Geotechnical Engineering: Principles and Practices of Soil Mechanics and Foundation Engineering (Civil and Environmental Engineering)

1048 Pages·2002·31.86 MB·English

Dedicated to the Cause of Students
FOREWORD
Geotechnical Engineering: Principles and Practices of Soil Mechanics and Foundation
Engineering is a long title befitting a major work. I am pleased to introduce this superb volume
destined for a readership of students, professors, and consultants. What makes this text different
from other books on these subjects that appear each year and why am I recommending it to you? I
have been working and teaching in the area of geotechnical engineering for 25 years. I have read
and used scores of textbooks in my classes and practice. Dr. Murthy's text is by far the most
comprehensive text I have found. You will find that his organization of the subject matter follows
a logical progression. His example problems are numerous and, like the text, start from fundamental
principles and progressively develo p into more challenging material. They ar e the best set of
example problems I have seen in a textbook. Dr. Murthy has included ample homework problems
with a range of difficult y mean t t o help the studen t new t o th e subjec t t o develop his/he r
confidence an d t o assis t th e experience d enginee r i n his/he r revie w o f th e subjec t an d in
professional development .
As the technical editor I have read the entire manuscript three times. I have been impressed by
the coverage, the clarity of the presentation, and the insights into the hows and whys of soil and
foundation behavior. Often I have been astonished at Dr. Murthy's near-conversational approach to
sharing helpful insights . You get the impression he's right there with you guiding you along,
anticipating your questions, and providing instruction and necessary information as the next steps
in the learning process. I believe you will enjoy this book and that it will receive a warm welcome
wherever it is used.
I thank Dr. Murthy for his commitment to write this textbook and for sharing his professional
experience with us. I thank him for his patience in making corrections and considering suggestions.
I thank Mr. B. J. Clark, Senior Acquisitions Editor at Marcel Dekker Inc., for the opportunity to be
associated with such a good book. I likewise express my appreciation to Professor Pierre Foray of
1'Ecole Nationale Superieure d'Hydrauliqu e et de Mecanique d e Grenoble, Institu t National
Polytechnique de Grenoble, France for his enthusiastic and unflagging support while I edited the
manuscript.
MarkT. Bowers, Ph.D., P. E.
Associate Professor of Civil Engineering
University of Cincinnati
FOREWORD
It gives me great pleasure t o write a foreword for Geotechnical Engineering: Principles and
Practices of Soil Mechanics and Foundation Engineering. This comprehensive, pertinent and up-
to-date volum e i s well suite d fo r use as a textbook fo r undergraduate student s a s well as a
reference book for consulting geotechnica l engineers an d contractors. This book is well written
with numerous examples on applications of basic principles to solve practical problems.
The early history of geotechnical engineering and the pioneering work of Karl Terzaghi in
the beginning of the last century are described in Chapter 1. Chapters 2 and 3 discuss methods of
classification of soil and rock, the chemical and the mechanical weathering of rock, and soil phase
relationships an d consistenc y limit s fo r clay s an d silts . Numerou s example s illustrat e th e
relationship between the different parameters. Soil permeability and seepage are investigated in
Chapter 4. The constructio n of flow net s and methods to determine th e permeability i n the
laboratory and in the field are also explained.
The concept of effective stress and the effect of pore water pressure on effective stress are
discussed in Chapter 5. Chapter 6 is concerned with stress increase in soil caused by surface load
and methods to calculate stress increase caused by spread footings, rafts, and pile groups. Several
examples are given in Chapter 6. Consolidation of soils and the evaluation of compressibility in
the laboratory by oedometer tests are investigated in Chapter 7. Determination of drained and
undrained shear strength by unconfined compression, direct shear or triaxial tests is treated in
Chapter 8.
The important subject of soil exploration is discussed in Chapter 9, including the use of
penetration tests such as SPT and CPT in different countries. The stability of slopes is investigated
in Chapter 10. Methods using plain and circular slip surfaces to evaluate stability are described
such a s the methods proposed b y Bishop, Fellenius, Morgenstern, an d Spencer. Chapte r 1 1
discusses methods to determine active and passive earth pressures acting on retaining and sheet
pile walls.
