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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
An essential guide to improving preliminary geotechnical analysis and design from limited data
Soil Properties and their Correlations, Second Edition provides a summary of commonly-used soil engineering properties and gives a wide range of correlations between the various properties, presented in the context of how they will be used in geotechnical design.
The book is divided into 11 chapters: Commonly-measured properties; Grading and plasticity; Density; Permeability, Consolidation and settlement; Shear strength; California bearing ratio; Shrinkage and swelling characteristics; Frost susceptibility; Susceptibility to combustion; and Soil-structure interfaces. In addition, there are two appendices: Soil classification systems; and Sampling methods.
This new, more comprehensive, edition provides material that would be of practical assistance to those faced with the problem of having to estimate soil behaviour from little or no laboratory test data.
Key features:
- Soil properties explained in practical terms.
- A large number of correlations between different soil properties.
- A valuable aid for assessing design values of properties.
- Clear statements on practical limitations and accuracy.
An invaluable source of reference for experienced professionals working on geotechnical design, it will also give students and early-career engineers an in-depth appreciation of the appropriate use of each property and the pitfalls to avoid.
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Veröffentlichungsjahr: 2016
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Table of Contents
Cover
Title Page
Preface
Acknowledgements
List of Symbols
List of Property Values and Correlations in the Tables and Figures
1 Commonly Measured Properties
1.1 Moisture Content
1.2 Grading
1.3 Plasticity
1.4 Specific Gravity of Soil Particles
1.5 Soil Density
1.6 Permeability
1.7 Consolidation
1.8 Shear Strength
1.9 Standard Compaction Test
1.10 California Bearing Ratio
1.11 Other Properties
References
2 Grading and Plasticity
2.1 Grading
2.2 Plasticity
References
3 Density
3.1 Density in the Context of Soils
3.2 Compacted Density
3.3 Relative Density
References
4 Permeability
4.1 Effects of Soil Macro‐Structure
4.2 Typical Values
4.3 Permeability and Grading
References
5 Consolidation and Settlement
5.1 Compressibility of Clays
5.2 Rate of Consolidation of Clays
5.3 Secondary Compression
5.4 Settlement of Sands and Gravels
5.5 Assessment of Settlement Parameters from Static Cone Penetration Testing
References
6 Shear Strength
6.1 Stresses Within a Material
6.2 Shear Strength in Soils
6.3 The Choice of Total or Effective Stress Analysis
6.4 Peak, Residual and Constant‐Volume Shear Strength
6.5 Undrained Shear Strength of Clays
6.6 Drained and Effective Shear Strength of Clays
6.7 Shear Strength of Granular Soils
References
7 California Bearing Ratio
7.1 Correlations with Soil Classification Tests
7.2 Correlations with Soil Classification Systems
7.3 CBR and Undrained Shear Strength
7.4 An Alternative to CBR Testing
References
8 Shrinkage and Swelling Characteristics
8.1 Identification
8.2 Swelling Potential
8.3 Swelling Pressure
References
9 Frost Susceptibility
9.1 Ice Segregation
9.2 Direct Measurement of Frost Susceptibility
9.3 Indirect Assessment of Frost Susceptibility
9.4 Choosing a Suitable Method of Evaluating Frost Susceptibility
References
10 Susceptibility to Combustion
Reference
11 Soil-Structure Interfaces
11.1 Lateral Pressures in a Soil Mass
11.2 Friction and Adhesion at Interfaces
References
Appendix A: Soil Classification Systems
A.1 Systems Based on the Casagrande System
A.2 The AASHTO System
A.3 Comparison of the Unified, AASHTO and BS Systems
References
Appendix B: Sampling Methods
B.1 Pits and Borings
B.2 Sampling and Samplers
B.3 Probes
Reference
Index
End User License Agreement
List of Tables
Chapter 03
Table 3.1 Typical values of natural density.
