-3.
The terminology ttl be used for describing
grain size of igneous rocks is also shown on Fig. 8-3.
For metamorphic rocks, standard metamorphic
textural terms should be used.
In addition, grain
size may be very critical; therefore, the actual grain size should be given in millimeters.
The lithologic description should include, as appropriate, color, mineralogy, degree and type of cementation, secondary mineralization/alterations, and special physical characteristics such as water solubility, high or low density, etc. Textural terms depend on the major rock type: for sediments,
include grain size and shape, sorting, and bedding (type, thickness, and inclination to core axis); for igneous or metamorphic rocks, any anisotropic features such as foliation, lineation, cleavage, flow structure or cataclastic structure as well as the character of crystallization should be fully described.
Color is not usually a critical rock property; however, in certain cases it can be effectively used to correlate beds, units, or weathering horizons.
Because colors are seen and
described differently by different
peop~e
or eVen by the
same person at different times, qlil:tandard chart; such as the Geological Society of Ame:r;:i9i;ln (Ref. 30) should be used.
(G1~)'<".R6~k
Color Chart"
Allqolorsshould be reported as
seen on moist core.
In rna.ny caselill especial.1¥.with igneous and metamorphic rocks, the texture may result in an ill-defined or variable color.
In such cases, the color of the dominant minerals or
the overall ground mass should be described and the colors of secondary features should be described separately.
The
secondary coloration usually has a characteristic geometric pattern which may be described by one of the following terms: banded -
approximately parallel bands of varying color
streaked -
random streaks of color
8-8
blotched -
large irregular patches of color (greater than 3/4 cm in diameter)
mottled -
irregular patches of color
speckled -
very small patches of color (less than 1 mm in diameter)
stained -
faint coatings along bedding, joints, fractures
8.4.2
Description of Physical Condition
Physical condition of the rock mass includes degree of weathering, fracturing, jointing, --,-j,)ell.ding, and hardness . ----
avoid ambiguous terminoiogy
.-.-.
the;f~llOWing
To
--
tables and discussion
outline the terms used indescribiJ")g the physical condition of the rock core.
8.4.2.1
Further deSCl:'ipti0l]:s can be found in Ref. 40.
Degree of Weathering.
are somewhat subjec,tive.
The definitions of weathering
However, Table 8-1 outlines the
discoloration extent, fracture conditions, surface character-' istics, original texture and grain boundary conditions for five degrees of weathering.
This guide should be used in
describing the relative degree of weathering.
8.4.2.2
Discontinuities.
A discontinuity surface is
defined, as any surface across which some property for a rock mass is discontinuous, Ref. 31.
The term includes
fracture surfaces, weakness planes, and bedding planes. fracture is the general term for any discontinuity in the
8-9
A
rock; it is the collective term for joints, faults, cracks, or mechanical breaks due to drilling.
Therefore, when
breaks (other than mechanical) are present in the core in a random, irregular fashion, they can properly be referred to as fractures.
Systematic breaks which clearly belong to a
system or set of joints should be referred to as joints. Whereas joints can be referred to as fractures, it is possible that all fractures are not joints.
Furthermore,
joints do not have visible movement parallel to the surface of discontinuity.
When planar surfaces have significant
development of slickensides and/or deyelapmentof gouge or breccia, the terms sheared or shear zone Jas appropriate) can be used.
The word fault should be reserved for major
features along which significant mo;rement can be identified.
An example of the twofold discontinuity spacing description could be "thinly bedded, widely jointed".
This description
would apply to a sedimentary rock with a bedding plane spacing of 60 to 200 mm and joint plane spacing of 60 cm to two meters.
Depending upon the nature of the engineering problem for which the core logging is being done, a number of other discontinuity surface features should be described in the core log.
These may be:
8-10
1)
discontinuity surface type origin,
2)
separation of fracture walls,
3)
filling, its absence or presence;
4)
roughness and degree of weathering, and
5)
orientation, apparent or true dip.
The field representative should be aware of the different discontinuity surface types and should describe only those surfaces which have occurred as a result of geological processes.
Fractures resulting from the drilling process,
or subsequent to core removal from the boring, are not described.
The terms to be used in descri,bingthe separation of fracture walls are given in Table 8-3.
Su~gested terminology to be used
to indicate the presence or absence of fracture filling materials is given in Table 8-4.
All materials occurring between the fracture walls are referred to as fracture filling.
The term includes in situ
weathered materials, fault zone materials, and foreign materials either deposited or intruded between the fracture surfaces.
only the presence or absence of fracture filling should be noted in the discontinuity surface description.
Where
applicable, a separate description of the fracture filling should be given after the discontinuity surface description.
8-11
Roughness asperities usually have a base length and amplitude measured in terms of millimeters and are readily apparent on a core-sized exposure of a fracture.
The applicable
descriptive terms are defined in Table 8-5.
The two necessary and sufficient conditions for the definition of the orientation of a particular plane are its strike and dip.
There are a number of specialized methods that can
be used to obtain the strike and dip of discontinuity surfaces in drill core.
One method is to remove an oriented core
from the rock mass using a special cor.e· orienter barrel. Alternatively the discontinuity surf·ace orientation can be measured in the wall of theboringusihg an oriented boring periscope, camera, or devicescctpable:of viewing or taking an impression of t.heboring sides.
where a feature of known
strike and dip;· L e., bedding, intersects the core at an angle, this may be used to orient the core.
Another method
requires the presence of at least one easily identifiable marked band and the use of a minimum of three borings.
This
latter method enables three dimensional geometry, usually aided by stereographic projection.
The above methods are
costly and only used on projects where discontinuity orientation is critical to the design of the facilities. However, the apparent dip of discontinuity surfaces should be routinely logged on all projects.
Apparent dip is the
maximum inclination of the discontinuity surface measured at right angles to the core axis.
8-12
8.4.2.3
Rock Hardness.
In geotechnical engineering, rock
material strength is very important in design when considering factors such as excavation methods, bearing capacity, and tunnel support requirements.
Although rock material
strength and rock hardness are indirectly related, they should not be confused.
Rock strength cannot be evaluated
without laboratory or in situ testing while rock hardness is a field evaluation, unless a laboratory hardness test is to be conducted later.
Point load tests or uniaxial compressive
strength tests are required to distinguish between the upper limi ts of rock hardn'ess, such as very hard or extremely hard.
Rock hardness is defined
or scratching.
Table 8-6 illustr
scale to be used for field core logging descriptions.
8.4.2.4
Order of DejlcriptiveTerms.
The order of rock
descriptions should be the same throughout a log.
The rock
name should be stressed by capital:_zing the name and puttin':j it first.
The modifying terms should follow in a logical
sequence.
For example:
"GRAYWACKE - gray-brown, fine-
grained, medium weathered, medium hard, 'closely fractured to medium fractured below 15'."
Additional description of
lithology and/or physical properties should follow the rock name and principal modifiers such as "iron stained, medium rough, closed fractures with average apparent dip of 60°. few thin (lo" wide) calcite veinlets in irregular pattern".
8-13
A
8.5
WATER PRESSURE TEST
Arrows should be placed in column 5 to indicate the positions of packers for all water pressure test zones.
If the base
of the test zone was the bottom of the boring, indicate by a notation.
8.6
Section 10 discusses water pressure test procedures.
REMARKS
This is one of the most important columns of the form.
Data
entered here might include such information as water loss (or gain), change of color of return water, coring record, drilling rate, bit changes, unusual or characteristic behavior
I
of drilling tools, and driller's judgment of subsurface conditions.
If not covered elsewhere on log, clear notations
should be made regarding casing sizes, casing depths, and sequences of installing casing.
At end of log a statement
should be made regarding condition of the boring on completion, especially recording of how much casing has been removed.
8.7
CORE PHOTOGRAPHY
It is recommended that color print photographs of all core be obtained for a permanent record and for comparison with the descriptive log.
Core photography should be carried out
systematically; preferably in a controlled environment,
8-14
under even lighting, and with a standard photography setup, so that variables between photographs are minimized.
For
some work, employment of a commercial photographer is justified. 1)
The following procedures are recommended. One or more core boxes may be photographed at a time.
2)
A label with the name of the site, project number, and boring number should be included in each picture.
3)
All lettering should be well-spaced and have a minimum size of 20 mm.
4)
Color bars should be fWi.ofuded in eachj;licture.
5)
A frame is usefl.ll:to SUPI;lClttthe camera vertically
'~~-~>'
above the core l;,qX8/j.
----
Af~~;!;natively, the core box
can be supporte4 in •..~ . . tl..lted (60 0
)
position so
that itsSllrface:i,s normal to the direction of Pho.togl:."aphy . - ---.
6)
-
Ma.Chineprinting of photographs is not recommended .
.. .J:£ is useful to obtain prints on a scale of 1: 10 . 7)
Core should be photographed while moist but not wet.
A hand spray bottle is useful for keeping
the core moist.
Figure 8-4 shows a typical title block that can be re-used for photographing individual core boxes with a photograph of core which has been clearly labelled.
8-15
TABLE 8-1 DEGREE OF
D I A G N o S TIC
f!EATHERI~G
FEATURE
DESCRIPTIVE TERM
DISCOLORATION EXTENT
UNWEATHERED
NONE
SLI GHTLY WEATHERED
LESS THAN 2Q% FRACTURE SPACING ON BOTH SIDES OF FRACTURE,
cOtlTAIN THIN FILLING
MEDiUM WEATHERED
GREATER THAN 20~ OF FRACTURE SPACING ON BOTH SIDES OF FRACTURE,
CONTAIN THICK FILLING
HIGHLY WEATHERED
THROUGHOUT
-----------
COMPLETELY WEATHERED
THROUGHOUT
FRACTURE
0,
CONDITION
ORIGINAL
CLOSED OR DISCOLORED
UNCHANGED
PRESERVED
TIGHT
DISCOLORED, MAY
PARTIAL DISCOLORATION
PRESERVED
TIGHT
DISCOLORED~
MAY
:;ISCONTJN~1TY
TEXTURE
CONDI TlON
PARTIAL TO COMPLETE 015- PRESERVED COLORATION NOT FRIABLE EXCEPT POORLY CEMENTED
PARTIAL OPENING
FRIABLE AND POSSIBLY PITTED
MAINLY PRESERVED
PARTIAL
RESEMBLES A SOIL
PARTLY
ROCKS,
-----------
TABLE 8-2
PRESERVED
SEPARATION
COMPLETE CEPARATION
SPACING
DESCRIPTION FOR STRUCTURAL fEATURES:
GRAIN BOUNDARY
SURFACE CHARACTER I STiCS
DESCRIPTION FOR JOINTS,
BI;DDING, FOLIATION,
OR FLOW BANDING
FAULTS OR OTHER FRACTURES
SPACING
2 METERS
6 FEET
VERY T~ICKLY (BEDDED, FOLIATED OR BANDED)
HORE THAN
THICKLY
60 CM - 2 METERS
2 - 6 FEET
WIDELY
MEDIUM
200 MM - 60 CM
8 - 24 INCHES
MEDIUM
THINLY
60 - 200 MM
2 1/2 - 8
CLOSELY
VERY THINLY
20 - 60 MM
3/4 - 2 1/2
INTENSE,Y (LAMINATED, FOLIATED, OR CLEAVED)
6 - 20 MM
1/4 - 3/4
VERY INTENSEI.Y
LESS THAN 6 MM
LESS THAN IlL! INCH
MORE THAN
INCHES INCHES
VERY WIDELY) (FRACTURED OR JOINTED
VERY CLOSELY
DESCRIPTION FOR MICROSTRUCTURAL FEATURES' LAMINATION, FOLIATIONS, OR CLEAVAGE INCH
EXTREMELY CLOSE
TAm 8-3 SEPARATION OF FRACTURE WALLS
TABLE 8-~ FRACTURE FILLING
SEPARATION OF WALLS IN MM
DESCR I PTI ON CLOSED
0
DESCRIPTION
DEFINITION
CLEAN
NO FRACTURE FILLING MATERIAL
VERY NARROW
o - 0.1
STAINED
NARROW
0.1 - 1 1 - 5.0 5 - 25+
DISCOLORATION OF ROCK ONLY. NO RECOGNIZABLE FILLING MATERIAL
FILLED
FRACTURE FILLED WITH RECOGNIZABLE FILLING MATER IAL
WIDE VERY WIDE
TABLE 8-5 SURFACE ROUGHNESS CLASSIFICATION
DESCRIPTION
TABLE 8-6 ROCK HARDNESS CLASSIFICATION
FIELD TEST
SMOOTH
APPEARS SMOOTH AND IS ESSENTIALLY SMOOTH TO THE TOUCH. MAY BE SLICKENSIDED ••
VERY SOFT
CAN BE PEELED WITH A KNIFE, MATERIAL CRUMBLES UNDER FIRM BLOWS WITH THE SHARP END OF A GEOLOGIC PICK.
SLIGHTLY ROUGH
ASPERITIES ON THE FRACTURE SURFACES ARE VISIBLE AND CAN BE DISTINCTLY FELT
SOFT
MEDIUM ROUGH
ASPERITIES ARE CLEARLY VISIBLE AND FRACTURE SURFACE FEELS ABRASIVE TO TOUCH.
CAN JUST BE SCRAPED WITH A KNIFE, INDENTATIONS OF ~ TO ~ MM WITH FIRM BLOWS OF THE PICK POINT.
MEDIUM HARD
CANNOT BE SCRAPED OR PEELED WITH A KNIFE BUT CAN BE SCRATCHED WITH KNIFE POINT. HAND HELD SPECIMEN BREAKS WITH FIRM BLOWS OF THE PICK.
HARD
DIFFICULT TO SCRATCH WITH KNIFE POINT, CANNOT BREAK HAND HELD SPECIMEN.
ROUGH
LARGE ANGULAR ASPERITIES CAN BE SEEN. SOME RIDGE AND HIGH SIDE ANGLE STEPS EVIDENT.
VERY ROUGH
NEAR VERTICAL STEPS AND RIDGES OCCUR ON THE FRACTURE SURFACE.
* WHERE SLICKENSIDES ARE OBSERVED 1 THE
DIRECTION OF THE SLICKENSIDES SHOULD BE RECORDED AFTER THE STANDARD DISCONTINUITY SURFACE DESCRIPTION.
1'1- 4315 - 01
Pmjcet No.
ST. HELENA DAM
Pmjeet
N359, os~
Coordinates
Hole No.
ROCK BORING LOG Feature 379. 51q
E "
.ype of Bo,;"9 K't.~Y/N)t. COR e:
~I(;I-\'r
Ground Elevation
Total Depth_...!5",'1,,-'_ _ _ _ _ Start
Angle with Horizontal_--=4,..,S,-0 __
8/1:1,./7'1
Water Level - Deplh. ElevatOon. Date --"...!Il'-'_--=\?"'I'-',"'2..,,/.J7c::'lL.._ _ _ _ _ _ _ _ _ Logged By
LONG YEAR,
Drming Co. Angle Depth
Elpvation Sizp
(FEEr)
;--
.--- -------------------------------
1410- START RuN:\. WP,'fER LosS l;ts P5; P.WN PRESSURE 1435 - PUL.L RUN L \5Locl. ISilO - PULL RUN :t IS!)S - STI\IH RuN 3
t
* 1 J-
"', - - - ".0 KT 1 10
"
:r ~
75;4.
+ +
-
+
I '" -
t
... ~ +
~15
-
"'~-
~ )(
&i
100
"''is
+-
Og~S
-
- Pll L.L RuN '-I
- STf'lRT ,",uN 5 13I
q,/13/?"I OQ30 - I'ULL 'RUt-!
5
CLOSEt.'( SPI\CEl), CLOSlOD, CLEAtv, MEDIUM 0 '(OU"'M FRI\c.TURSS crolNiS <:) @:> 75 A"p/'lP.ENT PIP; ..0.5' To ~::>...7'
100
-
<-25
-
"72
100 !>- 100
ll< IV)
-
~
-I-
... +
+ +
WIDEL-.... "''''/'Ic.TURe.D, 1'11'11'.1)(0) ;<,<0.4'
Ii' u.
13(..ocl< ING OFF
~ C.LOSEt>, C~E"'N. ROU6H, \,\EDIU\,\ lOINTE.l) @30o A~PI\RENT \)IP; ;1.1.5' To ;L1f.S'
W'+ +
SILICIT'II'-t>, I'I/>''Rb To '10.1'.'-/ I-I"RD
1\15 - PULL RUN 7 1135 - STI'-RT RuN 1!
+ + . +.:.
'-ttILL "''''RGIN 3" TKICK ~ 5\'\1\"...,', l\"IRL.Il-IE., \'\i:REGU~IIR c..ol-lTIlc.T
~ EPll)oTe.-l-\oElJFEI-S; I>I\Rl< liRE\;:NIS" G-Rli-Y ~ SI'E.c.I"CI'-D FP.IICTuI\ES, ~~\ \'IMD To VER.... HI'.RD -
'"
\015 - PUL.L RUN (P 103S - SiART RUN 7
-I
-
30
Ii
'I
:1.0
I"
110
UNWEATi"tE.REP (ii)·I$.O'
I?~S
WIPe., CLA"I FILLEO, SLI
~- To
X
1""40 - srARr RuN
...
1><_
.s_
II-
11.0;1.0 - PULL RuN 3
C"I-oF.ITE., 'Fe:~\)"PI\P' INCII'IE'IVTLY ,,~n;:~E.D To c.LA.'f. I'IOST I"RAC.TuRE-S @ 30o l\{>l'I'<"EN"f \)IP SI-IGttTL.'r' We.ATtlERI:D@ 10.7'
+
4-
SET UP
1030 - OVERBoRt>eN PRIl.l. IN Q,
?", - l%
.... II
Remarks (Water Loss and Color. Cilsing Record, Time of Drilling, etc. )
1,00 -
+- + BEl)!<,oc.l<. - ~\oilTE G\'..ANOOIOR,I1"e.; SO,.. +- SPEC.KU'-I) GI\~eN\SH 13L.I'ICK {PINKISH +- + + GR."""/13LUISI-\ Wf\I,E-, Me.Dluf'\ GRI'-INED, MEOIlJl'l WEl'm,E.R.£.!), ME"()luM FI\(o..CTuIU.D, ">WITH l'<\oDE-I<,ATE. I3ROWN SlAIN ALoNG +- + t'\E.l>luM l'\ouGH, NAI<.RoW f'RACTuRES; 22.. ... +........ Me.DIUi'\ HI'IRt>; illoTlTE ToTIILL.~ "'~TaR..e.t> To
I
S MIT H
(,," CASINr. 0'.(,'
1-0bSE., 1"\01$,-
7.
R S. Sheet
Watl.'t Pressure Test
OVER.BURDEIJ • TI\.L.US i I'IN(,.ULI\R. ROc..K. 'FRI\GMENT.s WlTf\ t<\INoi't SA"'b/SI~T)
-
,----5
i-tuc"o PolTS
Classification and Physical Condition
RQD
-
DrOller
"k
HRe.
Box No.
DRILLING CO
Bparing N ~O E..
Al'MJ,NlENT &;to.7
_---=8"--____
-
~
-
"
SflE.I'\RE!), C"UStlED WITH, NARRoW, CLII'I-F'LLI'.\:i : 5",,0<>1>\, S~ICKENSIPED FR"c.TUI\ES (!i) 'Is'" Mpl'IREm OIl'; 39.3' To 39.8'
'--a
ConverseWard DaVIS Dixon
Geotechnicil Con,uUlntl
Figure 8-1
...
01 _
:2 10) J-.~ lAl
~In ,
I'aoo - PUL.L RuN S'
Pmjecl No. _7"-q-'-----'4-=3_1.:::5_ _ __
Hole No. _ _~'i!~___
ROCK BORING LOG
Pmjecl _ _S"-"J.:,'--"""E"L"E"'N"'A:!-L>=Al!:i"IL_ _ _ _ _ _ _ _ _ Fe,'ure Rlc;,~T PlaUTI') ",NT
Bearing _ _ _ __
Coordinates _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ground Elevation _ _ _ _ Angle with Horizontal _ _ _ __ Type of
B.'i"~ _ _ _ _ _ _ _ 1'ot.1 Depth _ _.:::5'--4'--'_ _ _ _ St.rt _ _ _ _ _ _ _ _ Finish '6/13/7Q
Water Levp\ - Depth, E\f'vation, Dale _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Logged By Drilling Co.
Sheet
Driller
Angle Depth
Elpvation
% Rec.
Sizp BOl{ No.
Classification and Physical Condition
RQD
P. S. S l'liT H
Walf>r Pressure Test
o
Remarks (Water Loss and Color, Casing Record, Time of Drilling, pte.)
1
It
PULL. RUN 9 1515 - STA'RT 'RUN \0
1450-
1(0'1.5 - 'PULL RuN \0 (.,~ USING- LEFT STEi'\ CA?PED, PAINTED A/JP STAMPED :1,'
-
-
WITt! BO~ING NiJMBC~
-
-
-
-
-
-
I
.
-
ConverseWard DaVIS Dixon
aeotechnlc,l Conlultontl
Figure 8-1 (continued)
I
MAJOR DIVISIONS
TYPICAL NAMES ._~, ."Iomerate, graywacke-conglomerate, rkosic-conglomerate, lithic-conglomerate
CONGLOMERATE (BRECCIA)
.::.::::: -', k k ::::::- q". te, quartz wac e, graywac e, 1 - - - - - - - - - - - - - - - :: .. ::.:. ~v.~, tuffaceous sandstones . .
. II
SANDSTONE SILTSTONE
·v
"y,
calcareous, siliceous, or micaceous siltstone
~----------------~ CLAYSTONE/MUDSTONE f=====::::::: clay shale, marl
....Cl Vl
~=-=-::==~
==~,c'lr·'bolnac:eou'.I'. calcareous, .sil iceous,
SHALE
~ ~,
CHERT V1
ow Z
o
VOLCANIC PLUTONIC
bedde41 chert, porcellanite 1\
/' /
rhyolite, flIJartz latit~ rhyodacite, dacite, IdHte,andesite, basalt, tuff
II . . " '>,," "'"
~!
t!. '"~
,.,.".quartz monzonite, granodiorite, tonalite
dI.d .., dI.b.~, pod'.';",
'"H.
schist, phyll ite, slate, phyllonite
SCHtSTOSE GRANOBLASTIC
or micaceous shales
calcarenite, dolon.itlc or sil iceous limestone, calcitic dolostone
LlMESTONE/DOLOSTONE
::J
-r
~-;--;--" ~~
..
granulite, marble, amphibolite, tactite, skarn, serpentinite
\\" ::\'
SEMISCHIST HORNFELSIC
~~ gneiss, banded gneiss
~~---------j ~~~- albite-epidote-hornfels, pyroxene-hornfels, hornb Ie nde-hornfe Is
~~
t[~~ mylonite, phacoldal rocks, melange "r---------------~~~~~,.~~~.~--------------------~
'"
!:d
CATACLASTIC
z ol -
BRECCIA ZONE
w
SHEAR ZONE/FAUL T
V
I-
:~::.,::
fault breccia, crush breccia • -:.::_~ crush conglomerate /5/
/F/
clay gouge, slickensides, use S for shear and F for fault
LOG SYMBOLS Figure 8-2
SEDIMENTARY ROCKS AND SOILS UNIFIED
WENTWORTH
BURMIS'l'ER
~ 4026 2048
boulder gravel
boulder
1024
cobbles
512
12-
9"
6
256 128
cobble
)
64 coaese gravel
coarse gravel
cobble gravel
l
T 3/1],;
'"
16
medium grll.vel
, ,
tine gravel
)/'
~,.76
No.4*
fine gravel
sand No.lOIl
coar~e
1
2 00 • 1. 00
granule gravel
0.<12-
No.4QoIIo-
0.25
fine sand
0.125 0.074 -
2
very coarse sand
coarse BAnd
medium sand
32
1
---No,30" medium Band
coarse sand
--No.50'"
mediUlll -sand
1/2 1/' fine sand
fine sand
very fine sand
No.200·
1/' "t/16
1/32 silt
1/64 1/128
0.005
. i l t or clay
"1/256
dlt
1/512 0.001-
clay
1/1024 -1/2048
·u,S.
Standard sieve Number
IGNEOUS ROCKS NAME
SIZE LIMITS (inches)
glassy, aphanitic (no grain size visable ) cryptocrystalline (faint polarization effects in thin section, grains not individually visible) microcrystalline (grains too small to be seen with a hand lens but visible under microscrope)
<1
< 0.04
1- 5
0.04 - 0.2
medium-grained
5 - 30 > 30
0.2 - 1,2
coarse-grained
> 1.2
fine-grained
very coarse
GRAIN SIZE Figure 8-3
TYPICAL CORE PHOTOGRAPH
Figure 8-4
)
SECTION 9
9
LOGS FOR OPEN SUBSURFACE EXPLORATIONS
In general, open subsurface explorations made for engineering purposes are not logged in the detail that fault investigation trenches are logged.
Below are described the
basic requirements of various field logs needed to record observations made after exploratory test pits, dozer cuts, test shafts, and trenches are excavated. investigation trenches are described.
Later the fault
The log should
reflect field conditions at the time of excavation in as complete and accurate manner as prs'cticable. in logging cannot be overemphasized.
Thoroughness
Field logs may
become the only record of geotechnical conditions affecting the project feasibility.
The examples of field logs included are not intended to become "standard" formats, although those shown have been in use for several years by various offices.
However, the
examples do show the basic data needed for analyzing field conditions in an objective manner. that should be recorded.
There are minimum data
The following paragraphs indicate
the required data and outline the importance of recording such data.
9-1
9.1
OPEN EXCAVATIONS FOR ENGINEERING PURPOSES
9.1.1
Basic Required Data
Although open excavations for engineering purposes may include test pits, test trenches, dozer cuts, and test shafts, the basic data recorded on the logs are the same. The basic data required for subsurface exploration logs for engineering purposes consist of heading data, the graphic sketch with a brief description of the subsurface materials, and the conditions observed at the time of the excavation and logging. 1)
A list of the required heading data follows.
Project Name and Number.
Assigned by Project
Manager. 2)
Test Pit/Trench/Dozer Cut/Shaft Number.
A simple
consecutive numbering system should be used throughout the project regardless of the phase of work, thus avoiding confusion between various years work. 3)
Excavation Equipment Used. These data allow evaluation of excavation rates for estimating costs in future work and evaluation of contractor performance.
4)
Logged By.
During future evaluation of logs the
proper person can be located. 5)
Date Started/Completed/Backfilled.
Allows evaluation
of excavation rates and documention of the date of backfilling.
9-2
6)
Water Level.
The depth, or preferably elevation,
of first water seepage encountered and the date observed should be recorded. 7)
Elevation.
The elevation of highest ground
surface should 'be recorded if available; a + symbol is used for estimated elevations. 8)
Orientation.
The bearing of the side(s) logged
should be recorded.
For example, Bearing N20 o W,
SW (or NE) wall logged. 9)
Total Depth.
The depth of deepest exploration
should be recorded.
9.1.2
Graphic Sketch
A graphic sketch of the logged exploration surface is useful for locating samples, constructing profiles of subsurface conditions, and showing field conditions.
If possible, all
logs should be sketched at the same scale throughout the project.
Graphic scales commonly use ratios from 1:12 to
1:240 depending upon the complexity of the field conditions, size of excavations, and final drawing size of the project report.
The graphic sketch should portray the general geometry of the excavation, the location of contacts between differing materials, the nature of discontinuities, and the presence of ground water.
In addition to the graphic sketch, photo-
graphs are often useful.
A "Polaroid" type camera is a
9-3
useful tool in obtaining quick field photographs.
Stereo-
graphic photos of field conditions can be made by selecting a distant focal point, taking a picture, then offsetting five to seven feet in the same plane as the first photo, remaining at the selected focal point and taking a second picture of the same scene.
The two photos of the same scene
can then be viewed with a pocket stereoscope to produce a three-dimensional picture of the excavation.
9.1.3
Descriptions
Descriptions of soil should follow the guides outlined in Section 7 and rock descriptions should follow Section 8. The written description should contain some comments on excavation ease or difficulty, caving problems, and noted changes in ground water.
Some examples of field logs of various types of exploration pits, trenches, cuts, and shafts are shown on Figs. 9-1 through 9-3.
9.2
9.2.1
FAULT INVESTIGATION TRENCH LOGS
Basic Required Data
The basic data required for fault investigation trenches consist of heading data, the detailed log, and descriptions
9-4
of the subsurface materials.
A principal difference between
open excavation logging for fault investigations and logging for engineering purposes is that fault investigation trenches require 1) more detail and accuracy of the subsurface mapping and 2) the review and approval of the logs in the field by senior level personnel.
Thus, due to the complexity
of determining fault displacements, slip rates, and age of movement, special techniques are required that are not needed for most exploration trenches.
The heading data should include the
Pt'ojec:t name and
number; trench number; excavatiohequipment used and dates excavation and mapping were startedahd completed; date trench was backfilled; orientatiohCof wall (face) mapped; -
-;-
graphic scale/and names 'o,f piO!:tspnsittapping , reviewing, and/or approving the logs.
A plan view sketch showing the
trench location with respect to the local topography, geology, and cultural features should be made.
9.2.2
Trench Mapping Methods
Before fault investigation trenches are mapped, the trench walls are shored (Appendix B).
Then the trench wall showing
the clearest geologic relationships is selected for mapping. The opposite wall is rarely mapped but should, nevertheless, be closely viewed to clarify geologic relationships. Following trench wall cleaning, horizontal and vertical control reference lines are established on the wall to be mapped.
9-5
Several methods of trench wall cleaning are available depending upon the materials exposed.
The best way to
remove a smeared clayey surface is by forcibly pushing the broad-blade of a hand pick into the trench wall and then pulling a small wedge of material into the trench. Experience with this technique has revealed many shear planes not otherwise recognized.
Use of a sharp-pointed
pick is not satisfactory for this purpose.
Cleaning the
entire trench wall by use of a broad-blade pick is very time-consuming and tiring work.
"
Another, lesst.ifue-consuming
method is to clean the wall along a 91:"iclii,patte:rrt. be done by:
cleaning 2-foot
at 5-foot centers along
Wide'~~Wgf~s from
This can
tJl',to bottom
th¢G§1:"enchi~~~lW';:;leaning <,t;;"foot
wide horizontal swaths at
5f).f6b£!.,int~~y,alS ;->,,;,_~
---C_\\,:~_: __ ,j.,
->---';;_: _ '~~.-c
down the wall;
and following cdnta:Cfsbetween mi.fb~i'iari3 with 2-foot wide -,,,;"--
swaths ':
'<,. it",
Air bloWing hai:!,..•,, proven to be a' fast method for revealing ;,
structural
ana
lithologic details in bedrock, semi-consolidated
materials, and some soils.
Hand washing with a fine spray
has the advantage of enhancing color differences but often erodes or obscures some of the finer fault or shear details.
It is inappropriate to attempt to map a trench wall for fault investigations without the use of some linear reference system.
For survey control of the mapping, hori-
zontal and vertical reference lines are established along
9-6
the trench wall being mapped.
Normally, a large nail or
spike is driven into the trench wall at one end and a string-level is established from that point by driving nails or spikes along the level lines at convenient points keeping the string close to the trench wall by tied off horizontal or vertical sections between points.
In deep trenches, two
level lines may be established to aid mapping.
A fiberglass
tape may be used to label appropriate horizontal stations along the string line.
Other intervals can be added by
marking the string line with a marking pen or leaving the tape in place while mapping.
A plumb bob is used to make
vertical breaks in the horizontal string line.
Once the
level line is established, the ground surface and trench bottom can be quickly mapped ,by using a carpenter's rule, Philadelphia Rod, or a field expedient rod (such as a long, l"x2" strip of wood).
One person holds the rod vertically
at close intervals along the string line while the other person records and plots the distances from the reference line to the ground surface and trench bottom.
Obvious
contacts can be plotted this way at the same time as the trench profile is being drawn.
After cleaning the trench
wall and establishing a string line, contacts between major units are usually painted with DayGlo spray paint (orange, red, green, or yellow is best).
This speeds mapping and
greatly clarifies photography of the trench wall.
9-7
Once a linear reference line is established along the trench wall, a grid template may be used along the wall providing a faster, more accurate method of mapping.
(Alternatively,
but far more time-consuming, a string grid system may be established using the string level line as a reference.)
A
grid template can be made from concrete reinforcing wire mat with six-inch squares.
The mat is cut to a convenient size
to fit between the trench shoring and sprayed with DayGlo paint.
Nails are driven into the wall to hook the grid
template in alignment with the reference string line.
One
section of the wall is mapped and thent!le grid is moved in a leap-frog fashion using the reference points.
alrea.dy~driven
nails·as
The fine details in each six-inch grid
square can thus be accurately mapped in :rapid fashion.
All
details are shown, not in sui!lnlarized~:fasliion, but in actual representative detail. easiest to map.
Key planar features are often the
The feature of interest is mapped on
gridded mylar at the feature's intersection with the wire template and is carried across the mylar grid, noting intersections with each of the reference grid squares on the trench wall.
Symbols may be used to label key features and
to note features that are too small or poorly defined to show on. the map, such as degrees of weathering, color changes, moisture changes, and direction of discontinuities.
9-8
Normally, fault investigation trenches are mapped at a scale between 1:10 and 1:50.
Commonly, a scale of 1:12 or 1:24 is
selected when using English units.
At these scales, an
average pencil line (0.5 rom Pentel mechanical pencil) represents a feature
~
to
~
inches thick.
All details
larger than the threshold level of resolution should be recorded when mapping the actual zone of deformation. Beyond the zone of deformation, the level of resolution can be modified to reflect only those geologic features which may demonstrate the absence of deformation from faulting.
Although no standard log format exists for fault investigation trenches, the following guides have been helpful. 1)
A masonite board if cov$red by a sheet of white (exposed blue-line diazo) paper.
Fade-out blue,
grid mylar is then mounted (with the frosted side out) over the white paper. 2)
A mapping board of 24" by 36" is easily handled in the trenches and accommodates an unbroken trench profile at scales of 1:12 to 1:24.
3)
A grid on the mylar is an aid in locating the horizontal and vertical reference lines and drawing the geologic features as previously discussed.
4)
A survey stationing is made from left to right, unless opposite walls of the same trench are mapped on the same log.
5)
A recording of the elevation of the horizontal reference line is an aid in subsequent evaluation.
9-9
6)
An indication of all sample locations is an aid in interpretation.
7)
A standard use of geologic symbols provides consistency with other geologic mapping.
An example of both the detailed mapping needed for fault investigations and a typical field log format are shown on Fig. 9-4; Trench Log.
9.2.3
Trench Photography
Once the trench has been mapped, the entire wall should be photographed using color print film~
E:x;p1:;)rience has shown
that the following procedure~sproduCe good results. l)~
String level stationirigissl¥own every five feet . ,-
~
-
with two-inch highnumera.ls to assist in locating items in photos and in matching adjoining photos. The field vision for a 35-mm camera is about six feet when standing along the opposite wall of a three-foot wide trench.
Adequate overlap of the
photos should be obtained. 2)
Photos are taken with the trench wall shaded, often using flash unit to enhance the detail in dark shadows.
When the trench wall is in full
sunlight, the contrast from small shadows along the irregular surface and the reflected light obscures important features.
The ideal lighting
condition for trench photography is when it is overcast.
9-10
3)
Log of trench photos is maintained to aid in later identification of the photos.
An example Trench
Photo Log is provided, Fig. 9-5.
9.2.4
Displacement Evaluation Techniques
One of the primary purposes of fault investigations is to evaluate the amount and nature of both incremental and total displacements along or across a fault.
Displacement measure-
ments to evaluate fault activity are usually dependent on the recognition of subtle textural differences and/or similarities of Quaternary age (less than 2, 000 ,0'('0 years ago) deposits or younger soils that are offset by the ,'1fault.
Recording particle proper,tiesof cl
Thus,
these properties need to be carefully described during the fault investigation trench mapping.
Other subtle features, such as weathering rinds on clasts, clast lithology distributions, soil weathering profiles, and grain-size distribution skewedness or kurtosis, are not described by the engineering classifications of soils discussed in Section 7 of this Exploration Guide, nor by the Soil
9-11
Conservation Service, Soil Taxonomy, Ref. 55.
For this
reason, engineering and agricultural classification of soils for fault investigation are inappropriate and should be discouraged.
The techniques described in Refs. 44, 55 and
52 are more appropriate for recognizing and describing soil profiles during fault investigations.
Field geologists
inexperienced in trench mapping for fault investigations should become familiar with the techniques and the use of soils in Quaternary stratigraphic relationships.
A brief
summary of the data necessary for describing a sot,l profile for fault investigations is provided in Table9;"Z.
When
describing soil profiles, the correct "designation of color is extremely important for making 6I;i':t;"rell1'bive andi11)terpretive judgements.
The use of the GeOlogical/ Society of America
Rock Color chart, Ref. 30, is irll!tde'guat~, for describing soil --.';;-'
color for fault investigations.
The complete Munsell color
chart, Ref. 53, sl\.0I11dbe,used'for describing soil profiles, as color is of,ten a:guide to the relative development, and consequently age, of soils, particularly buried soils.
9.2.5
Age Evaluation Techniques
Another primary purpose of fault investigation trenches is to evaluate the frequency of displacement or slip rate along the fault.
The estimation of the frequency of displacement
relies on the ability to date materials that have (or have
9-12
not) been displaced, which is usually a difficult task. Field geologists should become familiar with methods summarized on Table 9-1, thus minimizing the possibility that critical samples be contaminated, destroyed, or overlooked during the trench wall cleaning process.
9-13
.
(
I
0-
Q)
~
-~• Q)
~
0:
-g o
c:
g r-------~--
__
.;
,aOl
..;
..;
..:
.,;
,;.
~ 'lV~l~mnW _ _ _ _J...._ _: ... - - - - ............... -....
.3
...:
"
..;
.: ... --""'-..,. .....:. .... ,..,..-:;
L... ____ .......... .,.. .... __ ........ ___
,QmU~N ~:lV-~,U.LV1:n1
'0 u <+.:
L -________________-L____~________________________________~________~------~~
..
