SOIL MECHANICS AND FOUNDATION ENGINEERING Dr. K.R. Arora SOIL MECHANICS AND FOUNDATION ENGINEERING [ IN SI UNITS ] Dr. K.R. ARORA B.E: (Civil)-, M.E. (Hons.)-. Ph. D. (itTD) F.I.E.; M.I.G.S., FISDT; MlWRS Former Professor and Head of Civil Engg. Department Engineering College, KOTA (Raj.) STANDARD PUBLISHERS DISTRIBUTORS NAI SARAK, POST BOX No.: 1066, DELHI-110006 Phones : 23262700, 23285798, Fax: 23243180 email: [email protected] www.standardpublishers.com Published by : A. K. Jain For Standard Publishers Distributors 1705-B, Nai Sarak, Delhi-110006. First Edition, 1987 Second Edition, 1989 Third Edition, 1992 Fourth Edition, 1997 (Revised and Enlarged) Reprint, 2000 Fifth Edition, 2000 Reprint, 2001 Reprint, 2002 Sixth Edition, 2003 (Revised and Enlarged) Reprint, 2004 © K.R. ARORA Exclusive rights by Standaid Publishers Distributors, Delhi for publication, distribution and export. All rights reserved. No part of tliis publication in general and diagrams in particular may be reproduced or transmitted in any form or by any means, electronic, mechanical, photo copying, recording or any information storage and retrieval system, without the prior written permission of the publisher and author. Price : Rs. 275-00 ISBN : 81-8014-028-8 Laser Typesetting by : Bhargave Laser Printers, Delhi. Printed by : Lomus Offset Press, Delhi. ACKNOWLEDGEMENT Fig. No. 32.2 on page 839 and Fig. No. 32.7 on page 848 of this publication have been reproduced with permission of BIS, from IS: 1893 (Part I)-2002 to which reference is invited for/further details. It is desirable that for more complete details, reference be made only to the latest version of this standard, which is available from Bureau of Indian Standards, Manak Bhawan, New Delhi. PREFACE TO THE SIXTH EDITION In this edition, the text has been revised and updated. A new chapter on ‘Geotechnical Earthquake Engineering’ has been included to introduce the readers to the recent developments. The importance of geo­ technical aspects of earthquake engineering has considerably increased in recent years, especially after the Bhuj Earthquake of 2001. On the suggestions received from readers, this chapter has been included in this text book. The author heartily thanks his wife Mrs Rani Arora and son-in-law Dr. B.P. Suneja, Lecturer (Selection scale) in Civil Engineering, Engineering College, Kota for the assistance provided. The author also thanks Sh. Bhagwan Sawroop Sharma, Draughtsman, Engineering College, Kota for excellent drawings. The author gratefully acknowledges the courtesy of the Bureau of Indian Standards, 9 Bahadur Shah Zafar Marg, New Delhi-110002 to include two figures from IS: 1893 (Part 1)—2002. Suggestions for further improvement of the text will be gratefully acknowledged. 2K4, Dadabari, ...... KOTA (Raj.) —Dr- KR- ARORA July, 2003 PREFACE TO THE FOURTH EDITION The basic aim of the fourth edition of Soil Mechanics and Foundation Engineering is the same as that of the earlier three editions, namely, to present (he ftuidamenials of the subject in a simplified manner. In this edition, a number of improvements and additions have been incorporated to make the text more useful. A large number of multiple-choice questions and objective type questions (with answers) have been added at the end of each chapter. Chapter 30 gives die detailed procedure for conducting nineteen common laboratory experiments. Chapter 31 covers the basic principles of Rock Mechanics. Appendix A gives the glossary of common terms for ready reference. Selected referei ces and a list of relevant publications of Bureau of Indian Standards are given at the end for further study. It is gratifying that the