Table 3.2 Typical compacted densities and optimum moisture contents for soil types using the Unified soil classification system. Adapted from Al‐Hussaini and Townsend (1975).
Table 3.3 Typical compacted densities and optimum moisture contents for soil types using the AASHTO soil classification system. Adapted from Gregg (1960).
Table 3.4 Relative density descriptions and correlation with SPT
N
‐values in sands and gravels.
Table 3.5 Summary of published SPT correction factors for overburden pressure.
Table 3.6 Summary of rod energy ratios for standard penetration tests. Adapted from Skempton (1986).
Table 3.7 Approximate corrections
A
to measured SPT
N
‐values. Adapted from BS (2011).
Chapter 04
Table 4.1 Typical values of permeability. Adapted from Krebs and Walker (1971).
Chapter 05
Table 5.1 Typical values of the coefficient of volume compressibility
m
v
and the descriptive terms used.
Table 5.2 Some published correlations for compression index
C
c.
Reproduced from Azzouz
et al
. (1976).
Table 5.3 Typical values of the coefficient of consolidation
c
v
. Adapted from Holtz & Kovacs (1981).
Table 5.4 Typical values of the ratio of secondary compression index to compression index. Adapted from Mesri and Godlewski (1977).
Table 5.5 Typical values of coefficient α used to estimate
m
v
values from static cone penetration testing. Reproduced from Meigh (1987).
Chapter 06
Table 6.1 Typical values of the undrained shear strength of compacted soils.
Table 6.2 Values of undrained shear strength based on consistency descriptions.
Table 6.3 Typical values of the effective angle of shearing resistance of compacted clays.
Table 6.4 Typical values of the angle of shearing resistance of cohesionless soils.
Table 6.5 Typical values of the angle of shearing resistance of compacted sands and gravels.
Chapter 07
Table 7.1 Some variations that can affect CBR test results.
Table 7.2 Estimated CBR values for British soils compacted at the natural moisture content. Adapted from TRRL (1970).
Chapter 08
Table 8.1 Free swelling data for clay minerals.
Table 8.2 Typical Atterberg limit values for common clay minerals.
Table 8.3 Descriptive terms for swelling potential.
Table 8.4 Identification of swelling soils based on plasticity index.
Table 8.5 Suggested guide to the determination of potential for expansion using shrinkage limit and linear shrinkage. Adapted from Altmeyer (1955).
Table 8.6 Estimation of potential volume changes of clays. Adapted from Holtz and Gibbs (1956). Reproduced with permission of American Society of Civil Engineers.
Table 8.7 Estimating probable swelling pressure. Adapted from Chen (1988). Reproduced with permission of Elsevier.
Chapter 09
Table 9.1 Preliminary identification of frost susceptible soils. Adapted from TRRL (1970).
Table 9.2 Frost susceptibility of soils related to soil classification. Adapted from US Army Corps of Engineers (1965).
Chapter 11
Table 11.1 Typical values of friction and adhesion at interfaces. Adapted from US Naval Publications and Forms Center, US Navy (1982).
Table 11.2 Values of
K
s
and δ for driven piles. Adapted from Broms (1979).
Appendix A
Table A1 The Unified soil classification system.
Table A2 The Unified soil classification system. Extended soil groupings for coarse‐grained soils defined by specific laboratory test values, as used in ASTM D2487.
Table A3 The Unified soil classification system. Extended soil groupings for fine‐grained soils defined by specific laboratory test values as used in ASTM D2487.
Table A4 The British Standard soil classification system.
Table A5 Description of soil types in the AASHTO soil classification system.Classification of materials in the various groups applies only to the fraction passing the 75 mm sieve. The proportions of boulder‐ and cobble‐sized particles should be recorded separately and any specification regarding the use or A‐1, A‐2 or A‐3 materials in construction should state whether boulders are permitted.
Table A6 The AASHTO soil classification system.