Q)
e Q)
c:
"C C
o
g
'0 U
Data necessary for describing a soil profile
Plasticity is measured by rolling the soil between thumb and foretin' n attempt to form a thin rod. Several classes are recognized: nonpiastic ..Id forms~ slightJ... plastic-weak rod forms that is easily deformed and bro"ke-n: plastic-a rod forms that will resist moderate deformation and breakage during moderate handling; ['er.v plastic-a rod forms and is readily bent and otherwise manipulated before breakage. Wet consistence is very important in determining change in soil texture with depth and textural class: it is a major field cluE' to textural change if several adjacent soil horizon~ in a profile lie within the same textural class. Texture Determine the textural class of the less than 2 mm fraction. by noting the grittiness and wet consistence. Broad guidelines are given in the rating chart. but for more accuracy one should determine the limits for himself using n.,h,m
L,,:om
g Sill i n I" ,
..::
sili I,,"m
!:;
co
:::'"'
It is important that the terminology developed by soil scientists is used to describe soils.2 Examples of a variety of soil-profile descriptions with accompanying laboratory analyses are given by the 80il Survey 8taf[3 The followi~ properties should be recorded:
~
I
I
'
I I Sill, d,,; I.",m
iI
I
Loam'- ""nd' I and ;::;;:;c!-----j
S.nd~- ;"am
1::
i
'I:.:JE
I
Sand;' d:,,:I lo>~m
[
Depth The top of the uppermost mineral horizon (A or E) is taken as zero
Consistence This is a measure of the adherence of the soil particles to the fingers. the cohesion of soil particles to one another, and the resistance of the soil mass to deformation. Because this property varies with moisture content, it is taken when the soil is dry, moist, and wet. The wet consistence (natural wetness or artificial wetness) is useful in determining texture classes in the field and is composed of two quant.ities, stickiness and plasticity. Stickiness is measured by compressing the soil between thumb and forefinger and noting the adherence of the soil to either upon release of pressure. The classes recognized are nonsticky-no adherence when pressure is released; slightly sticky-soil adheres slightly upon release of pressure and stretches only slightly before being pulled apart; sticky-soil adheres on release of pressure and stretches before being pulled apart; very sticky-soil adheres strongly and will sustain a fair amount of stretching before rupture.
I
l-----~d,d,I\'
I
I,
I
Slight
iI/one
[
I
I
depth. The O-horizon thickness is measured up from that point (2 to 0 cm), and all other horizons down from that point (0 to 8 cm).
Color List dominant color and size and color'variation of prominent mottles. Use Munsell Soil Color Chart'(Munsell Color Co., Inc., Baltimore) Or other suitable charts that use the Munsell color notation. List moisture state when taken.
~ill'd";1I
I
---
II I
Sticky ~nd plastIC
I
Very
SnrK!:-.:r:s.<; A:-':D PLASTICITY RATI",(;
samples with known particle-size distribution. Greater than 2 mm particles should be described according to size, and volume per cent of the soil they occupy. Be watchful for shape and lithologic changes, as they may indicate parent-materials -of mOre than one origin. Structure Describe ty-pe (Table 1- 3). size. and grade of structurp. Size classes vary with type of structure as shDwn in the following tabulation.
Size class vf (very fine) f (fine) m(medium) c (coarse) vc (very coarse)
Granule or crumb diameter
Plate thickness
Block diameter
Prism diameter
(mm)
(mm)
(mm)
(mm)
<1
<1 1-2
<5
5--10
2-5 5-10
20-50
>10
>50
<10 10·20 20·50 50-100 >100
1~2
2-5 5-10 > 10
Ref: Birkland, 1974 Table 9-2: SOIL PROFILE DESCRIPTION
10··20
Grt classification of structural development: single grain-no bonding bet", particles; massive-no ped formation, but there is enough interparticle bonding for the soil to stand in a vertically cut face: weak-few peds are barely observable, and much material is unaggregated: moderate-peds are easily observable in place and most material is aggregated; strong-mass consists entirely of distinctly visible peds. In generaL structural grade is stronger with increasing amounts of day-size particles. Clay films Record their occurrence, frequency, and thickness. Films occur as colloidal stains on grains, as bridges between adjacent grains, or aligned along pores or ped fac-es. Frequency classification is based on the, per cent of the ped faces and/or pores that contain D.lms: very few-less than, -5%: few-5-:..25%; common-25-50%; many-50-900/0; and continuous-90-1000/0. Thickness of films is determined with a hand lens: thin-film is so thin that very fine ~and grains stand out; moderately thick-very fine sand grains are so envelpped by film that grain outlines are indistinct. yet grains impart microrelief to film: and thick-very fine and fine sand grains are enveloped by clay, forming a film with a smooth appearance, and films are visible without magnification.
Carbonates Note distribution of carbonate, estimate the v-olume per cent, and classify on stage ofdevelopment 1 (Fig. A-I); see following table. III
Thin discontinuous pebble coatings
Few filaments or faint coatings on sand grains
II
Continuous pebble coating: matrix is calcareous but loose
Few to common nodules of varying hardness: matrix is commonly calcareous
III
All grains are coated with carbonate; best developed where voids are fill€'d with carbonate
Internoduiar matrix grains are coated with carbonate: voids can be filled with carbonate
IV
Laminar horizon of nearly pure carbonate overlies horizon of stage III development
Indicate effervescence with dilute (..... 1 N) Hel: very slight few bubbles: slight-bubbles readily observed: strong-·- hubbIes form a low foam; violent foam is thick and has a "boiling" appearance.
pH Record field value, using a field test kit.
II
'I " IV
K2
K22m
K3
, K3
0",
r
",,)?f , 'i
Horizon boundaries Record width of transition zone from the overlying to the underlying horizon (distinctness) and the topography of the zone. Distinctness classes are very abrupt-no greater than 1 mm; abrupt--l mm 2.5 cm: clear-2.5-6 cm; gradual-6-12.5 cm; diffuse- > 12.5 -em. Topography descriptions are smooth·-boundaries are parallel to ground surface; wau)' boundary undulates and depressions are wider than they are deep; irregular· boundary undulates and depressions are deeper than they are wide; broken parts of horizon are disconnected laterally. Percentage estimate It is important to estimate the per cent by volume of various soil features, such as gravel or carbonate content or extent of mottling. The chart below is provid-ed to aid with such -estimates. (Taken from Yaaion,4 C 1966, The Williams & Wilkins Co., Baltimore.)
. ............. .... : ....-..... .. .........' ........... ::.. ·• • ..•...'.••... •••• • •• • • ..... ,
Fig. A-I Sketch of carbonate buildup stages (1. II, III, and IV) for gravelly {top) and nongravelly (bottom) parent materials. (Taken from Cile and others,l c 1966, The Williams & Wilkins Co .. Baltimore.)
...
•
Cementation Record the kind of cementing agent, whether it is continuous or discontinuous, estimate the volume per cent it occupies. and estimate how strongly the horizon is cemented: weak-material is brittle and can be broken with the hands; strong-material is brittle and brokE>n easily with a hammer; indurated-material is brittle and broken only with a sharp hammer blow.
':. ",,'. ':::::!~!
",
•
Ref: Birkland, 1974
NOfljJran>/I. . . parent material
Gra['ell.v parent mataiai
Stage
------------"
"'....
•
5%
..
II_ •
.~
~.~.~::,
II
t
lO'if
Table 9-2 (continued)
I·;· ; I
..
i· •
2O'if
30%
40%
SOIL PROFILE DESCRIPTION
Convel'$eWarc/ Davis Dixon, Inc. Geotechnical Consultants TEST PIT No. 1
Started Oat!! :U_ MARCH 1'11'1
lim!!
Dj!~5
Proi. No.
Finished Oat!! 2.'--
Ii!!ll
0'130
Proi. Narl')tlGORILLI>.. GROTTO
~lient
MIIRc.H
'PL{>.NN AND DRl\w ARct-\ITE.C.TS
S!1rface Elevation
-r 1<'7.7 FT.
I2gtum MSL Water EI!!l!ation DE PTH E[r
SeE NOTE.
COLOR MOIST
COM (0)>..;
by
i"\
M
Ot'
M
1"\
SAMPLE
oY-
by
C\\EMICAL CP. E><.PANS"loIV
~l\cavator
O'DEl..L E)(.c.AvATlol\J
~!;I!1il2me[!t
CA~E
!&gged By-
A.
co.
ql/o
Sl..EE.P
REMARKS
DESCRIPTION OF SOIL
NO.
T01"SOIl.. - SoIL'Iy SAIVDCS'M) SoME.. CL@ O'i" 5MRS£ t>1t;.Ct;.S of cDIIRSE ':;"''''0.1.- - R<>d'I"s
IBP
1.0' CLAYt;.y ,,'LTCML)" SILTY CLAY(CL') LIWE:REI) WITfj .solliE. THIN (<.1") 5P-~M LENSS:5
:<.5 I
CI.IWE'( SILT (f/lL) ... c.c.Aye.y SAND Csc) - LII'r'ERED, W 1'1'1\ Soo!'l\ lO- THIN (4 I':,) 5P-SM LE:NSr.S
It "'~ -to i - It
q.oFT.
Total De[1th
-0
b..
N;l.OW
Orlentgtion
Site AJAX
5
VM
sr::ef>A&1:. (>.FTER 1. \\OuI\
I3El..oW :2..5' 'PIT WA(...LS SLouGHING
ZBP
to YS 7.S'
or-br
...
01<. <6
\..oj
.s
Go~I>..VEI,.('"
3BP
y SAN\') (Sf» 10 FINE SAI-lt> (.1'\) WITt'< -SoME
!"IL.
'1.0'
?IT BI'ILK riLLE I>
@ \030
13dfToM of PIT
f-l05 70°E,
I -r
12.' : . TopsoiI , ... ."
f-15-
q.O'
---
I
-
_l,...
-
-
I
SM ..... . .
I'1L - CL
-
I
3l
-
ML-SC _se:.-s~
~SP~M
-.
-:
- . . .j
-=-S.f?=SN}=~
7
=SEsa~
a>
20 EXAMPLE TEST PIT LOG Figure 9-1
--,-....
oi:Z
SE£1>I'I(;cIO MIN, A'fTE'R c)I,CAVATIotJ
:s:
5 o cJJ
~.
Q
~ :::. NOI.l.'iIl.3'i:3
SHAFT No. ? ELEv"noN ~""'E. SEA LEVEL.
WALL
(j)
1.0'1.0-
-~O'I.O
t,,,
·txl2.
txlZ,
2.xl2-
t"xl2.
t.)(IZ,
'1\9.EGUL.hR, 'f'lc..IPIE"NT Hf\ltt,UNE. SKEARS
@ 201.0-
® 1.00.0-
-1'1/0.0
-Iq~.o
LAfl\INATi:J) F1\RTING ALoNG IRREGU!...A'R St'\EA'R 'PL..f\NES, SoME SLiC.l QJRFACE.S, MiNoR FRAc'iUI\ES SoMETlfot\i:S I'IL1.ED WITH C~'1 'DR sHALe. --Z-" CLAY A'-ONe> FRACTuReS; fREOOfqINANi. SHEAR AT'fITUOE Nlf.Sl.IJ1 .... 6to-70NEj SHEARING CON· ~1'ED IN i't,AC.'ES wrrH TIGHT RADIOS CU~VE$i SM"L£
I~I.
rbOE-AATE YEUoWIS~ 1O~WN 1t) G-RA"f1S1-\ O~NGE GrRA'r'w,te.KEj F.G. To V,F.G., HAP-D, MEt)IUft\ WEATt\EREO, IR'P.EGtIJI.,.A~ St..oa'T'. CloSEL.1( TO VEf'..,- CWSEl.'1' SVACEO FAAC.TUI\E.S; Stl.EAREO· SAND'-( CJ.I..'1 I'TlATftIX SUP.'kOUNOINGr C.~-'" DI"I'\E."'e.~ ClASTS IN PLAC:E.S, SANDi' ClAY MAT1'!1K IN
/
a"'I!:e:"'ISt\ GoRAl{ TO 0#'11\1( YELLOWisH ORANGE,. CLAY (CL/c:.H); MOIST. FIRM; SII'\ILM\ TO ~EPT RELIC sAAI..E. 'PM\TINr:rS NoOT .sEEN.
rb
i?'MIOEI;) Gt\E'E.t&tSI\ GRAY CLIoY s~ ~'I ~ J4f.~ WIOE ALoNG. SHEAR 'PlANESj
®
OVSkY SLUE. TO bARK G~AY INTENSELY' St{£II\RE.O SHAl~j ! SO. . OF SI\~LE. ...:!.... Cl""l.1 (CL) F'11\"", ftlOIST; CONTAINS OISc.o/>lTINUOUS vEINL£.TS OF lOtl.rE. QlIII1\Tl. IN A FEW f"LACES; SHA/..E IS SOFT, SLIGHTLY WEATt\ERED To UNwEATIi.R.t::D, E)(TP.EI"'\E.L"r' c.L.oSE. SPI\C.e.O PA1\TINGALoNa. SLICI(EJJSIDE'O, 'POLISHED SH'EA.'R. ?l.)..N~ Tt\.....T AP.E CONTORTED IN CURVEt) IN PLACESj SI-'AL.E. OCCASION/l.U'r' SuRROONDItJG 3'-Gl" P'''METER FoG.. GoAA'I'WAc.KE INCLUSIoN,
®
/lJAPPE£)
NOTE. NUMBER
Y.F:c;..' GR~'c'wAC"£; HIGKL'T WEATttE.P.E.D, MEOllJ~ HM\D"TtI H,o..RD,--
@
-1'12..0
ew
LIG~T OUVE SROWN To G!\AVISH ·OMNG-E. S~EARED SHAL-E wrrH
'--'3"
~
SEeN
ATTiTUDE OF SHEAR. "PLANES WITH "RESPE"c.T "n3 tioRrzAJTAL "PLANt::.
~etoNt>S H"''RDEQ. GrfVtttWt'.c.k&. INCUJSIONS UP 1b (,1I_ogIlIN Oh'.METeR.
-1'111.0
.Jss
OLIVE: SL/t.C.~ TO MEDIUM. BLUISH Gf\I\V IN''fENSE-LY CR,USI'\ED SHAL.E ..I......,. CL"Y(CL), )o\OISTJ FIRM, CAN STILL SEE Rf.,L..\C- S\\Al.E. 'PI\RTltJGS ALONG- St\EA,f\S1': INCLuDliS \ott II DlNf\E.T"EP. SUBR.ouNDe.O CLASTS OF F: G. Go.....vwl\C..Ke.
Cl.o~EL'"
-200.0
Airm..lDE. Of SHEAF.. PLANES ALONG 8E.l>PING
FACE wALL
®
hi.. -~O2.0
SYMBOLS
EXPLANATION
"',. ....
GEOLo6/C u)NrAc.r BETWEEN DIFFERING fttAreR/ALS, PRo:rec..rE.p BeHIND LAGGING
DoTTE..D WlfERE.
WPlTE.1\ SURFACE. TOft. VANE. S"EA.'R TEST WITH SHfJ'R STRENGTt\ IN' KIPS
®
SEVE.. ,.L RooTS
G1tOWI~ ,,1J)Nt;
SEA/'I\.
NOTES TOP 0"F SMI'\FT it.A..
ELEVf\nO(lJ
I~.(.,''''
ABOVE- O>NCReTE. SLAB WITH !u'R'lE.VE.O
:toS,i
LoNG AXIS O~I~NTA:noN: N7W
OLIVE ~PJIN To DARK. u~EENISH GRfW GAAYWACI<'E..j f,G., 'BLOCKY, SPAcED SHEARS, HARD 10 Ffl..ACTIJR,,£.S "LON(; CLOSE"'", TO VER!.r' CLOSE VERY H~I"'1); SI\P\'E AS @ I3UT COARSER GRAltvED. G~EEN\S'"
l .. '.
GMV CJ.,/\y (el/e",), . FIRM, MOIST" TO VERY (WIST, /..LIrrt\. CLA'r' SHALE
•
fAAGrI'tlENTS ORIENTED ALONG. StlEAA PLANE; S\otA.Le.. IS FRIA"SLE. VERY CLoSE.LY L.J.."'INATED. ~/..lsHEO SKEA~ ?lANES.
DARK OrRoEEf..iIS" GlRAy SH.ftLE; ClOSE.LV LAMINATED, MEotUf'W\ Hhl\t> TO t\frI."RD, 'PLATE'!', FREsH, EASILlf BRE:J..J(S OUT AU>N6 BEDDfNtl PlANE.S. TO QARK GRAY I1\G\-k.Y SH"EARED St\~L.E.i SOFT, f'RIA8LE,
'f~.~~~,,~~;~~M~~~
CLOSE S'PACED PARTIMG ALON& PoLISHEI>, ,~ "PU\N~S THAT ~RE INTERl.AC.ING-, i.JJI>,VEV ANo Sl\6\-\'TloV cotJTORTE.D IW PLACES; IO-,U)°/.. OF SttAc...E. ToP .. CJ..I.,~, SoME.. CUlY ALONG- tWRLlNe. $HEARS •
'132.10
ScALE. IN FEET
.. ~.-~~@&"h~~.
GREENISl\ G.~t.i' To ,OL.NE. G\\AY (UNWEA.T-HeRE-D) GJ\fWu.w:.KE.; L.OCA/../..'{ t3e:COMES F..G" HARD TO VEfty ~l~:~-:::{:tf~·,,·,·~~oAAijB~'YJJNt.oEA'-HEREt> To 'SL.IGHTt-"r' WEAn,ERED, ~n_ .,,- CLAV SEAMS --""""N'" A~"ii~EDt>lNG- "PLI\NE. SHE....RS, Suc/<'E.NSIDED SURFAaS AL0N<7
....<:~~~s;f::;3.;i')~~'0.9ffUNII.TEW V.FoG. 'BUT
bY}f::f
-162.0
-H:::;'~~~Hl7+'n;tf~'jrrttl-::::'--r~ffi*,rH~+*t-i- 18'.o-l~~?f, :c.'\}'S\
~Si\'tti~oaiD:~CU)~ES; s:~:~ ~~~~~JR:A~~~~~6fS M.\'!:;$41?:Jg6JuSIl>~[)i O
~~~;:Th5~~V~~f}i~rt~M, "PU\S\lC, {Itolsr; SoME. IiIGHLY POL/SHtm SLJCJ
: ",:·~sr<;:::-';:-<·<'FACI5.S
NEAR BOTroM. OF stMFT'" I.oITH CU\Y ~TIN6-; GRAYWACI
'.;~;;~::~c>,
®
.. - I"
~
Lt~
TE.R\l.A.CE.
Pr.j.Numb..r: 77· 4IQ'l'07 Sh....t i'of 1 DQ.te: I'll-I'! Auqust 1917
Geol"'lY by: D.I<. ROGERS C nec.kILd by: A.L.O. AI>provILd by: 1\. L. O.
WIDE. CRliSHED sHEAR WITH O'f\A<3- FotDS ON EACIl SIt>E UP To FRoM Sf"l.EARj CRUSHED GRAYWACKE. FRAGMli-NTS IN ,.,
fJ.IJJI\y
. SAND" CLAY M~TRIX:
®
fIoa;. No.m.. : LAKEVIE.W
'
I·~r..." WIDE. HIG/Wr' 'SftEI\RED ZoNE WITH. BRAIDED, EXT-REME.L.
EXAMPLE TEST SHAFT lOG
..
Seal.
EXPLORATION GUIDE
,
Projo<'''Io.
78-0078
Preport
Chocl
@CoriverseWardDavlsDixon
G.al.chnicil COMu1lan11
Approved by
9-3 '.
G) CoII"i..1 slope ",..sh, ~, SILTY, SMALL COBBLE ~ (see sh ...t 1 10"
® Blotkvin. , ...",..f,on: TUFFACEOUS, FINE SANDY CONGLOMERATE
C. . .
o....cRlption)
meto.morphlc(?) fra.qm ..nts tho.t o.re po.rti ..l1~ to toto.lly o.ltered to chlorite a.nd minor c\a.I,J; medium ha.rd a.nd rnodaro.tell) cema:C\tl2.d (Y(l.·cemented ?l
shout 1 r... description)
LOCATION
® LANDSLIDE DEBRIS: light broUJn to IIqht brownish qrey, heterogeneous, chO-otic mixture of &1.
(I;) INTENSELY FRACTURED ~:~.lIowish qre~ wi,h liqht btown coeded c1o.sts; ·,nta.hs..ly fmct.ura4 and crusha.d ma.tctt"io..\ with incipilloot, lineo.t' s'neo.Y's subpa..ro.\\Il.\ to the o..d)o.cent f..,lt; sl'~"t o.liqnment of pebbles and cobbles, approxlmaie\lj 30" of the of the do.st, a.t.
MAP
few andesite cobbla.s o.nd many Clngular cobbl .. fro.gments; highly varia.ble In composition a.nd physical cha.ro.ct.eriS1.1cSi qenerQJly Inta.nsel"J fra.c.tured, medium ",eather..d, medium ho.rd to soft, mo.ny hClitline, cla.yfilled, ra.ndom fro.ctures.
anqulo.r lithic fra.qment. of metoJT\orphic rocks (slo.te, schlst(1') and posslbl~ greenstone); n few a"qulnr fra.qmen\.s or "",In (7) 'lvo.rtZ o.to. nJso present o.!thouqh Inr.ensely 'hea.red, zone Is medium hntd ""d modero.tely cemenr..a (rocement"d?)
!Ill PALEOSOL: modero.te yellOWish brown (\0.,,1'1 5'~) ~ C.LAY,
(i). ~ fRACTURED ZQMf..: modernte oro.nq. pink to light brown, closely frO-ct.ur..d B\oc.~vi II.. formo.r.lon with YOlo.ted and vo.quely aligned andesite clo.st.; cio.sts have clay coa.ted surfa.ce. with thinly spa.ced otriO-tions a.nd sho.ll.... 9roo".... ; clay coo.tlng i. commonly waxey; shqhtly tra.nsluco.nt, hiqhly hydroscOPIC, and occo.sionally vary flnoly lamlno.ted when flllln'l fro.cturos; do..t sutfD.C"S Clppeo.t 'pollshed' from mov"mcznt o.long sheo.r plo.ne. or from clast toto.tion between sheo.r plo.nes; commonly the clayey ma.hlx surrounding the clo..~. Is closely fro.ctured Into very friable, crumbly fro.qments les. tha.n V,,' In dla.meter.
stic:.k~, v12r'1 plo.stlc, c,oa.rs£ to very coa..rae, modero.te to &tronq prisma.tic peds, common, t~in cla.y Film coa.ting peds;: stronq cemehta.tion when dr~, cleo.r to qro.duo.l boundaries wit'" overlylnq collUVium. @ Slickensides have ro.ke of 6Q' south Indica.ting right normo.l, obli'lue-slip mov..men\...
@FClults hClve genera.l trend of N~4W, 7qE.
(jj) BI..kville formation: TUffACEOUS, SILTY, VERY fiNE SAND; same as ® above but ",ilhout o.n~ cobbles of o.ode.lte; IIttl" fra.cture., medium .... Sh••t 1
ho.rd to
ho.rd, medium ",oo.thered.
. ® CRUSHED ZQ!:i1: dark greonlsh qrey micro· breccia. with o.pproxlmo.tely"kO" a.ngulo.r, coo.rse . sand·s,ze quartz i'r<1gments, 30" anqula.t, ver~.;;.~rse son~:sJ;,(HlJ!Jl& meto.morphic frnqments of slate, schist (?) Md greenstone (?) IQ';~" cr~!!Ml\ill:>i'_'CCrobd qroundmo.s. of
'1<40'
i't~~i<,}S"
TRENCH BEARING N56W, NE WALL MAPPED
.JI
-.1._
.1'0.1
4:; / Se.etior. c.orN&. \" 15, It.. l.I, 'l.l., T10N, 1'.351;:
•
ap~~noo ~~~~~~~~~~~~~~~~ o Cobbles, boulders of ptedominat"l~ andesite and porphyritic andeslt.e (;' Cobb/.. -boulder c.ost - c.laSl removed during excavatIOn
fiv' faull. with slickensides and fluted grooves ",y Fault with )o\'-.li~ clay tilled shear:s
,pi' Shear zone;
many polished cobbles with well-developed linear shear planes
::;: Inciplentl\! sheared and sho:l::tered zone; few polished cobbles; some with pa.ro.llel Clhgnment to shear zone :.f:~
Mlcrobrecia. zone
/
Fro.ttures - JOints Lo.ndsl1de Fo.Ilure pla.ne; !Ii'-~: Wide, moderate brown to 9reQIsh brown ~ CLAY (CH); strlo.tlons 0.1009 plone perpenclicvlo.r to trench/rood cut.
/ /
/ / Contact between colluvial soils; pClleosolls, Io.ndslld" debris and bedrock. 3~O
Surve.~ control point.
Nates: QShorinq ~
not shown.
Zone of d.formoilon from 3W to 60.0
:1, L
..
0
:~~~~:t=~~~~~*~]~~~~~~~:--
l'\o.j.Narne"ST. THOm 1"t.,i.Numb.r: 7Q-41%-02. Fo.ult Investlgo.tlon Trench: TR-2.(sheet Z of q) EXco.va.tlon E"ulpment Used: HOPTO 500 D ""t.h 3' wid .., 7 tooth bucket E,co.vo.tlon Started: &/12./79 COl'lpleted: 8!1~/7~ Backfilled: q/ll7q Loqqed B~, D.K.Ro~ers 81lq- Silbl7Q Check.d By: HAS. 8/1~179 Approved &Y' RAH., I\.L.Q 8/?SI7Q
FAULT INVESTIGATION - TRENCH LOG
8<.,.
P,.)<.,No
P,.p.",dO.
"""....,~~.--
EXPLORATION GUIDE
......'.-- 9-4 A~o<
~~-----------------~"."'
~ConverseWardDaylsDixon
ao.todtllo.ICo_
...
Roll No. ST- \
Project:_ S~ TI'lorvll\$ J)AM 7Cj- Lfl "if&> - o~
TRENCH PHOTO LOG
Film Type KoDAcHRoME.
tographer D.I<. "RO&E.RS Frame Trench Name Station Ref. Date
Geologic Description
I
TR-:l.
~
II
35 - yo
/I
3
1/
40 - 45
"
4
/I
4S
-So
II
If
S
II
50
-ss
If
1/
If
{p
II
SS-l.IJo
"
/I
/1
30-35
Page~of_\
'8/11(/71 UN f> l.s/vR BED
BLC>CI
FORMATION
FAULT ?.oNE. (ANDSLI DE- Dt:BRIS OIJe.R OLD St/EARS II
II
II
I,
"
If
"
If
If II
-
• .
@ConverseWardDavlsDlxon Finll ... 9-5
Geolechnical Consultants
10
FIELD PERMEABILITY TESTS
Field permeability tests measure the coefficient of permeability (hydraulic conductivity is another name used) of in-place materials.
The coefficient of permeability is the
factor of proportionality relating the rate of fluid discharge, per unit of cross-sectional area, to the hydraulic gradient '(the pressure or "head" inducing flow, divided by the length of the flow path).
This relation is usually expressed
simply:
Q/A
=
H
L
where Q is discharge (volume/time); Ais cross-sectional H
area;
L is the hydraulic gradienu;, (dimensionless) ; and K is :
- '.
'
<-.---
the coefficient dfpermeability, expressed in length per -. -
uni t
-
,
time (cm/sec, ft/day, a'te.) .,' The area and length
factors are oftencombine'd' 'in a "shape factor" or " conductivity coefficient".
He'reinafter "permeability" will be used to
signify "cOefficient of permeability".
Evaluations of permeability are require,d whenever discharge or seepage quantities, subsurface fluid pressures, and/or velocities of groundwater movement are important.
Field
permeability tests and field percolation tests are conducted in many geotechnical explorations.
In addition, in many
environmental and water resource investigations knowledge of material permeability is important.
10-1
Field percolation tests
(paragraph 10.4) are generally near surface tests whereas permeability tests are usually conducted in exploration borings or wells.
Permeability is the most variable of all the material properties commonly used in geotechnical analyses.
A
permeability spread of ten or more orders of magnitude has been reported for a number of different types of tests and materials.
With such a great range of possible results, it
is not surprising that the measurement of permeability is highly sensitive to both natural and test conditions.
The
difficulties inherent in field permeability testing require that great care be taken by the field representative to minimize sources of error and to correctly interpret, and compensate for, deviations from ideal test conditions.
10.1
EVALUATING THE BEST TYPE OF TEST
Many types of field permeability tests can be performed. All the tests discussed in this Guide are conducted by measuring the rate of flow for a given head change applied to a boring.
In geotechnical exploration, equilibrium tests
are the most common.
These include constant and variable
head gravity tests and pressure (packer) tests conducted in single borings.
In a few geotechnical investigations, and
commonly in water resource or environmental studies, nonequilibrium "aquifer" or "pump" tests are conducted (a well is pumped at a constant rate for an extended period of time) •
10-2
Permeability testing methods differ in the manner in which the head differential is applied, in the geometry of the test zone, in the duration of the test, in the number of observation-points used, in interpretation techniques, and in other ways.
In spite of the wide variety of testing
procedures, one or two methods are generally best suited for a given set of conditions.
Decisions as to test method are
made at both the office and the field levels.
This Guide is
primarily concerned with field operations; however, awareness of the overall objectives of testing is important in the selection of the most accurate field procedures and methods of observation.
The following five physicalcl;laracteristics influence the performance and applicability of permeability tests: 1)
position of the water level,
2)
type of material - rock or soil,
3)
depth of the test zone,
4)
permeability of the test zone, and
5)
heterogeneity and anisotropy of the test zone.
These variables usually have a greater influence on the method by which the test zone is to be isolated than on the basic testing method to be used.
The influence of the
variables on testing procedures and methods is discussed in the following paragraphs.
General points concerning various
types of tests are:
10-3
1)
In geotechnical investigations, the most generally applicable permeability test is the constant head test.
It may be difficult to perform in materials
of either very high or very low permeability since the flow of water may be difficult to maintain or to measure. 2)
In a saturated zone with sufficiently permeable materials, the rising head test is more accurate than a constant or a falling head test.
Plugging
of the pores by fines or by air bubbles is less apt to occur in a rising head test.
In an
unsaturated zone, the rising head test is inapplicable. 3)
In zones where the flow rates are very high or very low, the falling head, test may be more accurate than a constant head test.
In an area of unknown
permeability the constant head test should be attempted before a falling head test. 4)
In large scale seepage inves,tigations or groundwater resource studies, the expense of "aquifer" or "pump" tests may be justified as they provide more useful data than any other type tests.
Pump tests
require a test well, pumping equipment, and lengthy test times.
Observation wells are desirable.
A vast number of interpretive techniques have been published for specialized conditions.
10-4
5)
In a boring, gravity and pressure tests are appropriate.
The segment of the boring tested is
usually 5 to 10 feet, but may be larger.
A large
number of tests must be conducted to achieve an overall view of the seepage characteristics of the materials.
The zone of influence of each test is
small, usually a few feet or perhaps a few inches. These methods can detect changes in permeability over relatively short distances in a boring, which conventional pump or aquifer tests cannot. Exploration boring (as oppc;Jsed to "well") methods are therefore useful in geotechnical investigations, where inhomogeneity and anisotropy may be of critical importance,.
Results from pressure tests
using packers in fract\:tred rock may provide an indication of static heads, inflow capacities, and fracture deformation characteristics, but conventional interpretation methods do not give a true permeability in the sense that it can be measured in porous media. 6)
In all cases, running different types of permeability and pressure tests on the same zones and materials will provide desirable redundancy and allow a more positive interpretation of groundwater conditions.
10-5
10.2
PRE-TEST PROCEDURES
Borings for foundation investigations are primarily for geotechnical exploration and sample recovery, thus selection of the type of drilling equipment is usually made with only secondary consideration given to the requirements of permeability testing.
Certain basic drilling and preparation
procedures should be followed if permeability tests are to be conducted in a boring.
The primary consideration is to
avoid plugging, or to ,restore the natural openings (pores and fractures) that may have been distUirbed by drilling, so the permeability measured is representative of the in-place materials.
Factors affecting permeability test results in a boring include: 1)
vibration from drilling operations compacting granular soils,
2)
movement of drilling tools or casing past the boring wall smearing natural openings in cohesive materials, and
3)
fluid containing drilling additives and/or cuttings carrying materials into open pores and fissures.
These can be mitigated by appropriate drilling procedures and test preparation.
10-6
10.2.1
Drilling and Casing
Ground water or water introduced for permeability testing will generally cause a boring to cave in granular materials coarser than fine silt; therefore, borings in unconsolidated material must often be supported, either by casing or by the hydrostatic pressure of fluid (water with or without drilling additives) standing in the boring.
In addition, drilling
fluid serves to carry cuttings to the surface and to cool and lubricate the drill bit.
Excellent referet'l:c::es for
drilling procedures to be used in con1,lnction. wi th permeability testing are Refs. 34 and 38.
It
would be ideal to avoi~dr,:i.llin(:f,by methods that require: 1)
the use ofcircul(i1:,ing l'1~iili'ng fluid to remove ."." drill' cuttings, or:,
2)
the
US""
of forceful driving of casing.
In actual practice, however, drilling fluid may be necessary to advance the boring, and driving casing may be the most effective method of isolating test zones in unconsolidated materials. -Common drilling methods that neither use a drilling fluid nor drive casing include augering and airrotary.
Augering is generally practical only in unsaturated
materials at shallow to moderate depths.
The air-rotary
method, in which cuttings are carried up the annulus by compressed air, is usable over a wider range of materials
10-7
and conditions than the auger.
Generally the use of air-
rotary methods exerts a minimal influence on natural porosity and permeability.
Unfortunately, the bits used with air are
easily clogged in cohesive materials, and sludge forms rapidly in a boring beneath the water level.
The conventional
air-rotary method works best in dry, consolidated, granular materials.
The Becker hammer drill, Fig. 4-11, employs compressed air and was designed specifically for granular, unconsolidated materials.
Casing is continuously advanced and"fairly
representati ve disturbed samples can/be recovered.
(A
cutting edge is used, reduqing forI1ll'l'tiQn disturbarioe.) Casing may be withdrawn, wi thspecial'~quipment, for .
permeability testing.
,
water;;'bea:tlll:';ilib:i1es are easily detected.
However, the Becker drill is not in widespread use and may be unavailable in many areas.
When rotary drilling with fluid, and undisturbed or penetration samples are not required, the reverse circulation technique may reduce plugging problems as cuttings are carried up the drill pipe rather than up the annular space outside.
Erosion
of the boring is lessened by a lower fluid velocity than in conventional hydraulic rotary methods.
However, with the
reverse circulation system, some plugging still occurs from fines that circulate through the settling pit.
10-8
Caving sections in unconsolidated materials may be the most critical seepage zones, and thus the most important zones for permeability testing.
If the test zone will stand un-
supported during drilling, casing may be set in reamed, rotary-drilled borings then driven the last few feet to establish a good seal.
The boring can then be deepened by
r?tary or a small wire line bit, gravel packed, if necessary, and tested.
Alternately, a telescoping well screen
of perforated casing may be installed and swedged tightly into the blank casing (Ref. 34, Ch. 12).
This is a relatively
expensive procedure and would not normally be used unless the installation is to be permanent.
As a last resort, well
points may be driven in granular soils.
10.2.2
Boring Cleaning
Every boring should be cleaned prior to permeability testing. This is similar to water well development (Ref. 34, Ch. 14), with the major exception that natural permeability is not to be increased, only restored to its pre-drilling state.
The
time and effort required to clean the boring depends on the drilling method used and the types of materials penetrated. Air-rotary and reverse circulation drilled borings in granular or consolidated materials will generally require the least attention, whereas rotary borings drilled with fluid or drilled in clays require the most attention.
10-9
A scratching tool applied to the sides of a shallow boring may be adequate preparation for simple gravity tests conducted above a low permeability layer.
In most cases,
however, some flushing of the boring is necessary, particularly if a drilling fluid, with or without additives, has been used.
The most effective flushing technique is to move a
surge block or bailer (Fig. 10-1) slowly up and down (an upward velocity equal to or slightly greater than the freefall velocity of the tool is about right) inducing a gentle flow in and out of the boring walls.
The surging tool
should be just slightly smaller than the boring.
A flap
valve allowing water to pass thr()ug'~!16n the downstroke is desirable as i t reduces theflowi:i~i.,f(l}:t.Gid.Y water :!..nto the formation.
Short test sections (5 tq10 feet)
surged for about 5 minutes and then bailing, pumping, or airlifting.
t~
should be
water removed by
The cycle should be
repeated until the wa.teris reasonably clear.
Longer test
sections should be surged in 5-to 10-foot sections (longer sections are permissible in relatively clean borings) and water removed after each surging.
The water does not need
to be completely clear after cleaning each short section, but the entire test section should be surged until the return water is free of most of the sand- and 'silt-sized particles, but not necessarily clear.
In granular or
consolidated materials, or when drilling mud has not been used, surging may be unnecessary and the final cleaning may be accomplished by alternately filling and pumping the
10-10
boring or by circulating the water through a settling pit until the return flow is clear.
Unless a bailer is used,
the pump should be turned on and off at intervals to generate turbulence in the boring.
In consolidated formations, alternative "cleaning" methods include the use of a rotating, stiffly bristled brush while washing and jetting with water.
An average jet velocity of
150 feet per second is desirable.
This is approximated by
a rate of pumping equal to 1.4 gallons per minute per 1/16inch-diameter hole in the drill rod.
On completion of
jetting, the boring should be blown or bailed out to the bottom.
10.2.3
Test Section Isolation
Exploration borings drilled in consolidated materials are generally uncased.
with uncased borings, mechanical or
pneumatic packers are conveniently used to isolate sections of a boring for permeability tests.
A test section near the
bottom of a boring can be isolated by a single packer and different zones can be tested as the boring is drilled or is backfilled.
Multiple test zones can be isolated by double
packers, connected by a perforated pipe, in 5- to 20-foot lengths throughout the boring.
Schematic single and double
packer configurations are shown in Fig. 10-2.
10-11
Mechanical and pneumatic packers are the two principal types used.
Types of mechanical packers include wedge, bottom-
set, and screw-set.
Wedge packers are simple but useful
only to pressures of about 25 psi.
Both bottom-set and
screw-set packers can be used to higher pressures.
Each has
a rubber cylinder which is mechanically expanded against the sides of the boring by compressing the cylinder.
With the
bottom-set type, the rubber cylinder is located between the drill rods attached to the drill and the drill rods extending to the bottom of the boring.
The rubber cylinder is compressed
and expanded laterally by using the drill rods to transfer the load onto the cylinder from thE!. drilling machine.
with
the screw-set solid rubberpacker,ahadjusting nut is used to compress the packer.
Mechanical packers are suitable for
hard rock and moderately jointed,.non-'c';'wing, non-erodible formations.
Although mechanical packers may be used with
higher water pressures than pneumatic packers, the difficulty of sea.t:ingthe packers properly at greater depths severely limits the use of the mechanical packers.