book has been appreciated by students, teachers and practising engineers throughout die country. The book has established itself as a useful text in most of die engineering colleges and technical institutions of the country. The author is grateful to the teachers and students who have sent their comments, suggestions and letters of appreciation. The author thanks his colleagues Dr. R. C. Mishra and Sh. N. P. Kaushik for their help in proof reading. The author also thanks his wife Mrs. Rani Arora for her assistance in the revision of the book. The help received from Shri Bhagwan Sawroop Sharma, Draughtsman, in improving the diagrams is appreciated. Efforts made by the publisher Sh. N. C. Jain and his sons Sh. Ajay Kumar Jain and Sh. Atul Kumar Jain for bringing out this edition in a short time and in a good form are appreciated. In spite of every care taken to ensure accuracy, some errors might have crept in. The author will be grateful to the readers for bringing such errors, if any, to his notice. Suggestions for the improvements of the text will be gratefully acknowledged. KOTA (Raj.) —Dr. K.R. ARORA February 26, 1997 PREFACE TO THE FIRST EDITION Soil mechanics and Foundation engineering (geotechnical engineering) is a fast developing discipline of civil engineering. Considerable work has been done in the field in the last 6 decades. A student finds it difficult to have access to the latest literature in the field. The author has tried to collect the material from various sources and to present in the form of a text. The text has been divided into two parts. The first part deals with the fundamentals of soil mechanics. The second part deals with earth retaining structures and foundation engineering. The subject matter has been presented in a logical and organised manner such that it may be taken up serially without any loss of continuity, '.he book covers the syllabi of undergraduate courses inn Soil Mechanics and Foundation Engineering prescribed by most Indian universities and institutes. An attempt has been made to explain the fundamentals in a simple, lucid language. Basic concepts have been emphasised throughout. The author, who has about 25 years of teaching experience, has paid special attention to the difficulties experienced by students. A large number of illustrative examples have been given to show the application of the theory to field problems. Numerical problems, with answers, have been given for practice. Some objective type questions have also been given al the end of each chapter. The. text is profusely illustrated with diagrams and charts. Latest IS codes have been followed, as far as possible. References are given at the end of each chapter. As complete switch over to SI units has not taken place in India, both MKS and SI units have been used. The book will be useful for the undergraduate students. The students appearing for various competitive examinations and AMIE will also find the text useful. A large number of charts and tables have been included to make the text useful for'practising engineers. The author is grateful to Prof. Alam Singh of Jodhpur University who introduced the subject to him about 3 decades ago as a student at M.B.M. Engineering College, Jodhpur. Ilie author is indebted to Prof. A. Varadarajan of ITT, Delhi, who helped him in understanding some of the intricate problems during his doctoral programme. The author thanks the faculty of Geotechnical Division of IIT, Delhi, for the help extended. The author also thanks his fellow research scholars, Dr. K.K, Gupta, Dr. B. Shankcriah, Dr. T.S. Rekhi, Dr. B.S. Satija, and Dr. R.N. Shahi for the fruitful discussions. 