Table Of ContentFundamentals of
Geotechnical Engineering
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Fundamentals of
Geotechnical Engineering
THIRD EDITION
Braja M. Das
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Fundamentals of Geotechnical Engineering, Third Edition
by Braja M. Das
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Preface
Principles of Foundation Engineering and Principles of Geotechnical Engineering
were originally published in 1984 and 1985, respectively. These texts were well
received by instructors, students, and practitioners alike. Depending on the needs of
the users, the texts were revised and are presently in their sixth editions.
Toward the latter part of 1998, there were several requests to prepare a single
volume that was concise in nature but combined the essential components of Principles
of Foundation EngineeringandPrinciples of Geotechnical Engineering. In response to
those requests, the first edition of Fundamentals of Geotechnical Engineering was
published in 2000, followed by the second edition in 2004 with a 2005 copyright. These
editions include the fundamental concepts of soil mechanics as well as foundation
engineering, including bearing capacity and settlement of shallow foundations (spread
footings and mats), retaining walls, braced cuts, piles, and drilled shafts.
This third edition has been revised and prepared based on comments received
from the users. As in the previous editions, SI units are used throughout the text.
This edition consists of 14 chapters. The major changes from the second edition
include the following:
• The majority of example problems and homework problems are new.
• Chapter 2 on “Soil Deposits and Grain-Size Analysis” has an expanded discus-
sion on residual soil, alluvial soil, lacustrine deposits, glacial deposits, aeolian
deposits, and organic soil.
• Chapter 3 on “Weight-Volume Relationships, Plasticity, and Soil Classification”
includes recently published relationships for maximum and minimum void ratios
as they relate to the estimation of relative density of granular soils. The fall cone
method to determine liquid and plastic limits has been added.
• Recently published empirical relationships to estimate the maximum unit weight
and optimum moisture content of granular and cohesive soils are included in
Chapter 4 on “Soil Compaction.”
• Procedures to estimate the hydraulic conductivity of granular soil using the
results of grain-size analysis via the Kozeny-Carman equation are provided in
Chapter 5, “Hydraulic Conductivity and Seepage.”
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viii Preface
• Chapter 6 on “Stresses in a Soil Mass” has new sections on Westergaard’s solu-
tion for vertical stress due to point load, line load of finite length, and rectangu-
larly loaded area.
• Additional correlations for the degree of consolidation, time factor, and coeffi-
cient of secondary consolidation are provided in Chapter 7 on “Consolidation.”
• Chapter 8 on “Shear Strength of Soil” has extended discussions on sensitivity,
thixotropy, and anisotropy of clays.
• Spencer’s solution for stability of simple slopes with steady-state seepage has
been added in Chapter 9 on “Slope Stability.”
• Recently developed correlations between relative density and corrected stan-
dard penetration number, as well as angle of friction and cone penetration
resistance have been included in Chapter 10 on “Subsurface Exploration.”
• Chapter 11 on “Lateral Earth Pressure” now has graphs and tables required to
estimate passive earth pressure using the solution of Caquot and Kerisel.
• Elastic settlement calculation for shallow foundations on granular soil using the
strain-influence factor has been incorporated into Chapter 12 on “Shallow
Foundations––Bearing Capacity and Settlement.”
• Design procedures for mechanically stabilized earth retaining walls is included
in Chapter 12 on “Retaining Walls and Braced Cuts.”
It is important to emphasize the difference between soil mechanics and founda-
tion engineering in the classroom. Soil mechanics is the branch of engineering that
involves the study of the properties of soils and their behavior under stresses and strains
under idealized conditions. Foundation engineering applies the principles of soil
mechanics and geology in the plan, design, and construction of foundations for build-
ings, highways, dams, and so forth. Approximations and deviations from idealized con-
ditions of soil mechanics become necessary for proper foundation design because, in
most cases, natural soil deposits are not homogeneous. However, if a structure is to
function properly, these approximations can be made only by an engineer who has a
good background in soil mechanics. This book provides that background.
Fundamentals of Geotechnical Engineering is abundantly illustrated to help
students understand the material. Several examples are included in each chapter. At
the end of each chapter, problems are provided for homework assignment, and they
are all in SI units.
My wife, Janice, has been a constant source of inspiration and help in com-
pleting the project. I would also like to thank Christopher Carson, General Manager,
and Hilda Gowans, Senior Development Editor, of Thomson Engineering for their
encouragement, help, and understanding throughout the preparation and publica-
tion of the manuscript.
BRAJAM. DAS
Henderson, Nevada
Contents
1 Geotechnical Engineering—A Historical Perspective 1
1.1 Geotechnical Engineering Prior to the 18thCentury 1
1.2 Preclassical Period of Soil Mechanics (1700–1776) 4
1.3 Classical Soil Mechanics—Phase I (1776–1856) 5
1.4 Classical Soil Mechanics—Phase II (1856–1910) 5
1.5 Modern Soil Mechanics (1910–1927) 6
1.6 Geotechnical Engineering after 1927 7
References 11
2 Soil Deposits and Grain-Size Analysis 13
2.1 Natural Soil Deposits-General 13
2.2 Residual Soil 14
2.3 Gravity Transported Soil 14
2.4 Alluvial Deposits 14
2.5 Lacustrine Deposits 16
2.6 Glacial Deposits 17
2.7 Aeolian Soil Deposits 17
2.8 Organic Soil 18
2.9 Soil-Particle Size 19
2.10 Clay Minerals 20
2.11 Specific Gravity (G) 23
s
2.12 Mechanical Analysis of Soil 24
2.13 Effective Size, Uniformity Coefficient, and Coefficient
of Gradation 32
Problems 35
References 37
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