Inflatable rubber packers (pneumatic packers) ,which reduce testing time and maintain a tighter seal, are usually more economical than mechanical packers, particularly in roughwalled, out-of-round, or erodible borings (Ref. 38, p. 249). The packers are inflated through tubes extending to the packers from a cylinder of compressed air or nitrogen at the surface.
The packers should be at least 5 times as long as
10-12
the boring diameter; however, permeable, erodible, or irregular surfaces may require even greater lengths.
Care should be
taken that the packer is attached to the drill rods right side up, as some pneumatic packers require installation with a particular end toward the top to seat properly.
Stable borings in unconsolidated materials are most conveniently tested in sections as the casing is advanced or withdrawn, Fig. 10-3(a).
The best time to test a boring is
immediately after it is drilled and, in most types of drilling, a good casing seal can only be obtained as the boring is advanced.
When casing has been continuously driven, however,
it may be possible to
test~
advantage of testing as the
as
the~casing
ca~sing
is withdrawn.
The
is withdrawn is that a
complete geologic log is available from which to select test sections.
If the casing makes a tight, leakproof seal with
the wall above the test section, but the open zone is unstable, gravel backfill should be used, or perforated casing or well screens should be installed.
Fig. 10-3(b)
illustrates two configurations for cased test sections. Procedures for installation have been discussed previously and are given by Refs. 37, pp. 37-42, and 34, Ch. 12.
The gravel backfill method is generally more practical than installing perforated casing or well screen.
Gravel back-
fill is especially applicable to loose granular materials that might tend to heave or to flow into a perforated casing. Fig. 10-3(c) shows
a typical
configuration.
10-13
For adding
water and measuring heads, one rigid PVC pipe for variable head tests, or two pipes for constant head tests, must extend from the.ground surface to within about 12 inches of the bottom of the gravel backfill. be 1"
The pipes should generally
(+/- !:i") in diameter, but if very permeable materials
are to be tested, one pipe must be large enough to conduct the maximum flow of water that surface equipment is capable of providing.
If the boring is not cased, or if casing has been·set rather than driven, it will generally be necesf3ary to seal off the test section.
(If neither the maximum applied head nor the
groundwater level extend above thetes~tzone, as in.Fig. 10-3(d), sealing will not be necessary).
Ca.sing should be pulled up
far enough above the test zone to>,pl:l;rmit: installation of a minimum3-foot-thick tamped bentonite or puddled clay seal. A non-retrievable> packer may be required to provide a base for the seal. 'Thicker seals, up to 10 feet, should be used to isolate test zones separated by relatively pervious beds. Alternating one-foot layers of sand and bentonite may be used for thicker seals, and one part cement to two parts bentonite can be added when extremely impervious seals are required.
A 24-hoursetting time should be allowed if
cement is used.
10-14
When the formation takes very high quantities of water, as in uniform, permeable sands and gravels, or when quantitative measurement of anisotropy is desired, the open-end blank casing test method, Fig. 10-3(c), may be the only practical technique; however, it should be avoided in rout: permeability testing of low-permeability or stratified materials.
10.3
PERMEABILITY TEST PROCEDURES
The information necessary ·to conduct routine types of field permeability tests is presented in this Section.
For detailed
discussions of theory, interpretation, and variations of these and other tests used for specialized purposes, see the following references: Ref. 32 (tests in the unsaturated zone) Ref. 33 (boring test interpretation) Ref. 34 (water well evaluation) Ref. 35 (specialized pump tests) Ref. 36 (hydraulics of wells) Ref. 37 (boring permeability testing) Ref. 38 (general)
10.3.1
Equipment
The equipment needed for permeability tests depends on the conditions and the test being conducted. equipment is given in paragraph 2.3.4.5.
10-15
A checklist for
For pump tests, a submersible pump of sufficient capacity to draw down the aquifer is the easiest pump to install and use where conditions permit.
In a large volume pump test an
off-line water measuring device such as a Parshall Flume, weir, or orifice may be used instead of a water meter.
10.3.2
Data to be Recorded
Figs. 10-4, 10-5, and 10-6 are data sheets to be used for each the three major types of test.
The forms are largely
self-explanatory, but a few points should .. be emphasized. One of the most important pieces of data in any seepage analysis is the static, or un(listurbe.d,···groundwaterlevel. In a typical stratified section, groundwater levels may vary from one test zone to another..
While drilling techniques
may preclude measuring·the levels independently, any useful information such as relative moisture contents should be recorded on the rooring log.
Static water levels should be
measured and recorded when the boring is completed and at frequent intervals thereafter to establish when equilibrium has been reached.
If that is impossible, an appropriate
note should be made in the Remarks section of the data sheet.
To have a complete understanding of the relationship of the test section and conditions, a sketch should be supplied (with measurements) showing the depth of casing, test section, water level prior to test, and any other conditions useful in the interpretation of the data. 1
-1
The data forms include
generalized boring diagrams on which appropriate dimensions may be merely filled in.
For pressure tests, a sketch of
surface apparatus is also necessary, showing all fittings, pipe and hose diameters, and lengths from the pressure gage (so that friction head losses can be computed).
In all cases, a graph of the results should be plotted in the field as the test progresses, to evaluate when to terminate the test.
Formats for plotting the data vary
among the tests and are described in the appropriate subparagraphs below.
10.3.3
10.3.3.1
Types of Tests
Rising Head Tests.
for a rising head test.
Figure 10-4 is a data sheet
The static water level must be
established at least three feet above the top of the test section, or even higher for relatively permeable materials. water should be bailed or otherwise rapidly removed to a level no lower than the top of the test section. of water removed should be measured and recorded.
The quantity Water
levels should be measured every 30 seconds during the first 5 minutes and at longer intervals, generally 1 to 5 minutes, thereafter.
Methods of measuring water levels in deep
borings are discussed in paragraph 10.3.3.5.
Observations
should be continued until the water level has recovered 90%
10-17
of its initial drawdown, or at least 30 minutes has elapsed and an adequate test is indicateq by three or more points on a graph of time vs. the logarithm of the ratio H/Ho forming a straight line, Fig. 10-7(a). by either the 90%
equali~ation
If such a plot is not obtained or an elapsed time of one
hour (longer times may be designated for particular projects) , check for leakage and errors in measurement or recording. By probing with the drill rod or a length of plastic pipe, check for caving or heaving of the boring. has occurred, backfill the boring with
gravel~&$:!ti.llustrated
in Fig. 10-3 and conduct a constant he~",\ test.
If disturbance
or
faping head
If no reason can be foundfoi~the lack of~~ a straight ---"'-:-,-->-.
line semi-log plot, a constant heidrtl;!!3~tshould b,,{.,conducted, but the test cavity does not need ,tc)cbe modified. Note 10-2 at the end of
section6n~intEi~pretation - _"J
(See of
variable-head tests.)
10.3.3..2
Constant ,'M'ead Tests.
for constant head tests.
Fig. 10-5 is a data sheet
Note that the static water level
and the depth to the nearest underlying low permeability layer (0.5 or more orders of magnitude less than test zone permeability) are required data for a proper interpretation. The depth to the underlying low permeability layer may have to be noted later when the boring is deepened.
Temperatures
of the ground water and added water (slightly warmer where possible) should also be recorded.
Water is added to the
boring to maintain a constant level at or above the top of the test zone.
The top of the casing is often a convenient
10-18
level; however, in uncased borings in unsaturated materials, the water level should be kept just at the top of the test zone.
For sealed test sections or in saturated materials,
it may be desirable to maintain a level consistent with the maximum water level anticipated after completion of the proposed project.
If the water level is to be maintained at a constant head below the ground surface, two electric probes can be lowered into the boring to the desired depth, one several inches above the other.
A constant head can be maintained with one
probe continuously on and the other continuously off. Unless the water level is near the ground surface, it is handy to use separate PVC pipes for adding water and for , lowering measuring probes.
To
maintain the desired constant
height of water, vary the flow.
If the flow is from a
constant head tank (Ref. 38, p. 579), volumes are recorded from a calibrated rule in the tank.
Otherwise, record the
flow rate by the volume passing a totalizing meter over oneminute intervals.
In a low-permeability medium, it may be
possible to measure the flow by very carefully pouring water into the boring from a calibrated container or through a measuring device over one-minute intervals.
The following measuring intervals are generally suitable, but the field representative should adapt the timing to
10-19
conditions, as indicated on a graphical plot of the data: I-minute intervals for 10 minutes S-minute intervals for 30 minutes IS-minute intervals for 4 hours I-hour intervals for 24 hours The test may be terminated at any time after the first 20 minutes of constant discharge as indicated by 3 or more data points falling on a straight line in an arithmetic plot of cummulative volume of water added vs. time, Fig. 10-6(b). Additional points are useful if time permits.
As described for rising tests, irregular readings should be checked for sources of error and gravel,backfill cil!lided, when appropriate.
Falling head ,tests should be used to supplement
any suspect test data.
(See Note 10-lconcerning interpretation
of constant head tests.)
10.3.3.3
Falling Head Tests.
Falling head tests should be
used only where it is not practical to conduct rising or constant head tests, or in instances where it is convenient to use the test to check on the results of' others.
Falling
head tests above the static water level are often inaccurate and very difficult to interpret.
Therefore, constant head
tests are preferred in unsaturated or partially saturated test zones.
The boring water level should not fall below
the top of the test zone.
Data are recorded as in the
rising head tests (Fig. 10-4), and the same criteria apply for duration and validity.
(See Note 10-2 at the end of
this section concerning interpretation of variable head tests.)
10-20
10.3.3.4
Pressure (Packer) Tests.
Pressure tests using
either mechanical or pneumatic packers are generally performed on consolidated (rock) formations to measure the flow of water in fractures, or the changes in flow, over a range of pressures.
10.3.3.4.1 test setup.
Setup.
Fig. 10-8 shows a schematic of a pressure
All connections should be kept as short and
straight as possible with a minimum number of changes between the diameters of hose, pipe, etc., to minimize friction losses.
All joints, connections, and hose between the water
meter and the packer or casing should be tight, allowing no water losses to occur between the meter and the test section. Worn or damaged drill rod or water pipe connections should be "wicked" (a short lengthdf cord placed in the joint) to reduce leakage.
Pressure is usually measured by a gage, which should be located as close as practical to the collar of the boring to. minimize errors.
Downhole pressure monitoring devices are
preferable to the surface device, but they are not in common use.
Friction losses in pipes and fittings below the pressure gage are a potential source of error in the test.
Swivels
used on most drill rigs have a narrow constriction which results in a considerable loss of pressure as the water passes through.
If the pressure gage cannot be placed below
the swivel, then a swivel with a uniform inside diameter is recommended. 10-21
Drill rods are commonly used as intake pipes in pressure and permeability tests.
NX and NW drill rods can be used without
seriously affecting the reliability of the test data if the intake of the test section does not exceed 12 to 15 gallons per minute and the depth to the top of the test section does not exceed 50 feet.
Fig. 10-9 shows head losses per 10-foot
section at various flows of water for different sizes of drill rod hoses and
l~-inch
pipe, as compiled from experimental
tests, Ref. 37.
The length of the test section is' g,c;>vern.E'!d by the character -~-, --_--_. -_"'
-~-,-'-;-:--:
'- 0 --
--
Z-':}:
goods~a! cann
of the rock.
When a
packer at the
planneddePthb~bause;;fbridging,
raveling,
'"'-'
or the presence of fractures.,thlif.J!l.'l'ff>t section length should be increased or .decreased,
or
,test sections overlapped to
produqe a test madEl,wi th.
In some
formations, a H)-foot section will take more water than the • pump carideliver; hence, no pressure can be developed. The length of the test section should be shortened until pressure can be developed, or the falling head test used. L
The test sections should never be shortened to a ratio,
D,
of less than 5, where L is the length of the test section and D is the diameter of the boring.
Unless the casing has
been grouted in the boring, no packer should be set inside the casing when making a test.
The use of test sections
greater than 20 feet in length is inadvisable.
10-22
Longer test
sections usually do not permit sufficient localization of permeable zones and may complicate the ·computations.
Tests are often conducted using a mud pump for pumping the water.
Such pumps are generally of the multiple cylinder
type and generally fluctuate in pressure.
Many of the pumps
have a maximum capacity of about 25 gallons per minute and, if not in good condition, the capacities may be difficult, if not impossible, to analyze.
When pumps do not have
sufficient capacity to develop pressure in·the test section, the tests are generally reported: no pressure developed".
"took capacity of pump,
Such test results do not permit an
accurate evaluation of the permeability of the material tested, other than 'it is proJ:5ablyhigh.
The fluctuating
pressures of multiple cylinder pumps," even when an air chamber is used, are ofteh difficult to read accurately because the high and low readings must be averaged to approximate the true effective pressure.
In addition,
multiple cylinder pumps occasionally develop instantaneous excessively high pressures which fracture the rock or blow out a packer.
permeability tests made in borings ideally should be performed using centrifugal or auger type positive displacement pumps having sufficient capacity to develop pressure in the test section.
A pump with a capacity of up to 250 gallons
per minute against a total head of 160 feet would be adequate
10-23
for most testing.
Head and discharge of such pumps are
easily controlled by changing engine speed or with a control valve on the discharge.
10.3.3.4.2
Pressures to be Used in Testing.
When
sub-
surface conditions for proposed reservoirs or other waterimpounding or storage facilities are being explored, the pressure range imposed on the test section should include, as a minimum, the head to be imposed by the maximum proposed reservoir level (1 foot of water is .43 psi).
:However, when
tests are made in locations where the 'iJ!I;ound surface is well below the proposed maximum pool level, the use of such test pressures may be impracticcal cbecau$~c6;f the danger" of blowouts or hydraulic fracturing., For consolidated rock a
'" maximum pressure of 1 psi pe:rt:ootofdepth from the ground surface to the top of the test section is a rule-of-thumb guide, in th.~absence of other criteria imposed by the project.
Multiple pressure tests are conducted in the same manner as other pressure permeability tests except that the pressure is applied in three or more approximately equal steps.
For
example, if the allowable maximum differential pressure is
90 psi, the test might be run at pressures of about 30, 60, and 90 psi.
10-24
10.3.3.4.3
Length of Time for Tests.
The minimum length of
time for a test depends upon the nature of the material being tested.
Tests should not be conducted until stabili-
zation occurs; that is, until three or more readings of water intake and of pressure taken at I-minute intervals are essentially equal.
If this is not practical, each pressure
step should be maintained for at least 20 minutes with intake and pressure readings taken at no more than 5-minute intervals and, as the pressure is decreased, each pressure step should be maintained for 5 minutes.
stability is
obtained more rapidly when testing below the static water level than when testing in unsaturated material.
In tests
above the static water level, water should be pumped into the test section at the desired pressure for about 10 minutes in coarse-grained materials or 20 minutes in fine-grained materials before making measurements.
After stabilization of flow, each step of a multiple pressure test should be maintained for a minimum of 5 minutes and intake readings made at I-minute intervals. may then be raised to the next step.
The pressure
On completion of the
highest step, the process is reversed with the pressure being maintained for 5 minutes at approximately the same middle and the lowest pressure steps.
A plot of intake
against pressure for the five steps in a multiple pressure test may be useful in assessing hydraulic conditions. in different borings on the same project should all be conducted at the same pressures, to permit comparison.
Tests
10.3.3.4.4
Calibration and Detection of Leaks.
The accuracy
of packer test results depends significantly on the correct estimation of the head loss in the system.
If precision in
a pressure test is desirable, the head loss in the drill rods or water pipes can be determined by pressure testing the system of drill rods (water pipe), swivel, pressure gage, water meter, and pump at ground level.
The procedures
for conducting this test can be found in Ref. 37.
Packer leakage can be investigated by monitoring the pressure in the test section while commencing inflowin:to the system and then incrementally increasing paoRe:r pressure. .
..~
will also aid in the removal of the test section.)
any
.
.
(This
large air pockets within
As the packer b't~ssure increases, leakage
past the packers will decrease, the p:r~ssure in the test section will increase ,and the flo.l rate into the test section (measured by the water meter at the top of the boring) will consequently decrease.
After a certain point,
further increase of packer pressure will not cause any increase in cavity pressure when the packer pressure is increased.
Figure 10-10 illustrates typical relationships
between packer pressure, test section pressure, and test section inflow throughout the packer sealing procedure.
10.3.3.4.5
Test Procedure.
Prepare the boring and, if
necessary, calibrate testing equipment, as previously described. Prior to setting the packer(s), record the pre-test water pressure, if the test section is below the static water level. The difference between the pre-test pressure and the test
10-26
section pressure measured during testing is the excess pressure applied to the immediate ground mass.
The excess
pressure is plotted vs. the observed flow rate into the test section.
Investigate packer leakage by the method described
in paragraph 10.3.3.4.4 as the packers are inflated.
Record the data on a form similar to that in Figure 10-11. Plot excess pressure (vertical scale) vs. flow.
A high
quality test should provide a linear plot indicative of laminar flow.
A non-linear plot may indicate problems such
as leakage around packer, erosion of test zone, clogging of fissures, or hydraulic fracturing.
10.3.3.5
Well-pumping Tests.'
The construction and testing
of wells are specialized tasks that -must be adapted to the conditions of each site.
The selection of a pump, location
and depth of observation wells, and type and duration of test depend on the analyses of a number of variables and will normally be performed in the office.
Thus only
generalized test procedures for constant discharge pumping tests are given in this Guide.
The quantities recorded in a pumping test are initial static water level, discharge (constant), elapsed time, and pumping water level, for all observation wells as well as the pumped well.
Drawdown is computed by subtracting the depth to the
static water level from the depths to water measured at intervals over the duration of the test.
Compass bearing
and distance from the pumped well to the observation wells, and to all bodies of water or discharging wells affecting the test, should be recorded to the nearest foot. should be prepared showing the layout.
A sketch
A sample data sheet
for a single pumped or observation well is shown in Fig. 10-11.
Provision should be made to transport discharged water away from the test site.
Such water should not be allowed to
seep into the ground and recycle to the test well.
Control
of the pumping rate during the test reqciires an.accurate device for measuring the dischargeof.tJ:i~ pump and a con"c.-.-, .__., _.-..c:;,;. ,_~
venient means of as possible.
adjUsting~herat~,i~keep
A v.aive in the,
dI·tdl}arg~.;;l.ine of the pump
'1.'h~
provides the best control.
i t as constant
size of the discharge pipe
and the valve should be aucI1that the valve will be from one-half to three"'t9urths open when pumping at the desired rate.
A simple and accurate method of determining the pumping rate is to observe the time required to fill a container of known volume.
This method is most practical for measuring rel-
atively small pumping rates.
10-28
A commercial type water meter may be employed to measure quantity pumped in a given time.
The dials on the meter
show the total volume in cubic feet or in gallons discharged through the meter.
subtracting two readings taken exactly
one minute apart gives the pumping rate. the easiest apparatus to use.
This is perhaps
Its main disadvantage is the
unavoidable delay in getting initial values at the start of the test when the pumping rate is being adjusted to the desired level.
Figure 10-12 shows how to make measurements and compute the discharge for various pipe sizes.
An approximate discharge
can be computed from a horizontal pipe, flowing full and with free fall from the end, by measuring horizontal and vertical distances from the end of the pipe to a point in the flowing stream of water.
The point, P, may be located
at the outer surface of the stream rather than at the center, if desired.
In such a case, the vertical measurement must
be made from the top of the stream at the open end of the pipe.
When brooming or spreading of the flow occurs, the
center of the falling stream can be located more reliably than can a point on the surface.
The discharge pipe should
be a straight length, at least 5 feet long, so that the open end is at least 5 feet from the nearest elbow, bend, or valve.
10-29
other measuring techniques include flumes, weirs, and pipe orifice devices (Refs. 34, pp. 83-88 and 38, pp. 233-243).
The depth to water must be measured many times during the course of the pumping test.
Readings should be taken at
close intervals during the first 2 hours of the test with the time between readings being gradually increased as the test continues.
water level measurements should be recorded
to the nearest ... inch or 0.02 foot in all
obser'l!!~ion
wells.
This same accuracy should be attempted, .butC·ri!ajr not be __.--.
_
c
practical, when measuring the wateFJ)l.evel in the pumped well because of pump vibration or otheir·~ntE¥·t£erence fr~ the
'f~('"c1,~ .
pump.
".~;:'~i;,:)_,
Measurements inthepU!1lped
well
should be made every l:i
minutedurihgthefirst5~iri~tes after starting the pump; then'E!very 5 '1lI1nutes for an hour; then every 20 minutes for about 2 hours •. Then readings taken at hourly intervals are sufficient.
Water level measurements in the observation wells should be taken every 2 minutes at the start of the test for a period of one hour. Readings every 5 minutes should be taken for the next hour; then every 10 minutes for the next 2 hours; and then every 20 minutes until the test is completed.
10'- 30
When the pump is stopped after running the test, the drawdown and time at which it was shut down are recorded. Measurement of the water level is immediately initiated in the pumped well and in all observation wells.
The same
procedure and time pattern is followed as at the beginning of the pumping test.
As in the pumping test, the time and
depth to water are noted for each measurement.
The recovery
usually will not return to the original static water level within a reasonable length of time, so, when several measurements at I-hour intervals show less than 0.1 foot difference in recovery, measurements may be discontinued.
The data
may be even more useful than the original drawdowns in computing aquifer constants, and recovery information should always be recorded.
The handiest device to use for measuring water levels is the electric sounder or electrical depth gage which is available from several manufacturers.
An electrode is suspended by a
pair of insulated wires and an ammeter indicates a closed circuit and flow of current when the electrode touches the water surface.
Flashlight batteries supply -the current.
To
improve the accuracy of readings, the electrode and wire should be left hanging in the well for a series of readings, thus eliminating errors from kinks or bends in the wires changing the length slightly when the device is raised and lowered.
The change in water level should be measured along
the wire with a steel tape, using one of the reference marks -
which are commonly attached to the wire by the
manufacturer at about 5-foot intervals.
The wetted tape method is also a very accurate way of measuring depth to water and can be used readily for depths up to 80 or 90 feet.
First, a lead weight is attached to a
steel measuring tape.
The lower 2 or 3 feet of the tape are
wiped dry and coated with carpenter's chalk or keel before making a measurement.
The tape is lowered in the well until
a part of the chalked section is below water and one of the foot marks is held exactly at the top of the casing or at some other measuring point that may have been selected.
The
The wetted. line on the tapEI; can be
tape is then raised.
-
read to a fraction of an inch on the chalked
--.'Ij:), ~
se~·tion.
The
reading is subtracted from the foot ...·ma.rk held at: the meas--;-~I~,(':-;
uring point, the differencebeing>£hea~ual depth to the , -_. -__ .-, _'c ',-_ ~
water level.
A disadvantagebf thi$:tnethod is that the
approximate depth to water mustibe know@. --,:: -, so that a portion of the chalked section will beSubm~i'ged each time to produ¢e a wetted line • of any other me.thod.,
Tl1e a.ccuracy, however, exceeds that Where the depth to water is mOre than
80 or 90 feet, 'the tape is difficult to handle.
A third measuring technique, the air-line; is described in Ref. 34, p. 90-91.
This method is less accurate than the
first two, but may be the most practical method for the pumped well.
10-32
10.4
PERCOLATION TEST PROCEDURE
percolation tests are used to ascertain the acceptability of the site for septic tank systems and assist in the design of subsurface disposal of residential waste.
Generally, the
length of time required for percolation tests varies with differing soils.
'rest holes are often kept filled with
water for at least four hours, preferably overnight, before the test is conducted.
In soils that swell, the soaking
period should be at least 24 hours to obtain valid test results.
The percolation test method most commonly used, unless there are specified local requirements, is the test developed by the Robert A. Taft Sanitary Engineeripg Center as outlined in the HUD, Public Health Service Manual of Septic Tank Practice (Ref. 56).
There are other methods available and
the Project Manager should specify the field procedure consistent with local regulatory requirements and/or local field conditions.
Regardless of the method used, the
principles are basically the same.
A specified hole is:
1)
dug (generally 2 fee-t square) or drilled (4 inches minimum) to the depth of the proposed absoprtion trench, 2) cleaned of loose debris, 3) filled with coarse sand or fine gravel over the bottom 2 inches, and 4) saturated for a specified time.
The percolation rate measurement is obtained by
filling the hole -to a prescribed level (usually 6 inches) and then measuring the drop over a set time limit (usually
30 minutes). minutes.
In sandy soils the time limit may be only 10
The percolation rate is used in estimating the
required leach field area as detailed in Ref. 56.
10.5
INSTALLATION OF PIEZOMETERS
Piezometer installations are special types of observation wells designed to permit measurement of the water level or piezometeric head in a particular geologic stratum or zone. Each installation, Fig. 10-13, should consist of;three basic components: 1)
a piezometer tip consist,i;ngOf a well lScreen, porous tube, or other stitiilar'&ature fine-grained or
llri~tableIt\~terials,
~a~
in
a surrounding
zone offil.ter sa.nd; 2)
a watertight standpipe, . M the smallest practical
d:Fa.met~iY';'tt.a.cJaed"
to the tip and extending to
the~urfa.e.e of the ground; and 3).
a seal or seals consisting of cement grout, bentonite slurry, or other similarly impermeable material placed between the standpipe and the boring to isolate the zone to be monitored.
Where several piezometers are required at a given location, but at different elevations, it may be possible, as a costsaving feature, to install them in a single boring with an impervious seal separating the respective zones.
10-34
Practical
difficulties may be encountered, however, in establishing effective seals between multiple piezometers.
If measurements
are needed in zones with 10 feet or less of vertical separation, it is generally best to install piezometers in separate borings.
In addition to the described standpipe-type piezometer, there are several commercially available instruments that are operated by hydraulic or pneumatic pressure, or by an electric signal.
Such instruments may be especially val-
uable for difficult subsurface or monitoring conditions, such as in very low permeability materials.
The casing or pipes in an observation well or piezometer installation usually extend above the ground surface at least a foot (unless pit installation is necessary).
Each
installation should be identified in a manner that will be permanent.
The top of the casing. or each pipe should be
fitted with a screwcap or locking cap containing a small hole to permit adjustment of air pressure in the pipe in response to water level fluctuations or barometric changes. Where artesian flow conditions are present, a tight-fitting cap which has been drilled and tapped for a Bourdon gage or mercury manometer should be used.
If climatic conditions
require protection against freezing, a suitable shelter equipped with heating facilities or the replacement of the water in the upper portion of the piezometer by a nonfreezing fluid may be necessary.
10-35
Facilities should be protected against standing surface water, and leakage alongside the casing, by proper grading of the surrounding ground and placement of grout or clay seals at the surface.
When an observation well or piezometer installation must be located in an open area where damage by livestock or farm machinery may occur, it should be adequately protected.
10.6
BACKFILLING BORINGS
Test wells and exploratory borings?illi;;~lia never be left in a state that could be hazardous topeqple, livestock, or wildlife.
Nor should they be allowed to contribute to
contamination of groundwater aqUifers".\~hich means adequately plugging, capping, or otherlliise'Pief'l1l'lnting surface water entryto>tl1e,boring.
When a·.. boring penetrates a groundwater
aquifer and it-is h.ot to be used as a well or piezometer installation, the boring should always be completely backfilled wi th the Jnost impervious material available to prevent contamination by surface runoff or intermixing of poor quality ground water from another stratum.
Bentonite is
usually adequate for sealing, but cementing of critical zones may be required where groundwater quality is potentially jeopardized.
There are regulatory requirements, and failure
to comply with them will leave CWDD and/or the client liable to various legal penalties.
10-36
Note 10-1: C u VALUES FOR CONSTANT HEAD TESTS ABOVE WATER TABLE (U.S.B.R. Method) For constant head permeability tests conducted above the water level, the U.S. Bureau of Reclamation (1977, p. 262) provides a chart giving values of the "unsaturated conductivity coefficient", C u , to use in standard formulas. The chart is reproduced in O'Rourke and others (1977, p. 107). Unfortunately, the chart is not applicable when applied head differential is more than 10 times the length of the test interval. In this situation, often encountered in deep borings, permeabilities may be computed from the following formula-'. Q ['h-1(L) Ll K -- 2n L (2Hc -L) Lin re - Hcj
The symbols are specified in the above references.
* Zangar, c'N., 1953, Theory and problems of water percolation: U.S. Bureau of Reclamation Engineering Monograph No.8, p. 48.
Note 10-2: COMPUTING BASIC TIME LAG FOR THE HVORSLEV FORMULAS (Variable Head) Unmodified use of the basic time log (Hvorslev) formvlas (Cedargren, 1977, p. 66-76; O'Rourke and others, 1977, p. 94-97) can lead to svbstantial errors in interpreting variable head tests if steady state flow conditions are not immediately attained, If the straight line segment of the semi-log plot does not pass through H/Ho=l.O, use the following procedure.rsymbols are defined in the references.)
1.0
••
Displaced straightline portion
•
\ 0.1
Original data plot
L-.._--+______ Time
Procedure: 1) Plot H/H o on log scale versus time on arithmetic scale.
2) Draw a line passing through t = 0, H/H o = 1 parallel to the straight-line portion of the original data plot. 3) Pick any points H/Ho and t on the new line and calculate T using the basic formula, T = -t/ln (H/H o )' If the line passes through or is easily projected through H/H o = .37, T can be read directly, as described in the references.
I
i
, .
; Sand pump$ and regular bailer, with details of ftat~valve bottoms.
Typical
valve~typc
surge plunger.
Johnson Divhlon UOP
TYPICAL BORING DEVELOPMENT DEVICES Figure 10-1
WATER IN
Packer ~b7:;bb77.1
f
~,.' 'lh
.\-.Test .... I Sectionl :: ...
Packer fection
...
-+-r~\ ~///~
I
I
I
'----'
SINGLE PACKER
PACKER ARRANGEMENTS Figure 10-2
DOUBLE PACKER
GftOUND SURFACE
H1---
PLASTIC
TUBI~G
+-It--- PLASTI C
_OOTER CASING
TUIING
_~RKING
CAS I NG
CASING CASING
CASING
5
GRAVE
to 10 It
WELL
SCREE.--I1!--~-!iI I'
5 ft MINIHUM
J
6 In
T
GRAVEL FILTER
PACK~
6
~
T 5 ft M,.,HOI<
'~ ,
"'-----10'
(b) Perforated Test Section, Cased Bori ng
(a) Unlined Test Section, Cased Above
SURFACE
~I--PLASTIC
CAS I NG _--f..l_1
TUBING
PLASTIC TUBING - -......+-l CAS I ." -__14__
+jf+fI--PLASTIC TUBING
GROUT SEAL
(Altornate layors of sand and bentonite) Severa 1- inches extension Into casing
FINE SAND
ft minImum
lin.
GRAVEL
GRAVEL GRAVEL
-----I1IlflI
In.
6
(c) Unlined Test Section, Cased Above and Gravel Filled
(d) Unlined Test Section, Gravel Filled and Sealed
TEST ZONE ISOLATION METHODS Figure 10-3
_ _1-
In.
(e) Open-End Blank Casing, Entire Boring Modified from US Bureau of Mines
FALLING/RISING HEAD TEST DATA SHEET (CROSS OUT ONE) PROJECT NO. _ _ _ _ _ __
LOCATION: DATE; ___________
E''''''ING NO. _ _ _ _ __
OBSERVER: .
IoAR ELEVATION: REMARKS: STATIC WATER DEPTH (Y·) _ _ _ _ _ _ _~ STATIC WATER ELEVATION: GROUNDWATER TEMPERATURE: TEMPERATURE OF ADDED WATER;
' f
BLANK CASING
oIr ~ GROUND
o
O~S.
·····7SURFACE
:•
en t:cr:0::; 'VI". vW z 4( 2~ ... 4( II
;
-I:JOz
:
w!Q"-
I, '
iii W
..a
II)
o ~:!
4'
!
1t------b-----t----1f----I.....:.=-I--..-f---I----I----I----l It----t-----t----If---J---I---_+---I-----I----I----l
11....--t---l---1f---1----I---+--4--4--+---l II
ID
0>
~ §~~~ ~: -- ........ ~~ r .: -r-I:::!.....
..,
...I~
..-J
.
ii:
- 1.... -·
.....
::
'._o~'1 ~ ~ ~
.. ..
!
,.
C[it:~~
.'
.
.. . .
,
.
GRAVEL CUSHION IMPERVIOUS"AYER /, \
-';." \
.I' ,
"
,
•.
f"
I,
t,
"
...
.•...
"
~ -Oi:.11 __ -. If--+-+--+----lf---I---l---\----\---I---l
! (J)
c
..J --
o
~
~I' HI' ~ ___ J 1f----t---t--4---t---J.--+---I----l---t---l 0I
I
~
II"
....
W
I _ ... (/)(,)
w-
~......
....:. ~
III U.
:5
r----llr---i---+---t---t----t--~--~--~--~-~ .....
)000
.
~ III 0
~ ... 1:J11----t---t----II----J---I'----I---I---_J.--_I_---I
cr: 0
>-
~
-
0
~
:!: 11----\----11---1---1--4----4---1----1-----1------1
I::: ~1 ~~~ ~ ~ -It ~·'-1 L~:.:...:.:~=-iltll------_-_t+-_-_-_-_i-l-_-:-_-_-1-:-:---_-_-_-Jt--_-_-_-_-t..-_-_-_-_--1.t:---_-_-_-_t-I--_-_-_-_++-_-_-_-_-1-1-_-_-_-_-1-1
(J)
~ ~
e! I I"
* I
~~ ~I' I
_
__
I
J If--+--+--l-----l---I---l---\----\---I---l
0
1-_
+I
(1)(,)
II
uz-l-
UI ';'!(
~
W
.... ::l CC -I
w......
cr:
0.-
00
Cl)W
~ -IL..-~I-----If___--_+---_+---l--_J.--_I_--_I_--_l__---l
O~III!:!*'r cr: 4( > " If----:f----II-----t----t---l---I----I----I----l-----l
I:J".IIIZ>
_;:'..J_m
ConverseWard DavIs Dixon Figure 10-4
CONSTANT HEAD TEST DATA SHEET "ROJECT NO. _ _ _ _ __
LOCATION: OBSERVER: _______________________________
DATE: ___________
JRING NO. COLLAR ELEVATION:
REMARKS,
STATIC WATER DEPTH (V') STATIC WATER ELEVATION: WATER LEVEL DURING TEST (V) HEAD (Y'-V) GROUNDWATER TEMPERATURE:, TEMPERATURE OF ADDED WATER:
f -. ' ' ". BLANK CASING
J.
I/)
a:o· 0
..... / '
WW...l
I, ,.
·
GROUND
t- a: (I):W::: t-O..lD: OU)_~
0(:::1
00 -D: (IlIw
....
UJa:
cn~t-w
Wua
*
.
0>-
~l '"
I--·· . ·.. · . u:~~ -'-I ...... tr • 1'00" . .
010
'.O~· 1
'.
.
'.
.
.'
:
~~:~~I~ [:c·o~ ~
-
.
"
.
•
......
/\.",.;,,,,'" ,
-
.'
,.
GRAVEL LSHION IMPERVIOUS LAVER I
eLAPSED VOLUME METER TIME IN ADDED OR CUM. MINUTES VOL.
.
! ..
s::~ ~
li.....
TIME OF DAV
ZN
zu:;,cn
...... •
'"
en
..I
·w!c:i'·
eLAPSED VOLUME METER TIME IN ADDED OR CUM. . MINUTES VOL.
V'W z-
'w/,
-C"z
;
TIME OF DAV
KEY TO SYMBOLS COl.LAR EL EVATION
(
(MAV BE ZER.O)
~ ff~
TEST-
V'
PR E-TEST- ~ (S TATIC) I
d
I
I"
---.l :1 .. I L
111
1--
ZW -z ,,0 zN WI>
1-1/)
.
~
oX. WATER LEVEL
=
·
LIMITATION:
~
<0 :I ... • W
I ___ 1-
..
*VOLUME ADDED COLUMN MAV BE OMITTED IF TOTALIZING METER OR FLOW BARREL IS USED.
L~5d
ConverseWard DavIs Dixon Figure 10-5
PRESSURE TEST DATA SHEET 'ROJECT NO. _ _ _ __ NO. _ _ _ _ __
~ORING
LOCATION: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____ DATE:-_ _ _ _ __
COLLAR ELEVATION:
OB$ERVER. _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____
EQUIPMeNT SUMMARY: 1) pACKER(S): NO._ TYPE' _ _ _ _ _ _ _ _ _ _ _ __
STATIC WATER DEpTH(Y')'_ _ _ _ _ __
2) DRILL ROD/WATER PIPE: I.D. _ _ _ _ _ _ _ _ _ __ ___ TYPE: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
STATIC WATER ELEVATION: ________
~
3) HOSE BETWEEN DRILL ROD a pRIOSSURE GAGE: I.D. ___ LENGTH' _________________________
"RECORD EVEN IF BELOW TEST ZONE
4) METER TYpE: _________________________
GROUNDWATER TEMPERATURE, _______
5) SWIVEL: NOMINAL I.D.
TEMPERATURE OF ADDED WATER, _____
TYP": ___________
CALIBRATION RUN? VIIS _(ATTACH DATA SHEET) .. R... E-M... A... " ... K... S ' - - - - - - - - - - - - - - - - - - . . . . , NO_(STATE CONDITION OF EQUIPMENT AND DRAW SKETCH IN REMARKS OR ON BACK)
FILL IN ALL DIMENSIONS WATER IN
TIME INTER "LAPSED OF VAL'" TIME GAGE DAY (MIN.) (MIN.) PRESS.
PRESS. CORR. (ELEV.,
TOTAL HEAD PRESS. WATER "T (PTryw) METER
AVG. FLOW RATE OR CUM VOLUME
(COLLARELEV.F===~===i~~===F=.:;.~F=R~I;C=T~IO~N=)~ib==~===i======~======~ .
.. .
..
1
If:
>:
1
L
l =1
l=
11.:
'~ll
. II I
I
.J
In I
1 1
~
: ~
I~I ~ (X-OUT :~~':~R
,WI 1
,
TPACKER
I
L __ I_~--L
_IMPERVIOUS LAYER ",. \ . / ...... /
~
........ /
,/'-.,
STATIC (PRE-TEST) WATER LEVEL
ConverseWardDavlsDlxon . Figure 10-6
1.0 Straight-line semi-log plot indicates adequate test duration
" o
u
Vl
0.1
~------~----~-T--------~--------~ 10
20 Time (Minutes)
30
(a) Variable (Rising/Fallihg) HeCldTest
Straight-line arithmetic plot indicates adequate test duration
10
20 Time (Minutes)
30
(h) Constant Head Test
DETERMiNING ADEQUATE DURATION OF TEST Figure 10-7
"
.--,
I
,
\
SWIVEL (If required)
"ALTERNATE LOCATION FOR TEST )..-- WATER PRESSURE GAGE /
,/
'-r(
n
r- LL """\.