Table A7 Comparison of soil groups in the Unified and British Standard soil classification systems.
Table A8 Comparison of soil groups in the Unified and AASHTO soil classification systems.
Appendix B
Table B1 Standard cone sizes and attributes.
List of Illustrations
Chapter 01
Figure 1.1 Nested sieves.
Figure 1.2 Casagrande liquid limit apparatus.
Figure 1.3 Cone penetrometer liquid limit apparatus.
Figure 1.4 Specific gravity determination jars: (a) gas jar with stopper and glass plate; (b) pkynometer; and (c) specific gravity bottle.
Figure 1.5 Sand replacement method equipment.
Figure 1.6 Nuclear density meter modes of operation: (a) direct transmission mode; and (b) backscatter mode.
Figure 1.7 Basic layout of the falling head permeameter.
Figure 1.8 Basic layout of the constant head permeameter.
Figure 1.9 Consolidation test equipment.
Figure 1.10 Triaxial test equipment.
Figure 1.11 Example of a Mohr circle plot.
Figure 1.12 Schematic arrangement of a shear box.
Figure 1.13 Shear test types and typical uses.
Figure 1.14 Standard compaction test equipment.
Figure 1.15 Test arrangement for CBR.
Chapter 02
Figure 2.1 Some common definitions of soils, classified by particle size.
Figure 2.2 Principal features of a grading chart.
Figure 2.3 Electrochemical bonding between clay mineral particles and the resulting microstructures: (a) electrochemical charges within a clay; (b) semi‐orientated (or dispersed) structure; and (c) flocculated structure.
Figure 2.4 Consistency limits: (a) change from liquid to solid as a soil dries out; and (b) volume and consistency changes with water content change.
Figure 2.5 Plasticity chart.
Chapter 03
Figure 3.1 Theoretical relationships between density, porosity, voids ratio and moisture content.
Figure 3.2 Relationship between dry density, moisture content and percentage of air voids.
Figure 3.3 Type of density–moisture relationship obtained in the standard compaction test with some sands.
Figure 3.4 Relationships between optimum moisture content, maximum dry density and plastic limit for red tropical soils.
Figure 3.5 Typical moisture–density curves for rapid determination of maximum dry density and optimum moisture content.
Figure 3.6 Plots of SPT correction factors for overburden depth.
Figure 3.7 Relationships between cone resistance and vertical effective stress for different relative densities
D
r
.
Figure 3.8 CPT–SPT correlation with grain size.
Chapter 04
Figure 4.1 Typical permeability values for soils.
Figure 4.2 Permeability of sands and gravels.
Chapter 05
Figure 5.1 Basic features of plots of compressibility test results.
Figure 5.2 The compression process in terms of the model soil sample.
Figure 5.3 Correlation of coefficient of volume compressibility
m
v
with plasticity index and SPT
N
‐value.
Figure 5.4 Typical values of factor
μ
for a foundation of width
b
on a compressible layer of thickness
H
.
Figure 5.5 Typical values of consolidation factor
μ
for various types of soil.
Figure 5.6 Typical values of time factor
T
V
.
Figure 5.7 Approximate correlations between the coefficient of consolidation and liquid limit.
Figure 5.8 Plotting and calculation of secondary compression.
Figure 5.9 Correlation between modified secondary compression index and natural moisture content.
Figure 5.10 Approximate correlation between moisture content and the modified coefficient of secondary compression.
Figure 5.11 Chart for estimating allowable bearing pressures on sand from standard penetration test results.
Figure 5.12 Chart for estimating allowable bearing pressures on sand from standard penetration test results based on recommendations by Bowles (1982).
Figure 5.13 Correlation between influence factor
I
c
and SPT
N
‐value for estimating settlements on sand using the method of Burland and Burbridge (1985).
Figure 5.14 Correlation between deformation modulus
M
and SPT
N
‐value for granular soils based on recommendations by Menzenbach (1967).