'Rie author is grateful to Prof. A.V. Ramanujam, Principal, Engineering College, Kota for constant encouragement. The author thanks his colleagues at Engineering College, Kota, especially Sh. Amin Uddin, Draughtsman. The author also thanks his wife Mrs. Rani Arora who helped in proof reading and other works related with this text. The help received from his daughter Sangceta Arora and son Sanjeev Arora is also acknowledged. In spite of every care taken to ensure accuracy, some errors might have crept in. The author will be grateful to readers for bringing such errors to his notice. Suggestions for improvement of the text will be acknowledged with thanks. KOTA (Raj.) —K.R. ARORA January 4, 1987 (V) NOTATIONS The notations have been explained wherever they appear. Thefollowing notations have been more commonly used. A = Pore pressure parameter Pa = Active pressure force Ww - Weight of water = Activity of soils Pp= Passive pressure force Wj = Weight of solids Av= Area of voids p= Pressure Wq= Water table factor A° = Angstrom pa= Active pressure Wy = Water table factor Ac= Air content pp= Passive pressure w= Water content av = Coefficient of compressibility ph= Horizontal pressure M = Mass, total mass B = Pore pressure parameter Q= Force, Load Mw = Mass of water Cc= Compression index = Total quan ti ty of water Ms= Mass of solids = Coefficient of curvature Qa = Allowable load wi= Liquid limit Cu= Uniformity Coefficient Qu= Ultimate load wp= Plastic limit = Coefficient of elastic uniform q = Surcharge m'x= Shrinkage limit compression = Intensity of Load Y = Bulk unit weight c= Unit cohesion = Discharge Y</= Dry unit weight c' = Effective unit cohesion qc = Static cone resistance '/sai = Saturated unit weight cu = Apparent cohesion qn = Net footing pressure capacity y'= Submerged unit weight cv = Coefficient of consolidation qns= Net safe bearing capacity Yj= Unit weighi of solids Z>io= Effective size qnp = Net safe settlement pressure Yh>= Unit weight of water Df= Foundation depth qna = Allowable bearing pressure 6 = Angle of wall friction Dr= Relative density qu= Ultimate bearing capacity e- Strain E= Modulus of elasticity = Unconfined compressive r|= Coefficient of viscosity e = Void ratio strength p= Poisson’s ratio FS = Factor of safety S= Degree of saturation = Micron f= .Friction = Surface area = Coefficient of viscosity G = Specific gravity of panicles Sn = Stability no. p = Displacement g= Acceleration due to gravity Si = Sensitivity = Settlement h- Hydraulic head s= Shear strength p/ = Final settlement 1 = Moment of inertia =. Settlement o = total stress lp = Plasticity index T= Tangential component o = Effective stress j- Hydraulic gradient = Temperature 01,02, 03 = Principal stresses = Angle of surcharge Ts = Surface tension 01,02,03 = Effective principalstresses K= Coefficient of absolute r= Time ©<•= PreConsolidation pressure KKoa == CCpoeorereemsfftffeiiccaiibeeinnlittt ooyff eaacrttihv ep preressssuurree at Uu === TDPooetrgaerl e wpeao otreefr cw poarnetsesosrl uipdrreaetsisounre oOix,, Ootrv ,= == SVHheeorartiircz saotlnr etsastslr esstsress Kp = Coefficient of passive pressure u = Hydrostatic excess pore pressure Tm = Mobilised shear strength k= Coefficient of permeability V= Volume, total volume, Velocity 4 = Angle of sheari ng resistance = Coefficient of subgrade reaction Vj= Volume of dry soil A'= Effective angle of shearing ks = Coefficient of subgrade reaction Va= Volume of air resistance kp= Coefficient of percolation Vw= Volume of water <|>« = Apparent angle of shearing nNPna= ===== NPNPPFooeeourrrrrmcccomeeesbnniatelttyr afc goionefme barpilroo wvnoesin d(tSs PT) VVWvvsi>, ====== VVVCSWereooeiellltiouupieccmmahaigttleey.e