. 1",1
\~:L ___ I:],
r---~
Ii-in. WATER PIPE (PREFERRED) OR DRILL RODS
PlASTIC TU8111G AIR LINE PREFERRED LOCATION FOR TEST WATER PRESSURE GAGE ~
---PUMP
~---;
PRESSURE RELEASE XL-- VALVE
GRClJIID SURFACE
PACKER PRESSURE
BYPASS VALVE
~ OVERflOW
Mi GAS PRESSURE/, REGUlATlR
IlFlATA8LE* PACKER UIIIT
CYLINDER PRESSURE
~
COMPRESSED GAS
----I--
* USE
SAME IMTER ASSEMBLY FGR OTHER TYPES OF PACKERS
WATER
~
US Bureau of Mines
PRESSURE TEST SETUP Figure 10-8
o o o
u..!:'-~
'lJ
5
~
0.
0
C I.':) 4l}
~ ~"' ~ E .- 0 :I "0 ~ C il)
....
o o
Q)
;J
..
\II
"t:l..c
Col I...
:J
~"O
>-
'-'.-c;u :J"cQ)O
..c
c..+__+_+_-f___+-+-
111.- I-
-g '"00 a.
....
I...
(Il
. "0
III _
0.........
I..
o _
0.., ,_ C
.~ •
EO
It!
o
I-.
~
I
~.
.-
Q)
L.
L
U
11)
l~.in.
..
!RONPIPE*
0'1 ..,. C);::IlIl\llL_-I--I---_l-__ --I-'.......+--_---jL-J~-..,.~.:..+-....,.-~+--"""':~+----+_---__l C 111 ...... C
...... .-
VI
QJ
111'-
C 0
~
g.
~
0. ....
r:J
C ...... 0
DRI LL RO 0
Vl·-OU
A* B* AW"
2
aw; N
o
lo~~~~~~~~::I:::::~_~ 10
20
30
ROD 1.0. COUPliNG (I nche.) 1.0. i nche,
1-1/8
9/16
1-1/4 1-1/4
5/8 5/8
1-3/4
3/4
2
_ _ _ ~_ _ _ _ ~_ _ _ _ ~--~~~~p~IP~e~D:~~~~~~~ Rod Len th
40
FLO W
50
Q ,
60
2,5, or 10ft
'Parallel wall type (Acker , 1974) 70 80 90
9 P m US Bureau of Mines
AVERAGE FRICTION LOSSES IN DRILL RODS, PIPE,AND HOSE Figure 10-9
~
"
7
E
...... VI
6
L
...
~
5
STEADY STATE
cI
. >-
4
;:;:
3
l
I-
u
ZO ...... VI
0.
16
D-
12
UJ
I-
LEAKAGE TERMINATED
I-
z
::. u..
w• rs:
II> II>
2
o
g
u
:::>
IVI
~
+
0
0
8 UJ rs: DIt 0
>-
t-
> « u
10 15 20 5 25 30 P (psi) PACKER PRESSURE
(a) TYPICAL DATA INDICATING SEALING OF PACKER us Bureou of MlmlS
PACKER LEAKAGE ANALYSIS Figure 10-10
AQUIFER TEST OAT A SHEET
Ii
Project No.: Well No. or Name: Date Test Started: Ground Elevation:
Location: Pumped/Observation Well (x-out one) Blank Casing Length: Total Depth: to Screened or Perforated from
Static Water Depth:
Screen, Perf. Casing, or Open WELL I.D.:
Static Water Elevation:
Type of Well Screen/Perforated Casing:
Groundwater Temperature: Size Gravel: Gravel Pack O.D.: If Observation Well, Bearing and Distance from
Depth to Aquifer Base: Depth to Aquifer Top: Saturated Thickness: ·Inltial Pumping Rate:
Pumped Well: Type of Observati on We II: Open Cased to Depth Cased , Standpipe PleZOI!It"r (open), I.D. Standpipe F'",itOIMter with grout seal at top of fllt.rl"fk~I.D.
Constant Discharge Maintained? Yes No How Measured?:
o
o
o o o
..' "
Time of Day
Elapsed Time (min)
Drawdown .
Depth to Water
ReiriDl'I
.. ' .........
-
~
.. , ,
.... .
.
... ..... ...
'
. .
','
'
'.
.
....
.
'" ..,.•,......
.
'.'
"i
··C, .
.
'.
..
. <
.. \ ..." ..
.'
.,...•...
.
'.
• .
,
-
.. I
ConverseWard DavIs Dixon Figure 10-11
.----J_:::~=_~----1 "-------"'-E2~~~~
~~0""0_."'~
\.. ~~~\\ ~\
0:~Z:",\
\\\\\
12"
\ I
P
Rate of flow from a horizontal pipe can be estimated from the distance x.
Dischar~eJrom horhtbntql • fl • f II . -~ IEle owing u l m9E!m Distance X in
'.
Pipe diameter
inchlls. at 12"
drop
6 7 8 9 10 11 12 15 20
'"
3"
21 46 24 54 28 61 69 31 35 77 38 84 42 92 52 11 5 70 154
4"
...80 93 106 119 133 146 159 199 265
5"
125 146 167 188 208 229 250 313 417
'"
B"
181 312 211 364 242 416 272 468 520 302 332 572 362 624453 780 604 1040
. Johnson Division UOP
ESTIMATING RATE OF FLOW FROM PIPE DISCHARGE Figure 10-12
PROTECTIVE COVER WITH LOCK
THREADED CAP
--.--.!!4I:;;;I=- "'-........'
z
o
..
~
to-
W
w
"'tol:'"'!
~::
): ',:
.'. '.
::. ~STANDPIPE
..
'. ~
" SAND OR SAND AND GRAVEL.. BACK FI LL----,~____irLi I ,
;
Cl A '( OR BENTON ITE . BACKFILL
.--t"U,jUL.C.U
"
" "
"
s..---sElECTED BACKFILL MATERIAL
~
.'
,
CEMENT/SAND OR PUDDLED CLAY BACKFILL
~R
COAL?
SAND OR GRAVEL BACKFILL
z
:
"' :::: -:: ~ '.1
.W;~--
ZE~Il>-- PUDDLEO CLAY
OR BENTONITE BACKFILL
I·
'·1 ..: I I. ".1 I:, "I 1"
..JL-_-J.:",j '" :.~.. I
PLUG
. PLUG
.' :: ."'-.
NOTE TEST SECTIONS WITH SLOTS OR
MAY BE PERFORATED DRILLED HOLES
MESA
OPEN STANDPIPE PIEZOMETERS Figure 10-13
References
1.
Hvors1ev, M.J.: "Subsurface Exploration and Sampling of Soils for Civil Engineering Purposes," waterways Experiment Station, Vicksburg, Miss. 1949. Reprinted 1962 and 1965 by The Engineering Foundation.
2.
Hough, B.K.: "Basic Soils Engineering," Ronald Press Co., New York, 1969.
3.
Nichols, H.L. Jr.: "Moving The Earth, The Workbook of Excavation," North Castle Books, Greenwich, CT. r 1976.
4.
Earth Manual, U.S. Bureau of Reclamation, 1974.
5.
Acker, W.L. III,: "Basic Procedures for Soil Sampling and Core Drilling," Acker Drill Co., Inc., Scranton, PA. 19
6.
"Excavating and Trenching Operations, Safe Work Practices, Series," OSHA 2226, U.S. Department of Labor Occupational Safety and Health Administration, 1975.
7.
"Trench Shoring," California Geology, Division of Mines and Geology, August, 1976.
8.
"State of California Construction Safety Orders," Title 8, . Chapter 4, Subchapter 4 - Division of Industrial Safety, as amended to December 14, 1975.
9.
"symposium on Soil Explora·tion," ASTM Special Technical Publication No. 351.
10.
"Annual Book of ASTM Standards," Part 19, Soil and Rock; Building Stones; Peats, American Society for Testing and Materials, Philadelphia, PA.
11.
Equipment Catalog, Acker Drill Company, Inc., scranton, PA.
12.
Equipment Catalog, Sprague & Hanwood, Inc., Scranton, PA.
13.
Equipment Catalog, Diamond Drill Contracting Co., Spokane, WA.
14.
Equipment Catalog, Longyear Company, Minneapolis, MN.
15.
Hunt, R.E.,: "The Tools and Methods of Exploration," Joseph S. Ward and Assoc., Caldwell, NJ.
R-l
I 16.
Terzaghi, K., and Peck, R.B.: "Soil Mechanics in Engineering Practice," John Wiley & Sons Inc., New York, 1968.
17.
Gibson,' R.E., and Anderson, W.F.,: "In-Situ Measurement of Soil Property with the Pressuremeter," Civil Engineering, May 1961.
18.
Dixon, S .. J., and Jones, W.V.,: "Soft Rock'Exploration with Pressure Equipment," civil Engineering, October 1968.
19.
Calhoun, M.L.,: "Pressure-Meter Field Testing of Soils," civil Engineering, July, 1969.
20.
Schmertmann, J.H.,: "Static Cone Penetrometers for Soil Exploration," Civil Engineering, June 1967.
21.
"The Unified Soil Classification System," '):'echnical Memorandum No. 3-357, U.S. Army Corps o:t;.·.i;)ilJ!gineers, March 1953. o_~"'l -;j~/2~D--<_~~-::-:_;t Casagrande, A.: "Classif ica·t+9l'ii.,4hd Idetlb';if ica tion of Soils," ASCE Transactiol'\~i~;.Pa:l?er No. 2~5'l, 1948.
22. 23.
24.
Burmister, D.M.,: "§J.!.'Jgest~~~;~~~l1.&ds of T~liI~. for Identification of So'¥i!l:t!&·,," ASTMiSpecial Technical Publication No. 479 ,·l;9!1iO•• :,,_(v-;~:):_ -_:-:;tP:, -~~\~kC~j>:,__ - ~:~\}?~ Burmister"p"M'H. ":r~~:m~~~W<;l~tl;9n and Classification of Soils·i(p. An Aj;1l?rais~i;;~p.d,s;:e'atement of Principles," ASt:~., sp~pial~~dhniclfl'[Publication No. '113, 1951.
2 5.;'§61~s:,~~riU~4;df;ttp.eri~sign of Asphalt Pavement ;"OC$tructt@!:ls ,IW;~he Asphalt Institute, Manual series No. <10 (MS--lOD Miili.ch 1978. --, :__ i '!.
~
.
.
~--'
26.
":PCAsoil Primer," Portland Cement Assoc., 1973.
27.
"Classification of Soils and Soil Aggregate Mixtures for Highway Construction Purposes," .AASHTO Standard Ml45.
28.
"Airport Paving," DOT-FAA Advisory Circular No. l50/5320-6A, May, 1967.
29.
deMello, V.F.N.,: "The Standard Penetration Test," Fourth PanAmerican Conference on Soil Mechanics and Foundation Engineering, Vol. 1, ASCE, June 1971.
R-2
30.
"Rock Color Chart," Geological Society of America.
31.
"Final Repoft (July), Commission on Terminology, Symbols, and Graphic Representations," International Society of Rock Mechanics, 1975.
32.
Bouwer, Herman,: "Groundwater Hydrology," McGraw Hill, Inc., New York, 1978, Chapter 5, p. 90-131.
33.
Cedergren, a,R.,: "Seepage, Drainage, an~ Flow Nets," John Wiley & Sons, Inc., New York, 1977, Chapter 2, p. 26-85,
34.
"Groundwater and Wells," Johnson Div., Universal Oil Products Co., St. Paul, MN., 1972.
35.
Krul3eman, G.P. and DeRidder, N.A.,: "Analysis and Evaluation o;E Pumping Test Data," Inte):'national Institute for Land Reclamation and Improvement, Bull. 11, (P.O. Box 45, Wageningen, Netherlands), 1970.
36.
Lohman, S. W. , , "Groundwater HydrauliCI3," U. S. Geological Survey Brofe~9ional Paper 708, 1972.
37.
"Field·Permeability Test Methods with Application to Solutiqn Mining," U.S. Bureau of Mines, Open ·File Report 136-77 (N.T.I.S. Accession No. PB 272 452), 1977.
38.
"Groundwater Manual," U.S. Bureau of Reclamatih'n, CO. 1977.
Denve~,
39.
"Engineering and Design Manual - Coal Refuse Disposal Facilities," Mining Enforcement and Safety Administration, Dept. Interior, 1975.
40.
Core Logging Con~ittee, South Africa Section, AEG, 1978, "A Guide to Core Logging for Rock Engineerinsr": Assoc. Engineering Geol. Bull., v. XV, No.3, pp 295328.
41·
Geological Society Engineering Group 'i'Jorking Party, 1977, "The Description of Rock Masses for Engineering Purposes", Quart. Journ. Engng. Geol. V. 10, pp 355388.
42.
Geological Society Engineering Group Working Party, 1970, "The Logging of Rock Cores for Engineering Purposes": Quart. Journ. Engng. Geol. v. 3. pp 1-24.
43.
Deere, D.U., Dunn, J.R., Fickies, R.H., Proctor, R.J., 1977, "Geologic Logging and Sampling Rock Core for Engin~ering Purposes:" Assoc. Prof. Geo1. Sci., 15 pp w/App. A-N.
R-3
44.
Birkland, P.W., 1977, Pedology, Weathering and Geomorphological Research: Oxford Press, New York 285 pp.
45.
Hatheway, A.W., 1978, "Trench, Shaft and Tunnel Mapping": AGI/AEG Short Course, Engng. Geol. for Geologists, pp 61-76.
46.
Colman, S.M., and Pierce, K.L., 1977, Summary Table of Quarternary Dating Methods: U.S. Geol. Survey Misc. Field Studies Map ~!lF 904.
47.
Peck, R.B., Hanson, W.E., Thornburn, T.H., 1974, "Foundation Engineering", John Wiley and Sons; Inc., New York.
48.
"Underwater Soil Sampling Testing and Construction Control", 1972, A Symposium presented at the Seventy-Fourth annual meeting, American Society for Testing Materials, Atlantic City New , 27 June2 July, 1971, ASTM Special tion 501, American Society for Testing , Philadelphia, Pa.
49.
"civil Engineering in issues, the York, N.Y.
50.
Offshore
ts, 1969 and of Mining, '1g:th1ee.rs, Inc. 'A[)r-IT
.
°
Soil..,.Geomorphic Mojave Desert, California and Soi Is (Wrn. C., Mahaney, ed.) england, pp 187-207.
52.
R.B., 1978, Quaternary Soil Stratigraphy , Methods, and Problems: in Quaternary soils Mahaney, ed.) Geo Abstract~ Norwich, England, pp. 77-108.
53.
Munsell Color Company, 2441 N. Calvert St., Baltimore, Maryland 24218.
54.
Department of the Navy, 1971, Design Manual, Soil Mechanics, Foundations, and Earth Structures: NAVFAC D11-7, March 19 7J., Table 2-2, pp 7-2-3 and 7-2-4.
55.
Soil Survey Staff, 1976, Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys, U.S. Dept. Agriculture Handbook No .• 436: Washington, U.S. Gov't. Printing Office, 754 pp.
R-4
56.
HUD, Public Health Service, 1959, Manual of SepticTank Practice, Developed in Cooperation with the Joint Committee on Rural Sanitation. NTIS PB-218 226, Public Health Services Publication 526, 85 pp.
INDEX
Adits, 4-4,5 American Association of State Highway and Transportation Officials System (AASHTO), 7-7 Augers, 4-15,17 bucket, 4-19; 5-2,23; 7-14 disc, 4-19; 5-23 flight, 4-19; 5-4,23 hollow stem, 4-19; 5-4 hand, 4-18 power, 4-18 Backfilling borings, 10-36 Becker Hammer drill, 4-23; 10-8 Bedrock, 8-6 Boring types, 4-15 BU9ket auger, see augers Bulk samples, rock, see rock sampling soil, see soil sampling Burmister, 7-6 Checklists, 2-12 to 16; 3-9,10; 6-4; 7-14 Churn drill, 4-15,20,24 classification systems (soil), AASHTO, 7-7 Burmister, 7-6 FAA, 7-7 USCS, 7-2,3; 8-7 USDA, 7-7 Wentworth, 8-7 Ccmstant Head Test, 10-4,18,19,20 Contractor Selection, 2-10 Color charts, rock, 8-8 soil, 9-12 Core drilling, 6-3 to 10 Core drilling equipment, 6-10 to 14 Core photography, 8-14 Core recovery (percentage), 8-3,4 Core storage, 6-9 Daily Report, 3-5,10; 6-5 Diamond core barrels, 6-11 to 14 Discontinuities (rock), 8-9 to 12 Disturbed samples, see soil sampling Downhole percussion unit, 4-22 Dozer cuts, 4-4; 9-1,2 Drifts, 4-4 Drive energy, 5-7, 7-14
I-l
Excavation test pits, 4-4,6,7,8; 9-1 to 4 trenches, 4-4,11; 9-1 to 4 Exploration methods, 2-9 direct, 4-1 to 27 indirect, 4-1 offshore, 4-1,2; 5-42 onshore, 4-1 to 27 Falling head test, 10-4,20 Fault investigation evaluation techniques, age dating, 9-12 displacement, 9-11,12 log, 9-4 mapping methods, 9-5 to 10 photography, 9-10 trenches, 4-11 Federal Aviation Agency (FAA), Flight Augers, see augers Fractures (Rock), filling, 8-11 orientation, 8-12 roughness, 13-12 Fugitive data,6'"T;·']'-13,a ..... 1, Geo10giyquadrahgl€!lI'Iaps,
2·:t;{
Geo~oQfca.l~l.)rv~¥ofAt!leric!a,;(GSA) Geop~ysicak'!Olllrv~YI3' 4...a;'i2 --. ------,-,.-.---: . Hollq~stem au~er ,see augers
color chart, 8-8, 9-12
Hardness (rock), 8-13 1s01ati6hof Test section, 10-11 to 15 Log, boring, rock, 8-1,2 soil, 7-1,13 to 16 fault investigation, 9-4 heading data, 7-11,12,13 open subsurface explorations, 9-1,4 Maps, 2-2,3 Mechanical probing (soundings), 4-1 to 4 exploration, 4-3 field testing, 4-3 Munsell color chart, 9-12
1-2
Ob~ervation
wells, 10-27 to 35 Offshore exploration, 4-1,2; 5-42 Opsnore exploration, 4-1 to 27 Packers, 8-14,10,11,12,21,22 Penetrometers, cone, 5-37,38,39 standard, 5-15,36 pocket (Torvane), 5-46 Percolation Test, 10-33 Percussion drills, 4-15,20,21,22 permanent data, 7-13 Permeability, coefficient, 10-1 data to be recorded, 10-16 test equipment, 10-15 Permeability tests, constant head, 10-18,19,20 falling head, 10-20 rising head, 10-17,18 well pumping, 10-27 to 32 Per~its, 2-11; 6-3 Photographs, core, 8-14 trench, 9-10,11 Piezometers, 10-34,35,36 Pressure (packer) test, 8-14; 10-4, 10"21 to 27 leak detection, 10-26 Probing, mechanical, 4-1 to 4 Pump (aquifer) test, 10-4. 10-37 to 32 ReGonnaissance, preliminary, 2-4 supplemental, 3-11 Recovery, core (percentage), 8-3,4 Right of entry, 2-5 Rising head test, 10-4,17,18 ROCk,
drilling bits, 6-10 lithology, 8-6,7,8 sampling, bulk, 6-1,2 core drilling, 6-3 to 10 RQI'l, 8-3,4 Rotary drill (ing) , 4-15,25 to 29; 5-3; 10-8 skid mounted, 4-27,28,29 truyk mounted, 4-25,26,27
1-3
Safety, 3-5 to 8; 10-35 Shafts, 4-4,5,6,9; 9-1,2 Side scan sonar, 4-2 Site, access, 2-5 mobility, 2-6 reconnaissance report, 2-4; 3-11 Soil Conservation Service (SCS), 2-3 Soil Sample, bulk, 5-17,22,23; 7-15 bulk containers, 5-34 channel, 5-22 disturbance, 4-5; 5-20,26,27 frequency, 5-20 grab, 5-17 hand trimmed, 5-14 loss, 5-23 to 27 marking, 5-33,35; 7-15 packing and shipment, 5-33,35 preservation, 5-31 ring, 5-16 sealing, 5-32 size, 5-28,29,30 .... tube, 5-8,9,11,12,15 , lilY 17 , 31 Soil samplers, .. '. Converse, 5-16:; 7-14 Dennison ,5-13 '" . double tube corellarrel,· !)';f~ hydraulic ,piston, 5-11 J'itche r't. 5 "'13 . ;retract~qle'H~ug, S""h7 Shelbyt.URe ,5,;"8 spli t barrel, 5'\-15 stationcf;ry piston, 5-9 sUbmari.ne (subaqueous), see submarine samplers Soil Sampling, bulk, 5-4,17,22,23 disturbed, 4-23; 5-1,10 to 18,22,28,34 grab, 5-17 hammering (driving), 5-5,16,17,21,27 hand trimmed, 5-14 operations, 5~18 to 22 preparation, 5-2,20 pushing (pressing), 5-4,9,10,16,21 rotating, 5-5 undisturbed, 4-19,24; 5-1,6 to 14,20,23,31,32 Soundings, 4-1 to 4 Standard Penetration Test (SPT), 4-24,27; 5-34,36; 7"'8,14
1-4
State Geological Survey Reports, 2-3 Sub-bottom seismic reflection profilers, 4-2 Submarine samplers, Petersen dredge, 5-42 open barrel gravity corer, 5~43 Phleger corer, 5-44 piston gravity corer, 5-45 vibratory corer, 5-46 Test pits, 4-5 to 7; 9-1,2 Test trenches, exploration, 4-4,7,10; 9-1,2 fault investigation, 4-11; 9-4/
•
se~
f.ultinyest~ga~ipn
undisturbed samples, see soil sampling Unified Soil Classification System (USCS), 7-2,3; 8-7 U S Department of Agriculture (USDA), 2-3) 7-7 U S Geological Survey (USGS), 2-2 Vane shear test, 5-41 Wash boring, 4-15,19; 5-2 Water pressure test, see pressure .teSt Weathering (rock), 8-9 Well, . observation, 10-27 to 32 piezometer, 10-33,34,35 pump test, see pump test Wentworth, 8-7
1-5
f
)
Standard Definitions of Terms and Symbols Relating to
SOIL AND ROCK MECHANICS' This Standard is issued under the fixed designation 0 653; the number immediately following the designation indicates the year of original-adoption OT, in the case of revision, the year of last revision. A number in parentheses indicates the year of lasl reapproval. These definitions were prepared jointl)' by the American SOciel}' of Civil Engineers and the Amen'can Society for Testing and Materials.
INTRODUCTION
A number of the definitions include symbols :~_Q_~»~:djcate the u~hs of measurement. The symbols appear in italics jmmediatel_X-__ QJ~~_~)he' name of thejerm, followed by the unit in parentheses. No significance=. _stJ:~uld be placed on the _ 6~-der in which the symbols are presented where two or m-(j~e_ are _giy~n for an individual term. The applicable units are indicate
F - Force, such as pounJ~f();~~;;_:}_?n-fOrc~-~jtre~~~n L-Length. such as inch,J~_Qf;~,:~n-limetre T - Time, sUfh,as second;--minute·_>;-/
D - Dimensiohless Posidve_ expon~rtts~ desigrtile;_,~m_~uYtipl~~-
,Tn the numerator. Negative exponents designate-multipleS-:-ifi'the den_o_rilin-ator. Degrees of angle are indicated as "degrees."' -_--':f:xpre~si-ng---t-he--Ul1its either -in _5.1 or the U.S. customary system has been purposely QmJUed in::(),rder to'-le,ave~:the -choice of the system and specific unit to the engineer and-the pa-rti~uJar appliOO;iion, for example: FL:"''':-may;Jje expressed in pounds-force per square inch, kilopascals, tons per square foot, etc. LT".'.l-may be expressed in feet per minute, centimetres per second, etc. Where synonymous terms are cross-referenced, the definition is usually included with the earlier term alphabetically. Where this is not the case, the later term is the more significant. Definitions marked with (ISRM) are taken directly from the publication in Ref 42 and are included for the convenience of the user. For a list of ISRM symbols relating to soil and rock mechanics, refer to Appendix Xl. A list of references used in the preparation of these definitions appears at the end. AASHTO compaction -see compaction tesf. abrasive-any rock, mineral, or other sub"A" Horizon-see horizon. stance that, owing to its superior hardness, abrasion - a rubbing and wearing away. toughness, consistency, or other properties, (ISRM) is suitable for grinding, cutting, polishing, I These definitions are under the jurisdiction of ASTM Committee 0-18 on Soil and Rock for Engineering Purposes. Current edition approved Sept. 30, 1977. Published December 1977. Originally published as D 653 - 42 T. Last previous edition D 653 - 17. This extensive list of definitions represents the joint efforts of Subcommittee D18.93 on Nomenclature and Definitions of ASTM Committee D-18 on Soil and Rock for Engineering Purposes, and the Committee on Glossary of Terms and Definitions in Soil Mechanics of the Soil Mechanics and Foundation Division of the American Society of Civil Engineers. This list includes some terms from ASTM Definitions D 1707, Terms Relating to Soil Dynamics, which were discontinued in 1967.
122
~m)l scouring, or similar use. abrasiveness-the property of a material to remove matter when scratching and grinding another material. (ISRM) absorbed water-water held mechanically in a soil or rock mass and having physical properties not substantially different from ordinary water at the same temperature and pressure. absorption loss-that part of transmitted energy (mechanical) lost due to dissipation or conversion into other forms (heat, etc.). active earth pressure -see earth pressure. active state of plastic equilibrium -see plastic equilibrium. " adhesion-shearing resistance between soil and another material under zero externally -applied pressure. Symbol Unit Adhesion Total Adhesion
'.c.
0653 water and subsequently deposited by sedi~ mentation. amplification factor-ratio of dynamic to static displacement, velocity, or acceleration. amplitude (L. LT-'. LT-') - maximum deviation from mean or center line of wave. angle of external friction (angle of wall friction). 8 (degrees)-angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting be_tween soil and surface of another mat~Jl~~t~~$ angle of friction (angle()!.,~i~icill between solid bodie.) s (~~gr.,eS)7~ngle whose tangent is betwee-t)ftJi~ maximum value that r~~i~js slippage bodies at ~--r~st- with reand the normal stress
Unit
FL~I --_--,> ;.;:-.,:..•...•... ngle ForFL-I"h--
of
~-::~r~ce),
-.
adsorbed water-water in a soi_~ ~o,_r rock mas~:;?' -\,:~~r~al held by physicochelTli.5~1;:;(:Jo,r~_s" havin$:< cQ¥clppe
physical properties . su~s!ilntialIycdiffererif'faiJ~f<1titf~SS from absorbed wateb."r chemically com~,c !!,.~·oto~""uity. "'.
(angle of sh~~r~esist.. between the axis of tangent to the Mohr representing a given
for solid material.
13. "'1' (degrees)-the
bined water,__ at the --'fa-die tempe-tature and:_'t "-'->angie between the direction of the resultant
a~~1!!!~~::~~~rj;£~@i~:~:~M~I~5J~1 an~~::~~;.;!~r.t~~lf!:~~s~
air-splice ratio G. (I)}"- ratiOipl, (1) volume of water that can- be; drairiea~'if'rorn a saturate(f'$O:i-~~or roc~\~riaer the -action of force of gravi~,t.o(2)tot'al volume of voids. air-void "'tlel,G; (D) - the ratio of: (1) the volume of-air space, to (2) the total volume of voids in a soil or rock mass. allowable bearing value (allowable soil pressure), q/;IJ Pa (FL -2) - the maximum pressure that can be permitted on foundation soil, giving consideration to all pertinent factors, with adequate safety against rup-ture of the soil mass or movement of the foundation of such magnitude that the structure is impaired. allowable pile bearing load, Qal Pa (F)-the maximum load that can be permitted on a pile with adequate safety against movement of such magnitude that the structure is endangered. alluvium - soil, the constituents of which have been transported in suspension by flowing
:i:::l:l::;w::: the horizontal and the maximum slope that a soil assumes through natural processes. For dry granular soils the effect of the height of slope is negligible; for cohesive soils the effect of height of slope is so great that the angle of repose is meaningless. angle a/shear resistance-see angle of internal friction. angle 0/ wall friction -see angle of external friction. anisotropic mass-a mass having different properties in "different directions at any given point. anisotropy-having different properties in different directions. (ISRM) apparent cohesion -see cohesion. aquifer-a water-bearing formation that pro-vides a ground water reservoir. arching - the transfer of stress from a yielding part of a soil or rock mass to adjoining less-yielding or restrained parts of the mass. area of influence of a well, a (L2)-area
123
~~1~
0 653
bedrock (Iedge)-rock of relatively great thickness and extent in its native location. bench-(1) ~he unexcavated rock having a nearly horizontal surface which remains after a top heading has been excavated, or (2) step in a slope; formed by a horizontal surface and a surface inclined at a steeper angle than that of the entire slope. (ISRM) bending-process of deformation normal to the axis of an elongated structural member A, ~ [(D; - Df)/ Dr] x 100 when a moment is applied normal to its long axis. (ISRM) where: maximum external diameter of the bentonitic clay - a clay with a high content of D,. sampling spoon, and the mineral montmorillonite, usually charminimum internal diameter of the acterized by high swelling on wetting. D, sampling spoon at the cutting edge, berDl-a shelf that breaks the continuity of a attenuation-dying out (decay), reduction of slope, " '.'.. , amplitude or change in wave form due 10 biaxial compression -compr,e~sidn::ta'used by energy dissipation or distance with time the application of nQrni~t:·sttesses in two perpendicular d\recfiI?I1S.(iSJi.M) (see also energy loss). "8" hor;zofl-see horizon. biaxial state g~,,~f,i"¥-.-s'iate of sJf~~_s in which b@ck-packing-any material (usually granuone o\,,'_tp:~:~;:i~-l·ee· principal str,~~,~e.s is zero, lar) that is used to fill the empty space (ISRl>ir·.· .,_ between the lagging and the .rock surface. binder (~g~~bi~f\~dS~portion of soil~:passing ( I S R M ) ' , No. 40 (42-~"ff!l¥1,ti.s. standard si~"'e'. base course (base)-a layer of specified of·:'o ~~,~~_~HbilitY~:in~,-ex value of the resistance of a selected material of planned thickness coo~;/ ',."--~"t~C,~~ format.io~, to blasting. (lSRM) slrUl;lt:u un tlie subgrade,,9L~~~~,~se for the,:,; . b'-all:i~_t ;cap '(~~nator, inifiator)-a small purpose of serving one,'ot,'~more'_ ,~unctions';', tu~,~ _ ;¢9.ntainfiftf~:a"flashing mixture for firing such as distributing load, provitfi!l;g drain- ... ' .e~l>los[v~¥,,(ISRM) age, minimizing frost',acHon, etc,:' '--X\JJlodUng""::'''wood blocks placed between the base e,xclt~,n.,e,~:~h~ phys_i~o~h~"ItH£alprocess ~.',' excavated surface of a tunnel or shaft and y!herehY'o"'e;$~~cies (jfj9~s'adsorlSed on ' the main bracing system. (ISRM) 's,oiJj~artic1es in',e'pl~ced I:ty;~~pother"spa~les, body force - a force such as gravity whose beai"i,1i8,'capacit)' -se(Vultimat~':b:~aring cllpaceffect is distributed throughout a material it,)' ~"o body by direct action on each elementary bearingalpacity (of. pile), Q,,, P" (F)-the part of the body independent of the others. (ISRM) load per pile re(juired to produce a condition offa.Uure. bottom charge-concentrated explosive charge bedding-applies to rocks resulting from conat the bottom of a blast hole. (ISRM) solidation of sediments and exhibiting surboulders - a rock fragment, usually rounded faces of separation (bedding planes) beby weathering or abrasion, with an average tween layers of the same or different matedimension of 12 in, (305 mm) or more. rials, that is, shale, siltstone, sandstone, boulder c1ay-a geological term used to deslimestone, etc. (ISRM) ignate glacial drift t~at has not been subbedding - collective term signifying the exisjected to the sorting action of water. and tence of layers of beds. Planes or other therefore contains particles from boulders to clay sizes. surfaces dividing sedimentary rocks of the same or different lithology. bulb of pressure - see pressure bulb. bedrock-the more or less continuous body bulkhead-a partition built in an underground of rock which underlies the overburden structure or structural lining to prevent the soils. (lSRM) passage of air, water, or muck. (ISRM) surrounding a well within which the piezometric surface has been lowered when pumping has produced the maximum steady rate of flow. area ratio of a sampling spoon, sampler, or sampling tube, A r (D) - the area ratio is an indication of the volume of soil displaced by the sampling spoon (tube), calculated as follows:
_
"
"
.,
.,"
124 .j
0653 bulking - the increase in volume of a material centrifuge moisture equivalent-see moisture due to manipulation. Rock bulks ul-'on equivalent. being excavated~ damp sand bulks if 10Dsely chamber-a large room excavated underdeposited, as by dumping, because the apground, for example, for a powerhouse, parent cohesion prevents movement of the pump station, or for storage. (ISRM) soil partic1es to form a reduced volume. chamber blasting (coyotehole blasting)-a buoyant unit weight (submerged unil weight)method of quarry blasting in which large explosive charges are confined in small tunsee unit weight. burden - distance between charge and free nel chambers inside the quarry face. (ISRM) surface in directiDn of throw. (ISRM) "e" Horizon -see horizon. Chip-crushed angular rock fragment of a size California bearing ratio, eBR (D)-the ratio. smaller than a few centimetres. (ISRM) of: (1) the force per unit area required to chisel- the steel cutting tool used in percuspenetrate a soil mass with a 3 in.~ (19 cm 2 ) sion drilling. (ISRM) circular piston (approximately 2-in. (51clay (clay soil) - fine-grained soil or the finemm) diameter) at the rate of 0.05 in. (1.3 grained portion of soil that can be made J() mm)/min, to (2) that required for correexhibit plasticity (putty-like prop~t-lf¢!l;)\ sponding penetration of a standard matewithin a range of water contents~ jlud,",i-hat rial. The ratio is usually determined at 0.1exhibits considerable streIl,gth_~J;leiUlI~:,,_pry. in. (2.5-mm) penetration, although other The term has been,_ -_~~-q)o -designa~e:; ~he penetratJons are sometimes used. Original percentage fine~,JIia.h"O:002 mm (0;005 California procedures required determinamm in some',~a~~s):o- but it~~is strongly -_r~_~_ tion of the ratio at 0 .1-in. intervals to 0.5 om~_ended thatit4~~ us~g~-~_~e_ discontinue,d~ in. (12.7 mm). Corps of Engineers' proce~i~_~-e,:~~ere is ari1~-',~;~yitlen-Ce from an engi'"dures require determination of the ratio at n-~rf~g::Nandpoin:~;-~.t~a-t the properties de0,1 in. and 0.2 in. (5.1 mm). Where the sQl;J~ed';J9::;the abdY~.::~_definition are many ratio at 0.2 in. is consistently high~()_han times m-or.~jmportan(·at 0.1 in., the ratio at 0.2 in. is-used~"~>_-'_-' clay:osiU-thaVpoq}on-'--6fothe soil finer than camoufiet -_the underground _cavity created 0.002, !11!11'«LO'!:i'mm in some c",es) (see by a fully contained explosive. (!SRM) also"dIlY); I capillary .ction «lIpillarity) - tbe , rise Or clay sQU ~ see clay. movement -ot_watet-- in~ th~ _interstices-,of-_a ----_cl_eavdge';;;...in crystallography, the splitting, or soil or rdc)ta~e to capill~ry_::~orce-~~-;> --'~tendency to split, along planes determined capillary flow_ j::s.~e capillary--rnigratiolh:_\, . by the crystal structure. In petrology, a capillary fringe z~ne - the zontiabove _th~Jree tendency to cleave or split along definite, water elevation in which: wtiier is held. by paranel, closely spaced planes. It is a seccapillary aetioll-. ondary structure, commonly confined to capillary head, h (Lr-the potential, exbedded rocks. cleavage - the tendency to cleave or split pressed in head-_~or-water, that causes the along definite parallel planes. which may water to flow by capillary action. be highly inclined to the b,dding. It is a capillary migration (capillary Oow)-the secondary structure and is ordinarily acmovement of water by capillary action. companied by at least some recrystallization capillary rise (height of capillary rise), hI' (L)-the height above a free water elevaof the rock. (ISRM) cleavage planes - the paraliel surfaces along tion to which water will rise by capillary which a rock or mineral cleaves or sepaaction. rates; the planes of least cohesion, usually capillary water-water subject to the influparallel to a certain face of the mineral or ence of capillary action. crystal. cavity - a natural underground opening that cleft water-water that exists in or circulates may be small or large. (USBM) along the geological discontinuities in a cavity - underground opening created by a rock mass. fully contained explosive. (ISRM)
125
~~l~ closure-the opening is reduced in dimension to the extent that it cannot be used for its intended purpose. (ISRM) cobble (cobblestone)-a rock fragment, usually rounded or semirounded, with an average dimension between 3 and 12 in. (75 and 305 mm). coefficient of absolute viscosity -sec coeffi~ cien. of viscosity. coefficiem a/active earth pressure-see coefficient of earth pressure. coefficient of compressibility (coefficient of compression), a (L2 F-l)-the secant slope, for a given pressure increment. of the pressure-void ratio curve, Where a stress-strain curve is used, the slope of this curve is equal to ",./(1 + e). coefficient of consolidation, c/, (L2T- 1 )_a coefficient utilized in the theory of consolidation, containing the physical constants of a soil affecting its rate of volUlfJe change. ,
j
0 653 principal stress, to (2) the minor principal stress. This is applicable where the soil has been compressed sufficiently to develop an upper Hmiting value of the major principal stress. coefficient of friction (coefficient of friction between solid bodies) f (D)-the ratio betwecn the maximum value of shear stress that resists slippage between two so1id bodies with respect to each other, and the normal stress across the contact surfaces, The tangent of the angle of friction is cJ>s, coefficient offricfion-a constant proportionaWy fac~or. p.. relating normal stress and the corresponding critical shear stress at which sliding starts between two surfaces: T = WCT. (ISRM) . coefficient of internatJtittiolf /.L (D)-the tangent of the a~-gle~~of il)ternal friction (angle of _$I:te.~r resistance) _(see internal
fric!I~_"}(TWl1~,--::-
:,~<,'<:-
coeffiiii.~iJl·iif permeability (pedneabilily) k where: (L 1'~1)'c- thera,ltt of dischargepf,water unk coefficient of permeability, LT~_\ :_'~, der -1~tnina-(J(Qw-'conditions through a unit e void ratio, D. - _:/~/~~ cross-s~C:t~()nal area of a porous medium ll'," coefficient of compressibility, L~-,:?f; _;~:~~ under a'-~:\jhit hydraulic gradient and stan-" -"'<_'_,:- _ "" -"" -i--~. .--b. --~.-?.c. .).tern. p..·.'.e.."rature conditions (usually and 'Y1I" unit weight of.\Y'ater;- FL"'a, c..(J.e. ffi' Cit:.tll.,.of-shear resistance - see coefficient NOTE-In the Iiteratui~--published pnor to lc}3~_/-, ' the coefficient of conso,lid"tion, usually designate-d,'---- ~ --'- --6f iil~i11al friction p. (D). c, was 9~fi~ed l;Ir the eqlttt_!Ion::;::;,~_- '" coefficient of subgrade reaction (modulus of ~,,,,klacY~(!+.') subgrade reaction), k, k, (FL-')-ratio of: (1) load per unit area of horizontal surface This :original definiti~n otth~_~~effidi~rit-of:~~"nsol of a mass of soil, to (2) corresponding idation may be fou:!'IU --,in sori1~~more rece-nt papers and_care should be'taKen to 3v()iaconfusion, settlement of the surface, It is determined as the slope of the secant, drawn between co.ffident of .arth pre.su:e'~· (D) - the printhe point corresponding to zero settlement cipal-~tress ratio a point in a soil mass, and the point of O.05-in. (1.3-mm) settleco.(!ffici~-'li. of earth pressure, active, KA ment, of a load-settlement curve obtained (D)-the rninimum ratio of: (1) the minor from a plate load test on a soil using a 30principal stress, to (2) the major principal in. (762-mm) or greater diameter loading stress. This is applicable where the soil has plate, It is used in the de"sign of concrete yielded sufficiently to develop a lower limpavements by the Westergaard method. iting value of the minor principal stress. coefficient of earth pressure, at rest, Ko coefficient of uniformity, C (D) - the ratio D6<~/Du" where Duo is the particle diameter (D)-the ratio of: (1) the minor principal corresponding to 60 % finer on the grainstress, to (2) the major principal stress. size curve, and DIU is the particle diameter This is applicable where the soil mass is in corresponding to 10 % finer on the grainits natural state without having been persize curve. mitted to yield or without having been coefficient of viscosity (coefficient of absolute compressed, viscosity), T/ (FTL -2)-the shearing force coefficient of earth pressure, passive, KI' per unit area required to maintain a unit (D)-the maximum ratio of: (1) the major C
= k(I c
+ e)/a,.'1,'
at
jj
126
0653
primary consolidation (primary compres~ sion) (primary time effi'ct) - the reduction in volume of a soil mass caused by the application of a sustained load to the mass and due principally to a squeezing out of water from thc void spaces of the mass and accompanied by a transfer of the load from the soil watcr to the soil solids. secondary consolidation (secondary compression) (secondary time effect) - the reduction in volume of a soil mass caused by the application of a sustained load to the mass and due principally to the adjustment of the internal structure of the soil mass after most of the load has been transferred from the soil water to the soil solids. consolidation curve - see consolidation time curve. consolidation ratio, U.~ (D)-the ratio of: (I) the amount of consolidation at a given distance from a drainage surface and at a given time, to (2) the total amount of consolidation obtainable at that point under a given stress increment. consolidation test - a test in which the specimen is laterally confined in a ring and is compressed between porous plates. consolidation-time curve (time curve) (consolidation curve) (theoretical time curve)-a curve that shows the relation between: (/) the degree of consolidation, and (2) the elapsed time after the application of a given increment of load. constitutive equation-force deformation function for a particular material. (ISRM) contact pressure, p (FL -2) - the unit of pressure that acts at the surface of contact between a structure and the underlying soil or rock mass. contraction -linear strain associated with a decrease in length. (ISRM) controlled blasting - includes all forms of blasting designed to preserve the integrity of the remaining rocks, that is, smooth blasting or pre-splitting. (ISRM) controlled~strain test - a test in which the load is so applied that a controlled rate of strain results. controlled-stress test - a test in which the stress to which a specimen is subjected is applied at a controlled rate. convergence - generally refers to a shortening of the distance between the floor and roof
128
of an opening, for example, in the bedded sedimentary rocks of the coal measures where the roof sags and the floor heaves. Can also apply to the convergence of the walls toward each other. (ISRM) core drilling; diamond drilling - a rotary drilling technique, using diamonds in the cutting bit, that cuts out cylindrical rock samples. (ISRM) cover - the perpendicular distance from any point in the roof of an underground opening to the ground surface. (ISRM) crack-a small fracture, that is, small with respect to the scale of the feature in which it occurs. (ISRM) crater-excavation (generally of conical shape) generated by an explosive charge. (ISRM) creep - slow movement of rock debris or soil usually imperceptible except to observations of long duration. Time-dependent strain or deformation, for example. continuing strain with sustained stress. critical circle (critical surface) -·the sliding surface_assumed in a theoretical analysis of a soil massJor which the factor of safety is a minimum. critical damping-the minimum viscous damping that will allow a displaced system to return to its initial position without oscillation. critical density ..... the unit weight of a saturated granular material below which it will lose strength and above which it will gain strength when SUbjected to rapid deformation. The critical density of a given material is dependent on many factors. critical frequency, It:' - frequency at which maximum or minimum amplitudes of excited waves occur. critical height, Hr (L)-the maximum height at which a vertical or sloped bank of soil or rock will stand unsupported under a given set of conditions. critical hydraulic gradient - see hydraulic gradient. critical slope-the maximum angle with the horizontal at which a sloped bank of soil or rock of given height will stand unsupported. critical surface - see critical circle. critical void ratio - see void ratio. crown-also roof or back, that is, the highest point of the cross section. In tunnel linings,
a_ 0653 the term is used to designate either the arched roof above spring lines or all of the lining except the floor or invert. (ISRM) cryology - the study of the properties of snow, ice, and frozen ground. cuttiugs - small-sized rock fragments produced by a rick drill. (ISRM) damping-the dissipation of energy with time or distance. damping -- reduction in the amplitude of vibration of a body or system due to dissipation of energy internally or by radiation. (ISRM) damping ratio - for a system with viscous damping, the ratio of actual damping coefficient to the critical damping coefficient. de(:ay time-the interval of time required for a pulse to decay from its maximum value to some specified fraction of that value. (ISRM) decoupUng - the ratio of the radius of the blasthole to the radius of the charge. In general, a reducing of the strain wave amplitude by increasing the spacing between charge and blasthole wall. (ISRM) deOocculaUng agent (denoceulant) (dispersing agent) - an agent that prevents fine soil particles in suspension from coa1escing to form floes. deformation - change in shape or size. deformation -a change in the shape or size of a solid body. (ISRM) deformation resolution (Ielormallolt sensiMity) Rd (t.)-ratio of thesmallest:subdivisian of the- indicating stale of a -deformation-measuring device to :the sensitivity of the device. degree of consolidation (percent consolidation), U (D)...;.the ratio, expressed as a percentage, of: (1) the amount of consolidation at a given time within a soil mass, to (2) the total amount of consolidation obtainable under a given stress condition. degree-days - the difference between the average temperature each day and 32° F (0° C). In common usage degree-days are positive for daily average temperatures above 32° F and negative for those below 32 F (see freezing index). degrees-of-freedom-the minimum number of independent coordinates required in a mechanical system to define completely the positions of all parts of the system at any 0
instant of time. In general, it is equal to the number of independent displacements that are possible. degree a/saturation -see percent saturation. degree of saturation - the extent or degree to which the voids in rock contain fluid (water, gas l or oil). Usually expressed in percent related io total void or pore space. (ISRM) degree of sensitivity (sensitivity ratio) -see reg molding index. delay - time interval (fraction of a second) between detonation of explosive charges. (ISRM) density - see unit weight. NOTE-Although it is recognized that density is defined as mass per unit volume, in til,e:'field of soil mechanics the term is frequently,useddn place of unit weight.