Bearing capacity and settlement of foundation and the evaluation of compressibility in the
laboratory by oedometer tests are discussed in Chapters 12, 13, and 14. The effect of inclination
and eccentricity of the load on bearing capacity is also examined. Chapter 15 describes differen t
pile types, the concept of critical depth, methods to evaluate the bearing capacity of piles in
cohesive and cohesionless soils, and pile-driving formulae. The behavior of laterally loaded piles
is investigated in Chapter 16 for piles in sand and in clay. The behavior of drilled pier foundations
VII
viii Forewor d
and the effect of the installation method on bearing capacity and uplift are analyzed in Chapter 17.
Foundations on swelling and collapsible soils are treated in Chapter 18 as are methods that can be
used to reduce heave. This is an important subject, seldom treated in textbooks. The design of
retaining walls is covered in Chapter 19 , as well as the different factors that affect active and
passive earth pressures. Different applications of geotextiles are covered in this chapter as well as
the topic of reinforced earth. Cantilever, anchored, and strutted sheet pile walls are investigated in
Chapter 20 , a s are methods to evaluate stability an d the moment distribution. Different soil
improvement methods , suc h a s compactio n o f granula r soils , san d compactio n piles ,
vibroflotation, preloading , an d stone columns , are described in Chapter 21. The chapte r als o
discusses lime and cement stabilization. Appendix A provides a list of SI units, and Appendix B
compares methods that have been proposed .
This textbook by Prof. V. N. S. Murthy is highly recommended fo r students specializing in
geotechnical engineering and for practicing civil engineers in the United States and Europe. The
book include s recent development s suc h as soil improvement an d stabilizatio n methods an d
applications of geotextiles to control settlements and lateral earth pressure. Numerous graphs and
examples illustrat e the mos t importan t concept s i n geotechnica l engineering . Thi s textboo k
should serve as a valuable reference book for many years to come.
BengtB.Broms, Ph.D.
Nanyang Technical University, Singapore (retired).
PREFACE
This book has the following objectives:
1. T o explain the fundamentals of the subject from theory to practice in a logical way
2. T o be comprehensive and meet the requirements of undergraduate students
3. T o serve as a foundation course for graduate students pursuing advanced knowledge in the
subject
There are 21 chapters in this book. The first chapter traces the historical background of the
subject and the second deals with the formation and mineralogical composition of soils. Chapter 3
covers the index properties and classification of soil. Chapters 4 and 5 explain soil permeability,
seepage, and the effect of water on stress conditions in soil. Stresses developed in soil due to
imposed surfac e loads , compressibilit y an d consolidatio n characteristics , an d shea r strengt h
characteristics of soil are dealt with in Chapters 6,7, and 8 respectively. The first eight chapters
develop the necessary tools for computing compressibility and strength characteristics of soils.
Chapter 9 deals with methods for obtainig soil samples in the field for laboratory tests and for
determining soil parameters directly by use of field tests. Chapters 1 0 to 20 deal with stability
problems pertaining to earth embankments, retaining walls, and foundations. Chapter 21 explains
the various methods by which soil in situ can be improved. Many geotechnical engineers have not
appreciated the importance of this subject. No amount of sophistication in the development of
theories will help the designers if the soil parameters used in the theory are not properly evaluated
to simulate field conditions. Professors who teach this subject should stress this topic.
The chapters in this book are arranged in a logical way for the development of the subject
matter. There is a smooth transition from one chapter to the next and the continuity of the material
is maintained. Each chapter starts with an introduction to the subject matter, develops the theory,
and explains its application to practical problems. Sufficien t example s are wor1:ed out to help
students understand the significance of the theories. Many homework problems are given at the
end of each chapter.