Figure 5.15 (a) Estimation of coefficient of consolidation from piezocone values. (b) Estimation of rigidity index for use in chart (a).
Chapter 06
Figure 6.1 Stresses within a material and the Mohr circle construction: (a) stresses on a block of material; (b) resolution of stresses in relation to a sloping plane; (c) geometry of a circle in Cartesian co‐ordinates; and (d) the Mohr circle representation of stresses.
Figure 6.2 Examples of the principal stresses: (a) next to a smooth cantilever retaining wall; and (b) in a triaxial test specimen.
Figure 6.3 Mohr diagram representations of stress and failure criteria: (a) a generalised
c‐φ
soil; (b) a purely frictional soil; and (c) a purely cohesive soil.
Figure 6.4 Correlations between remoulded shear strength and liquidity index.
Figure 6.5 Correlation between sensitivity and liquidity index.
Figure 6.6 Relationship between the ratio of undrained shear strength to effective overburden pressure and plasticity index for normally consolidated clays.
Figure 6.7 Correlations between shear strength and liquidity index.
Figure 6.8 Correction factor for field vane test results depending on plasticity index, based on back‐analysis of embankment failures.
Figure 6.9 Approximate correlations between undrained shear strength and SPT
N
‐values.
Figure 6.10 Correlation between undrained shear strength, SPT
N
‐value and plasticity index for overconsolidated clays.
Figure 6.11 Correlations between effective angle of shearing resistance and plasticity index.
Figure 6.12 Typical values of density and angle of shearing resistance for cohesionless soils.
Figure 6.13 Estimation of the angle of shearing resistance of granular soils from standard penetration test results.
Figure 6.14 Examples of relationships between relative density and angle of shearing resistance.
Chapter 07
Figure 7.1 Relationship between CBR and plasticity index for various consistency index values.
Figure 7.2 Correction of CBR values for partial saturation.
Figure 7.3 Relationship between suitability index and soaked CBR values.
Figure 7.4 Relationship between the ratio of maximum dry density to plasticity index and CBR for laterite–quartz gravels.
Figure 7.5 Correlations of plasticity index, maximum dry density and optimum moisture content with CBR.
Figure 7.6 Approximate relationships between Unified soil classes and CBR values.
Figure 7.7 Approximate relationships between AASHTO soil classes and CBR values.
Figure 7.8 Relationship between California Bearing Ratio and modulus of subgrade reaction.
Chapter 08
Figure 8.1 A comparison of various correlations between swelling potential and plasticity index.
Figure 8.2 Classification chart for swelling potential.
Figure 8.3 Simplified relationship between plasticity index and clay content.
Figure 8.4 Relationships between volume change and colloid content, plasticity index and shrinkage limit, for air‐dry to saturated conditions under a load of 6.9 kPa.
Figure 8.5 Relationship between swell index and swelling pressure for a range of liquid limits.
Chapter 09
Figure 9.1 Mechanisms of ice lens formation.
Figure 9.2 The influence of permeability and capillary action on frost susceptibility of soils.
Figure 9.3 Relationship between the average rate of frost heave and the percentage of soil particles finer than 20 μm.
Figure 9.4 A selection of proposed limits of frost susceptibility based on grading according to (a) Beskow (1935) for Denmark, Greenland and Sweden; (b) Armstrong and Csathy (1963) for Canada; and (c) Croney (1949) for UK.
Figure 9.5 Average rate of heave plotted against percentage finer than 20 μm from laboratory tests of a range of natural soils.
Chapter 10
Figure 10.1 Correlation between calorific value and mass loss on ignition.
Chapter 11
Figure 11.1 Correlation between coefficient of earth pressure at rest and angle of shearing resistance for normally consolidated sands.
Figure 11.2 Correlation between coefficient of earth pressure at rest and angle of shearing resistance for normally consolidated clays.