detonation-an extreme~y rapid--and violent chemical reaction ,'Causing the production . of a large volume Otllas. (ISRM) deviator stre$S,oi-4; 'u (FL -2)_the diffec¢lfce b_etween the_-::-ni~jor _~nd. ,minor princit1al stresses in a trlaxiahest. deviator, of stress (slrain) - the stress (strain) teo so, "lJtained bY'-subtracting the mean of --the normal stress _($tt~in) components of a -stress (stI'ainl."tensot-\from each normal stress (straih)·cnmponent. (ISRM) dilitancy~property of volume increase under loading. (ISRM) dilitaftcy - the expansion of cohesion less soils ,'>. when subject to shearing deformation. direct shear test - a shear test in which soil or rock under an applied normal Load is stressed to failure by moving one section of the sample or sample container (shear box) relative to the other section. discharge velocity, v, q (LT-t)-rate of discharge of water through a porous medium per unit of total area perpendicular to the direction of flow. discontinuity surface - any surface across which some property of a rock mass is discontinuous. This includes fracture surfaces, weakness planes, and bedding planes, but the term should not be restricted only to mechanical continuity. (ISRM) dispersing agent-see denocculating agent. dispersion-the phenomenon of varying speed of transmission of waves, depending on their frequency. (ISRM)
129
0653 displacement - a change in position of a material point. (ISRM) distortion-a change in shape of a solid hody, (ISRM) divergence loss-that part of transmitted energy lost due to spreading of wave rays in accordance with the geometry of the system, double amplitude - total excursion or over-all height of wave (peak-t(}-pcak, crcst-totrough) or for sinusoidal wave twice the amplitude. drag bit-a noncoring or full-hole boring bit, which scrapes its way through n:latively soft strata. (ISRM) drawdown (L) -vertical distance the free water elevation is lowered or the reduction of the pressure head due to the removal of free water. drift -see adlt. (ISRM) drillabilify-index value of the resistance of a rock to drilling. (ISRM) drill carriage; jllmbo - a movable platform, stage, or frame that incorporate:>._ several rock drills and usually travels on tht! ,funnel track; used for heavy drilling work in large tunnels. (ISRM) drilling pattern-the number,position. depth; and angle of the blastholes, forming the complete round in the face of a tunnel or sinkingpit.(ISRM) dry unit weighr (dry density)-see unit weight. ductility-condition in which materIal can sustain permanent deformaNon withl'ut lqsing its ability to resist load'. (ISRM) earth - see soil. earth pressure - the pressure or forC"\:." exerted by soil on any boundary. Symbol
Pressure Force
p p
l';'lil FL- , F('[ FL-I
active earth pressure, PA , PA - :he minimum value of earth pressure. Tbs condition exists when a soil mass is pe!:"milted to yield sufficiently to cause its inter:1al shearing resistance along a potential f:.;.ilure surface to be completely mobilized. earth pressure at rest, Pm po-lhe value of the earth pressure when the s. . . . il mass is in its natural state without ha\'ing been permitted to yield or without ha \'ing been compressed.
passive earth pressure, PI" Pl.-the maxi~ mum value of earth pressure. This condi~ tion exists when a soil mass is compressed sufficiently to cause its internal shearing resistance along a potential failure surface to be completely mobilized. effect diameter (effective sb.e) , DHI! D" (L)particle diameter corresponding to 1() % finer on the grain-size curve, effective drainage porosity -see effective porosity. effective force, F (F) - the force transmitted through a soil or rock mass by intergranular pressures. effective porosity (effective drainage porosity), n, (D) - the ratio of: (l) the volume of the voids _of a soil or rock mass that can be drained by gravity, to (2) the total volum~ of'the mass. effective pressure - see stress. effie/ive size .-see effective diameter. effective_stre~s -see stress. effective f,lnit weight-see unit weight. ~Iasticlty - property of material that returns to it$ __original form or condition after the appliedlorce is removed. (ISRM) ellis_tic liuiit-point on stress strain curve at wh-ich transition from elastic to inelastic behavior takes place. (ISRM) elastic state of equilibrium - state of stress within a soil mass when the internal resist~ ance of the mass is not fully mobiHzed. elastic strain energy - potential energy stored in a strained solid and equal to the work done in deforming the solid from its un~ strained state less any energy dissipated by inelastic deformation. (ISRM) equipotential line -see piezometric line. equivalent diame.er (equivalent size), D (L) - the diameter of a hypothetical sphere composed of material having the same specific gravity as that of the actual soil particle and of such size that it will settle in a given liquid at the same terminal velocity as the actual soil particle. equivalent nllid-a hypothetical fluid having a unit weight such that it wi!] produce a pressure against a lateral support presumed to be equivalent to that produced by the actual soil. This simplified approach is valid only when deformation conditions are such that the pressure increases linearly with depth and the wall friction is neglected.
130
D 653
excess hydrostatic pressure - see hydrostatic fauU - a fracture or fracture zone along which pressure. there has been displacement of the two exchange capacity - the capacity to exchange sides relative to one another parallel to the ions as measured by the quantity of exfracture (this displacement may be a few centimetres or many kilometres). (See also changeable ions in a soil or rock. excitation (stimulus)-an external force (or joint fault set and joint fault system. other input) applied to a system that causes (ISRM) the system to respond in some way. fault breccia - the assemblage of broken rock extension-linear strain associated with an fragments frequently found along faults. increase in length. (lSRM) The fragments may vary in size from inches external force -- a force that acts across exterto feet. (lSRM) oal surface elements of a material body. fault gouge-a clay-like material occurring (ISRM) between the walls of a fault as a result of extrados - the exterior curved surface of an the movement along the fault- ~\h:faces. arch, as opposed to intrados, which is the (ISRM) _-_,/-,_ ----->---'-. interior curved surface of an arch. (ISRM) field moisture equivalent_;;;;-,S¢"e,--pjoisture equivalent, __ c_;:.:-,_-:'::\ <-_--_-:_--~: fabric - the orientation in space of the elements composing the rock substance. fiU- man-ma?:tg}_~9_~_pOgits of natur~t:~soiJs or (ISRM) rock pr'1du~I~:and waste materials"", face (heading) - the advanced end of a tunnel, filling - ge~~_!~;IIy, _t,~~At!!tIterial occupyj~g the drift, or excavation at which work is pro_~;_-:space bet"'_~:C;P{Jg.iJ:l:f--~urfaces, fauh~-.--,~and gressing. ( I S R M ) ! ) t h e r ro&pJsc,oniinuities. The fillingmafailure (in rocks) -exceeding the maximum _:~,~;'\~~tqt!._ may h~l{~!ay, gouge, various natural strength of the rock or exceeding the stress '. :--;--< cetij:~.t.i_ng ag~~i$._J _or alteration products of or strain requirement of,asp~Cificdesign..' thea'ilja~~nt ro!i~!,,(ISRM) (ISRM) , ".r"ter,gro~~f!~ve fUlcr)-a layer or combinafailure by rupture -see sll~~~ failure,__-_ -~Eifi9.t_tof-lay~rs"bf pervious materials designed failure crite_~i-~_D;.s_-s~_ecifiCi\t~;9n_o~,~~-~-;m~chan- ---,:):-afHfinstalled in such a manner as to provide ical, ~?fl_~h~on-:c_U~_ger wh,~5~~;;~6!~d_--;~,~!~Ei~ls --:<:grainage, yet prevent the movement of soil fail~l':Jf.cturi"g;oi'"y d¢(ptxnlngbeYej)~. .. particles due to flowing water. some,:~sp_ecified Iim-tf?r~is s~c_i~ication~may fines-portion of a soil finer than a No. 200 be in)erms of the st:re_sses. st:~arns, rate-of(75-Jl.m) U.S. standard sieve. change __ .-of stresses~ _"~ rate-at,,;.-change of finite element - one of the regular geometrical strains~--()r: :s~me c()-",~illation of these quanshapes into which a figure is subdivided for tities, in -the--ll1a_~et~~ls: the purpose of numerical stress analysis. failure criterioD:-'theoretically or empirically (ISRM) derived stress or strain relationship characfissure - a gapped fracture. (ISRM) terizing the occurrence of failure in the floc -loose, open-structured mass formed in rock. (ISRM) a suspension by the aggregation of minute particles. fatigue - the process of progressive localized permanent structural change occurring in a flocculation-the process of forming floes. material subjected to conditions that pro- flocculent structure - see soil structure. Ooor- bottom of near horizontal surface of duce fluctuating stresses and strains at some point or points.and that may culminate in an excavation, approximately parallel and cracks or complete fracture after a sufficient opposite to the roof. (ISRM) number of fluctuations. (D 671, D-20; flow channel-the portion of a flow net E 206, E-9) bounded by two adjacent flow lines. fatigue-decrease of strength by repetitive now curve-the locus of points obtained from loading. (ISRM) a standard liquid limit test and plotted on a ratigue limit-point on stress-strain curve begraph representing water content as ordilow which no fatigue can be obtained renate on an arithmetic scale and the number gardless of number of loading cycles. of blows as abscissa on a logarithmic scale. (ISRM) now failure-failure in which a soil mass
131
D 653
moves over relatively long distances in a fluid-like manner. flow index, Ftc'. I, (D)-the slope of the flow curve obtained from a liquid limit test, expressed as the difference in water contents at 10 blows and at 100 blows. now line-the path that a particle of water follows in its course of seepage under laminar flow conditions. flow net - a graphical representation of flow lines and equipotential (piezometric) lines used in the study of seepage phenomena. flow slide-the failure of a sloped bank of soil in which the movement of the soil mass does not take place along a well-defined surface of sliding. flow value, NdJ (degrees)-a quantity equal to tan [45 deg + (/2)J. fold-a bend in the strata or other planar structure within the rock mass. (ISRM) foliation - the somewhat laminated structure resulting from segregation of different minerals into layers parallel to the schistosity. (ISRM) footing - portion of the foundation of a st~uc-. ture that transmits loads directly to- th_e . soil. footwall-the mass of rock beneath a discon .. tinuity surface. (ISRM) forced vibration (forced oseilliltiUlI) - vibration that occurs if- the response __j_!; imposedby the excitation. If the_ excitation is pc.:. riodic. and __cofltimiin-g? -~he- '_o~~iHation Js steady-state; forepoling - driving [orepotes (pointed boards or steel rods) _ahead of _i'he excavation, usually over the last set ere"cted, to furnish temporary overhead protection while installing the next set. (ISRM) foundation -lower part of a structure that transmits the load to the soil or rock. foundation soil- upper part of the earth mass carrying the load of the structure. fracture- the general term for any mechanical discontinuity in the rock; it therefore is the collective term for joints, faults. cracks, etc. (ISRM) fracture - a break in the mechanical continuity of a body of rock caused by stress exceeding the strength of the rock. Includes joints and faults. fracture frequency - the number of natural
132
discontinuities in 8 rock or soil mass per unil length, measured along a core or as exposed in a planar section such as the wall of a tunnd. fracture pattern-spatial arrangement of a group of fracture surfaces. (ISRM) fragmentation - the breaking of rock in such a way that the bulk of the material is of a convenient size for handling. (ISRM) free water (gravitational water) (ground water) (phreatic water)-water that is free to move through a soil or rock mass under the influence of gravity. free water elevation (water table) (ground water surface) (free water surface) (ground water elevation)-elevations at which the pressure in the water is zero with respect to the atmospheric pressure. freezing index, F (degree~days)-the number of degree-days behveert -the highest and lowest points on -the curmllative degreedays ~__ ti~e'_ctirve for one-freezing season. It is used- as a measure of --the combined duration and magnitude of be.}o_w-freezing temperature occurring during 'any given freezing season. The index determined for air temperatures at 4.5 ft (1.4 m) above the ground --is commonly designated as the ',- air-Jreezing index, while that determined for-temperatures immediately below a surface is, 'known as the surface freezing index. free vibration - vibration that occurs in the absence of forced vibration. frequency, f (T-l)-number of cycles occurring in unit time. frost action - freezing and thawing of moisture in materials and the resultant effects on these materials and on structures of which they are a part or with which they are in contact. frost boil- (a) softening of soil occurring during a thawing period due to the liberation of water from ice lenses or layers. (b) the hole formed in flexible pavements by the extrusion of soft soil and melt waters under the action of wheel1oads. (e) breaking of a highway or airfield pavement under traffic and the ejection of subgrade soil in a soft and soupy condition caused by the melting of ice lenses formed by frost action. frost heave - the raising of a surface due to
D 653
the accumulation of ice in the underlying soil or rock. fundamental frequency -lowest frequency of periodic variation. gage lenglh, L (L) -distance over which the deformation measurement is made. general shear failure -see shear failure. glaciallill (liII) - material deposited by glaciation, usually composed of a wide range of particle sizes, which has not been subjected to the sorting action of water. gradation (grain~size distribution) (texture)the proportions by mass of a sailor fragmented rock distributed in specified particle~size ranges. grain~size analysis (mechanical analysis) (particle-size analysis) - the process of determining grain-size distribution. gravel- rounded or semirounded particles of rock that will pass a 3-in. (76.2-mm) and be retained on a No.4 (4.75-/Lm) U.S. standard sieve. gravitational water-see free water. ground arch - the theoretical stable rock arch that develops some distance back from the surface of the opening and supports the opening. (ISRM) ground water-see free water. ground water elevation - see free water eleva~ tion. ground waler level-lhe .leveLbelowwbich the rock-and subsoU,'-fo urikno\\in depths, are salurated. (ISRM) ground wafer surface --see---Iree wa,fer elevation. hanging waD-the mass-of rock above a discontinuity surface. (ISRM) hardness- resistance of a material to indentation or scratching. (ISRM) hardpan - a hard impervious layer, composed chiefly of clay, cemented by relatively insoluble materials, that does not become plastic when mixed with water and definitely limits the downward movement of water and roots. head - pressure at a point in a liquid, expressed in terms of the vertical distance of the point below the surface of the liquid. (ISRM) heave-upward movement of soil caused by expansion or displacement resulting from phenomena such as: moisture absorption, I
133
removal of overburden, driving of piles, frost action, and loading of an adjacent area. height of capillary rise - see capillary rise. heterogeneity-having different properties at different points. (ISRM) homogeneity - having the same properties at all points. (ISRM) homogeneous mass - a mass that exhibits essentially the same physical properties at every point throughout the mass. honeycomb structure-see soil structure. horizon (soil horizon) - one of the layers of the soil profile, distinguished principally by its texture, color, stru·cture, and chef!1ical content. "A" horizon - the uppermost layer of a soil profile from which :inorganic colloids and other soluble _. materials have been leached. UsuaUy--contains remnants of organic life. "8" horizon -tile jayer of a soil profile fn -which mater_i_at--Ieached from the overlying "A" horizon is accumulated. HC~ -horizon ~undisturbed parent material from- 'rhich-_ the overlying soil profile ... has been dew:loped. humus.;...a oro'W,u:or black material formed by - the partial
D 653
combination of any of these, with organic linear (normal strain) - the change in length matter (see humus). It is sometimes called per unit of length in a given direction. topsoil in contrast to thl)! subsoils that con(ISRM) tain little or no organic matter. line of creep (path of percolation) - the path that water follows along the surface of local shear failure - see shear failure. loess - a uniform aeolian deposit of silty macontact between the foundation soil and terial having an open structure and relathe base of a dam or other structure. tively high cohesion due to cementation of line of seepage (seepage line) (phreatic clay or calcareous material at grain conline)-the upper free water surface of the tacts. A characteristic of loess deposits is zone of seepage. that they can stand with nearly vertical linear expansion, L" (D) - the increase in one slopes. dimension of a soil mass, expressed as a logarithmic decrement - the natural logarithm percentage of that dimension at the shrinkof the ratio of any two successive ampliage limit, when the water content is intudes of like sign, in the decay o( a-,singlecreased from the shrinkage limit to any frequency oscillation. given water content. longitudinal wave, VI (LT~!l.,.;;-wave in which linear shrinkage, Ls (D)-decrease in one direction of displa<;em'eijt---a-t ea.cJ-t point of dimension of a soil mass, expressed as a medium is n~r~ruirt~" wave front~--)Yith proppercentage of the original dimension, when agation v_el.9C:ity}:calculated as fb1l9WS: the water content is reduced from a given value to the shrinkage Hmit. VI = V(E1A)[(1 . v)/(I + v)(I 2v)]'" lineation - the parallel orientation of strucV ("'.""t"'zcc'i<")/-p tural features that are lines rather than where: planes; some examples are parallel orienta> ~ -_~7-__ 'Young'fi,ll0dulus, tion of the long dimensions of minerals; c:long axes of pebbles; striae _ ~_I1,SIi~~~nsides; '--' p-'-:#~ '~~ss deU!*¥~ A ari'd')l ~=:=_Lam:~V_$-~eonstants, and and cleavage-bedding pl~n~::--.Ifft~rsections. v __= :P~iSSQll'S iatl~. (ISRM) liquefaction (spontaneot.$ iiquefacti~~l:~ the lonl wave (quer wave), W (LT-I)-dispersive surface wave with one horizontal composudden lar~_~Aecr_ease of the s~e~ring resistnent, generally normal to the direction of ance _of.a_-_~hesion}~f1~ soi.L-NJs_ catis,~d -~X _,a propagation, which decreases in propagaconapse of the str~c~ure bys/tock oroW~r, tion velocity with increase in frequency. type --)jf-~ strain arid:~;;-i~ assQc,iated with -~ °3 sudden -but tempor-afy--.i~crease_~f the pre- -major principal plane -see principal plane. fluid p(essure. It involves a 'temporary major principal stress - see stress. mass unit weight - see unit weight. transformation of the '-material into a fluid mathematical model- the representation of a mass. _ physical system by mathematical expresliquid limit, LL, L~., WL (D)-(a) the water sions from which the behavior of the system content corresponding to the arbitrary limit can be deduced with known accuracy. between the liquid and plastic states of (ISRM) . consistency of a soil. (b) the water content at which a pat of maximum density (maximum unit weight)see unit weight. soil, cut by a groove of standard dimensions, will flow together for a distance of mechanical analysis -see grain..size analysis. microseism - seismic pulses of short duration 112 in. (12.7 mm) under the impact of 25 and low amplitude, often occurring preblows in a standard liquid limit apparatus. vious to failure of a material or structure. liquidity index (water-plasticity ratio) (rela(ISRM) tive water conteRt), B, Rw. IL (D)-the ratio, expressed as a percentage, of: (1) minor principal plane - see principal plane. the natural water content of a soil minus its minor principal stress - see stress. modulus of deformation -see modulus of plastic limit, to (2) its plasticity index. elasticity. loam-a mixture of sand, silt, or clay, or a
135
/
0653 modulus of elasticity (modulus of deformsfield moisture equivalent, FME - the mintion), E. M (FL -2) _ the ratio of stress to imum -water content expressed as a percentstrain for a material under given loading age of the weight of the oven-dried soil, at conditions; numerically equal to the slope which a drop afwater placed on a smoothed surface of the soil will not immediately be of the tangent or the secant of a stressstrain curve. The use of the term modulus absorbed by the soil but will spread Qut of elasticity is recommended for materials over the surface and give it a shiny appearthat deform in accordance with Hooke's anee. law; the term modulus of deformation for muck -stone, dirt, debris, or useless material; materials that deform otherwise. or an organic soil of very soft consistency. modulus ofsub grade reaction -see coefficient mud-a mixture of soil and water in a fluid of subgrade reaction. or weakly solid state. modulus 01 volume change - see coefficient of multibench blasting - the blasting of several 'Volume compressibility. benches (steps) in quarries and open pits, Mohr circle-a graphical representation of either simultaneously or with small delays. the stresses acting on the various planes at (ISRM) multiple-row blasting-the-drl1ling. charging, a given point. Mohr circle of stress (strain)-a graphical and firing of several-tow-s. of vertical holes representation of the components of stress along a,,_q_~_~~y o-.toperica:sl:face. (ISRM) mus_k_eg;.J~iel~ practically 'tre~less areas sup(strain) acting across the various planes at ~_t.t,ijj-g- -'dense growth consi~Hng primarily a given point, drawn with reference to axes otgtasses.___T~_~_ ~urface ofthe'sQiI is covered of normal stress (strain) and shear stress (strain). (ISRM) with·. layer of partially decayed grass and Mohr envelope - the envelope of a segli~~_ce gras~:>r()ots 'which is usually' wet and soft . whe-t(itbt frozen. of Mohr circles representing stress ~~Jldi~ tions at failure for a giyen,I11aterial. (IS~M) '-'--Inylonit~~-'~~ microscopic breccia with flow Mohr envelope (rup\urti.envelope) (rIlJit"re.rt~ctur"fermed in fault zones. (ISRM) IiDe)-the envelope ~of a~etiies of¥ohrlli!tiirii\freqliency-the frequency at which a circles represent~g_ stress cQri~,itions at-,aiJ--:'-- body--;' or system vibrates when unconure_ fot a given~_,_rI\at{!_rjat:'-!A:_ccordiri~:>to strained by external forces. (ISRM) Mohr's-ruRW_re hypp:tpe,$is;,_ a';~UI1~ure e~ve;.- natural frequency (displacement resonance), In-frequency for which phase angle is 90 lope is the_:IPc':!s oteplnts thec).iB~r9in'ates of which iep~~sent--lJi_~_ combiriafions of deg between the direction of the excited force (or torque) vector and the direction normal and shearing sfr~s'S_es that win cause of the excited excursion vector. a given material to faiC-, moisture contenf(water content), w (D)-the neutral stress-see stress. ratio, expressed as a percentage, of: (1) node-point, line, or surface of standing wave the_weight of water in a given soil mass, to system at which the amplitude is zero. (2) the weight of solid particles. normal force-a force directed normal to the moisture content-the percentage by weight surface element across which it acts. of water contained in the pore space of a (ISRM) rock or soil with respect to the weight of normal stress - see stress. normally consolidated soil deposit-a soil dethe saUd material. (ISRM) moisture~densily curve-see compaction posit that has never been subjected to an curve. effective pressure greater than the existing moisture-density test-see compaction test. overburden pressure. moisture equivalent: open cut-an excavation through rock or soil centrifuge moisture equivalent, We. CME made through a hill or other topographic (D)-the water content of a soil after it has feature to facilitate the passage of a highway I railroad, or waterway along an alignbeen saturated with water and then subment that varies in topographic relief. An jected for 1 h to a force equal to 1000 times that of gravity. open cut can be comprised of single slopes
.<"
136
~m~
D 653
or multiple slopes, or multiple slopes and of rigid pavements, under the action of horizontal benches, or both. (ISRM) traffic. optimum moisture tontent (optimum water peak sheaf strength-maximum shear strength content), OMC, w, (D) - the water content along a failure surface. (ISRM) at which a soil can be compacted to a peat-a fibrous mass of organic matter in maximum dry unit weight by a given comvarious stages of decomposition, generally pactive effort. dark brown to black in color and of spongy organic clay - a clay with a high organic cooconsistency. tent. penetration-depth of hole cut in rock by a organic silt - a silt with a high organic content. drill bit. (ISRM) organic soil-soil with a high organic content. penetration resistance (standard penetration In general, organic soils are very compressresistance) (Proctor penetration resistance), PR, N (FL-2 or Blows L-l)-(a) number of ible and have poor load~sustaining proper~ ties. blows of a hammer of spe~f~ed weight oscillation-the variation, usually with time, falling a given distance reqllfie:,(t-to produce a given penetratlon:~Qt()_ S()_ilbf a pile, casing of the magnitude of a quantity with respect to a specified reference when the magnitude or sarnpling},9~e. ~~);;-o~---'---'- ----,_--'-;-:{: is alternately greater and smaller than the (b) ,-~(-t~~;14iJ~ required ~t~:::}llaintain const~R~_'l~tl:;ofpenetration into=_~q~_ of a probe reference. outcrop - the exposure of the bedrock at the or~li(~~ffi~ent. _,_;~:o:_ --'_:~;~:'~ 7-:;: surface of the ground. (ISRM).,,, (ll~\1jl1H,lg.~d;~equired to pro'~~~e a specoverbreak - the quantity of rock that is. e~~~:-:;_ ified ~-~:ffe~iJiHo-n into soil at '-';{--'specified vated or breaks out beyond the periril,~iei:_ - rate o{~)~~{)be or instrument. For a Proctor specified as the finished excavated tu~~:e-l-- ·:\,~needle,--t.ll,c.t--~pecified penetration is 2112 in" outline. (ISRM) .<" ..".,')(l':>:.~ mffiY;;\nd the rate is II, in. (12.7 overburden-the IQo~'$oil'.- san~~,:_silt, or d",Y:-__ ~m~t~-~ -;':~?i::-' that overlies bedl;"ook. In some-: usages>JF - --p'llet~~ resistance curve (Proctor pene.. refer~_to_--~ll materiaJ:'?ved~(inlr!he poin(cit(/ tration curve)-the curve showing the rela~n.t~t~~f.:~-(t~_nn~l cro)Yn»)~:~t,~,_~~J_~_J,;_;t?e t01~r tionship between: (l) the penetration re~ --'59ve-r-of soiJ.jt~~_ roc_~f;:90yerLyi-i\&;~a~:;:tHlder:':---> sistance, and (2) the water content. _~9und exca,'--aUQ_~. (IS~M) - -- percent compaction-the ratio, expressed as overbtlrden load~the loa:tJ,;~n a horizontal a percentage, of: (1) dry unit weight of a sulface underground duei~to' the column of soil, to (2) maximum unit weight obtained in a laboratory compaction test" material located vertically above it. (ISRM) overconsOlid8_ted~:soi1 deposit-a soil deposit percent consolidation -see degree of consolithat ,_ha$'<-bee-n subjected to an effective dation. pressure greater than the present overbur- percent saturation (degree of saturation), SrSr den pressure. (D) - the ratio, expressed as a percentage, of: (l) the volume of water in a given soil parent material- material from which a soil or rock mass, to (2) the total volume of has been derived. particle-size analysis -see grain-size analysis. intergranular space (voids). particle-size distrr"bution -see gradation, perched water table-a water table usually of grain-size distribution. limited area maintained above the normal passive earth pressure - see earth pressure. free water elevation by the presence of an passive state a/plastiC equilibrium -see plastic intervening relatively impervious confining equilibrium. stratum. path of percolation (line of creep)-the path perched watertable-groundwater separated that water follows along the surface of from an underlying body of groundwater by unsaturated soil or rock. Usually located contact between the foundation soil or rock at a higher eleyation than the groundwater and the base of a dam or other structure. table. (ISRM) pavement pumping-ejection of soil and water mixtures from joints, cracks, and edges percolation-the movement of gravitational
__
137
i
0653 water through soil (see seepage). pi1lars; rib pillars; sm pil1ars; chain pillilTS. percolation - movement, under hydrostatic etc. (ISRM) pressure of water through the smaller inter~ pilot drift (pioneer tunnel) - a drift or tunnel stices of rock or soil, excluding movement first excavated as a smaller section than the dimensions of tbe main tunnel. A pilot drift through large openings such as caves and solution channels. (ISRM) or tunnel is usually used to investigate rock percussion driUing-a drilling technique that conditions in advance of the main tunnel, uses solid <:>T hollow rods for cutting and to permit installation of bracing before the crushing the rock by repeated blows. principal mass of rock is removed, or to (ISRM) serve as a drainage tunnel. (ISRM) period - time interval occupied by one cycle. piping - the progressive removal of soil partipermafrost-perennially frozen soil. des from a mass by percolating water, permanent strain-the strain remaining in a leading to the development of channels. pi. - an excavation in the surface of the earth solid with respect to its initial condition after the application and removal of stress from which ore is obtained as in large open greater than the yield stress (commonly pit mining or as an excavation made for test purposes, that is, a testpit.(ISRM) also called "residual" strain). (ISRM) permeability-see coefficient of permeability. plane of weakness-surface -or -narrow zone permeability - the capacity of a rock to conwith a (shear or --terisile) strength lower than that Qf_":~,the:~-surr'ounding material. duct liquid Of gas. It is measured as the proportionality constant, k, between flow (ISRM). . ... " velocity, v, and hydraulic gradient, I; v = plan~ stri.ss--,(strain) - a state ofsiress (strain) k ./. (ISRM) in 8. solid body;n which allst~ess (strain) pH, pH (D) -an index of the acidity or al~~_corripo_n~-"ls -_noimal to a certairLplane are linity of a soil in terms of the logaritntijof zero. (ISRM) the reciprocal of the hydrogen ion couceri:" _p,an,e wave ~wave in which fronts are parallel >;'t,()__ plane-tu)(wal to direction of propagation. tration. pbase difference - difference- 'bt}.tween ph'ase plasUc defo':'ri£a~ion - see plastic Dow. p!~,~tit_:_--eq,uilibrium - state of stress within a angles of two waves 6f'same- frequency. ~ phase of periodic qoandty-fractional part of -~-son- ,or rock mass or a portion thereof, period through wliich:indepen-detlt variable-which has been deformed to such an extent bas advanced~ measured- from an arbitrary that its ultimate shearing resistance is rnaorigin. bilized. phreatic line - see line of seepage. active Slate of plastic equilibrium - plastic phreatic surface :':"'8e6, free-wafer elevation. equilibrium obtained by an expansion of a phreatic water-see free wafer. mass. piezometer-an instrument for measuring passive slate of plastic equilibrium -plaspressure_ head. tic equilibrium obtained by a compression piezometric:; line (equipotential line)-Iine ofa mass. along which water will rise to the same plastic now (plastic deformation)-the deforelevation in piezometric tubes. mation of a plastic material beyond the piezometric snrface - the surface at which wapoint of recovery; accompanied by continter will stand in a series of piezometers. uing deformation with no further increase piezometric surface-an imaginary surface in stress. that everywhere coincides with the static plasticity - the property of a soil or rock which level of the water in the aquifer. (ISRM) allows it to be deformed beyond the point of recovery without cracking or appreciable pile - relatively slender structural element volume change. which is driven, or otherwise introduced, into the soil, usually for the purpose of plasticity-property of a material to continue providing vertical or lateral support. to deform indefinitely whiJe sustaining a pDlar-in-situ rock between two or more unconstant stress. (ISRM) derground openings: crown pillars; barrier plasticity index, lp, PI, Iu' (D)-numerical
138
0653 difference between the liquid limit and the plastic limit. plastic limit, w J" PL, P w (D)-(a) the water content corresponding to an arbitrary limit between the plastic and the semisolid states of consistency of a soil. (b) water content at which a soil will just begin to crumble when rolled into a thread approximately 1/8 in. (3.2 mm) in diameter. plastic soil- a soil that exhibits plasticity. plastic state (plastic range) - the range of consistency within which a sailor rock exhibits plastic properties. pore pressure (pore waler pressure) - see neutra. stress under stress. porosity, n (D)-the ratio, usually expressed as a percentage, of: (1) the volume of voids of a given soil or rock mass, to (2) the total volume of the sailor rock mass. porosity,- the ratio of the aggregate volume of voids or interstices in a rock or soil to its total volume. (ISRM) portal- the surface entrance to a tunnel. (ISRM) potential drop, MI (L) - the difference in total head between two equipotential. lines>:' .." power spectral density-the,:limiting trie~nsquare value (for exampi~., ~f acceieratioii., velocity, displa~em,~nt, stre~';:.::or other.r~ndom vari~bl~)perunit bandwidth, ,that is the liOli~,}-Rf.~.·the -- tne~~t:s9uare;:,~.,,~lue in :;.3:;' given rectangular banCl)\'i~th divl~¢~ by tile' bandwidth~' as the bandwi~th aPBt:oaches zero. preconsolidatioir pressure - ·tprestress), PI' (FL -I!) _ the' --greatest' effective pressure to which a soil has been subjected. pressure, p (FL -2)-the load divided by the area over which it acts. pressure bulb - the zone in a loaded soil or rock mass bounded by an arbitrarily selected isobar of stress. pressure-void ratio curve (compression curve)-a curve representing the relationship between effective pressure and void ratio of a soil as obtained from a consolidation test. The curve has a characteristic shape when plotted on semilog paper with pressure on the log scale. The various parts of. the curve and extensions to the parts of the curve and extensions to 'the parts have been designated as recompression, compression, virgin compression, expan-
sion, rebound, and other descriptive names by various authorities. primary consolidation (primary compression) (primary time effect)-see consolidation. primary lining - the lining first placed inside a tunnel Of shaft, usually us'ed to support the excavation. The primary lining may be of wood or steel sets with steel or wood lagging or rock bolts and shot-crete. (ISRM) primary state of stress - the stress in a geological formation before it is disturbed by manmade works. (ISRM) principal plane-each of three mutually perpendicular planes through a point in a soil mass on which the shearing stress is.·.?;ero . intermediate principal plane-.,.th~:~pliine normal to the direction of the..'lnteril!ediate principal stress. .,. ',~. -,major princi~ahfi.l#~f;"'the plafl(:f.rio~mal to the dire.ctiQIV;9f- -the major p-rh]~pal stress. .. minor pri"~ip~J eJ~!lfHhe plane norm,l!l to .,.,tlle directiQrt.