The subjec t matte r deal t wit h i n eac h chapte r i s restricte d t o th e requirement s o f
undergraduate students. Half-baked theories and unconfirmed test results are not developed in this
book. Chapter s ar e up-to-dat e a s pe r engineerin g standards . Th e informatio n provide d i n
Chapter 17 on drilled pier foundations is the latest available at the time of this writing. The design
Preface
of mechanically stabilized earth retaining walls is also current. A new method for predicting the
nonlinear behavior of laterally loaded vertical and batter piles is described in Chapter 16.
The book is comprehensive, rational, and pertinent to the requirements of undergraduate
students. It serves as a foundation course for graduate students, and is useful as a reference book for
designers and contractors in the field of geotechnical engineering .
ACKNOWLEDGEMENTS
It is my pleasure to thank Marcel Dekker, Inc., for accepting me as a single author for the
publication of my book. The man who was responsible for this was Mr. B.J. Clark, the Executive
Acquisition Editor . It was my pleasure to work under hi s guidance . Mr . Clar k i s a refine d
gentleman personified, polished, and clear sighted. I thank him cordially for the courtesies and
help extended to me during the course of writing the manuscript. I remain ever grateful to him.
Writing a book for American Universities by a nonresident of America is not an easy task.
I neede d a n America n professo r to edi t m y manuscript an d guid e m e wit h regard s to th e
requirements of undergraduate students in America. Dr. Mark T. Bowers, Associate Professor of
Civil Engineering, University of Cincinnati, accepted to become my consultant and chief editor.
Dr. Bowers is a man of honest y and integrity. He is dedicated to the cause of his profession. He
worked hard for over a year in editing my book and helped me to streamline to make it acceptable
to the undergraduate students of American Universities. I thank Dr. Bowers for the help extended
to me.
There ar e many in India who helped me during the course o f writing this book. Som e
provided m e useful suggestion s and others with references. I acknowledge their services with
thanks. The members are:
Mr. S. Pranesh Managin g Director
Prism Books Pvt Ltd
Bangalore
Dr. K.S.Subba Rao Professo r of Civil Engineering
Indian Institute of Science Bangalore
Dr. T.S. Nagaraj Professo r of Civil Engineering
(Emeritus), Indian Institute of Science,
Bangalore
Professor of Civil Engineering
Dr. C. Subba Rao India n Institute of Technology
Kharagpur
Chaitanya Graphics , Bangalore , provide d th e artwor k fo r th e book . I than k M r S.K .
Vijayasimha, the designer, for the excellent job done by him.
My so n Prakas h wa s associate d wit h th e boo k sinc e it s inception . H e carrie d o n
correspondence with the publishers on my behalf and sent reference books as needed. My wife
Sharadamani wa s mainly responsible fo r keeping my spirit hig h during the years I spent in
writing the book. I remain grateful to my son and my wife for all they did.
I sincerely thank Mr. Brian Black for his continuous efforts in the production of this book. I
immensely thank Mr. Janardhan and Mr. Rajeshwar, computer engineers of Aicra Info Mates Pvt
Ltd., Hyderabad, for their excellent typesetting work on this book.