voo tvoeffetl vsaolooloc lcwiiitdidytesysipht <pjp>mp<'/== == rSmrBDeeuusrsobyiilbsskm dtit aladeeinnsenrcecgnsedeiset idyty daenngsliet yof shearing (vi) CONVERSION FACTORS (a) MKS to SI Units From To Multiply by Equivalence kgf N 9.81 1 kgf = 9.81 N gmf N 9.81 x 10-3 Igmf = 0.00981N tonne kN 9.81 11 = 9.81 kN kgf/cm2 kN/m2 98.1 1 kgf/cm2 - 98.1 kN/m2 kgf/cm" N/mm2 9.81 x IO-2 1 kgf/cm2 = 0.0981 N/mm2 gmf/cm2 N/m2 98.1 1 gmf/cm2 = 98.1 N/m2 t/m2 kN/m2 9.81 1 t/m2 - 9.81 kN/m2 kgf/m3 kN/m3 9.81 x 10‘3 1 kgf/m3 = 0.00981 kN/ m3 t/m3 kN/m3 9.81 1 t/m3 = 9.81 kN/m3 grnf/cm3 kN/m3 9.81 1 gmf/cm3 = 9.81 kN/m3 kgf/m N/m 9.81 1 kgf/m = 9.81 N/m kgf-m N-m 9.81 1 kgf-m = 9.81 N-m kgf-sec/m2 N-s/m2 9.81 1 kgf-sec/m2 - 9.81 N-s/m2 (b) SI to MKS Units From To Multiply Equivalence by N kgf 0.102 1 N = 0.102 kgf N gmf 102.0 1 N - 102 gmf kN tonne 0.102 1 kN - 0.1021 kN/m2 kgf/cm2 0.102 x 10-1 1 kN/m2 - 0.0102 kgf/cm2 N/mm2 kgf/cm2 10.2 IN/mm2 - 10.2 kgf/cm2 N/m2 gmf/cm2 0.102 x 10-1 1 N/m2 - 0.0102 gmf/cm2 kN/m2 t/m2 0.102 1 kN/m2 - 0.102 t/m2 kN/m3 kgf/m3 0.102 x 103 1 kN/m3 - 102.0 kgf/m3 kN/m3 t/m3 0.102 1 kN/m3 - 0.102 t/m3 kN/m3 gmf/m3 0.102 1 kN/m3 - 0.102 gmf/cm3 N/m kgf/m 0.102 1 N/m - 0.102 kgf/m N-m kgf-m 0.102 1 N-m - 0.102 kgf-m N-s/m2 kgf-sec/m2 0.102 1 N-s/m2 - 0.102 kgf-sec/m2 Note : 1 poise= 0.1 N-s/m2 = 1.02 x 10;' kgf-sec/m2 1 bar= 100 kN/m2 CONTENTS Chapter Page No. PART I. FUNDAMENTALS OF SOIL MECHANICS 1. Introduction 3-12 1.1. Definition of soil, 1; 1.2. Definition of soil mechanics, 2; 1.3. Definition of Soil Engineering and Geotechnical Engineering, 2; 1.4. Scope of soil Engineering, 2; 1.5. Origin of Soils, 4; 1.6. Formation of Soils, 5; 1.7. Transportation of Soils, 6; 1.8. Major Soil Deposits of India, 7; 1.9. Comparison of Soils with other materials, 8; 1.10. Limitations of Soil Engineering 8; 1.11. Terminology of different types of soils, 9; 1.12. Cohesive and Cohesionless Soils, 18; 1.13. Brief History of Soil Engineering, 11; Problems, 12. 2. Basic Definitions and Simple Tests 13-44 2.1. Introduction, 13; 2.2 Volumetric Relationships, 14; 2.3 Water content, 15; 2.4. Units, 1; 2.5 Volume Mass Relationship, 16; 2.6. Volume-Weight Relationships, 17,2.7. Inter-relation between Mass and Weight Units, 18; 2.8. Specific Gravity of Solids, 19; 2.9. Three-Phase Diagram inn Terms of Void ratio, 20; 2.10. Three-Phase Diagram in Terms of Porosity, 22; 2.11. Expressions for Mass Density in Terms of Water Contant, 23; 2.12. Expression for mass density in terms of water content, 24; 2.13. Relationship between Dry Mass Density and Percentage Air Voids, 25; 2.14. Water Content Determination, 26; 2.15. Specific Gravity Determination, 30; 2.16. Measurement of Mass Density, 32; 2.17. Determination of Void Ratio, Porosity and Degree of Saturation, 36; Illustrative Examples, 37; Problems, 42. 3. Particle Size Analysis 45-68 3.1. Introduction, 45; 3.2. Mechanical Analysis, 46; 33. Sieve Analysis, 46; 3.4. Stokes' Law, 47; 3.5. Preparation of suspension for sedimentation analysis, 49; 3.6. Theory of Sedimentation, 50; 3.7. Pipette Method, 51; 3.8. Hydrometer Method, 52; 3.9. Relationship Between Percentage Finer and Hydrometer Reading, 55; 3.10. Limitation of Sedimentation Analysis, 57; 3.11. Combined Sieve and Sedimentation Analysis, 57; 3.12. Particle Size Distribution Curve, 57; 3.13. Uses of Particle Size Distribution Curve, 59; 3.14. Shape of Particles, 59; 3.15. Relative Density, 60; 3.16. Determination of Relative Density, 61; Illustrative Examples, 62; Problems, 66. 