stres§.
pr,iiicipafsitess - see-:'su~ss.
p~(.ipal 'str~~. (strQ:j_~~,\.the stress (strain) -np~~al t:?pne':pf thrt1,~,'tnutually perpendicuhlr.::planes Qll;(which the shear stresses (strains) at a~'point in a body are zero. (ISR,M) froctof' compaction curve - see compaction 'curve. Proctor penetration curve -see penetration resistance curve. Proctor penetration resistance -see pene.ra~ tion resistance. profile-see soil prome. progressive failure-failure in which the ulti~ mate shearing resistance is progressively mobilized along t~e failure 'surface. progressive failure - formation and development of localized fractures which, after additional stress increase, eventually form a continuous rupture surface and thus lead to failure after steady deterioration of the rock. (ISRM) protective filter-see filter. pumping of pavement (pumping)-see pavemenl pumping. pure shear-a state of strain resulting from that stress condition· most easily described by a Mohr circle centered at the origin. (ISRM)
139
0653 quarry-an excavation in the surface pf the earth from which stone is obtained for crushed rock or building stone. (ISRM) Quer-wave (love), W - dispersive surface wave with one horizontal component, generally normal to the direction of propaga-
remolded soil-soil that has had its natural structure modified by manipulation. remolding index, I. (D)-the ratio of: (I) the modulus of deformation of a soil in the undisturbed state, to (2) the modulus of deformation of the soil in the remolded
tion, which decreases in propagation velocity with increase in frequency.
quick condition (quicksand)-condition in which water is flowing upwards with sufficient velocity to reduce significantly the bearing capacity of the soil through a decrease in intergranuJar pressure. quick test- see unconsolidated undrained test. radius or influence of a well- distance from the center of the well to the closest point at which the piezometric surface is not lowered when pumping has produced the maxirnum steady rate of flow. raise - upwardly constructed shaft; that is, an opening, like a shaft, made in the roof of one level to reach a level above. (ISRM) range (of a deformation-measuring instrn.. ment)-the amount between the maximum and minimum quantity an instruT?_ept,,-~~an measure without resetting. In sci~,~;~-Jnstances provision can be made fo(.-inere--_ mental extension of th~_,range. -:_:,_::-,;~.- - -, Rayleigh wave, JIll _(LT"-:1)--dispersive -~_~,rface wave in which _elemenf-ha~- retrogia(jing elliptic orbit with one major verticaI/illii;l one ~_ minor hor~zonta] cOIn_ponent both In plane_--ofp[opag8;~ion-v~loRity: >, Vn
=
(IV,
wiOi 0:91O'-<,,'a;-< 0.995J~l5~~ II < 0.5
reDected (or ~fractedr-""a-ve-components of wave incident upon second medium and reflected into first medium (or refracted) into second medium. reflection and refraction loss-that part of transmitted energy lost due to nonuniformity of mediums. relative consistency, I" C, (D)-ratio of: (I) the liquid limit minus the natural water content, to (2) the plasticity index. relative density, Dd • In (D)-the ratio of: (1) the difference between the void ratio of a cohesion less soil in the loosest state and any given void ratio, to (2) the difference between the void ratios in the loosest and in the densest states. relative water content-see liquidity index.
state. remolding sensitivity (sensitivity ratio), Sf (D)-the ratio of: (1) the unconfined compressive strength of an undisturbed specimen of soil, to (2) the unconfined compressive strength of a specimen of the same soil after remolding at unaltered water content. residual soil- soil derived in place by weathering of the underlying material. residual strain - the strain in a solid associated with a state of residual stress. (ISRM) residual stress-stress ren:ll,i~jng in a solid under zero external stress::itfier some process that causes~J~l/" dhi'le_,nsions of the various part;s;~:~f the-soli~_:_to_ be incompatible und.er~~~o-stress, for ~l<.tnple. (I) defor-rnatloif under the action_ of'external stress \V_h~'n so~~ p~rts of the bodf~uffer perm an~iH:- ~tf~_i~~ror (2) heating {)r",'~ooling of a bo~ijp---Which the thermal expansion coef_ 'fici~i!l'is not uniform throughout the body. ___ -_-(ISR:f¥il.' - --re_~-~"lutio~;_---"(/of a deformationMmeaslIring iOM :~tn.J:I1ent;r2.the ratio of the smallest divisit)9id increment of the indicating scale to the sensitivity of the instrument. Interpolation within the increment may be possible, but is not recommended in specifying resolution. resonance - the reinforced vibration of a body exposed to the vibration, at about the frequency, of another body. resonant frequency-a frequency at which resonance exists. response-the motion (or other output) in a device or system resu1ting from an excitation (stimulus) under specified conditions. retardation-delay in deformation. (ISRM) rise time (pulse rise time) - the interval of time required for the leading edge of a pulse to rise from some specified small fraction to some specified larger fraction of the maximum value. rock-natural solid mineral matter occurring in large masses or fragments. rock - any naturally formed aggregate of mineral matter occurring in large masses or
_
140
0653 fragments. (ISRM) sand-particles of rock that will pass the No. rock anchor- a steel rod or cable installed in 4 (4.75-mm) sieve and be retained on the a hole in rock; in principle the same as No. 200 (75-l'm) U. S. standard sieve. rock bolt, but generally used for rods longer sand boil-the ejection of sand and water than about four metres. (ISRM) resulting from piping. rock bolt - a steel rod placed in a hole drilled saturated unit weight-see unit weight. in rock used to tie the rock together. One saturation curve - see zero air voids curve. end of the rod is firmly anchored in the scattering loss- that part of transmitted enhole by means of a mechanical device or ergy lost due to roughness of reflecting grout, or both, and the threaded projecting surface. end is equipped with a nut and plate that schistosity - the variety of foliation that occurs bears against the rock surface. The rod can in the coarser-grained metamoJphic rocks be pretensioned. (ISRM) and is generally the result of the parallel rock burst - a sudden and violent expulsion arrangement of platy and ellipsoidal minerai grains within the rock substance. of rock from its surroundings that occurs when a volume of rock is strained beyond (ISRM) the elastic limit and the accompanying fail- secant modulus-slope of the line_connecting the origin and a giyen point on- the stressure is of such a nature that accumulated energy is released instantaneously. strain curve. (ISR.M). rock burst - sudden explosive-like release of secondary ci!~sohllatlon (secondary compressi~n) (seco'ndary time efleet) - see consolienergy due to the failure of a brittle rock dation. of high strength. (ISRM) :_s_econdaty- lining-the second-placed, or perrock flour - see silt. marieh.t,--~tructifral..lining of a tunnel, which rock mass - rock as it occurs -in situ, induding may: -:be/ o{ cori'crete, steel, or masonry. its structural discontinuities. (ISRM) (ISRM) rock mechanics - the _application C!f the knowled-ge of the mechanical behavior of s_econdary state of stress - the resulting state of stress in the rock around man-made rock_ to engineering problern.s -dealing wit~ excavations or structures. (ISRM) rock. Rock mechanic_s overlaps with strfle;.. seepage - the infiltration or percolation of watural. geology, geophysics, and s?il mechan.ter through rock or soil to or from the ics. surface. The term seepage is usually rerock mechanics - theoretical and applied scistricted to the very slow movement of ence of the mechanical behaviour of rock. ground water. (ISRM) (ISRM) roof - top of. excavation or underground seepage (percolation) - the slow movement of gravitational water through the soil or rock. opening, particularly applicable in bedded rocks where the lOp surface of the opening seepage force - the frictional drag of water flowing through voids or interstices in rock, is flat rather than arched. (ISRM) causing an increase in the intergranular round - a set of holes drilled and charged in a pressure, that is, the hydraulic force per tunnel or quarry that are fired instantaunit volume of rock or soil which results neously or with short-delay detonators. from the flow of water and which acts in (ISRM) the direction of flow. (ISRM) rupture - that stage in the development of a fracture where instability occurs. It is not seepage force, J (F) - the force transmitted to the soil or rock grains by seepage. recommended that the term rupture be used in rock mechanics as a synonym for seepage line - see line of seepage. seepage velocity, Va, VI (LT-l)-the rate of fracture. (ISRM) discharge of seepage water through a po-rupture envelope. (rupture line)-see Mohr rous medium per unit area of void space envelope. perpendicular to the direction of flow. sagging - usually occurs in sedimentary rock seismic support-mass (heavy) supported on formmions as a separation and downward springs (weak) so that mass remains almost bending of sedimentary beds in the roof of at rest when free end of springs is subjected an undergruund opening. (ISRM) >
141
D 653
to 5inusoidal motion at operating frequency. seismic ,-elocity - the velocity of seismic waves in ge . .,logical formations. (lSRM) seismometer-instrument to pick up linear tvertical, horizontal) or rotational displacement, velocity, or acceleration. sensithity-the effect of remolding on the consistency of a cohesive soil. sensith-it,' (of an instrument) - the differential quotient dQo/dQI' where Qo is the scale reading and QI is the quantity to be measured. sensilhit)' (of a transducer)-the differential qu . ,tient . dQo/dQI' where Qo. is the output and Ql is the input. shaft - generally a vertical or near vertical excavation driven downward from the surface as access to tunnels, chambers, or other underground workings. (ISRM) shaldng test - a test used to indicate the presence of significant amounts of rock flour, silt. or very fine sand in a fine-grained soil. It c. ,nsists . of shaking a pat of we!.~_-_soil, ha\ ing a consistency of thick past.~:;iJh;Jhe palm of the hand; observing the stiffa~e J?! a gl . .,SSY or livery appea~ance; then-__sq~ee~",;·· ing the pat; and oq~_er:vin_g_ jf a rapid}lppar>< ent drying and subsequent cracking at the soil occurs. ---, sheadaiIure (foilure by ".plilre) - failUrelri ~'h_i~h _ lD_?vem~li! _;_,~\ls-~d__ -_by she_a,~ng stresSes_ hi~l SOif-oT_ t~_ck mas~_is_{l~.~uffici~'nt magnitude :t~_~destfoy -:Qr serioUsl~';-efidanger a structure ~ gmeral shear failure_---failure in which the ultimate strength of the soil or rock is mc,-t'lilized along the entire potential surface of s.liding before the structure supported by the soil or rock is impaired by excessive mcwement. ;llcal shear failure-failure in which the ul:imate shearing strength of the soil or rClo:k. is mobilized only locally along the JX"':ential surface of sliding at the time the structure supported by the soil or rock is irr.paired by excessive movement. shear forte - a force directed parallel to the seriace element across which it acts. (ISRM) shur plane - a plane along which failure of rr:.lterial occurs by shearing. (ISRM) she.;" resistance - see internal friction.
shear strain-the change in shape, expressed by the relative change of the right angles at the corner of what was in the undeformed state an infinitesimally small rectangle or cube. (ISRM) shear strength, s, T, (FL-2) - the maximum resistance of a sailor rock to shearing stresses. See peak shear strength. shear stress-stress directed parallel to the surface element across which it acts. (ISRM) shear stress (shearing stress) (tangential stress) - see stress.' shear wave (rotational, equivoluminal)wave in which medium changes shape without change of volume (shear-plane wave in isotropic medium is traIlsxer,se wave). shrinkage index, SI (D)Athe"numerical difference between:--_th'e _'plastic and shrinkage limits. _____ ' shrink,~gt"mil, SL. w,(D).-the maximum X~I_~,tt:;:r;:-content at which a-t_eduction in water ~qnYent wi!trot cause a decrease in volume 'oHhe soil;mass. shriill;llilefllti';, R (D)-the ratio of: (I) a , giv~I:f--v~lume change. expressed as a perceofage', of the dry volume. to (2) the corresp~_hp.ing change in water content A-bove -the': shrinkage limit. expressed as a ::~~reenhlge of the weight of the oven-dried
s6iL shock pulse - a substantial disturbance characterized by a rise of acceleration from a constant value and decay of acceleration to the constant value in a short period of time. shock wave - a wave of finite amplitude characterized by a shock front. a surface across which pressure. density. and internal energy rise almost discontinuously, and which travels with a speed greater than the normal speed of sound. (ISRM) shotcrete - mortar or concrete conveyed through a hose and pneumatically projected at high velocity onto a surface. Can be applied by a "wet" or "dry" mix method. (ISRM) silt (inorganic silt) (rock Dour) - material passing the No. 200 (75-/Lm) U.S. standard sieve that is nooplastic or very slightly plastic and that exhibits little or no strength when air-dried. silt size - that portion of the soil finer than
142
~~I~
D 653
0.02 mm and coarser than 0.002 mm (0.05 to engineering problems dealing with soil as an engineering material. mm and 0.005 mm in some cases). simple shear-shear strain in which displace- soil physits-the organized body of knowlments all lie in one direction and are proedge concerned with the physical characterportional to the normal distances of the isties of soil and with the methods employed displaced points from a given reference in their determinations. plane. The dilatation is zero. (ISRM) soil profile (profile) -vertical section of a soil. single-grained structure - see soil structure. showing the nature and sequence of the size effect- influence of specimen size on its various layers, as developed by deposition strength or other mechanical parameters. or weathering, or both. (ISRM) soil stabilization - chemical or mechanical treatment designed to increase or maintain skin friction, f (FL-2)-the frictional resistance developed between soil and an elethe stability of a mass of soil or otherwise to improve its engineering proper_ties. ment of structure. slabbing - the loosening and breaking away soil structure - the arrangemenfa~a state of of relatively large flat pieces of rock from aggregation of soil pa~ti_~J¢riil' a soil mass. the excavated surface, either immediately flocculent structiife',;·;;,'-an arrangement composed,_g:f.'~ti~ of soil partiCles instead after or some time after excavation. Often _-_>,-'_ occurring as tensile breaks which can be of in~~i~j(J_~~rsdi'j particles. , recognized by the subconchoidal surfaces hortf!xc,omb stru,c;.ture -an arraifg~ment of left on remaining rock surface. (ISRM) soil pat!i~)eshl\~iljl! a comparati.vely.loose, slaking - the process of breaking up or slouglJ~->; stable -slrl;i~t:~~-- t'esembling a ho-neYcomb. ing when an indurated soil is immersed}tI_- ~ single~gi'aine'd structure - an arrangement _ a¢t~_~i,~,tic stru~_t!lre of coarse-grained soils. along a surface. witboi!f~-loss--'of contaCt~:'- soir-S_U$pe~sion-i'"ighly diffused mixture of between the bodies. (ISRM) . soil"aridwllter.' slope-the excavated rock surface_ that is in,.-_ ,soil'-rextuie-':-':'see gradation. elined to the! _verticaLpr_ h.orizQntal. or both-, _;-- spacing - the distance between adjacent blasta. il1.an·oPen·e!)t. (ISllMt I, holes in a direction parallel to the face. slowlest - see c.....S11lldated'lirainedi.st.·;, (ISRM) smooth.(.wall) blasling;-a Il)~*odofaecurate .pamng-(l) longitudinal splitting in uniaxial perimeter blastinlnhat leavest.ge remaining compression, or (2) breaking-off of platerock-----.. practically _-_undamaged. Narrowly like pieces from a free rock surface. (ISRM) spacedandUglttly charged blastholes, specific gravity: sometfme-s_Allteinating with empty dummy specific gravity a/solids, G, G'J S8 (D)holes, IQcated -along the breakline and fired ratio of: (l) the weight in air of a given volume of solids at a stated temperature to simultaneously as the last round of the excavation. (ISRM) (2) the weight in air. of an equal volume of soil (earth)-sediments or other unconsolidistilled water at a stated temperature. apparent specific gravity, G a, Sa (D)dated accumulations of solid particles produced by the physical and chemical disinteratio of: (l) the weight in air of a given volume of the impermeable portion of a gration of rocks, and which mayor may not contain organic matter. permeable material (that is, the solid matter soil binder-see binder. including its impermeable pores or voids) at a stated temperature to (2) the weight in soil-forming factors-factors, such as parent material, climate, vegetation, topography, air of an equal volume of distilled water at a stated temperature. organisms, and time involved in the transformation of an original geologic deposit bulk specific gravity (specific mass gravinto a soil profile. ity), G m, Sm (D)-ratio of: (I) the weight soil horizon - see horizon. in air of a given volume of a permeable soil mechanics - the application of the laws material (including both permeable and impermeable voids normal t~ the material) at and principles of mechanics and hydraulics
143
4~1~ a stated temperature to (2) the weight in air of an equal volume" of distilled water at a stated temperature. specific surface (L -I)-the surface area per unit of volume of soil partic1es. spherical wave - wave in which wave fronts are concentric spheres. spring characteristics, c (FL -1) - ratio of increase in load to increase in deflection: c ~ lie where: C = compliance. stability - the condition of a structure or a mass of material when it is able to support the applied stress for a long time without suffering any significant deformation or m,ovement that is not reversed by the release of stress. (ISRM) stability factor (stability number), N, (D) - a pure number used in the analysis of the stability of a soil embankment, defined by the following equation: N, = HcY,,/c
D 653
masses, a period of no relative displacement between the two masses, a sudden slip, etc. The oscillations may be regular as in a direct shear test, or irregular as in a triaxial test. sticky limit, Til' (D)-the lowest water content at which a soil will stick to a metal blade drawn across the surface of the soil mass. stiffness-the ratio of change of force (or torque) to the corresponding change in translational (or rotational) deflection of an elastic element. stiffness-force - displacement ratio. (ISRM) stone - crushed or naturally angular particles of rock that wil1 pass a 3-in. (75-mm) sieve and be retained on a No.4 (4.75-mm) U. S. standard sieve. ,train, < (D)-the changein,.IW'glh per unit of length in a given directi6jf~~~":' ,train (linear or norDlal),i (D)-the change in length pe~ unif-"of,"Jcngth in a given
directi,H9;-'~(:> :::,~
",-i,:-;,";;;"
strai:~",:~Uipj;oid-the repre~~~ation of the st!,a-i~}n the",~gt;m of an ellipS,()id into which
where: a -spb:~{~"o,9,r,tffl!l.xadius defor!Jl~,-,'a,nd whose He critical height of the sloped ba'l_~~-:-~~, axe-s~~1§tF-,,;:;,the( pri .... cipal axes'_--of strain. y, effective unit of weight of th~t~"oi1F (JSR"NI~E: and -~, '~~"~:-~.~ain (si~_s,) rate - rate of change of strain c cohesion of thesoil,·.I;'{§tress)~~ilj.time. (ISRM) NOTE- Taylor's '~st~bm~»i;j~ber" is thtii~,~ strall('J:'fSOr~l~on (strain sensitivity) R,1 (D)ciprocal of Terzaghi's'''stability"factbr.'' - -thih-smalle'st subdivision of the indicating stabilizatien_,-see ~~~~:_,~~ab~~~,~b": scaJe" of a deformation-measuring device standard t(J'?'f~flion:"s~,~ijll'1!ttion test,'{: divided by the product of the sensitivity of :s!a6dard pen,~~t~t,~9n r~~JSipitce-4,s~_~~~I~_~eir8the device and the gage length. The defor,Uon resistant"t_,,; - ,~,~:",,;, ',_ -- --: --mation resolution. Rd. divided by the gage Standing wave"~/~:,J~ave Pt~-~lJced by simultalength. neo~s trans"1issJon in 'opposite directions strain (stress) tensor - the second order tensor of -tw.o simi~ar' _Waves resulting in fixed whose diagonal elements consist of the norpolrits'of zeto,'iltnplitudes called nodes. mal strain (stress) components with respect steady~.;.state Ylb'ration _ vibration in a system to a given set. of coordinate axes and whose where: the velocity of each particle is a off-diagonal elements consist of the correcontinuing periodic quantity. sponding shear strain (stress) components. stemming-(1) the material (chippings, or (ISRM) sand and clay) used to fill a blasthole after streamline flow -see laminar flow. the explosive charge has been inserted. Its strength - maximum stress which a material can resist without failing for any given type purpose is to prevent the rapid escape of of loading. (ISRM) the explosion gases. (2) Ihe act of pushing and tamping the material in the hole. stress,u.p, f(FL-2)-the force per unit area (ISRM) acting within the soil mass. effective stress (effective pressure) (interstick-slip - rapid fluctuations in shear force as one rock mass slides past another, characgranular pressure), cT. f (FL-2)-the average normal force per unit area transmitted terized by a sudden slip between the rock
144
D 653
from grain to grain of a soil mass. It is the stress that is effective in mobilizing internal friction. neutral stress (pore pressure) (pore water pressure). u, Uw (FL -2)-stress transmitted through the pore water (water -filting the voids of the soil). normal stress, U', p (FL-2)-the stress component normal to a given plane. principal stress, 0" 1> 0"2, 0" 3 (FL -2)_ stresses acting normal to three mutually perpendicular planes intersecting at a point in a body, on which the shearing stress is zero. major principal stress, 0" I (FL-2) - the largest (with regard to sign) principal stress. minor principal stress, O"a (FL- 2 )-the smallest (with regard to sign) principal stress. intermediate principal stress, 0"2 (FL-2) - the principal stress whose value is neither the largest nor the smallest (with regard to sign) of the three. . shear stress (shearing stress) (tangentialstress), T, s (FL -2) - the stre-s-s-componerit tangential to a given plari-e.
IOtal stress, Cf, f(FL-')-thetol111 force per unit area acting within ama$s'of soil. It is the sum of the neutral and effective st.resses. ____ _,____ __,--_~ stresS --~ellipsoid - the tepnise-ritation of- -the state of stress in the:_ form of _,an ellipsoid whose_ semi-axes are: proportional to the magnitudes of the principal stresses and lie in the principal directions. The coordinates of a point P on this ellipse are proportional to the magnitudes of the respective components of the stress across the plane normal to the direction 0 p, where 0 is the center of the ellipsoid. (ISRM) stress (strain) field - the ensemble of stress (strain) states defined at all points of an elastic solid. (ISRM) stress relaxation - stress release due to creep. (ISRM) strike - the direction or azimuth of a horizon~ tal line in the plane of an inclined stratum, joint. fault. cleavage plane. or other planar feature within a rock mass. (ISRM) structure - one of the larger features of a rock mass, like bedding, foliation. jointing. cleavage. or brecciation; also the sum total
of such features as contrasted with texture. Also, in a broader sense, it refers to the structural features of an area such as anticlines or synclines. (ISRM) structure - see son structure. subbase - a layer used in a pavement system between the subgrade and base coarse, or between the subgrade and portland cement concrete pavement. subgrade - the soil prepared and compacted to support a structure or a pavement system. subgrade surface - the surface of the earth or rock prepared to s,:!pport a struc~ure or a " pavement system. submerged unit weight - see unit weig'ht. subsidence-the downward- displacement of the overburden;~t
145
0653 between rings, is subjected to an axial load theoretical time curve - see consolidation time and to shear in torsion. In-place torsion curve. shea,r tests may be pcrfonned by pressing a 'hermal spaDing - the breaking of rock under dentated solid circular or annular plate stresses induced by extremely high temperagainst the soil and measuring its resistance ature gradients. H.igh-velocity jet flames . to rotation under a given axial load . are used for drilling blast holes _with this . total stress - see' stress. . effect. (ISRM) toughness index, /1'. Tw :""-th-e ratio of: (l) the thermo-osmos~s--:-the process by _which water. plasticity index, to(2) the flow index. is caused to flow in small openings of a soil mass due to differences in teI.T1perature traction, SI> 52. S3 (FL-2)-applied stress. transronned flow net - a flow net whose within the mass. boundaries have been properly modified thickness-the perpendicular distance be(transformed) so that a net consisting of tween bounding surfaces such as bedding curvilinear squares can' be constructed'to or foliation planes of a rock. (ISRM) represent flow conditions in an anisotropic thixotropy - the property of a material that porous medium. enables it to stiffen in a_ relatively short time on standing, but upon agitation or transported soil- soil transport~d from the place of its origin by whid, water'~:or ice. manipulation to change to a. very soft consistency or to a fluid of high viscosity, the transverse wave, V, (LT-J).,:.;...wave in which direction of _di~pl~ce~ent .of element of process being completely reversible. medium i~_ pa~~lrel to wave front. The prop. throw - the projection of broken rock during agation vel~~ity. VI' is calculated as follows: blasting. (ISRM) thrust - force appJie<;l to a drill in the direction v, ~VG/p ~.ViiJi;~ V(E/p)[i/2(l +v)) of penetration. (ISRM) tight - rock remaining within the minim~m. of a bl.ast,.; where: excavation lines after completion ing record. (ISRM) G ,- shear modulus, till- see glacial till. p mas_s:"density. time curve -see consolidation time (urve. v:;:;: Poisson-'-s ratio, and time factor, Ttl, T (D)_-dimensionless factoT_; , g-: :; -Young"1:s modulus. utilized in the theory qf consolid_8tion, COO_R :--fransverse'. wave (shear wave)-a wave in taining the physical con~tants, of a: soil strawhich the displacement at each point of the medium is parallel to the wave front. turn influencing its time~ra~e of ,_~onso)jda~ lion. expressed as follows;. . (ISRM) trench - usually 'a long. narrow, neaf vertical T = k(J + e)tl(tit;yw H2)-=:_(CI , ·t)fHZ sided cut in rock or soil such as is made for where; utility lines. (ISRM) k coefficient of permeability (LT-I). triaxial compression-compression caused by e :::e void ratio (dimensionless). the application of normal stresses in three t elapsed time that the stratum' has perpendicular directions. (ISRM) been consolidated (1"). triaxial shear test (triaxial compression test)ai' coeffici~nt of compressibility (L2 F-I). a test in which a cylindrical specimen of 'Yw unit weight of water (FL -3). soil or rock encased in art impervious memH t~ickness of stratum drained on one brane is subjected to a confining pressure side only. If stratum is drained on and then loaded axially to failure. both sides, its thickness equals 2H triaxial state of stress-state of stress in which (L). none of the three principal stresses is zero. c,. = coefficient of consolidation (L'T-') (ISRM) topsoil-surface soil. usually cont~ining or- tunnel-a man-made underground passage ganic matter. constructed without removing the overlying rock or soil. Generally nearly horizontal as torsional shear test - a shear test in which a opposed to a shaft, which is nearly vertical. relatively thin test specimen of solid circular or annular cross-s~ction. usually confined (ISRM)
146
0653
turbulent flow - that type of flow in which of soil or rock mass; the saturated unit any water particle may move in any direcweight minus the unit weight of water. tion with respect to any other particle. and unit weight of water, 'Yw (FV')-the in which the head loss is approximately weight per unit volume of water; nominally proportional to the second power of the equal to 62.4 Ib/ft' or I glcm'. velocity. wet unit weight (mass unit weight), 1m. ultimate bearing capacity, qe, quit (FL -2) - the 'Yw.. (FL-3)-the weight (solids plus water) per unit of total volume of soil or rock average load per unit of area required to produce failure by rupture of a supporting mass. irrespective of the degree of saturation. soil or rock mass. unconfined compress~'ve strength - see ~om.. zero air voids unit weight, Yz, Y, (FL -3)_ pressive strength. the weight of solids per unit volume of a saturated soil or rock mass. unconsolidated-undrained test (quick test)-a _ __, soil test in which the water content of the unloading modulus - slope of thej'all'g"nt to test specimen remains practically unthe unloading stress-strai_n-'curve at a given stress value. (ISRl\!I,1 .' changed during the application of the ('on-' fining pressure and the additionaJ axial (or uplift-the upward:-~"-ter pressure:on-a struc, ture. - -- -,~' sh€aring) force. underconsolidated soil deposit- a deposit that Unit Symbol FL.:.t , unit sym!lriI. ~;,:. u is not fuUy consolidated under the existing total synibOl U For Fl>-J'.' overburden pressure. undisturbed sample - a soil sample that has' uplitl-.the hydrostatic force of water exerted been obtained by methods in which every or(-:()r--underne_~,U) a structure. tending to cause a dispblc~~ment of the structure. precaution has been taken,t.~:~-tfiiiiimjze disturbance to the sample.- __ >:-:-<-~ - -:- _»_::,_ ·.Z.(ISRM) ...",,'" uniaxial (unconfined) - -\.~l-im in-place shear test in -\vblch a rdd with thin radial vanes at the pression c~psed_l>y the:3.»pHcation;o_t-nor:-e1;1d is forced into the soil and the resistance mal stress ill a siogle direc!ion.
y.,.
147
D 653
which·a propagated disturbance first occurs. pied by solid mineral matter. This space wave front - (J) a continuous surface over may be occupied by air. water. or other gaseous or liquid material. . which the phase of a wave that progresses in three dimensions is constant, or (2) a void ratio, e (D)- the ratio of: (J) the volume continuous line along which the phase of a of void space, to (2) the volume of solid surface wave-is constant. (ISRM) particles in a given soH mass. wave length - normal distance between two critical void ratio, ec: (D)-the void ratio wave fronts with periodic characteristics in corresponding to the critical density. which amplitudes have phase difference of volumetric shrinkage (volumetric change), V~ one complete cycle. (D)-the decrease in volume. expressed as weathering - the process of disintegration and a percentage of the soil mass when dried. decomposition as a consequence of expoof a soil mass when the water content is sure to the atmosphere, to chemical action. reduced from a given percentage to the and to the action of frost, water, and heat. shrinkage limit. (ISRM) .., wall friction, f' (FL -2) - frictional resistance mobilized between a wall and the soil or wet unit weight- see unit welght. yielding arch-type ohupport of arch shape, rock in contact with the wal1. the jdints 01 which deform plastically bewater contenl - see moisture content. yond a:,.:ertain criticalload'-.Jhat is. continue water·holding capacity (D) - the smallest to~"def'O.rrri without increasing, their resistvalue to which the water content of a soil alIce. (ISRM) . or rock can be reduced by gravity drainage. water-plasticity ratio (relative water content) yield.$tr~§s "..thelltress beyondwftich the induced.:' deformation is not fu-Uy annulled (liquidity index) - see liquidity index. . after complete destressing. (ISRM) water table - see free water elevation. wnvc-- disturbance propagated in medium",iri . ~ro air voids curve (saturation curve) - the curye showi~g the zero air voids unit weight such a manner that at, any'po.int in med~tim as 0funcfiorl of water content. the amplitude is a furiction',of-- time, while at any instant the 'displacement at point 'is ~.eih ;tiip voids density (zero air voids unit weight) - see unit weight. function of position of point .. wave froilt'...... moving' surlace',in a medium,',at.
a
APPENDIX Xl. ISRM SYMBOLS RELATING TO SOIL AND ROCK MECHANICS
NOTB- These symbols may not correlate with the symbols appearing in the text. X1.1 Space fl,,., I b h r
A V
,.,v g
X1.3 Statics and Dynamics
solid angle length width hei~ht or depth radIUS area volume time velocity angular velocity gravitational acceleration
m p
Gm G, G. F
T W y Yd
~r
XI.2 Periodic And Related Phenomena T
f,., A
y, T I W W
periodic time frequency angular frequency wave length
148
mass density (mass density) mass specific gravity specific gravity of solids specific gravity of water force tangential force weight unit weight dry unit weight unit weight of water buoyant unit weight unit of solids torque moment of inertia work energy
D 653 X1.4 Applied Mechanics void ratio e porosity n water content w degree of saturation S, pressure p pore water pressure u normal stress stress components in rectangular c(}ordinates principal stresses 0",. 0"2. O"a applied stresses (and reactions) 5,.5 2,5 3 horizontal stress
= ulE
c
j k ~
~" tret t rel
T, q
Q
FS T {3
temRCrature _£~!ficlent of volume expartsion
XI.6 Electridty"
cohesion
.,'
!_ _
-eie§tfi~;:chirent
L-':
self·.:iy:d~ctance
~ f{
= TI'Y
an$le of friction between solid bod,es angle of shear resistance (angle of internal friction) hydraulic head hydraulic gradient seepage force per unit volume or seepage pressure per unit length c?effi~ient of permeability VISCOSity plasticity (viscosity of Bingham body) retardation time relaxation time surface tension quantity rate. of flow; rate of discharge quantity of flow safety factor
XI.S Heat
'-:a(; ,
principal strains shear modulus; modulus of rigidity G
p
et~_t,!Wdiarge cap'a~tl!nce rcsisl~!tce,_
:~~'_resistiv~w(·
RJ,lFERENCES (1) Terzaghi~ _-TheQretic_ot.. Soil ~~chari;is, .JQhn Wiley&Sons, Inc,. New Yor~,N, Y. (1943). ,. (2) Terzaghi and Peck, -Soil Mechanics in Engi"'_-.;:. neefitlg.::~Praclice, Jobn_:~WileY--:.i~~i:So"ns, Inc .• Newy"rk, N. Y. (1948).. (3) Taylot_i':_l);,-_W., Fundat?'!_e~uals of SpirMechan~ ics, John-Vliley & Sgns,-Jnc., New York, N. Y. (1948). ,', ," (4) Krynine, D. P._. SOi(Mechanics. 2nd Edition, McGraw-HilL Book Co., Inc., New York, N. Y. (1947). (5) Plummer and Dore, Soil Mechanics and Foundations, Pitman Publishing Corp., New York, N. Y. (1940). (6) Tolman, C. F., Ground Water, McGraw-Hill Book Co., Inc., New York, N. Y. (1937). (7) Stewart Sharpe, C. F., Land Slides and Related Phenomena, Columbia University Press, New York, N. Y. (1938). (8) "Letter Symbols and Glossary for Hr.draulics with Special Reference to Irngation, ' Special Committee on Irrigation Hydraulics, Manual of Engineering Practice, Am. Soc. Civil Engrs., No. 11 (1935). (9) "Soil Mechanics Nomenclature," Committee of the Soil Mechanics and Foundations Division on Glossary of Terms and Definitions and on Soil Classification, Manual of Ellgi~ lIeering Practice, Am. Soc. Civil Engrs., No. 22 (1941). (10) "Pile Foundations and Pile Structures," Joint Committee on Bearing Value of Pile Foundations of the Waterways Division, Construction
149
- Division, and Soil Mechanics and Foundations Division, Manual of Engineering Practice, Am. Soc. Civil Engrs., No. 27 (1956). (11) Webster's New International Dictionary of the English Language, unabridged, 2nd Edition, G. and C. Merriam Co., Springfield, Mass. (1941). (12) Baver, L. D., Soil Physics, John Wiley & Sons, Inc., New York, N. Y. (1940). (13) Longwell, Knopf and FJint, "Physical Geology," Textbook o/Geology, Part I, 2nd Edition, John WiJey & Sons, Inc., New York, N. Y. (1939). (14) Runner, D. G., Geology'for Civil Engineers, Gillette Publishing Co., Chicago, Ill. (1939). (15) Leggett, R. F., Geology and Engineering, McGraw-Hili Book Co., Inc., New York, N. Y. (1939). (16) Holmes. A., The NomellclaiUre of Petrology, Thomas Murby and Co., London, England (1920). (17) Meinzer, O. E., "Outline of Ground Water Hydrology with Definitions," U. S. Geologi~ cal Survey Water Supply Paper 494 (1923). (18) "Reports of the Committee on Sedimentation of the Division of Geology and Geography of the National Research Council," Washington, D. C. (1930-1938). . (19) Twenhofel, W. H., A Treatise on Sedimenla~ tion, 2nd Edition, Williams & Wilkins Co., Baltimore, Md. (1932). (20) Hogentogler, C. A., Engineering Properties of Soils, McGraw-Hili Book Co., Inc., New
~B1~
0 653
York, N. Y. (937). Harper and Bros" New York, N. Y. (1951). (21) "Procedures (aTTesting Soi1s," Nomenclature (35) Ries and Watson, Engineering Geology, John and Definitions, Standard Methods, SugWiley & Sons,lnc., New York. N. y, (1936). gested Methods, Am. Soc, Testing Mats., (36) Ross and Hendricks, Minerals of the MontPhiladelphia, Pa., September 1944. morillonite Group, U. S, Geological Survey (22) "Glossary of Terms and Definitions," PrelimProfessional Paper 205~B (1945). inary Report of Subcommittee G-3 on No(37) Hartman, R. J., Colloid Chemistry, Houghton menclature and Definitions of ASTM ComMifflin Co" New York, N. Y. (1947). mittee 0-18 on Soils for Engineering PUT(38) "Frost Investigations," Corps of Engineers, poses. Frost Effects Laboratory. Boston, Mass" (23) Sowers and Sowers, Introductory Soil MeJune 1951, chanics and Foundations, The Macmillan Co., (39) "Standard Specifications for Highway Mate~ New York, N. Y. (1951). rials and Methods of Sampling and Testing," (24) Lambe, T. William, Soil Testing for EngiParts I and n. adopted by the American neers, John Wiley & Sons, Inc., New York, Association of State Highway Officials N. Y. (1951). (1950). (40) Coates, D. G., "Rock Mechanics Principles," (25) Capper and Cassie, The Mechanics of Engineering Soils, McGraw-Hill Book Co., Inc., rev ed. Mines Br., Dept. Mines and Tech. New York, N. Y. (1949). Surv., Br. Mon. 874 (1970). (26) Dunham, C. W" Foundations of Structures, (41) Gary, Jr,. and Wolf, C. L., (eds.), American Ge(}McGraw-Hili Book Co., Inc., New York, N. Y. (1950). logical (27) Casagrande, A' I "Notes on Soil Mechanics," (42) Graduate School of Engineering, Harvard University (1938). (28) Tschebotarioff, G. P., Soil Mechanics, Foundations, and Earth Structures, McGraw-Hi1I (43) Book Co., Inc., New York, N. Y. (1951). (29) Rice, C. M., "Dictionary of Geological Terms," Edwarm. Bros., Inc., Ann Arbor, (44) . of Mich. (1940). (30) Creager, Justin and Hinds, Engineering for Dams, John Wiley & Sons, Inc., New York, N. Y. (1945)'.«~i (31) Krumbein and Sloss, Stratigraphy and ~~~(~\;~~ >(45) mentation, W. H. Freeman and Co., ::$.~J'f:~::Francisco, Calif. (1951). .,.;.-,:;,:;:,. ~;~F',:A John (32) Pettijohn, F. J., Sedi.'l'Ie~JP'!.t;JJ,ocks. Har,~:r; '-'(46fJjME (33)
~e~c~~~sP~~~~4~~~~~~\JJ~!~#::~ing prd4~\ ::-;}~]~~~.Wj.Jf. Produc.!s)~y'niversity (j.n~ew ;,(1lt::¥litu~~.
esses and MexIC9.:;: al., A DzctJonary of Press, .!\lbuquerqU~'f~' Mex ..q9;45), ~~!';-n:. ,:-.>-.. - Min1ifg, Mineral and Related Terms, U, S. (34) qa~.eJs~.:·.~,. M., --~-\fextp~o~~.~.'-'.t'!f Geolog'f{;~- -' Bureau of Mines (1968).