V.N.S. Murthy
CONTENTS
Foreword Mar k T. Bowers v
Foreword Beng t B. Broms vi i
Preface i x
CHAPTER 1 INTRODUCTIO N 1
1.1 Genera l Remarks 1
1.2 A Brief Historical Development 2
1.3 Soi l Mechanics and Foundation Engineering 3
CHAPTER 2 SOI L FORMATION AND CHARACTERIZATION 5
2.1 Introductio n 5
2.2 Roc k Classification 5
2.3 Formatio n of Soils 7
2.4 Genera l Types of Soils 7
2.5 Soi l Particle Size and Shape 9
2.6 Compositio n of Clay Minerals 1 1
2.7 Structur e of Clay Minerals 1 1
2.8 Cla y Particle-Water Relations 1 4
2.9 Soi l Mass Structure 1 7
XI
xii Content s
CHAPTER 3 SOI L PHASE RELATIONSHIPS, INDEX PROPERTIES
AND CLASSIFICATION 1 9
3.1 Soi l Phase Relationships 1 9
3.2 Mass-Volum e Relationships 2 0
3.3 Weight-Volum e Relationships 2 4
3.4 Comment s on Soil Phase Relationships 2 5
3.5 Inde x Properties of Soils 3 1
3.6 Th e Shape and Size of Particles 3 2
3.7 Siev e Analysis 3 3
3.8 Th e Hydrometer Method of Analysis 3 5
3.9 Grai n Size Distribution Curves 4 3
3.10 Relativ e Density of Cohesionless Soil s 4 4
3.11 Consistenc y of Clay Soil 4 5
3.12 Determinatio n of Atterberg Limits 4 7
3.13 Discussio n o n Limits and Indices 5 2
3.14 Plasticit y Char t 5 9
3.15 Genera l Considerations fo r Classification o f Soils 6 7
3.16 Fiel d Identificatio n of Soils 6 8
3.17 Classificatio n of Soils 6 9
3.18 Textura l Soil Classification 6 9
3.19 AASHT O Soi l Classification System 7 0
3.20 Unifie d Soil Classification System (USCS) 7 3
3.21 Comment s on the Systems of Soil Classification 7 6
3.22 Problem s 8 0
CHAPTER 4 SOI L PERMEABILITY AND SEEPAGE 8 7
4.1 Soi l Permeability 8 7
4.2 Darcy' s Law 8 9
4.3 Discharg e an d Seepage Velocities 9 0
4.4 Method s of Determination of Hydraulic Conductivity of Soils 9 1
4.5 Constan t Hea d Permeability Tes t 92
4.6 Fallin g Head Permeability Test 9 3
4.7 Direc t Determination of k of Soils in Place by Pumping Test 9 7
4.8 Borehol e Permeabilit y Tests 10 1
4.9 Approximat e Values of the Hydraulic Conductivity of Soils 10 2
4.10 Hydrauli c Conductivity in Stratified Layers of Soils 10 2
4.11 Empirica l Correlations for Hydraulic Conductivity 10 3
4.12 Hydrauli c Conductivity of Rocks by Packer Method 11 2
4.13 Seepag e 11 4
4.14 Laplac e Equatio n 11 4
Contents xii i
4.15 Flo w Net Construction 11 6
4.16 Determinatio n of Quantity of Seepage 12 0
4.17 Determinatio n of Seepage Pressure 12 2
4.18 Determinatio n of Uplift Pressures 12 3
4.19 Seepag e Flo w Through Homogeneous Earth Dams 12 6
4.20 Flo w Net Consisting of Conjugate Confocal Parabolas 12 7
4.21 Pipin g Failure 13 1
4.22 Problem s 13 8
CHAPTER 5 EFFECTIV E STRESS AND PORE WATER PRESSURE 14 3
5.1 Introductio n 14 3
5.2 Stresse s whe n No Flow Takes Place Through the
Saturated Soil Mass 14 5
5.3 Stresse s When Flow Takes Place Through the Soil
from Top to Bottom 14 6
5.4 Stresse s When Flow Takes Place Through the Soil
from Botto m to Top 14 7
5.5 Effectiv e Pressur e Due to Capillary Water Rise in Soil 14 9
5.6 Problem s 17 0
CHAPTER 6 STRES S DISTRIBUTION IN SOILS
DUE TO SURFACE LOADS 17 3
6.1 Introductio n 17 3
6.2 Boussinesq' s Formula for Point Loads 17 4
6.3 Westergaard' s Formul a for Point Loads 17 5
6.4 Lin e Loads 17 8
6.5 Stri p Loads 17 9
6.6 Stresse s Beneat h the Corner of a Rectangular Foundation 18 1
6.7 Stresse s Unde r Uniformly Loaded Circula r Footing 18 6
6.8 Vertica l Stress Beneath Loaded Areas of Irregular Shape 18 8
6.9 Embankmen t Loadings 19 1
6.10 Approximat e Methods for Computing c r 19 7
6.11 Pressur e Isobar s 19 8
6.12 Problem s 20 3
CHAPTER 7 COMPRESSIBILIT Y AN D CONSOLIDATION 20 7
7.1 Introductio n 20 7
7.2 Consolidatio n 20 8
7.3 Consolidomete r 21 2