Figure 11.3 Correlations between coefficient of earth pressure at rest and plasticity index.
Figure 11.4 Correlation between the coefficient of earth pressure at rest and overconsolidation ratio for clays of various plasticity indices.
Appendix A
Figure A1 Plasticity chart for the Unified/ASTM soil classification system.
Figure A2 Plasticity chart for the British Standard soil classification system.
Appendix B
Figure B1 Light cable percussive rig and tools.
Figure B2 Portable rotary power auger.
Figure B3 Schematics of open drive samplers.
Figure B4 Principles of the piston sampler.
Figure B5 Split spoon sampler and cone attachment.
Figure B6 Schematic arrangement of standard penetration test equipment in borehole.
Figure B7 Principal features of a static cone.
Figure B8 Soil identification based on cone resistance and friction ratio of static cone tests.
Guide
Cover
Table of Contents
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SOIL PROPERTIES AND THEIR CORRELATIONS
SECOND EDITION
Michael Carter
Geotechnical Consultant (Retired), UK
Stephen P. Bentley
Cardiff University, UK
This edition first published 2016© 2016 John Wiley & Sons, Ltd
First Edition published in 1991
Registered OfficeJohn Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom
For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com.
The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.
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Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book.
Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. It is sold on the understanding that the publisher is not engaged in rendering professional services and neither the publisher nor the author shall be liable for damages arising herefrom. If professional advice or other expert assistance is required, the services of a competent professional should be sought.
Library of Congress Cataloging‐in‐Publication Data
Names: Carter, Michael, author. | Bentley, Stephen P., author.Title: Soil properties and their correlations / Michael Carter and Stephen P. Bentley, Cardiff University, UK.Description: Second edition. | Chichester, West Sussex, United Kingdom : John Wiley & Sons, Inc., 2016. | Includes bibliographical references and index.Identifiers: LCCN 2016013755 (print) | LCCN 2016014304 (ebook) | ISBN 9781119130871 (cloth) | ISBN 9781119130901 (pdf) | ISBN 9781119130895 (epub)Subjects: LCSH: Soil mechanics.Classification: LCC TA710 .B4285 2016 (print) | LCC TA710 (ebook) | DDC 624.1/5136–dc23LC record available at http://lccn.loc.gov/2016013755
A catalogue record for this book is available from the British Library.
Preface
The aims of this book are to provide a summary and discussion of commonly used soil engineering properties and to give correlations of various engineering properties.
The book includes:
a compendium of published correlations;
discussions of the reliability, accuracy and usefulness of the various correlations;
practical advice on how soil properties are used in the assessment and design of geotechnical problems, including basic concepts, and limitations on their use that need to be considered; and
descriptions of the measurement of soil properties, and how results are affected by the method of measurement and the expertise of technicians carrying out the testing.
A consideration in describing the various properties has been an awareness by the authors that many geotechnical engineers and engineering geologists have little, if any, hands‐on experience of laboratory testing, and are often unaware of the procedures used to obtain the various soil properties and of the effects of poor or inappropriate practice.
The properties are also described in relation to their use in geotechnical analysis, in a way that we hope will give students and younger engineers an in‐depth appreciation of the appropriate use of each property and the pitfalls to avoid, and should also provide a useful reminder to more experienced professionals.
Many soil correlations were established in the early decades of soil mechanics, with there being no need to repeat the work once correlations had been established and verified by sufficient researchers. As a consequence, the correlations given in this book span a wide range of time, a few as far back as the 1930s, but we have also presented more recent work where this adds useful information. However, our intention in selecting correlations is to present those that will be of wide practical application, and the book is not intended as a research review. To aid their use in spreadsheet calculations, we have derived mathematical expressions to fit many of the correlations that were originally given only graphically. We have also tried to keep the work independent of national design codes, but it inevitably contains references to practices that are more prevalent in the English‐speaking world. Where references are made to classification systems and associated codes we have, where possible, included references to both UK and US practice.