4. Plasticity Characteristics of Soils 69 - 88 4.1. Plasticity of Soils, 69; 4.2. Consistency Limits, 69; 43. Liquid Limit, 70; 4.4. Cone Penetrometer Method, 73; 4.5. Plastic Limit, 73; 4.6. Shrinkage Limit, 74; 4.7. Alternative Method for determination of shrinkage limit, 75; 4.8. Shrinkage Parameters, 76; 4.9. Plasticity, Liquidity and Consistency Indexes, 78: 4.10. Flow Index, 78; 4.11. Toughness Index, 79; 4.12. Measurement of Consistency, 80; 4.13. Sensitivity 80; 4.14. Thixotropy, 81; 4.15. Activity of Soils, 81; 4.16. Uses of consistency Limits, 82; Illustrative Examples, 83; Problems, 87. 5. Soil Classification 89-106 5.1. Introduction, 89; 5.2. Partide Size Classification, 89; 53. Textural Classification, 91; 5.4. AASHTO Classification System, 92; 5.5. Unified soil Classification System, 72; 5.6. Comparison of AASHTO and USC systems, 95; 5.7. Indian Standard Classification System, 98; 5.8. Boundary Classification, 99; 5.9. Field Identification of Soils, 101; 5.10. General Characteristics of Soils of Different Groups, 103; Illustrative Examples, 103; Problems, 105. 6. Clay Mineralogy and Soil Structure 107-119 6.1. Introduction, 107; 6.2. Gravitational and Surface forces, 107; 63. Primary Valence Bonds, 108; 6.4. Hydrogen Bond, 109; 6.5. Secondary Vhlence Bonds, 110; 6.6. Basic Structural Units of Clay Minerals, (viii) 111; 6.7. Isomorphous Substitution, 112; 6.8. Kaolinite Mineral, 112; 6.9. Montmorillonite Mineral, 112; 6.10. Illite Mineral, 113; 6.11. Electrical charges on clay minerals, 113; 6.12. Base Exchange Capacity, 114; 6.13. Diffuse Double Layer, 114; 6.14. Adsorbed Water, 116; 6.15. Soil Structures. 116, Problems, 118. 7. Capillary Waler 120 - 133 7.1. Types of Soil Wafer, 120; 7.2. Surface Tension, 120; 7.3. Capillary Rise in Small Diameter Tubes, 121; 7.4. Capillary Tension, 122; 7.5. Capillary Rise in Soils, 123; 7.6. Soil Suction, 125; 7.7. Capillary Potential, 125; 7.8. Capillary Tension During Drying,of Soils, 126; 7.9. Factors Affecting Soil Suction, 126; 7.10. Measurement of Soil Suction, 127; 7.11.'>^f^f Heave, 128; 7.12. Frost Boil, 129; 7.13. Prevention of Frost Action, 129; 7.14. Shrinkage and §V/blling bf Soils, 129; 7.15. Slaking of Clay, 130; 7.16. Bulking of Sand, 131; 7.17. Capillary Siphoning; 13t; Illustrative Examples, 131; Problems, 132. 8. Permeability of Soil 134 -162 8.1. Introduction, 134; 8.2. Hydraulic Head, 134; 8.3. Darcy’s Law, 135; 8.4. Validity of Darcy’s Law, 136; 8.5. Determination of Coefficient of Permeability, 136; 8.6. Constant Head Permeability Test, 137; 8.7. Variable-Head Permeability Test, 138; 8.8. Seepage Velocity, 140;. 8.9. General Expression for Laminar Flow, 141; 8.10. Laminar Flow through Porous Media, 142; 8.11. Factors affecting Permeability of Soils, 143; 8.12. Coefficient of Absolute Permeability, 145; 8.13. Pumping Out Tests, 146; 8.14. Pumping in Tests, 148; 8.15. Coefficient of permeability by Indirect Methods, 151; 8.16. Capillarity- Permeability Test, 152; 8.17. Permeability of Stratified Soil Deposits, 154; Illustrative Examples, 156; Problems, 160. 9. Seepage Analysis 163-188 9.1. Introduction, 183; 9.2. Laplace’s equation 164; 9.3. Stream and Potential Functions, 165; 9.4. Characteristics of Flow Net, 167; 9.5. Graphical Method, 168; 9.6. Electrical Analogy Method, 168; 9.7. Soil Models, 171; 9.8. Plastic Models, 172; 9.9. Flow Net by Solution of Laplace’s Equation, 172; 9.10 Flow Net in Earth Dams with a Horizontal Filter, 173; 9.11. Seepage through Earth Dam with sloping Discharge face, 175; 9.12. Seepage through Earth Dam with Discharge angle less than 30°, 176; 9.13. Seepage through Earth Dam with Discharge angle greater than 30°, 177; 9.14. Uses of Flow Net, 178; • 9.15. Flow Net for Anisotropic Soils, 180; 9.16. Coefficient of Permeability,in an Inclined Direction, 182; 9.17. Flow Net in a Non-homogeneous Soil Mass, 182; Illustrative Examples, 184; Problems, 185. 