150
ng"
/
8648
RULES AND REGULATIONS
tlrow"'.d with the same protection r~(lulred for steam lines. Safety chains, or shall be provided for c~lt~~~~n, to prevent the
t.
around in case the
CO'JP~fng
line controls shall COIi/stst valves, one of lever
Marine operations and equip-
M"t,,-ial handling operations.
fitting the definition handling" shall be conformance with a~~~t:~ of Part 1918, .. ,\e'&>l.n Regulations for'LOnl!l,'r/,olrchapter. The term
a suItable means ·of alt"jnst falling from the First-aid and
Provisions for medical assistance acco\,clanlce with Subpart (1)
~::~~~~~~~
means the moving, materials, elco~r"~;~~4-'~ into, in. on, or fixed
of the water. If
e~~~~':,~~:;y~:rj.~~~~aVailable furnish
driver
.j
(b)
tn;at,ll1e Is working
Jloau.
driving pllcable (c)
Pile
neers and nals only men. (2) All emlpft>yees ,u;;,~~~~kePt clear when piling 19 Into the leads. (3) When excavated pit,
be sloped to sheet-plied
"~~~~lr.~:~~
When < "blown out", enlrltpy,~e; well beyond the rlals_ (5) When itt.":Is~,"'~;:;~~~·~ (4)
\the tops of
rl
operations where the c~~~g~tp~~~~~~:e:, ed at
"Jacob's ladder"-A of rope or chain with we,od",n rungs.
(6)
"Rail",
for the means ;" as a guard ata the outer edge ship's deck. Subpat1 P-Excavations, Trenching, and Shoring § 1.~:~'~~~'
§ 1926.604
(a)
1926.650 General protection requirements. 1926.651 Specific excavation requirements. 1926.652 General trenching requirements. 1926.653 Definitions applicable to this subpart.
§ J926.650 General menta.
, overhead covering r...,nml. structure shall be of 'A.-inch steel plate or wire mesh with openiing" ",.".l.P' than 1 inch, or eqlulvale,nt. in the rear ca.rJI h~;:~~,::~ s . shall be c01lerc,d ODV
than Y.~inch woven wire openings no greater than 1 Specific requirements.
:4rv;,dl
over
CO.fnhlB unless there Is a saf'eep"'iS.\Ire.
necessary to stand at or inboard edge of the ~~;~~:?r less than 24 inches of i, coaming, or other D~~r~~t~:~~ all employees shall rn;
proteetion
require-
(a) WB.!kways, runways, and sidewalks shall be kept clear of excavated material or other obstructions and no sidewalks shall be undermined unless shored to carry a minimum live load of one hundred and twenty-five (125) pounds per square foot. . (b) If planks are used for raised walkways, runways, or sidewalks, they shall be laid parallel to the length of the walk and fastened together against displacement. (c) Planks shall be uniform in thickness and all exposed ends shall be provided with beveled cleats to prevent tripping.
f£DEaAlIEGIml, VOL 44, NO_ 29-f1IDAY, FEI.IU,UY 9, 1979
8649
RULES AND REGULATIONS
(d) Raised walkways, runways, and sidewalks shan be provided with plank steps on strong stringers. Ramps, used in lieu of steps, shall be provided with cleats to insure a safe walking surface. (e) All employees shall be protected with personal protective equipment for the protection of the bead. eyes, respiratory organs, hands. feet, and other parts of the body as set forth in Subpart E of this part. (1) Employees exposed to vehicular traffic shall be provided with and shall be instructed to wear Wanling vests marked with or made of reflectorized or high visibility material. (g) Ernploy~es subjected to hazard ous dusts, gases, fumes, mists, or at· mospheres deficient in oxygen, shall be protected with approved respira tory protection as set forth in Subpart D of this part. (h) No person shall be permitted under loads handled by power shovels. derricks. or hoists. To avoid any spill~ age employees shall be required to stand a way from any vehicle being loaded. (0 Daily inspections of excavations shall be made by a competent person. If evidence of possible cave-ins or slides is apparent. all work In the excavation shall cease until the necessary precautions have been taken to safe~ guard the employees. w
w
(e) The determination of the angle of repose and design of the-supporting
(m) Special precations shall be taken in sloping or shoring the sides of cy
system shall be based on careful evalu~ atioD of pertinent factors such as: Depth or cut: possible variation in water content of the material while the excavation is open; anticipated changes in materials from exposure to air, sun, water, or freezing; loading 1mposed by structures; equipment, overlying material. or stored material: and vibration from equipment, blasting, traffic, or other sources. (f) Supporting systems; i.e., piling,
vations adjacent to a previously t filled excavation or a fill, particul. when the separation is less than the depth of the excavation. Particular attentlon also shall be paid to joints and seams of material comprising a face and the slope of such seams and jolhts. . ~(n) Except in hard rock. excavations below the level of the base of footing of any foundation or retaining wall shall not be permitted, unless the wall
cribbing. shoring, etc.. shall be designed by a qualified person and meet accepted engineering requirements. When tie rods are used to restrain the top of sheeting or other retaining systellfS, the rods shall be securely anchared well back of the angle of repose. When tight sheeting or sheet piling is used. full loading due to ground water table shall be assumed,
is underpinned and all other precautio05 taken to insure the stability of
unless prevented by weep holes or drains or other means. Additional stringers, ties. and bracing shall be provide(i to allow for any nece&'JarYJ, temporary removal of individUai·,'$ljp2 p o r t s . , ..i>rjir., , (g) All slopes shall b~_-,:t:S~~va.ted to at least the angle of repp~:except_ _fQr areas where solid rock fOXi;-jitie drilling or p:r,~~~_tting. ~"~~_~r':'/!fr:-,,_~?5~~> (h) The HJ':10~Ief;-'l'epose S~'J~e flattened when-'(a,-ti~~:-«!~~vation -'I\~_~-:water § 1926.651 Specific excavation requireconditions. sl:i:t~ in&t.i~!a_ls, lOQ~~_::_:boulments. ~fJJ'si-: and ~,whe:r~--;:_~_~osioil(~~_~eep (a) Prior to opening an excavationr' 'frost-;action, aJl~.sli~e;p~_~es_ appear. effort shall be made to determllie (i)el} In exl!!!Jr"tiohSc~C!l employwhether underground installations; ees mIW be reQ.'\l~c:t~to· enter, excavati.e .. sewer, telephone,_w.a~. fuel, etec... ed-or-other mate6al shall be effectlve tric lines, etc., w~})~ _ _ell~1W~I:ed, ~--lf--sto:re9 and retained at least 2 feet or if so, where su_c:l:(J,uidergi"o'U;li~tJ?sta.r;;-_; -nlore--~r~~Jhe'~dge of the excavation. lations are loca~-t:li_ When the\~_~~va..;~:~ _'. (2) AS-tUi~it1temative to the clearance tion approaches th~estimated lclciil.tion '~'Ptescribed in subparagraph (1) of this of such an installatio~, the exacf;lOca.- ~----piiragraph, the employer may use ef~ tion shall be detel"iilined and when it fecttve barriers or other effective reis Wlcovered, proper SUpports -shan be taming devices in lieu thereof in order provided for the exlstirigillstallMion. to prevent excavated or other materiUtility companies shiJI.be contacted als from falling into the excavation. and advised of propos<>4work prior to (j) Sides, slopes, and faces of all exthe start of actual excavation. cavations shall meet accepted engi(b) Trees, boulders, and other sur- neering requirements by scaling" face encumbrances, located so as to benching, barricading, rock bolting, create a hazard to employees involved wire meshing, or other equally effecin excavation work or in the vicinity tive means. Special attention shall be thereof at any time during operations. given to slopes which may be adverseshall be removed or made safe before ly affected by weather or moisture excavating is begun.. content. (k) Support systems shall be planned (c) The walls and faces of all excavations in which employees are exposed and designed by a qualified person to danger from moving ground shall when excavaUon is in excess of 20 feet be guarded by a shoring system, slop- in depth. adjacent to structures or iming of the ground, or some other provements, or subject to vibration or equivalent means. ground water. (d) Excavations shall be inspected by ()) Materials used for sheeting, sheet a competent person after every rain- piling, cribbing, bracing. shoring, and storm or other hazard-increasing o(}o underpinning shall be in good servicecurrence, and the protection against able condition, and timbers shall be slides and cave~ins shall be increased if sound. free from large or loose knots, necessary. and of proper dimensions.
lUl-ows
w
ap.4
. .
the adjacent walls for the protection of employees involved in excavation work or in the vicinity thereof. (0) If the stability of adjoining buildings or walls is endangered by excava-
tions. shoring, bracing, or underpinning shall. be provided as necessary to
insure their safety. Such shoring, bracing,
spected.Y:dail.--"-y or more often, as condi.t i9XUiwtdTant. by a competent person
\:=~~ protection effectively main· (ptOlversion ditches, dikes, or other suita1\lIr;means shall be used to prevent surttice water from entering an excavatlp~>and to provide adequate drainage\:~f{~he area adjacent to the excavatiotL--Water shall not be allowed to accumulate in an excavation. (q) If it is necessary to place or o' ate power shovels, derriCks, tn materials, or other heavy objects 0_ level above and near an excavation, the side of the excavation shall be sheet-piled. shored, and braced as nec~ essary to resist the extra pressure due to such superimposed loads. (r) Blasting and the use of explosives shall be performed in accordance with Subpart U of this part. (s) When mobile equipment is uti. lized or allowed adjacent to excavations, substantial stop logs or barri~ cades shall be Installed. If possible, the grade shonld be away from the excavation. (t) Adequate barrier physical protection shall be provided at all remotely located exca.vations. All wells. pits, shafts. etc .. shall be barricaded or cov~ ered. Upon completion of exploration and similar operations, temporary wells, pits. shafts. etc., shall be back· filled. (u) If possible,' dust conditions shall be kept to a minimum by the use of water, salt. calcium chloride. 011. or other means. (v) In locations where oxygen deficiency or gaseous conditions are possi~ ble. air in the excavation shall be tested. Controls, as set forth in Sub·· parts D and E of this part, shall be es· tabltshed to assure acceptable atmo<::pheric conditions. When flamm' gases are present. adequate ventila
fEDERAL IlEGlml., VOL 44, NO. 29-fRIDAY, fEBRUARY 9, 1979.
RULES AND REGULAliONS
8650
shall be provided or sources of ignition shall be eliminated. Attended emergency rescue equipment, such as breathing apparatus. a safety harness and line, basket stretcher, etc., shall be readily ·available where adverse atmospheric conditions may exist or develop in an excavation. (w) Where employees or equipment are required or permitted to cross over excavations, walkways or bridges with standard guardraUs shall be provided. (x) Where ramps are used for employees or equipment; they shall be designed and constructed by qualified persons in accordance with accepted engineering requirements. (y) All ladders used on excavation operations shall be in accordance with the requirements of Subpart L of this
part. § 1926.652 Specific menta.
trenching
require-
foot horizontal. When the outside diameter of a pipe is greater than 6 feet, a bench of 4-foot minimum shall be provided at the toe of the sloped por-
tion.
(d) Materials used for sheeting and
sheet plling, bracing, shoring, and un· derpinning, shall be in good serviceable condition, and timbers used shall
be sound and free from large or loose knots, and shall be designed- and installed so as to be effective to the bottom of the excavation. (e) Additional precautions by way of shoring and bracing shall be taken to prevent sUdes or ·cave-ins when excavations or trenches are made in locations adjacent to backfilled excavations, or where excavations are subjected to vibrations froIll... railroad or highway traffic, the operation of ID8.chinery. or any other source. (f)
Employees entering bell-bottom
pier holes shall be protected by tjle in(a) Banks more than 6 feet high stallation of a removable.tl',J>I!";;~1ng shall be shored, laid back to a stable of sufficient strength to_r~~$llf!ting slope, or some other equivalent means of the surrounding e~{fi~~~' tempoof protection shall be provided where rary protectlon!lh~,,~'jj~ded for employees may be exposed to moving the full depth_9{!:$ll,at part of,~h pier ground or cave-ins. Refer to Table P-l hole whle4i11";\j"Ove the bell. Wlifellne, as a guide in sloping of banks. Trench- sultab)~j~",mstant rescue a.ria'~ure es less than 5 feet in depth shall also ly fas*eji to __Q,,$houlder hl!t1iess, be effectively protected when examh shall be:-)i.i9!:Ilb~t~/!I!b employee'iln1:e r nation of the ground Indicates haza.:P,'i-'-in g the sll)lt:~i~-lifeline shall be'lnaus ground movement may be exp~~r;~~~viduallY'-I~ed and separate from ed. W!~~~t;;~~:;}ine us~~,t\O remove materials ex(b) Sides of trenChe~,;"~,,,JJnstable -~:QtL cay_~~_?_ frolf{.~J1~ bell footing. soft material, 6 feet'_l:Ir'IllQ!"in dePtl1{ (gltl,l:-MirliIf{lipt requirements for shall be shllred,' .hee~ brace4);trea~",tjn>betlt!g' shall be in accord· sloped, or othe~e supported llir,}~~WfWll1'able P-2. meanBof sufficleutstrengtjl:to proteCl"":';C,,:(2) Brillil!s and diagonal shores in a the-'~II1l>loyees wCirklngWlt4ln them,--wood shoring system shall no.t be sub· _,~T..bles'J171, p-2,(foJlo~ para' ,teeted to e~mpressive stress ill excess ll""i>h (g)' ilt:t~ seCtl9P.).':--§,,_ - - of values gIVen by the following for)(e) Sides Of,t:ioenehe!l:1n hard br'"tOm- mula: S_1300-20L/D -;':P!lCt soU, W~ljldlnf!;_\!)!llbankments, -$1Il\ll be shorecl,_ot otheliWfse supported Maximum ratio L/D=50 when the tre)l(lhiis more than 5 feet in ·deptl\an
FEDElAlREGlmR, VOL 44, NO. 29-RIDAY, FEUUAltY 9, \979
RULES AND REGULA nONS
8651
[4510-2&-C)
'I'
Table
~
1
APPROXIMATE ANGLE OF REPOSE FOR SLOPING OF SIDES OF EXCAVATIONS
..
SlIlo, l _ ., flGA .. No....,..... Soil.
110'1"''' ' .....1.,
eN
w.....
'P'K."
.,. ... Pr••~.ot R......'.. Tre •• m....
.--
c•
Hot•• a_
•E u•
1,..1...
-'" : ...
. ...
~
~
0
...
i0<
"l! 0
_
~
.1
u .. Do<
"'.
'"
;:l;
I::!.
~
0
.c
~
'1-,
•E.
a
:i" 0
ED
.•
~'t D.
.0
....,
'DD
u
....
..
.~
...-- - ...i.·It-• "'-..
.. ..... ::-
••
..... .. .. ..
.0
0"'"
• .f
~'"
.~
.:!!!!.c.
OrI,I...,
..
..... l~
'I ....
.!
I!o
0'" 0
.... ...
A
D· ul;;
E
•
U
.:;
.
~
G,_ LI..
',>-i'-:-:-;f:c::~_,: _
Jt
1926.652(g)(2)
p~~i_~';'
nX~~-~OlUN~~;~i.mi~~~~''''1II Bke and ap&C1na: of mem ben
.......
Depth of
Klnd or 00D4ItI0I1 Of eu1.b -
....
-... ........... ,......
I to 10 lhrd, oompaet•• _~~~".;-...~~~~.-. f, Or 2 Likely to craek __ ._.~-,:. __
1:'
:_.JJ:" 01'2.'
80ft, IUld7. ortl.lled •••••••• _.1:4G1'2xl
nydroltatle pressure •• _•••• •'x4 at 2.' 10&0 111 Bard._ •••• __ ••.•••••••••...1 J[ 4 or 2x'
Ll.tely to cnc1l: .• _•••• __ • __ •. lx4or 2xl Soft,
II
...
aand.,.. or ftlfd.. ____ • _•.1 J[ 4 Of' 2x I
Bydrostatlc prtt&SlU1I __ • _. _••
to 20 An kinds 01' oondIUOnt __ • ___
0 ... 210 AD klnih or oondJUODl ____ ._
6""""
U""P" ~um-
~
c_
-
e_
-line
...• •
........
CI_
CIooo JheeUnc
IhMUna:
C....
........ ........
Inch.
I .....
_Ina
"...
... ~-..... -...... -.. --.
., ••• ... h' h'
•••
B.I0
e_
... . ...... h.
dlmension
.~-
I
Ur..!:' •
Width
Mlnlrntlm Mulmwn
· ,.......
Foot
Cru!Jllbncea l
.. s 12
.. I
• •
• • • • • • •
...... ...••• ...••• ......
4:1 12
•• 12
Marlmam spednc
ot trencb
....
g to 12
. ,......
12 to 11
""
...... ,.............. ... •••U. ...... .., ..1••• ..•••. ,.. ...... ••• ...... •••••• ••• ••• . .. ••• Inehfll
h •
ex ....
•••
I.'
II: 10
I Treneb Jtoeb may be oaed In Ueo 01. 01' In oombtnaUcm wtth. m. btaca Bhortna Ia not required In lOUd rock, bard ab~, or 1uInI . . ._ Wbere oM1rabJe. lteellheet pllJ.n&: &I:'Id braelna oteqtHJ Itren«th tnay be mbsUtut.ed for wood.
FEDHAL IEGISTH, VOL 44, NO. 29-flIDAY, FE.IUAIlY 9, 1979
JlortwntsJ.
"oot
F...
•
• •
•
• • • •
•
• •
Bxl0
•
I ••
B xl0
•
• •
• xlO
lOs 10
•
•
lOs 12
•
,61.8
•••
V .......
~OJ:
10
8652
RULES AND REGULATIONS
[451G-26-MJ '~) When employees are required to ;-t trenches 4 feet deep or more, an quate means of exit. such as a ladder or steps, shall be provided and
located so as to require no more than 25 feet of lateral travel. (1)
Bracing or shoring of trenches
shall he carried along with the excava-
tion. (j)
Cross braces or trench jacks shall
be placed in true horizontal position, be spaced vertically. and be secured to
prevent sliding, falling, or kickouts. (k) Portable trench boxes or sliding trench shields may be used ·for the protection of personnel in lieu of a
shoring system or sloping. Where such trench boxes or shields are used, they shall be designed, constructed, and maintained in a manner which will
provide protection equal to or greater than the sheeting or shoring required for the
tren~h.
Backilliing and removal of trench supports shall progress together from the bottom of the trench. Jacks or braces shall be released slowly and, in unstable soil, ropes shall be used to pull out the jacks or braces from above after_ employees have cleared the trench. (I)
§ 1926.653 Definitions applicable to this subpart. ) "Accepted engineering require.:is (or practices)"-Tbose require-
lUents or practices which are compatible with standards required by a regiS~ tered arehitect, a registered profes:' sional engineer, or other duly licensed or recognized authority~ __ (b) "Angle of repose.......Th"great$t angle above the horizontal plane~lit which a material wilflie without sll\l'~. tng. ~ (c) "Bank"-A massot soli risillir above a digging level. (d) "Belled excavation·...:..-A-pat't_-QI-s. shaft or foottng excavatlQD.;USUally near the bottom and bell-shaPed; i.e., an enlargement of the cross section above. (e) "Braces (trench)"-The horizontal members of the shoring system whose ends bear agatnst the uprights or stringers. (0 "Excavation"-Any manmade cavity or depression in the earth's surface. including its sides, walLs, or faces, formed by earth removal and productng unsupported earth conditions by reasons of the excavation. If installed forms or similar structures reduce the depth-to-width relationship, an excavation may become a trenCh. (g) "Faces"-8ee paragraph (k) of this section. 'h) "Hard compact soiI'·-All earth ~rials not classified as running or able.
(0 "Kickouts"-Accidental release or (Employees shall not be permitte failure of a shore or brace. to rk above vertically protruding r . (j) "Sheet pile"-A pile, or sheeting, ing steel unless it has been pr that may fonn one of a continuous into eliminate the hazard of terlocking line, or a row of timber, ent. concrete, or steel piles, driven in close (3) uying: Reinforcing steel contact to provide a tight wall to resist walls, iers, columns, and similar v rtithe lateral pressure of water. adjacent cal st ctures shall be guyed and up.earth, or other materiaIs.. ported prevent collapse. (k) "Sides", "Walls". or uFa6es"_ (4) W e mesh rolls: Wire mes rolls The vertical or inclined earth surfaces shall be ecured at each end to p event formed as a result of excavation work. dangero recoiling action. (i) "Slope"-The angle with the (c) B concrete handling Bulk horizontal at which a particular earth storage b ,containers. or sil s shall material will stand indefinitely with- have coni or tapered botto with out movement.· mechani or pneumatic ans of (m) "Stringers·' (wales)-The hori- starttng th flow of material. zontal members of a shoring system (d) Cone ete placement whose sides bear against the uprights erete mix 78. Concrete mixers or earth. equipped wit I-yard or lar er loading (n) "Trench"-A narrow exCavation skips shall equipped ·th a memade below the surface of the ground. chanica] devi to clear the skip of maIn general. the depth is greater than terial. the width. but the width of a trench ts (2) Guanl,m Mixers not greater than 15 feet. paclty or !ll"~a r shall (0) "Trench jack"-Screw or hydrauwith protective ardra lic type jacks used as cross bractng In a each side of the kip. trench shoring system. ~ BUll /Wa . H dies on bull (p) "Trench shield"-A shoring ~ floats, used whe e th may contact system composed of steel plates and~ - - energized -tHectri I c ductors, shall bractng. welded or bolted t9i11!ther, be constructed of on nductive mate· which support the walls o('a-"-trench rial, or instilated th nonconductive from the ground level to tht(~,kencp.- --'sheath whose:-elec· and mechanibottom and whicilcan be movik!~,&JolIg'cal characteristiCS vide tile equivaas work progress~_.-_~ -:" __ -;";(_ -,_ , lent protection---6f a handle construct(q) "Unstable -so,Ut'~~h mRt(u1al, ed of nonconductive aterial. other than runnlitk;~tha,l;~~use 9P1;s (4) Powered ncrete trowe"'. natJ:l!e-_or the influ~llce -ol_)'~lated'-C»~~ Powered and ro t g~type concrete dltlODB,cannot bedependelfupon~~t.o' troweling machin t t are manually remain In place without citA-asupport, guided shall be e uip ed with a con· ,:-such as -_ -_would be -fUr:riished by a trol switch tha w· automatically :system of shoring. shut off the pow r whe ever the oper(r) 'c'Uprtghts"-The vertical mem- ator removes is h ds from tile bers or-a- shoring syStem. equipment han es. (s) "Wales"-.CSee paragraph (m) of (5) Concrete ggies. H thb.---section. gies shall n extend beyond the (t)"'Walls"-see ~paragraph (k) of wheels on elt r side of t e buggy. Inthis-section. stallation of uckle guar on buggy Subpart Q-,-Concrete, Concrete handles ts r mmended. Forms, and Shoring (6) Pumpc te S]lstems. similar sys ms ustng disc shall be pr vided with pip designed r 100 percent C9mpress air hose in suc systems shall be rovided with post ive failsafe Join: connectors to prey t sepa~ ration of ections when pressu ed. (7) C rete buckets. (i) ncrete buckets equipped with hydra Ic or tically operated gates shall have sitive safety latches or . Oar safety devices installed to preve t aggrega and loose material from umula ing on the top and sides 0 the bue t. (ll Riding of concrete buckets for any purpose shall be proillblted. d vib tor crews shall be kept out fr m er concrete buckets suspend d fr m cranes or cableways. ~ 8) Wben discharging on a slope. t eels of ready-mix trucks shall
,n
APPENDIX d j~«/;,~k
ASTM D 15~'~Ct~1. ,,~li~dard Me.t.hod fo:i,;"~en\\;mE,a ti~W,;"Tes t AI}dS'pii'ti. J3arr~W Sa,il\p'l!.ing','of Soils"
\~\Y~I~-t;j!:~?'~-'''~-;-,~,,,-!-~
4~J~
Designation: D 1586 - 67 (Reapproved 1974)
Standard Method for
PENETRATION TEST AND SPLIT-BARREL SAMPLING OF SOILS· This Stan~a.rd js issu~ under, the fixed designation D _1586; the number immediately following the designation indicates the year of ongmal adophon or, In the case of revision, the year of last revision. A number in parentheses indicates the year of last rcapproval.
This ,method has bun approved for use by agencies of lhe Department of Defense and for 14/i1ff'ln. the DoD Index of
Specifications and Standards,
._~ _ ,o_~-"_-:_--;~_-,,
I. Scope mm) (mini!Dum~'i~,,;i:4~)vent ports and shall contain,4i:b'aIL check valvc;<1f sizes other than 1.1 This method describes a procedure for th'\'~·Mj;¥50:8.mml sampl~V~~e permitted, the using a split-barrel sampler to obtain repre'fii;~liall be £qnspicuousIYII,9~d on all pene· sentative samples of soil for identification tr~\W~ r~r!\.: ii"~ purposes and other laboratory tests, .a,nd to 2;~:#iNl'Weight AssemblY-The assembly obtain a measure of the resistance ofthe-.sQiUo shaljt!!l!~sist of a 140·lb (63.5·kg) weight, a penetration of the sampler. ", ,driviri&',~~l!d, and a guide permitting a free fall 2. Apparatus ,<;,< ",> , 'sllf}O in;;tti;Z6 mI. Special precautions shall be 2.1 Drjl/ing~~l!{pmiln/~AIt)'drilling4uip:"!I!~~'t to;~iis~re that the energy of the falling ment shall be oI<:<:eJltable that';~"ovidenl,~~~"" Jwellifi('.is 'not reduced by friction between the sonablydean h1'l~;befo~~,.in~rtion iir;t~e drivt weight and the guides. saPlplertl>~n~ure"lfiat\h.P!'!1l:tration tojtis 2.4 Accessory Equipment-Labels, data ___,,_perl'orniei:L~~6,\#_~distQf~d soil;~~a~:t!_*_tpat~--\vil1 sheets, sample jars, paraffin, and other neeessary supplies should accompany the sampling permit the drivi!lg of th~,¥mpler til)bDtain the _s.a.mpte and pe:n~t:ration-;_ ~~l;ord in accordance equipment. 'with the proced,Ute descrilied in Section 3. To avoiduwhip$'h~nder the blows of the hammer, 3. Procedure it is reco!lin\'c,Med that the drill rod have a 3.1 Clear out the hole to sampling elevation stif(riess__cqual to or greater than the A-rod. An. using equipment that will ensure that the '"An -rOO is a hollow driU rod or "steel" having material to be sampled is not disturbed by the an outside diameter of IIVs in. (41.2 mm) and operation. In saturated sands and silts withdraw the drill bit"slowly to prevent loosening of an inside diameter of 1111 in. (28.5 mm), through which the rotary motion of drilling is the soil around the hole. Maintain the water transferred from the drilling motor to the level in the hole at or above ground water level. cutting bit. A stiffer drill rod is suggested for 3.2 In no case shall a bottom·discharge bit holes deeper than 50 ft (15 mI. The hole shall be permitted. (Side·discharge bits are permissi. ble.) The process of jetting through an open· be limited in diameter to between 2'" and.6 in. (57.2 and 152 mm).' tube sampler and then sampling when the 2.2 Spllt·Barrel Sampler-The sampler shall be constructed with the ditnensions inI this method is under the jurisdiction or ASTM Committee 0-18 on Soil and Rock ror Engineering Purposes. dicated in Fig. I. The drive shoe shall be of Current edition approved Oct. 20, 1961. Originally issued hardened steel and shall be replaced or reo 1958. Replaces D 1586:'- 64 T . • Hvorslev, M. J' Surface Exploration and Sampling of paired when it becomes dented or distorted. Soils for Civil Engineering Purposes, The Engmeering The coupling head shall have four Y,·in. (12.7· Foundation. 345 East 4?th St, New York, N. Y. 10011.
fi,'
t
283
01586
hermetically seal to prevent evaporation of the desired depth is reached shall not be permitted. soii moisture. Affix labels to the jar or make Where casing is used, it may not be driven notations on the covers (or both) bearing job below sampling elevation. Record any loss of designation, boring number, sample number, circulation or excess pressure in drilling nuid depth penetration record, and length of recov~ during advancing of holes. cry. Protect samples against extreme tempera~ 3.3 With the sampler resting on the bottom ture changes. of the hole t drive the sampler with blows from the 140-lb (63.5-kg) hammer falling 30 in. 4. Report (0.76 m) until either 18 in. (0.45 m) have been 4.1 Data obtained in borings shall be repenetrated or 100 blows have been applied. corded in the' field and shall include the 3.4 Repeat this operation at intervals not following: longer than 5 ft (1.5 m) in homogeneous strata 4.1.1 Name and location of job, and at every ch'ange of strata. 4.1.2 Date of boring-start, finish, 3.5 Record the number of blows required to 4.1.3 Boring number and c.oordinate, if effect each 6 in. (0.15 m) of penetration or available, ." .,:.::;?<.-~~.:;~~:. fractions thereof. The first 6 in. (0.15 m) is 4.1.4 Surface elevation,ira\lailable, considered to be a seating drive. The number of 4.1.5 SampI9,nufu!li.:.ndjlepth, blows required for the second and third 6 in. 4.1.6 Mj't\1til.If"pf advancirlg,sampler, pene(0.15 m) of penetration added is te·med the tratiqIJ,~"ct;~~8very lengths~-~-:-'~;,,:,-;' ~ penetration resistance, N. If the sampler is 4;1:7.Type and.size of sampler, driven less than 18 in. (0.45 m), the penetration 4.1.8J)escril'l'liin,of soil, , resistance is that for the last I ft (0.30 m) of layer, 4.1.9;Whicllitissof penetration (if less than I ft (0.30 Il!)~;is·· 4.1.l0~pth to water surface; to loss of penetrated, the logs shall state the numbCt'---:of: !>!a~.er; to"a~~sian head; time at which reading blows and the fraction of I ft (0.30 m) jl!o"": .
trated). .'<~}".< 3.6 Bring the sampler
-wa:~_~-:wade.-".:~,.~.,.:._:_;.
A.JJ'1 Ty,*j.nd make of machine, '4'.r;f2.'..'Size of casing, depth of cased hole, 4.l.fJ'Number of blows per 6 in. (0.15 m), 4.1.14 Names of crewmen, and 4.1.15 Weather, remarks.
284
~~I~ OR"'N'
i'i L
'HDEl Ii
[
I
0 1586
1---SPLIT BARREL
II
------I
SAMPLER. HEAD
SUITABLE SEATING
r
.. VENTS
DlA (minI
~~I~_~t¢:-:rz"72:2j-=r.l
~
l '
r
""JRr7Lzz5~1~ ~~I.~1---,!-'7¢J·~.Z"(.z,.,~~~~ 3" (min.I
IS" ! min.)
. I -----I
LSTEEL BALL f 0.0. PREFERABLY COATEO WiTH A MATERiAL OF SHOAf. HARDNESS OF 30 TO 40
1------------ 27" Imln.) (OPEN) ------------1 NOTE I-Split barrel may be ]lh in. inside diameter provided it contains'a liner of l6-gagc ""alPhickncss. NOTE 2-Corc retainers in the driving shoe 10 prevent loss of sample arc permitted. - ' NOTE 3-The corners at A may be slightly rounded. Melric Equiulenls
Y.6{16gage) !1
*
~*
I IS
mm
mm
in.
1.5 12.7 19.0
;L?: ~-;, ~!:~
'>f
50,8
3
76.2 -.: -'52.4
/1:'< -'21-
457.2 685.8
-----J~.I
The American Testing aiid.;'oteriab ~iijii;~~;-;i;i;;~'~~;;f~~cling the validity of any patent rights asserted in connectil!!t with any 1te"(!nMt{an.~dJ,.-.,hjs standa-'!Ji', .Users 0/ this standard are expressly advised that determination oft~e<~~I!t!!~_lf-:a.ny sucli~I.!-"1 !'i8"H;.fu~d. the risk ik/iri[ringement a/such rights. is entirely their own responsibility.
socielJi;c
-~. _.. ~.T1tj{~t~~d~j.{lii:~bject iii_T1f(jion ~I ~hy_~:i'fM-;"by lhe responsible technical committee and must be reviewed every five - .-~s. and if not r~~~,f/.~, elthe~;-;~proved or·tilitlr'drawn. Your comments are invited either for revision of Ihis standard or /fJrjliJditional stand~ifI(-'lIId sHt!I4.!~;b.e addres.fed to ASTM Headquarters. Your comments will reeel ..e careful consideratioll of -a .d't!eting of the t~ip({iJsible lec~lilcal committee, which you may attend. If you feel that your comments have not recej~ed a Iti'l'-~,arlng you sliqtJ(d;make yoril ~iews known to the ASTM Committee on Standards. 1916 Race St., Philadelphia, Po. J9iOJ.;:.',w/lich wiU.st:~.eJule a further hearing regarding your comments. Failing satisfaction there, you may appeal to the A STM/l!~~.W- Dif-tCI'JrJ.
285
unified Soil ,.
1.
Test of Soils Reconunended of Soils
AMERICAN NATIONAL ANSI/ASTM D 2487 - 69 (Reapproved 1975) STANDARD
Standard Test Method for
CLASSIFICATION OF SOILS FOR ENGINEERING PURPOSES· This Standard is issued under the filted desiJ!nation 02487: the number immediately following the designation indicates the year of original adoption or, in the caSe of revision. the year of last revision. A number in parentheses indicates the year of last reappro ... al.
I. Scope
ance with ASTM Method D 1452, for Soil Investigation and Sampling by Auger Borings,' ASTM Method D 1586, for Penetration Test and Split-Barrel Sampling of Soils,' ASTM Method D 1587, for Thin-Walled Tube Sampling of Soib. 2 or anothc:;r<_standard accepted procedure. _ -:-~:l:_(!.~:;-:~ 3.2 The sample shaU.,~,~refully identified as to origin by _.,a ~t~il'--'-~~m;~er and' sample number in_:f_~~:i:~ctron wif~~;_~~;job number, a
1.1 This method describes a system for classifying mineral and organo-mineral soils for engineering purposes based on laboratory determination of particle-size characteristics,
liquid limit, and plasticity index, and shall be used when preCise classification is required.
NOTE I-This method provide~ qualitative data only. When qud-ntitative information is required for detailed designs of important structures, this method must be supplemented by laboratory tests or other geolo~!~(!-~_~iJW\tin;t a pedoldgl9;~;:~orizon or a quantitative data to determine performance characloca~(~ij-~d~scripti~,~ with respeQi)o a perma~ teristics of the soil under expected field conditions. NOTE 2-This method may also be used as an aid nent';~,!,_?~Um~,~~_~;-_~!,~~:. grid system ;-?f2 a station in training personnel in the use of ASTM Req:)fIJ~ mended Practice 0 2488. for Description oCSi)H~-, numbM,'"~l1db:rriret with respectln' a stated centerliite~ (Visual-Manual Procedure). J -"-
2. Apparatus
3.3 The.:~li!11pleshould also be described in
~-; -
-"_ccordance----·with Recommended Practice D
148&.:.
2.1 Apparatusfor Prepiitpllo",ofSampl'$
See ASTM Meth~_ ;-~.4il, -for~:pty Prepa~~~ _
.-r.
-,1
1..;7.Apparatus/ot,LiqlildJtimit Test-See ASTMMethod D
3.1 Sampling shall be conducted in accord-
4. Test Sample' 4.1 Test samples shall represent that portion of the field sample finer than the 3-in. (75-mm) sieve and shall be obtained as follows:
4,1.1 Air dry the field sample, 4.1.2 Weigh the field sample, 4.1.3 Separate the field sample into two fractions on a 3-in. (75-mm) sieve, and 4.1.4 Weigh the fraction retained o'n the 3-in. (75-mm) sieve. Compute the percentage I This method is under the jurisdiction of ASTM Commiltee D-18 on Soil and Rock for Engineering Purposes. Current edition approved Nov, 14. 1969. Originally issued 1966. Replaces D 2487 - 66 T. I Annual Book oj ASTM Standards. Part 19.