We envisage and recommend that correlations be used in two ways: firstly, to obtain values of a property that has not been measured; and secondly, to provide additional values where some direct measurements of the property have been made. In the first case, where no values of a particular property have been directly measured, the values obtained from correlations should be viewed with caution and treated as preliminary, especially where the property value is critical to the predicted performance of a design. Where correlations are used in combination with direct measurements to provide supplementary values, the accuracy and reliability of the correlations can usually be verified, fine‐tuning the correlation if necessary, which may allow the values obtained by correlation to be viewed with more confidence.
While every care has been taken in the preparation of this book, with the very large amount of information that has been assembled it is possible that some errors have occurred; users should satisfy themselves that the information presented is correct. The authors can take no responsibility for consequences resulting from any errors in the book. The views expressed about the reliability and accuracy of correlations, typical values and other published information are based on the authors’ own experience and may not accord with those of other geotechnical specialists.
Acknowledgements
In creating a compendium of published correlations, we had to seek permission from many authors around the globe; for her role in this important and painstaking task, the authors would like to thank Carol Clark. Bringing together such a large number of disparate items of information from many sources also involved a great deal of checking, and our thanks go to ex‐colleagues Jason Williams and Max Lundie for their checking of some of the work, and especially to Mark Campbell who read through the entire script, noting errors and giving many helpful suggestions.
List of Symbols
Symbol
Name of variable
Typical units (SI)
*
α
A scaling factor for estimating footing settlements from plate bearing test results.
D
α
A factor for estimating values of coefficient of volume compressibility from static cone test results.
D
α
Adhesion factor, for pile calculations.
D
α
A factor used to estimate the pull‐out resistance of a soil reinforcement grid.
D
Δ
p
A distance above or below the A‐line on a standard plasticity chart.
%
θ
Angle of a plane, from the direction of maximum principle stress, on which stresses act.
Degrees
μ
Viscosity of permeant for general seepage calculations.
kN.s/m
2
ν
Poisson's ratio.
D
π
Ratio of the circumference of a circle to its diameter (≈3.14159).
D
ρ
Settlement.
m, mm
σ
Direct stress.
kPa (kN/m
2
)
σ'
Effective direct stress.
kPa (kN/m
2
)
σ
1
, σ
2
, σ
3
Maximum, intermediate and minimum principal stresses.
kPa (kN/m
2
)
σ
n
Effective earth pressure, used in soil nail calculations.
kPa (kN/m
2
)
σ
v
, σ'
v
Vertical stress, or overburden pressure, in total and effective stress terms, respectively.
kPa (kN/m
2
)
τ
Shear stress.
kPa (kN/m
2
)
γ
Bulk density of soil.
kN/m
3
γ
d
Dry density of soil.
kN/m
3
γ
dmax
Maximum dry density, for relative density calculations.
kN/m
3
γ
dmin
Minimum dry density, for relative density calculations.
kN/m
3
γ
p
Density of permeant for general seepage equation.
kN/m
4
γ
sub
Submerged density of soil.
kN/m
3
γ
w
Density of water.
kN/m
3
ϕ
Angle of shearing resistance (general, or in total stress terms).
Degrees
ϕ'
Effective stress angle of shearing resistance.
Degrees
ϕ
d
Drained angle of shearing resistance.
Degrees
ϕ
r
Residual angle of shearing resistance (general).
Degrees
a
Air voids content of soil.
%
a
Component of influence factor
I
c
for estimating settlements of footings on sands.
D
A
Area (nominal) of soil water flow.
m
2
A
A correction factor for rod energy ratio in the standard penetration test.
D
A
Percentage passing a 2.4 mm sieve, used in the calculation of suitability index.
%
A
A constant used in the estimation of swelling potential from plasticity index.
D
A
c
Activity value (of a clay).