10. Effective Stress Principle 189-217 10.1. Introduction, 189; 10.2. Effective Stress Principle, 189; 10.3. Nature of Effective Stress, 190; 10.4. Effect of Water Table Fluctuations on Effective Stress, 192; 10.5. Effective Stress in a Soil Mass under Hydrostatic Conditions, 193; 10.6. Increase in effective Stresses due to surcharge, 195; 10.7. Effective Stresses in Soils saturated by Capillary Action, 195; 10.8. Seepage Pressure, 197; 10.9. Force Equilibrium in Seepage Problems, 198; 10.10. Effective Stresses under Steady Seepage Conditions, 200; 10.11. Quick Sand Condition 201; 10.12. Seepage Pressure Approach for Quick Condition, 203; 10.13. Effect of Surcharge on Quick Conditions, 203; 10.14. Failures of Hydraulic Structures by Piping, 204; 10.15. Prevention of Piping Failures, 206; 10.16. Design of Graded Filter, 207; 10.17. Effective Stress in Partially Saturated Soils, 209; Illustrative Examples, 210; Problems, 215. 11. Stresses Due to Applied Loads 218-255 11.1 Introduction, 218; 11.2. Stress-Strain Parameters, 218; 11.3. Geostatic Stresses, 219; 11.4. Vertical Stresses Due to Concentrated Loads, 221; 11.5. Horizontal and Shear Stresses Due to Concentrated Loads, 223; 11.6. Isobar Diagram, 225; 11.7. Vertical Stress Distribution on a Horizontal Plane, 225; 11.8. Influence Diagram, 226; 11.9. Vertical Stress Distribution on a Vertical Plane, 227; 11.10. Vertical Stresses Due to a Line Load, 227; 11.11. Vertical Stresses Under a Strip Load, 229; 11.12. Maximum Shear Stresses at a Point Under a Strip Load, 232; 11.13. Vertical Stresses Under a Circular Area, 233; 11.14. Vertical Stress Under Comer of a Rectangular Area, 234; 11.15. Vertical Stress at any Point Under a Rectangular Area, 236; 11.16. Newmark’s Influence Charts, 237; 11.17. Comparison of Stresses Due to Loads on areas of Different Shapes, 239; 11.18. Vertical Stresses Under Triangular Load, 240; 11.19. Vertical Stress Under Trapezoidal Loads, 241; 11.20. Stresses Due to Horizontal Loads, 242;. 11.21. Stresses Due to Inclined Loads, 242; 11.22. Westergaard’s Solution, 243; 11.23. Fenske’s Charts, 244; 1L24. Approximate Methods, 245; 11.25. Contact Pressure Distribution, 247; 11.26. Limitations of Elastic Theories, 248; Illustrative Examples, 249; Problems, 253. (ix) 12. Consolidation of Soils 256 - 305 12.1. Introduction, 256: 12.2. Initial. Primary and Secondary Consolidation. 257; 12.3. Spring Analogy for Primary Consolidation. 257; 12.4. Behaviour of Saturated Soils Under Pressure. 258; 12.5. Consolidation Test. 259; 12.6, Determination of Void Ratio at Various Load Increments, 261; 12.7. Consolidation Test Results. 263; 12,8, Basic Definitions. 265; 12.9. Terzaghi’s Theory of Consolidation, 267; 12.10. Solution of Basic Differential Equation. 271: 12.11. Determination of Coefficient of Consolidation, 277; 12.12. Preconsolidation Pressure. 280; 12.13. CausesOf Preconsolidation in Soils, 281; 12.14. Final Settlement of a Soil Deposit in the Field, 281; 12.15. Time Settlement Curve, 283: 12.16. Field Consolidation Curve, 284; 12.17. Secondary Consolidation. 285; 12.18. 3-D Consolidation Equation in Cartesian Coordinates, 287; 12.19. 3-D Consolidation Equation in Cy lindrical Co-ordinates. 289; 12.20. Sand Drains, 291; 12.21. Effect of Lateral Strain on Consolidation. 294: Illustrative Examples, 295; Problems, 302. 13. Shear Strength 306-356 13.1. Introduction. 306: 13.2. Stress System with Principal Planes Parallel to the Coordinate Axes, 306; 13.3. Mohr’s Circle. 