CONTENTS 1- INTRODUCTION 1 1.1 Definition of Soil 1 1.2 Soil mechanics, Rock mechanics and Geotechnical Engineering 1 1.3 Brief History of Development of Soil Mechanics 2 1.4 SI Units 3 2 - BASIC TERMINOLOGY AND INTERRELATIONS 4 2.1 Soil Mass 4 2.2 Soil Mass as a Three Phase System 4 2.3 Soil Mass as a Two Phase System 4 2.4 Notations 5 2.5 Void ratio, Porosity, Degree of Saturation, Air Content and Percentage Air Voids 5 2.6 Water Content 6 2.7 Unit Weights and Densities 6 2.8 Specific Gravity 7 2.9 Interrelations 8 3 - INDEX PROPERTIES OF SOIL 16 3.1 Introduction 16 3.2 Specific Gravity 16 3.3 Water Content 19 3.4 Particle Size Distribution 21 3.5 Consistency of Soils 28 3.6 Determination of Field Density 37 3.7 Density Index 39 CHAPTER 4 - SOIL CLASSIFICATION SYSTEMS 43 4.1 Purpose of Soil Classification 43 4.2 Particle Size Classification Systems 43 4.3 Highway Research Board Classification Systems 45 4.4 Unified Soil Classification Systems 48 4.5 Indian Standard Soil Classification Systems 49 CHAPTER 5 - SOIL FORMATION AND SOIL STRUCTURE 61 5.1 Introduction 61 5.2 Weathering 61 5.3 Transportation and Deposition 61 5.4 Upheaval * 62 5.5 Soil Structure 62 5.6 Soil Particles in Soil Mass 64 5.7 Primary Valence Bond and Secondary Valence Bond 67 5.8 Diffuse Double Layer 68 5.9 Interparticle Forces in a Soil Mass 68 5.10 Some Additional Terms Relating to Soil Formation 69 CHAPTER 6 - SOIL WATER AND EFFECTIVE STRESS 72 6.1 Classification 72 6.2 Adsorbed Water 72 6.3 Capillary Water 73 6.4 Effective Stress, Pore Pressure and Total Stress 78 CHAPTER 7 - PERMEABILITY 86 7.1 Introduction 86 7.2 Darcy's Law and Coefficient of Permeability 86 7.3 Discharge Velocity and Seepage Velocity 86 7.4 Limitations in the use of Darcy's law 87 7.5 Factors Affecting Permeability 87 7.6 Determination of Coefficient of Permeability 89 7.7 Permeability of Stratified Soil Deposits 99 CHAPTER 8 - SEEPAGE ANALYSIS 108 8.1 Introduction 108 8.2 Seepage Pressure 109 8.3 Quick Sand 110 8.4 Two Dimensional Flow-Laplace Equation 114 8.5 Flow Net 115 8.6 Properties of Flow Net 115 8.7 Flow Net by Graphical Method 115 8.8 Application of Flow Net 116 8.9 Seepage Through Anisotropic Soil 122 8.10 Deflection of Flow Lines at Interface Between Two Soils with Different Permeability 125 8.11 Seepage Through Body of Homogenous Earth Dam 125 8.12 Electrical Analogy Method 130 8.13 Scaled Model Method 132 8.14 Piping 132 8.15 Protective Filter 134 CHAPTER 9 - STRESS DISTRIBUTION IN SOIL MASS 137 9.1 Introduction 137 9.2 Boussinesq Analysis 137 9.3 Isobar and Pressure Bulb 140 9.4 Vertical Stress Distribution on Horizontal Plane 141 9.5 Vertical Stress Distribution on a Vertical line 141 9.6 Vertical Stress under Uniformly Loaded Circular Area 142 9.7 Vertical Stress Due to Line Load 144 9.8 Vertical Stress under Strip load 147 9.9 Vertical Stress under a Uniformly Loaded Rectangular Area 148 9.10 Equivalent Point Load Method 154 9.11 Newmark's Influence Chart 154 9.12 Westergaard Analysis 157 9.13 Comparison of Boussinesq and Westergaard Theories 162 CHAPTER 10 - COMPACTION 164 10.1 Compressibility 164 10.2 Compaction 164 10.3 Standard Proctor Test 165 10.4 Modified Proctor Test 168 10.5 Field Compaction Method 168 10.6 Placement Water Content 169 10.7 Field Compaction Control 169 10.8 Factors Affecting Compaction 170 10.9 Effect of Compaction on Some Soil Properties 170 11 - CONSOLIDATION 174 11.1 Introduction 174 11.2 Primary Consolidation and Secondary Consolidation 174 11.3 The Spring Analogy 174 11.4 Consolidation of Laterally Confined Soil Specimen 176 11.5 Terzaghi's Theory of One-Dimensional Consolidation 180 11.6 Consolidation Test 184 11.7 Secondary Consolidation 191 12 - SHEAR STRENGTH OF SOILS 201 12.1 Introduction 201 12.2 Mohr Circle for Two-Dimensional Stress System 201 12.3 Theories of Failure for Soils 202 12.4 Terzaghi's Effective Stress Principle 204 12.5 Determination of Shear Strength Parameters 204 12.6 Direct Shear Test 204 12.7 Triaxial Compression Test 207 12.8 Types of Shear Tests Based on Drainage Conditions 212 12.9 Unconfined Compression Test 213 12.10 Vane Shear Test 214 12.11 Skempton's Pore Pressure Parameters 216 12.12 Brief discussion on Shear Strength of Different Soil Types 219 12.13 Sensitivity and Thixotropy 223 13 - STABILITY OF SLOPES 236 13.1 Introduction 236 13.2 Infinite Slope and Finite Slope 236 13.3 Stability Analysis of Infinite Slope 236 13.4 Stability Analysis of Finite Slope 238 13.5 Swedish Circle Method 239 13.6 Factors of Safety used in Stability Analysis of Slopes 242 13.7 Friction Circle Method 242 13.8 Stability Analysis of a Finite Slope using Taylor Stability Number 245 13.9 Bishop's Method of Stability Analysis 246 13.10 Fellenious Method for Locating Centre of Critical Slip Circle 249 13.11 Stability of Side Slopes of Earth Dam 250 ADDITIONAL QUESTIONS 264 - 281 APPENDIX-I IS SIEVES 282 APPENDIX - II SOLUTION TO TERZAGHI'S ONE DIMENSIONAL CONSOLIDATION EQUATION 283 REFERENCES 285 INDEX 287