D
A
p
End area of penetration cone in a 1standard penetration test.
mm
2
A
s
End area of penetration cone in a dynamic probe.
mm
2
a
v
Coefficient of compressibility. (See also
m
v
, coefficient of volume compressibility.)
m
2
/MN
b
Component of influence factor
I
c
for estimating settlements of footings on sands.
D
B
Footing width.
m
B
A constant used in the estimation of swelling potential from plasticity index.
D
c
Shape factor in general seepage calculations.
D
c
Cohesion.
kPa (kN/m
2
)
C
Percentage finer than 0.002 mm, used in the calculation of activity for a clay.
D
c'
Effective stress cohesion.
kPa (kN/m
2
)
C
1
Constant used in Hazen's formula to estimate the coefficient of permeability.
D
CBR
California Bearing Ratio.
%
C
c
Coefficient of curvature (coefficient of grading).
D
C
c
, C
r
Compression index, recompression index, respectively.
D
c
d
Drained cohesion.
kPa (kN/m
2
)
CI
Consistency index.
%
C
N
Correction factor for overburden pressure, applied to SPT
N
‐values.
D
c
u
Undrained cohesion, shear strength.
kPa (kN/m
2
)
C
u
Coefficient of uniformity.
D
c
v
Coefficient of consolidation.
cm
2
/s, m
2
/year
C
α
Secondary compression index.
(log
10
time)
–1
C
αε
, C'
Modified secondary compression index (sometimes referred to simply as the secondary compression index).
(log
10
time)
–1
d
Maximum length of drainage path in consolidation calculations.
m
D
Depth of foundation (when calculating allowable bearing pressures on sands).
m
D
10
The 10% particle size, also called the effective size.
mm (or μm)
D
30
, D
60
The 30% and 60% particle sizes, respectively.
mm (or μm)
D
n
The particle size at which
n
% of the material is finer. See also
D
10
,
D
30
,
D
60
.
mm (or μm)
D
r
Relative density (of granular soils).
D
D
s
An effective particle size for permeability estimates, usually taken as
D
10
.
mm
e
Voids ratio.
D
e
The natural number, approximately 2.718.
D
E
Young's modulus (also called the elastic modulus).
kPa, MPa
e
1
, e
2
Initial and final voids ratios in consolidation testing.
D
E
d
Deformation modulus (also called the constrained modulus).
kPa, MPa
e
max
Maximum voids ratio, for relative density calculations.
D
e
min
Minimum voids ratio, for relative density calculations.
D
ER
r
Rod energy ratio in standard penetration test.
D
F
The percentage passing the 75 μm sieve, used in the calculation of AASHTO classification group index.
%
f
l
, f
s
, f
t
Shape, layer thicknes and time factors, respectively, for estimating settlements of footings on sands.
D
F
p
Drop distance of monkey (falling hammer) in a dynamic probe.
mm
F
s
Drop distance of monkey (falling hammer) in a standard penetration test.
mm
G
Shear modulus.
kPa, MPa
G
s
Specific gravity of soil solids
D
h
Thickness of specimen in consolidation testing.
mm
H
Thickness of a compressible layer in consolidation testing.
m
i
Hydraulic gradient in soil water flow.
D
I
c
Influence factor for estimation of settlements of footings on sands.
D
I
r
Rigidity index, used in rate‐of‐settlement estimates based on static piezocone test results.
D
I
r
Swell index, used in the estimation of swelling pressure.
D
k
Coefficient of permeability.
m/s, m/year
K
A constant used in the estimation of swelling potential from plasticity index.
D
K
0
Coefficient of earth pressure at rest.
D
K
d
Depth factor for allowable bearing pressures on sands.
D
K
s
Earth pressure coefficient use in driven pile calculations.
D
L
Footing length.
m
LI
Liquidity index.
%
LL
Liquid limit.
%
m
Moisture (water) content of soil.