The American Society Jor Tesling and Materials ,akes no position respecting the validity of any patent rights aJserted in connection with any item mentioned in Ihis standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of ItJjringement of such rights. is enlirely their own responsibility.
374
~~I~ of plus 3-in. (75-mm) material in the field sample, and note this percentage as auxiliary information. 4.1.5 Thoroughly mix the fraction passing
the 3-in. (75-mm) sieve and select test samples. 5. Preliminary Classification Procedure 5.1 Procedure for the determination of percentage finer than the No; 200 sieve. 5.1.1 From the material passing the 3-in. (75-mm) sieve select" a test sample and determine the percentage of the test sample finerthan the No. 200 sieve in accordance with
Method D 1140. . NOTE 4-Step 5,1.1 may be omitted ir the soil can obviously be classified as fine.grained by visual inspection (see 5.3). 5.2 Classify the soil as coarse-grained if more than 50% of the test sample is retained on
0 2487 in which D lOt Du. and D80 are the partic1esize diameters corresponding respectively to lOt 30, and 60% passing on the cumulative particle-size distribution curve. 6.5.1 'Classify the sample as well-graded gravel, OW, or well-graded sand, SW. if C u is greater than 4 for gravel and 6 for sand, and C~ is between t and 3. 6.5.2 Classify the sample as poorly graded gravel, OP, or poorly graded sand, SP, if either the C u or the C~ criteria for well-graded soils are not satisfied. 6.6 If more than 12% of the tes~_.!sample
passed the No. 200 (75-I'm) sie~'lisdeter-
mined in S.l.1 determint;~}~#:~t~q~~a limit and the plasticity inde?",J~f a/"ortio_tl::;of the test sample passin~J~~~:}I~"": 40 sieve i~_~:~c~ordance with Meth~,~'A2~ and Method D"~2~. 6.6, 1 Cl~~,sIry the .,_s$l,mpie as s;11ji:';:B.,avel,
the No. 200 (75-I'm) sieve and follow SectionGM. or silfJ!i!~l1{/,rfflf,#II~· if the results'), the '}'Wits tests slil1",JijilFthe fines are silty, that is, 5.3 Classify the soil as fine-grained if 50% 'the/plo!' of th"-"liquid limit versus plasticity
6.
or more of the test sample passes the No. 200
(75-I'm) sieve and follow Secli!>(7, 6. Procedure for classllt.illion ofCjlarseGrained Soils(More tl!;\ri?O% rctiliij~d on No. 200 (7{)'ILIl1) sieve} ,'.. '.
6. I Select 't~st; ;~~PJes f;QijI','lhel1\ai';tfa;1
passingt,h~ 3-in. (75-min)sievd~t1the dete/In;"
~~:~,n a;NgI~::~~;i~~::~~a~~e{t~~~~~i~~;~ I\STM Mcthi>d D 421~oiMethod D 2217.
6.2 Determine the--_cumulative particle-size distribution or--the--fraction coarser than the No. 200 (75-l'm) sieve in accordance with
Method D 422. 6.3 Classify the sample as gravel, G, if 50% or more of the coarse fraction (plus No. 200
inde~}1;lI,ls helo:w.~-J-he "A" line (see Plasticity
Chari;FJg. I) ortlf~;l\lasticity indo< is less than
'4·i;;"c
,/,';6;J!l~Cla~$Ity the sample as clayey gravel. GC-.'or clayey sand, SC, if the fines are clayey, Jlj* is, the plot of liquid limit versus plasticity index falls above the "A" line and the plasticity index is greater than 7. 6.6.3 If the fines are intermediate between
silt and clay, that is, the plot or liquid limit versus plasticity index falls on or practically on the "1\" line or falls above the "1\" line but the plasticity index is in the range of 4 to 7, the soil should be given a borderline classification,
such as GM-GC or SM-SC. 6.7 If 5 to 12% of the test sample passed the No. 200 (75-I'm) sieve, the soil should be given a borderline classification based on both its gradation and limit test characteristics, (see
(75-l'm) sieve) is retained on the No. 4' (4.75mm) sieve.
6.6) such as GW-GC or SP-SM.
6.4 Classify the sample as sand, S. if more than 50% of the coarse fraction (plus No. 200 (75-I'm) sieve) passes the No. 4 (4.65-mm)
NOTE 5-ln doubtrul cases, the rule is to ravor the less plastic classification. Example: a gravel with 10% fines, a C u or 20. a C~ of 2.0, and a plasticity index of 6 would be classified as GW-GM rather
sieve.
6.5 If less than 5% of the test sample passed the No. 200 sieve as determined in 5.1.1, compute the coefficient of uniformity. Cu. and coefficient of curvature, C~ as given in Eq I and 2. Cz
=
C" ... Du/Dlo (D,o)'/(D 1o x 0,,)
(I) (2)
lhan GW-GC. 7. Procedure ror Classification or Fine..Grained
Solis (50% or more passing No. 200 (75I'm) sieve) . 7.1 From the material passing the 3-in. (75-mm) sieve, select a test sample for the 375
D 2487
determination of the liquid limit and plasticity index in accordance with Method D 421 or Method D 2217. NOTE 6-1t Is recommended that the method for wet preparation be used for soils containins organic matter or irreversible mineral colloids.
7.2 Determine the liquid limit and the plas. ticity index of a portion of the. test sample passing the No. 40 (425·l'm) sieve in accord. ance with Method D 423, and Method D 424. 7.3 Classify the soil as inorganic clay, C, if the plot of liquid limit versus plasticity index falls above the "A" line and the plasticity index is greater than 7. 7.3.1 Classify the soil as inorganic clay of low 10 medium plaslicily, ct, if the liquid Iimil is less Ihan 50' and Ihe pial of liquid Iimil versus plasticily index falls above 'Ihe "A "·line and the plasticity index is greater than 7. See area idenlified as CL on Ihe Plasticity Chari, Fig. I. 7.3.2 Classify Ihe. soil as inorganic clay of high plaslicily, CH, if Ihe liquid limit is grealer Ihan 50 and Ihe plot of liquid Iimil plasticily index falls above the" A area idenlified as CH on Ihe Plaslicily Fig. I. . NOTE 7-ln cases \\'.~.~~f~~l\ll~l(tlimit 100 or the plasticity;:j_p~C:i~~eiceeas~~;Jhe
chart may be exp;f~;_ by maintaJ~bg scales on both ax.es aiW_~_~~tendin&~Jfi~~~line
.i;~~~\iJt~~~!b~ s~&\t\Vilii~ii$({I,J(.. .•. . .
't~~Cplal of Iiqli!~j.\imit'\:cif*,us plastiililY'lndex
ra'I~.h.elow Ihe:t~~r Iin~~~!l,if the plasticity
less thaW;_~_t--:unless_:4flI'S suspected that org-~iii-~l_matter~:J*:-'p_tesent in sufficient amounts to inn~¥~s~J:t,tcf$-9il' properties, then tentatively c1assifl'Jlije;\~tiil:as organic sill or e/~y, O. 7.4.I"lf·the soil has a dark color and an organic odor when moist and warm, a second liquid limit tesl should be performed on a lest Inde,x;.IS
sample which has been oyen.dried at 110 '" 5 deg C for 24 h. 7.4.2 Classify Ihe soil as organlcsill orelay, 0, if the liquid limit after oven drying is less than three.fourths of Ihe liquid limit of Ihe original sample determined before drying. (See Procedure B of Melhod D 2217). . 7.4.3 Classify the soil as inorga~iesill of low plasllclty, ML, or as .organic silt pr slll.e/ay oflow plasllcily, OL, if the liquid limil is less than 50 and Ihe pial of liquid limit versus plasticity index falls below Ihe "A "·Iine or the plasticity index is less Ihan 4. See area ,identi. roed as ML and OL on Ihe Plasticity Char~ Fig. I. .,' 7.4.4 Classify the ~~H~~flli,.ganlc sill pf medium 10 high plas(lcI!Jlf'f41H, or as organic oIJ;;liltJlfltti,"lo high plaslicily, clay or OH, if Iiliiif is nlofothan 50 and the plol versus lllllDcily index falls See ardi!ll.~nlified a5M H Chll'((.if;ig. I. indlicate tlKiij'f~porderline some fin,~-graind:r-soits should dual symbols. of liquid limit versus plason or practically on the U A" "A" line where the plasticity the range of 4 to 7, the soil should be given af! appropriate borderline classification such as CL·ML Or CH·OH. 7.5.2 I f the plot of liquid limit versus plas. ticity index falls on or practically on the line liquid limit ~ 50, Ihe soil should be given an appropriate borderline classification such as CL·CH or ML·MH. NOTE 8-ln doubtful cases, the rule for classifica~ tion is to favor the more plastic classification. Example: 'a fine~grained soil with a liquid limit of 50 and a plasticity index of 22 would be 'classified as CH·MH rather than CL·ML.
This standard is subJect to rtvislon lit any time by tht lespons/ble ttchn/cill committee and musl be reviewed evtry fl~ years and if not revised. tither reapproved or withdrawn. Your comments are invited either for re'll/sion of this standard or for additional standards and should bt addressed to ASTM Headquarters. YoW' comments will rectivt cart/ul considelOtlon at a muting of the responSible technicil/ committtt, which you may Ilttend If you fetl that your commtnts ha'lle not received afair hearing you should mob your views known to the ASTM CommJJtee on Standards, 19M Ract St., Philadelphia, Pa. 19103, which will schedule a further hearing regarding your comments. Falling slltlsjaclion there, you may appeal to tilt ASTM Boord of Directors.
376
~~j)l
D 2487
TYPICAL NAMES
GROUP SYMBOLS
MAJOR OIVISIONS
We II-graded gravels and
•>
••>
c
0 0·-
~
~
GW
gravel-sand mixtures, little or no fines
.....
.-• '"-' • "',. .::t d~
~
.-• '" •c •u 0 • ,.-' g.!:z
'Poorl y graded gravels and
GP
'"
'"~ c0 • c0 • '"--' o' '" * ouu·_ '"-' '" !l "''''''' '" 0 •c ~ii: .. '" • '" '" .• '"'"w, •c •> '"'" '" 0 • "''" 0·'"u '"'" -'" • '" c ... _ • :......... • '" ~-~-:i .
gravel-sand mixtures, little or no fl nes -.-,
0 0
N
(\I OOC 1.1\
0
0
.. .
S 11 ty gravel s} grave 1_:.~~~~~ silt mixtures _---::~---:<~-/-;:
GM
C~
~
C
> f - '"
Clayey 9r~V"Il"i$,
GC
.' •• .. We i J;';'.9r aded. :.s"n~s
~
SW
~
~
C
C
".>
· ..
.,.
111
U~
o~
sP
~U""
~ ~
"0
~,_
0
.'
C
j!
"
V>.
••
Q)
~.4,)
~
U:IIJ
..
..•.
.'
....
••
> ;;•
~
g
-
N
0
••• ••
0
.. 0
0
~
.ML
Inorganic silts, 'very fine sand$, rock flour' , si I ty or (-1 ayey fine sands
CL
Inorgan I c c! ays of low: to medium pl~sticjty, gravelJ y clays1 sandy clays, s 11 ty clays, lean clays
OL
Organic s j I ts and-organic s 11 ty clays of low plasticity
HH
Inorganl c silts, mi caceous or diatomaceous fine sands or s i I ts, elastic s II t s
CH
Inorg'an I c days of h.i gh plasticity, fat cI ays
OH
Organi c clays of medium to high plasticity
PT
Peat, muck and other highly organic 50115
c
'"
V>
-'
~
:5 e ''"" V>
u 0
z 0( ~
-!:; '"
C
•
.••
.-~ ~ ~
1.,
sand-s i I t mixtures
Clayey sands, sand-clay mixtures
0 (;-I!
V>
I
si;
.~ ~VI
~
->.',;:>
'("
~,<
~~
c
;a:' .... : ;
d .-e •• -'"" .... &
i --' .- '" Q.
(i ~<~-
01(, .... -
~_Ut
i
'"'" '"'"~ '",
• ...'" "g
..
an'd
"Poorly g-":aded sands and gravelly -}S'einds, Ilt~l" or no fines
SIL.c I::~>ii'f~i;~ands
•••••.'
V>
-,----c
9rav~Hy-,-!j~!\di'~ " I ittle·'.9('no fines
;:,,-:.;:;>-;'C,
~-$
~--3---:
::
.
C
~
gravel ~'S_~~r;I-
clay mht"tt#"_S'
~
c,
....
,,~
-' c
m
Highly Organic Soi 15
• Based on the matenal passing the JMIn. (1S-mm) Sieve. FIG. I Soil aassiOcation Chart.
377
\
02487
CLASSIFICATION CRITERIA
,
•u
...
••c
...
o.u
0
U
~
0
•• .•
V)V)_.JJ
.,"'x"
~
•c • "'''' •c o.uc ~
"
.. _
~
•u '"''"' "
0
.~
~
.. L
4-
C
">:0 0
0-
'"''"''''
•
~
0
•
••
D
c
· ··-0
0
00'- 0 N VI 0-
2
-0
0
C
0
••
•> ••> '"c --• > --c •
- 00 OZN
....z
Z
~
~-
..
Atterberg limits plot below "A" line or plasticity index less than 4 Atterberg limits plot above 'W' line and plasticity index greater than 7 Greater than 6
•c
Between 1
C
0
• 0'; •u 0.•• • •• ~~ • ••
~
Not meeting both criteria for GW
/I)
Not meeting both
• •c ~'~ .soS-
W
••
·
0
c
~
O~ ~>:~
oil,)
Visual-Manual Identification. See ASTM Designation 0 2488
FIG. I Continued.
378
Atterberg 1 imits plotting in hatched area are border! ine classifications requir"lng use of symbols
~~l~
Designation: 02488 - 69!Reapproved 1975)
American National Standard A37.174-1972 Approl/6d June 30. 1972 By American National Stsfldards Institute
Standard Recommended Practice for
DESCRIPTION OF SOILS! (VISUAL-MANUAL PROCEDURE) This Standard;s ;j\sued under the fixed designation D 24K!:!: the number immediately following the de~ignati(1n indicates the }car of origin;.]\ adoption or. in the ca~e of rCl'is;on, the year of iust rcrision. A number in parenlhe~c~ indicates the year of iast reappro\'al,
I. Scope
1.1 This recommended practice describes a procedure for the identification and description of soils for engineering purposes based on visual examination and simple manual tests. NOTE I-It does not conflict with other methods of soil identification or classification and in fact the user is encouraged to supplement the descriptions recommended herein with geologic, pedolo$i~_~':ol' local terms of description. On the other hand:~:\Nhen) precise classification of soils for engineering:~pur· poses are required ASTM Method D 2487.-,-for Classification of Soils for Engineering PurpoSes.-2 should be employed.
3.1.1 Small supply of water,,~nl! 3.1.2 Pocket knife or sm~II;$llil.1:Ula. 3.2 UseJul Auxiliary Equiptitent: 3.2.1 Small bottl.'ofdihile hydrochloric acid, _,-__ -,--'._,.. «, 3.2.2Srii~lIlest tube and stj)p~er, 3.2,3'M unsell soil Color Chart or Rock ColorC~~rt, " " , < , ' , . ' 3.2AStn~llhll'ild lens, and 3.2.5 '~6c~et penetrometer or shear gauge.
'''.'Sampli~~}'
4"IAthe sa~~le shall be considered to be 1.2 This recommended practice: is to 'A;e ->represenfd;live orthe stratum from which it was used not only for ide-ntificatio l1 .of:;s-oils in t~t;:: ;obtain~d-'by an appropriate accepted or standard procedure. field_but als_O _i~_ Jhe office_ or hl the l_aborato~y or_---_r',~erever- _~-()i,! _ :sam-ples-~_:--are in:~~_t~"?,., an,a-NOTE 3-Preferably the sampling procedure should be identified as having been conducted in descnbed.,;,>' ";/",,. with ASTM Method D 1452, for Soil 1_-,l.I The pra~(t4~ has;~p~:~_ticular ~~Iue in accordance Investigation and Sampling by Auger Borings,l groupil1g similar:_ s~i-" samrl:le;s:so that .only a ASTM Method 0 1586, for Penetration Test and Split-Barrel Sampling of Soils,2 ASTM Method 0 minimum number-~~ laboratory tests need be 15S7 for Thin-Walled Tube Sampling of Soils. ~ etc. run for ppsitive -st!W classification. 4.2 The sample shall be carefully identified NoTE 1-~;":fhe ability to identify soils correctly is learned -h1ore readily under the guidance of ex~ as to origin. perienced personnel. but it may also be acquired systematically by comparing numerical laboratory test results for typical soils of each type with their visual and manual characteristics while pedorming the identification procedures.
2. Definitions and Description of Terms 2.1 The definitions of the soil components, boulders, cobbles, gravel, sand fines (silt and clay), organic soil, and peat are in accordance with ASTM Definitions D 653, Terms and Symbols Relating to Soil and Rock Mechanics. 2
NOTE 4-The sample identification may take the form of a boring number and sample number in conjunction with ajob number, a geologic stratum, a pedologic horizon or a location desc~iption with respect to a permanent monument, a grid system or a station number and offset with respect to a stated centerline.
5. General Procedure for Identification 5.1 On the basis of an examination of the I Thb recommt:nded pntctict: is under the jurisdiction of ASTM Committee D·IH on Soil and Rock for Engineering
Purpose~.
3. Equipment
3.1 Required Equipment:
Currt:nt edition approved Dec. 19. 1969. Originally 1966. Rcplace~ 0 2488 66 T. t Annual Book of.ASTM Standards. Parl 19.
issu~d
330
& ... 2 I. . . . . .
------·~. . . . 2. . . . . s. . . . . . . . . . .
F'
)
i
t;i 2488 characteristics of the particles wh ich make up have differently from typical inorganic soils a soil sample it is possible to assign it to one of ;,tnd the presence of relatively small amounts of organic matter should be noted wherever possi~ three primary groups. Although most soils have components representu,tjo..·1! of two or ble. Any soil which has a dark brown. dark more group!; it is usually possible to discern the gray or black color probably contains some finely divided organic material. The identifica~ most important component and assign the tion as an organic soil can usually be com~ sample to that group. A most important ploted by carefully noting the organic odor of 'distinction is made on the busis of size. lndivid~ fresh samples. If the sample Is dry it should be ual particles visible to the naked eye make up the coarse fraction and those two small to be moistened and warmed in the hand which may help to bring out the distinctive odor. seen individually make up the fine frat::tion or the fines. The organic component of soils may 5.1.4 Mixed·gralned soils are those inor~ consist of undecayed_ or partially decayed ganic or partly organic soil$ which contain twigs. leaves. needll!s. stems. roots. etC. which ml:!.terials representative of both the coarse and impart a woody or tibrous tcxturIC to the sailor fine soil fractions. A high percentage of natural soils arc rnixed~graiJled. In many of these. it may also be so finely divided that it can only be identified by its dark brown. dark gray or however. ~I';~~~.~.~;;~ extent thatone forfr.a~c;t:~lo~in~'. p black color and distinctive organic odor. be identified S.l.1 Coarse~gralned soils are those in which more than half (by weight) of the of the other As nejlrly as particles are visible to the naked eye. In l!'aking this estimate. particles coarser than 3 in. (76 mm) in diameter should be excluded. However. where such very col,trse particles can be observed in surface soils or in ' -- "within a gi~V~~t~:~~;::~y, identifying the walls of test pits an estimate Although qualitative percentage of a large volume; of soil whichiii.f', so.ne'wh,ut help[ul. positive occupied by cobbles and obtained by comparison made. This coior chart are even more independently of contains layers or patches rial smaller than 3 ' this should be noted and all 5.1. re 1,'{;;i'eplre"'"t,'thre colors should be described. If possible. color should' be descrlbe.d [or moist samples. on
~1;;:~~:~::~::Z~~n;~ a
basis of the
signiticant quantity of rganic soils are usually their bright or light colors. 5.1.3 Organic soils are those which contain significant quantities of organic matter. -Highly organic soils can readily be recognized by the presence of decayed roots. leaves. grasses and other fibrous vegetable matter in various stages of decuy. When moi~t. they have a dark brown. very dark gray or black color and a soft spongy feel. If the samples are fresh. a distinctive odor of rotting organic matter can usually be noted. Many soils are only partly organic and are io fact composed predominantly of inorganic material. Such soils. however, be~
331
NOTE 5-Charts especially prepared for describ~ ing the colors of soil and rock ure available respec~ tively. Such churts give typicul descriptive numes for the color chips and the correct M unsell color notil~ tion in terms of hue. value and chroma. Example: Pink (Moderate orange pink). 5 YR 8/4.
5.3 Soils containing'a significant amount of organic material usually have a distinctive odor of decaying vegetation-. This is especially apparent in fresh samples. but if the samples are dried the odor may often be revived by heating a moistened sample. If the soil is dark colored. the odor should be described as organlc, earthy. or none. 5.4 Whenever intact samples are described an estimate of the moisture condition should be noted. Dry materials require the addition of
D 2488 considerable moisture to attain optimum. for wooden stake more -than a few inches; howcompaction. Moist materials are near the ever, such a stake can easily be driven into optimum moisture content. Wet soils require Joose material. Obviously, this simple method cannot be used to determine the relative density drying to altain optimum moisture content and of cemented soils. saturated (very wet) soils come from below the water table. 5.7.1 The con.sistency of cohesive soils may 5.5 The structural characteristics of intact be determined in place or on undisturbed soil samples provide important clues to their samples in accordance with the identification, procedure given in Table I. The quantitative' performance as foundation materials. Whenever such samples are available or when the measure of the shear strength _is given as a .soil profile may be inspected during sampling basis for correlation with values optained from from a pit, the structur'al characteristics should pocket penetrometers or shear gauges, which be described. Stratified f!laterials consist of are often used to estimate consistency. alternating layers oJ varying types (or color). If 5.8 It is often desirable to add an ,estimate the layers are less than about 1 .. in. (6 mm.) of the classification of the soil in accordance thick, it may be described as laminalei (or with the groups used for engineer,Hlgtc,lassificavarved, if mostly fine-grained). Fissured mation (Fig. I of Method I? 2481') The group terials break along definite. planes of fracture symbol ,should be 'pla-~~J_n-~t>~le;:~theses at the with little resistance to fracturing. If the fracend of the de~~:r~pt;_~n 'in orde-r,.:t.Q}pdicate that ture planes appear polished or glossy, they the classJ_r~,~~\~-t¢1tas been estim~t.~~. should be described as slickensJded. If. a cohe6. Pr~citl~~ for Coarse-Grained Scill•. sive soil can be easily broken in,o. small >,,:_c<\ __'!-<:_',"-",'.l,;).' ___ c_ <;~" angular lumps which resist·further breakdo",n, 6.1 Select>.a'):epresentative sample-:ort!he soil the struct.ure may be described as b1ocky;_~A': -material fh~~f(lflan 3 in. (75 mm) sieve, spread lensed structure is indicated by the inclusion';'or-' {(o'ut for examInation and follow identification small pockets of different ,)c;*,lure, such a~.:· pro.cCdl,lres. <"'~small lenses of sand s~aJl~rtd~1~'r()\l~ a mass,' 6.1 :.(W()r a-c'c_~l.ate identification, the miniof clay. The presence .."cof -spe.ciaJ-: ~tfucturat !11,Ufi:i, at1i~~-nts or sample should be in accordcharacteristics such as:c.root holes,;_or,- porous ~--c-ance wjth~i.fhe following schedule: openings__ ,~~ou_ld also be--_n_oted. If ~9_:-siructural Nominal Max_imum Diameter Minimun:"I Sample Size chara~\eristics- are-
332
02488
(gap-graded). 6.3,2 Identify the soil as gravel withjines or sand with fines if the fines content is more than about 12%. 6.3.2.1 Identify the soil as borderline clean to with jines if the fines content is between about 5 and 12%. 6.3.2.2 Describe the fines as silty or cla.vey in accordance with identification procedures given under fine-grained soils. 6.4 Describe the grain shape of the sand and gravel portions of the coarse, fraction as angu~ lar, subangular, subrounded, or rounded, (see Fig. I). 6.4.1 A ngular particles have sharp edges and relatively plane sides with unpolished surfaces. 6.4.2 Subangular particles are similar to angular but have somewhat rounded edges. 6.4.3 Subrounded particles exhibit nearly plane sides but have well~rounded corners am!,'; edges. ",' 6.4.4 Rounded particles have smoothly::' ,.' curved sides and no edges. 6.5 Add appropriate" des~~ilni'yc,'\l1otes re,~':' garding maximum siz,c;,:size distrib-'ltlpn, per"", cent cobbles and boulde"fs" mineraio:g.j< color~, odor, moisUJrc.. "condition", natu"raf density. structure. ~mertt~Uon, 16satoi geol~gi~",n~me.
.',
",
'
'
".'
,:,~"",."
'
"
:"', NOTE 7 "~:lt~~,joif sample contains'ijry lumps. '·,;~t)"',experient#d 'iQperator can determine the dry :${i'cqJJh witho,uf'~reparing a pat for this particular p'(iq;O'~"The pr~s5 of molding and drying usually proiJu.~~,higher~~~itgths than are found in natural ag~regl1t~T: ~f soiJ.,:;:.The presence of high-strength wa:f~f~i()lubtc~,cementing materials. such as calcium :~ar:bOnates~",jiilay cause exceptionally high dry "$irengths but this can usuany be detected from the JJ1tensity of the reaction with dilute hydrochloric acid ~ ~ ~ ~ ~(see 5.6). andgrpup symbol. followch"ck list, Tablc,:2. 7.5.1.1 Describe as very low or none if the NQTE" 6-A compietc:-descrip-ti~bcof a river valley sampl~,tstimated to cQn~il:jn aboijr'2~~ gravel. 65% dry sample crumbles with the mere pressure of sand artd"15% silt coul4 take .the form of this handling. example: Silty Sand we~l::graded gravelly. Maximum 7.5.1.2 Describe as low if the dry sample size. 8 in. (203 mm). ab.out 5% cobbles. About 20% crumbles to powder with little finger pressure. subrounded igneous '~igravel, 65% subrounded to subangular quartz sand. and 15% low plasticity fines. 7.5.1.3 Describe as medium if considerable Light brown (7.5 YR 6/4). Moist. Dense. Stratified. finger pressure is required to powder the No reaction to He!. Alluvial sand (SM). sample. Usually, when the soil has medium dry 7. Procedure for Fine-Grained and Organic strength a smear of powder can be easily rubbed off the smooth surface of the sample. Soils 7.5.1.4 Describe as high if the sample can7.1 Select a representative sample of the not be crushed to powder by finger pressure, material for examination. See 6.1.1. even though it may be broken. Usually, when 7.2 Describe the color of the moist soil. the sample has high dry strength it is not even 7.3 Describe the odor of th.e moist soil possible to rub off a smear of powder from a (warming if necessary to intensify the odor). smooth surface of the dry sample. 7.4 Identify the soil as organic if it has a 7.5.1.5 Describe as very high if the sample black, dark brown or dark gray color (Munsell cannot be broken between the thumb and a value 4 or less, chroma 3 or less) and a hard surface. distinctive organic odor. 7.5.2 Dilatancy-Add sufficient. water, if 7.4.1 Identify the soil as highly organic if it necessary, to the other one of the samples to has predominantly a woody or fibrous texture produce a soft, but not sticky, consistency. resulting from a composition of partially de,
\
cayed leaves, twigs. needles, stems, roots. etc. Further identification is unnecessary. 7.4.2 Identify the soil as partl.1.' organic if it does not have a fibrous texture and appears to be predominantly mineral in character. Proceed with identification procedure for finegrained soils. 7.5 From the representative sample. select enough material to provide two cubes approximately I.~ in. (13 mm) in size after the gravel and coarse sand fraction has been removed. Use these samples to perform the dry strength. dilatancy and plasticity tests, 7.5.1 Dry Strength-Mold on~,'bf;the samples until it has the consiste_~oy~_or:pUlty. adding a small amount ofwatt:(ifnecessary, and form into a cube or~~IIi"Alfow th6satl!ple to dry complet~J¥jn~,~~¢;',sun: air or overntta., tempera~ ture nQk"l
'
,>. V
"
333
,
J
Smooth the soil pal in the palm of one hand with the blade of a knife or small spatula. shake horizontally, and strike the back of the hand vigorously against the other hand several limes. Note reaction. Squeeze the sample by closing the hand and note reaction. 7.5.2. I Describe the reaction as rapid if water appears on the surface during shaking and disappears quickly upon squeezing, The presence or absence-of the free water can be noted by the shiny or dull appearance of the
molded into a lump which is coherent and lough. 7.5.4 Plasticity-On the basis of its dry strength. dilatancy and toughness describe the overall plasticity as shown in Table 3. 7.6 Identify the soil as sill or cia}' with
appropriate adjectives. See Table 3. NOT'.: 8- Th e re' lat·lYe percen t age 0 r coarse and
fine-grained material ma~y be estimated by thor. oughly shaking. a mixture of soil and waler in a lest tube and then allowing the mixture to settle. The coarse particles will fall to the bottom and succes· surface. sively finer particles will be deposited with increasing time; the sand sizes will fall out of suspension in 20to 7.5.2.2 Describe the reaction as slow if vigorous tapping is required to bring water to 30 s. The relative proportions can be~e'$limated from the surface and squeezing causes little change the relative volume of each sile~"~~i1p::~ate. in appea ranee. 7.6.1 Sandy silt ha~s8cry:-lo~' dry strength or 7.5.2.3 Describe the reaction as none if the none, a reactioJl:~O {he'ditafancy. test of rapid, a test produces no visible change in the sample. plastic t_hr~_ a_g_~-;-WJlich is weal(~a~d soft, and a 7.5.3 Plastic Thread-Following the com~ signifif!:@l\~;-sand- content which--c~ri-_be noted by pletion of the dilatancy test the sample is a gr~!t(Jeel. It,-:_9,a,n be descri~d: ,as having shaped into an elongated pat and rolled by slight pl11~tJci,tr;9~-_~none. ____ ',~ hand on a smooth surface or betweeti<~he: 7.6.2 Silt has-very low to low diy-strength, a palms into a thread about I:~ in. (3 mmY-ir(-c: {eaction t~Jbe dilatancy test of rapid, and a diameter. (If the sample is too w_et to roll e;isity :plastic thread:which is weak and soft. It can be it should be spread oULint~(a-Jhin layer ~apd de~ri:b~d as-;~_~Ning slight plasticity or none. allowed to lose some: -~ate-r by ev_~porati~-".) _-7;6_~3_:;{;layey"'-'}i/t has low to medium dry Fold the sample threads and rej'otl-repeateQlystrerigthi~}a reaction to the dilatancy test of until the thread crumbles at. -a --diameter ;of - rapid to slow. and a medium stiff plastic about l'A. --in. (3 mm). The-thread will crumble---:{ thread. It can be described as having slight or near the plastic-limit. NOIe the prcs'stu:e, medium plasticity. quired to roll ounhe threadt~pecially'';ear the 7.6.4 Sandy clay has low to high dry plastk limit; also -'note thc:':$trength of the strength, a reaction to the dilatancy test of thread. After the th,tead crumbles, the pieces slow to none, and a medium stiff plastic thread shOUld-be lumped t~gether and kneaded until which may break prematurely because of the the lump crulllbles. Note the toughness of the presence of sand grains. It can be described as material during kneading. having slight or mediu'm plasticity. 7.5.3.1 Describe the thread as weak and soft 7.6.5 Silty clay has medium to high dry if. near the plastic limit, only slight pressure is strength. a reaction to the dilatancy test of very required to roll it, the thread has little or no slow to none, and a medium stiff plastic strength and after crumbling the thread pieces thread. It can be described as having slight or cannot be formed into a coherent mass. medium plasticity. 7.6.6 Clay has a high to very high dry 7.5.3.2 Describe the thread as medium stiff if. near the plastic limit, medium pressure is strength, no reaction to the dilatancy test and a required to roll it, the thread will support its very stiff plastic thread. It can be described as own weight when a few inches long, and after having high plasticity. crumbling the thread pieces can be molded into 7.6.7 Organic -silt has low to medium dry" a lump which crumbles with slight kneading. strength. a slow reaction to dilatancy test, and 7.5.3.3 Describe the thread as ver)-' stiff if, a weak and soft plastic thread. It can be near the plastic limit. considerable pressure is described as having slight plasticity. required to roll it, the thread will easily support 7.6.8 Organic c/o)' has medium to very high its own weight when several inches long. and dry strength, a reaction to the dilatancy test of after crumbling the thread pieces can be very slow to none, and a medium stiff plastic
ie-
334
02488 thread. It can be described as having medium or high plasticity. 7.7 Add appropriate descriptive notes re~ garding maximum size. size distribution, per· cent cobbles and boulders. plasticity of fines. color, odor. moisture condition. consistency, structure, cementation, local or geologic name and group symbol. Follow check list, Table 4.
TABLE I
H,rn
•
Identineation or Consistency or Fine-Grllined Soils From Manual Tests Shear Strength, tons/ftor kg/cm 1
Identification Procedure
Consistency
Sort Firm (medium) Stiff Very stiff
NOTE 9~A complete description of an undisturbed sample of a windblown silt could take the form of this example: Clayey silt. some fine sand .. Maximum size about 0.1 mm. About 10% fine sand, 90% slightly plastic fines. Yellowish brown (10 YR S/6dry). Dry. Firm. Nonstratificd. but with numer· ous vertical root hotes. Strong reaction to He!. Loess (ML).
Easily penetrated several inches by thumb Penetrated several inches by thumb with moderate effort Readily indented by thumb, but penetrated only with great effort Readily indented by thumb nail Indented with difficulty by thumbnail
TABLE 2
less than 0.25 0.25 t~,Qi;~: O).~.t~H.:.:
,~ .."iJlOtol.00
, .<~iltt-'2.00
Check Lisl For Description orco.~~~S~ils
Boulders Cobbles Gravel Sand ",~j .~:., Add descriptive adjectives ror minor constituents. .' ·.... '-;"Y!'~"'~" i-"o.;;,/\~:-;o 2. Gradation 'Well gr:lded Poorly graded ,~'::~iyniformly gradaf:~t:\~~lrliHed) , Describe mnge of particle sizes or predominant si~.~~~.r':s!~.as coarse.--m.tiIJlfm. or fine sand or gravel. 3. Maximum Panjcle Size Note percent boulders ap~~~lib~b., '<.~,.-,\~_ 4 Siu Distrihuti(Jn ~ppraximate percent gravel. syi:dl;'an!t;~fjn!~~)n frac~'i~ij:~;"Jler than 3 in. (16 mm). Indicate I. Typical Name
\
Groi!I~~!~~Y fin~~~:~;r1:~:)'ifihti~i~~~_.
Su'ij:~~~ded "'<:j:'i~09ndedU~:}~
5. of _. 6. Mineralogy Rock tY,~--Jqt-,'gravel. prti1~~~:inant mi~,~r.~s iJl.~sltn4,.~"~};:.~:"~h 'i' Note especially preseticc.of mica nakcis.-'5~aly particlCS?~"4 _ j)fgal1ic m-;a:tclial. 1. Color USt:.Munsell ootillion. ifpo~.$ib.le:' ' 8. Odor _ ., ...·f'.I~ne,~--,,~.. Eartby-~_ Orgatlil{ .td~f.~ negtC:C;!.ettt}~cepl (Of da;rk,.:~lottcf$Qil~: 9. l!I~OI~!t. content ' :."Dry ..' .Moist "',Wet)'!!. 'Saturated 10. Nii'JtraJ D~nsj()' . '~~e ' :~:-::-~nse ' .~;:~" II. Si11fcYI.te. . Stratifitd' Le.~:~, Nonstratified 12. Cem~!f(tl~on Weit.k: i'.. ': Stro~~'~L N'~i~f,~action with..':HCI.as nonei.weak or strong.
:< ...
13. Local lih--.(J,bJlogic NoJiJi"', ' 14. Group
S'-!JM{
'~eliHmate if desired. See Classification Chari, Fig. I. ASTM Method D 2487.
TABLE 3
Idenllfication or Fine-Grained Soil Fractions From Manual Tesls
Typical Name
Dry Strength
Sandy sUt Silt Clayey silt Sandy clay Silty clay Clay Organic silt Organic clay
none-very low very low-low low-medium low-high medium-high high-very high low-medium medium-very high
Dilatancy Reaction
Toughness of Plastic Thread
rapid rapid rapid-slOW slow-none slow-none none slow none
~ The term low may be substituted for slight in the description of plasticity·.
335
weak-sofi weak-sofi medium stiff medium stiff medium stiff very stiff weak-soft medium stiff
Plasticity~
Description none-slight none-slight slight-medium slight-medium slight-medium high slight medium-high
'.
q~l~ TABLE..
0 2488
Check List For Description of Fine-Grained And Partly-Organic Soils
Sandy Clay Sandy Silt Silt Clayey Silt Organic Clay Silty Clay Clay Organic Silt Maximum' Particle Siu Note percentage of boulders and cobbles. Siu Distribwtion Approximate percent gravel. sand and lines in fraction finer than 3 in. (76 mm) Dr,r Strength None Very Low Low Medium High Very Hi~h Dilatanc,r None Slow Rapid Pla,Hic Thread Weak and Soft Mediutn Stiff Very Stiff Plasticity 0/ Fines None Slight (low) Medium High Color Use Munsell notation. if possible. Note presence of mottling or banding. Odor None Earthy Organic May be neglected except for dark-colored soils. Moisture COn/ent Dry Moist Wet Saturated Consistency Soft Firm (Medium) Stiff Very Stifr Structure Stratilied Laminated (ValVed) Fissured Slickensided Blocky Lensed Homogeneous (Nonstratified) Cementation Weak Strong Note reaction with dilute hydrochloric acid as none. weak or stron,g. Local or Ge%gic Name Spllbo/ Estimate if desired. See Classification Chart. Fig. I, ASTM
I. Typical Name
2. 3. 4. 5. 6. 7. 8. 9. 10. II. 12
13. 14. IS.
H,w
,- '
.~
(b)Angular Id) Subangular
(3) Rounded (el Subrounded
FIG. 1 Typical Shapes of Bulky Grains.
The American Society for Tesl;nR and Maleria/.f takes no position rl!SpeclinR the validity of any parent rights asserted in connection with an), item mt'ntioned in this standard. Users of this standard are expreniy advised thai determination a/the _validity of any such palt?nt right,f. and the risk of infringement of such righls. is enll'rel)' their own responsibility.
336
.