307; 13.4. Principal planes inclined to the coordinate axis. 308; 13.5. Stress system with Vertical and Horizontal Planes not Principal Planes, 309; 13.6. Important Characteristics of Mohr's Circle, 311; 13.7. Mohr-Coulomb Theory. 312: 13.8. Revised Mohr- Coulomb equation, 313; 13.9. Different Types of tests and Drainage Conditions. 313; 13.10. Mode of Application Of Shear Force 314; 13.11. Direct Shear Test, 314; 13.12. Presentation of Results of Dilect Shear Test. 316; 13.13. Merits and Demerits of Direct Shear Test. 318; 13,14. Triaxial Compression Apparatus, 318; 13.15. Triaxial Tests on Cohesive Soils, 321 13 16 Triaxial Tests on Cohesionless Soils, 322, 13 17 Menis and Dements of Triaxial Test, 323; 13 18. Compulation of various Parameters, 324; 13.19. Presentation of Results of Triaxial Tests. 325 13.20. Effect of Consolidation Pressure on Undrained Strength 328; 13.21. Relationship Between Undrained Shear Strength and Effective Overburden Pressure, 329;; 13.22. Unconfined Compression Test. 330; 13.23. Vane Shear Test, 332; 13.24. Pore Pressure Parameters, 333; 13.25. Mohr-Coulomb Failure Criterion. 337; 13.26. Modified Failure envelope. 338; 13.27. Stress Path. 339; 13.28. Shear Strength of Partially Saturated Soils, 341; 13.29. Hvorslev’s Strength Theory. 342: 13.30. Liquefaction of Sands. 343; 13.31. Shear Characteristics of Cohesionless Soils, 344; 13.32. Shear Characteristics of Cohesive Soils, 345; 13.33. Choice of Test Conditions and Shear Parameters. 347 Illustrative Examples. 347: Problems. 353. 14. Compaction of Soils 357 - 375 14.1. Introduction. 357: 14.2. Standard Proctor Test, 358; 14.3. Modified Proctor Test, 360; 14.4. Compaction of Sands, 361: 14 5. Jodhpur Mini Compactor Test, 362; 14.6. Harvard Miniature Compaction Tesi, 362; 14.7. Abbot Compaction Test. 362: 14,8. Factors Affecting Compaction, 362; 14.9. Effect of Compaction on Properties of Soils. 364; 14.10. Methods of Compaction Used in Field, 366; 14.11. Placement Water Content. 367; 14.12. Relative Compaction, 368; 14.13. Compaction Control. 368; 14.14. vibroflotation Method. 369: 14.15. Terra Probe Method, 370; 14.16. Compaction by Pounding, 370; 14.17. Compaction by Explosives, 371; 14.18. Precompression, 371; 14.19. Compaction Piles, 371; 14.20. Suitability of Various Methods of Compaction. 371: Illustrative Examples, 372; Problems. 374. 15. Soil Stabilisation 376-390 15.1. Introduction. 376; 15.2. Mechanical Stabilisation, 376; 15.3. Cement Stabilisation, 377; 15.4 Lime Stabilisation. 380: 15.5. Bituminous Stabilisation, 381; 15.6. Chemical Stabilisation; 382; 15.7. Therm: I Stabilisation, 383; 15.8. Electrical Stabilisation. 384; 15.9. Stabilisation by grouting, 384; 15.10 Stabilisation by Geotoxtilp and Fabrics, 385; 15.11. Reinforced Earth, 387; Problems, 389. 16. Drainage, De-watering and Wells 391 - 414 16.1. Introduction. 391: 16.2. Interceptor Ditches. 391; 16.3. Single Stage Well Points, 392; 1.6.4. Multistage Well Points, 393; 16.5. Vacuum Well Points. 393; 16,6. Shallow Well System, 394; 16.7. Deep Well System, 394: 16.8. Horizontal Wells. 394; 16.9. Electro-Osmosis, 394; 16.10. Permanent Drainage After Construction. 395: 16.11. Design of Dewatering Systems, 396; 16.12. Discharge from a Fully Penetrating Slot, 396; 16.13. Discharge from a Partially Penetrating Slot. 399; 16.14 Discharge in a Slot from Both sides. 400; 16.15. Well Hydraulics. 401: 16.16. Terms Used in Well Hydraulics, 402; 16.17. Discharge From a Fully Penetrating Well, 403; 16.18. Discharge From a Partially Penetrating Well, 404; 16.19. Interference among Wells, 405: 16.20. Spherical Flow in a Well. 407; 16.21. Discharge From an Open Well, 407; 16.22. Adverse Effects of Drainage, 409; Illustrative Examples. 409; Problems, 412.