%
M
p
Mass of monkey (falling hammer) in a dynamic probe.
kg
M
s
Mass of monkey (falling hammer) in a standard penetration test.
kg
m
v
Coefficient of volume compressibility. (See also
a
v
, coefficient of compressibility.)
m
2
/MN
n
Porosity of soil.
D
n
A factor used to estimate undrained shear strength from consistency index or liquidity index.
D
N
SPT
N
‐value; blows of standard hammer to drive the SPT sampler or cone 300 mm.
Blows
N
1
SPT
N
‐value corrected for overburden pressure.
Blows
N
1(60)
SPT
N
‐value corrected for overburden pressure and to a rod energy ratio of 60%.
Blows
N
60
SPT
N
‐value corrected for rod energy ratio,
ER
r
. (the “60” refers to standardisation to 60% rod energy.)
Blows
N
corrected
SPT
N
‐value corrected for silts and fine sands below the groundwater table.
Blows
N
k
A factor used in the estimation of undrained shear strength from static cone tip resistance.
D
O
40
,
O
80
Pore diameters at which 40% and 80% of the pores are finer
mm, μm
OCR
Overconsolidation ratio.
D
p
Previous maximum overburden pressure, used in estimating settlements of footings on sands.
D
p
1
, p
2
Initial and final pressures used in a stage of consolidation testing.
kPa (kN/m
2
)
PI
Plasticity index.
%
PL
Plastic limit.
%
PM
Plasticity modulus.
%
P
p
Penetration for each blow count in a dynamic probe.
mm
P
s
Penetration for each blow count in a standard penetration test.
mm
q
Quantity of flow of water through soil per unit time.
m
3
/s, m
3
/year
q
Bearing pressure.
kPa (kN/m
2
)
q
a
Allowable bearing pressure.
MPa (MN/m
2
)
q
c
Measured cone resistance (pressure) in static cone tests.
kPa (kN/m
2
)
q
u
Ultimate bearing capacity.
kPa (kN/m
2
)
R
Component of influence factor
f
t
for estimating settlements of footings on sands.
D
S
Degree of saturation.
%
S
Swelling potential.
%
s, s
u
Undrained shear strength.
kPa (kN/m
2
)
S
t
Sensitivity
D
SL
Shrinkage limit.
%
t
Time, used in calculations or rates of consolidation and secondary compression.
s, years
t
1
, t
2
Start and end times for secondary compression calculations.
s, years
T
v
Basic time factor, used in calculations or rates of consolidation.
D
u
Pore water pressure.
kPa (kN/m
2
)
U
Degree of consolidation.
D
v
Nominal velocity of flow of water through soil.
m/s, m/year
v
t
True velocity of flow of water through soil.
m/s, m/year
W
LW
Weighted liquid limit, used in the estimation of swelling potential.
%
W
w
Weight of water (in the model soil sample).
g
Y
Rate of frost heave.
mm/day
* D = dimensionless; % values are also essentially dimensionless.
List of Property Values and Correlations in the Tables and Figures
1Commonly Measured Properties
The purpose of this chapter is to introduce the more commonly measured properties and give outline descriptions of how they are measured. This will allow engineers and geologists who are specifying test schedules, but who may have little or no experience of soils laboratory work, to have a clear understanding of the procedures used to carry out the tests they are scheduling, along with any problems that might occur. This, in turn, should help them to choose the most appropriate tests and to fully appreciate any problems or shortcomings related to the various test methods when appraising the results. It may also give an appreciation of the complexity of some tests to determine seemingly straightforward properties. For clarity, some details have been omitted; test descriptions are not intended to give definitive procedures or to be of sufficient detail to allow them to be used for actual testing. Such details should be obtained directly from the test standards being used, and will normally be the responsibility of the testing laboratory unless specific variations from the standards are required.
Deeper discussions of the nature and meaning of the various properties, and how they relate to other properties, are given at the beginning of subsequent chapters.
