PRINCIPLES OF GEOTECHNICAL ENGINEERING

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1 PRINCIPLES OF GEOTECHNICAL ENGINEERING Fourth Edition BRAJA M. DAS California State University, Sacramento I(T)P Boston Albany Bonn Cincinnati London Madrid Melbourne Mexico City New York Paris San Francisco Singapore Tokyo Toronto Washington

2 CONTENTS ONE SOILS AND ROCKS Preview Rock Cycle and the Origin of Soil Soil-Particle Size Clay Minerals Specific Gravity (G s ) Mechanical Analysis of Soil Particle-Size Distribution Curve Particle Shape 32 Problems 33 References 36 TWO WEIGHT-VOLUME RELATIONSHIPS, PLASTICITY, AND STRUCTURE OF SOIL Weight-Volume Relationships 38 Relationships Among Unit Weight, Void Ratio, Moisture Content, and Specific Gravity 41 Relationships Among Unit Weight, Porosity, and Moisture Content 44 Various Unit-Weight Relationships 45 Relative Density 52 Consistency of Soil 55 Liquidity Index and Consistency Index 64 Activity 65 Plasticity Chart 68 Soil Structure 70 General Comments 76 Problems 77 References 80 VII

3 VIII THREE CLASSIFICATION OF SOIL Textural Classification Classification by Engineering Behavior AASHTO Classification System Unified-Soil Classification System Comparison Between the AASHTO and Unified Systems 98 Problems 101 References 103 FOUR SOIL COMPACTION Compaction General Principles Standard Proctor Test Factors Affecting Compaction Modified Proctor Test Structure of Compacted Clay Soil Effect of Compaction on Clay Soil Properties Field Compaction Specifications for Field Compaction Determination of Field Unit Weight of Compaction Compaction of Organic Soil and Waste Materials Special Compaction Techniques General Comments 153 Problems 155 References 157 FIVE FLOW OF WATER IN SOIL: PERMEABILITY AND SEEPAGE Bernoulli's Equation Darcy's Law Hydraulic Conductivity Laboratory Determination of Hydraulic Conductivity Effect of Water Temperature on k Empirical Relations for Hydraulic Conductivity Directional Variation of Permeability Equivalent Hydraulic Conductivity in Stratified Soil Considerations for Hydraulic Conductivity of Clayey Soils in Field Compaction Moisture Content-Unit Weight Criteria for Clay Liner Construction Permeability Test in the Field by Pumping from Wells 193 s 5.12 Determination of Hydraulic Conductivity from Auger Holes 199

4 ix 5.13 Laplace's Equation of Continuity Continuity Equation for Solution of Simple Flow Problems Flow Nets Flow Nets in Anisotropic Soil Mathematical Solution for Seepage Uplift Pressure Under Hydraulic Structures Seepage Through an Earth Dam on an Impervious Base 216 Problems 219 References 225 SIX EFFECTIVE STRESS CONCEPTS Stresses in Saturated Soil without Seepage Stresses in Saturated Soil with Seepage Seepage Force Use of Filters to Increase the Factor of Safety Against Heave Selection of Filter Material Capillary Rise in Soils Effective Stress in the Zone of Capillary Rise Effective Stress in Partially Saturated Soil General Comments 251 Problems 251 References 255 SEVEN STRESSES IN A SOIL MASS 256 _, 7.1 Normal and Shear Stresses on a Plane The Pole Method of Finding Stresses Along a Plane Stress Caused by a Point Load Westergaard's Solution for Vertical Stress Caused by a Point Load Vertical Stress Caused by a Line Load Vertical Stress Caused by a Strip Load (Finite Width and Infinite Length) Vertical Stress Caused by a Linearly Increasing Load (Finite Width and Infinite Length) Vertical Stress Below the Center of a Uniformly Loaded Circular Area Vertical Stress at Any Point Below a Uniformly Loaded Circular Area Vertical Stress Caused by a Rectangularly Loaded Area Influence Chart for Vertical Pressure General Comments 295 Problems 296 i References 302

5 X EIGHT COMPRESSIBILITY OF SOIL Fundamentals of Consolidation One-Dimensional Laboratory Consolidation Test Void Ratio-Pressure Plots Normally Consolidated and Overconsolidated Clays Effect of Disturbance on Void Ratio-Pressure Relationship Influence of Other Factors on Void Ratio-Pressure Relationship Calculation of Settlement from One-Dimensional Primary Consolidation Compression Index (Q Swell Index (Q Settlement from Secondary Consolidation Time Rate of Consolidation Coefficient of Consolidation General Discussion of Determination of c v Calculation of Consolidation Settlement Under a Foundation Immediate Settlement Calculation Based on Elastic Theory Total Foundation Settlement Some Case Histories 354 Problems 359 References 364 NINE SHEAR STRENGTH OF SOIL Mohr-Coulomb Failure Criteria Direct Shear Test Drained Direct Shear Test on Saturated Sand and Clay General Comments on Direct Shear Test Triaxial Shear Test General Consolidated-Drained Triaxial Test Friction Angles <f> and cf> r for Clays Consolidated-Undrained Triaxial Test Unconsolidated-Undrained Triaxial Test Unconfined Compression Test on Saturated Clay General Comments on Triaxial Tests Stress Path Vane Shear Test Effect of the Rate of Rotation of Vane on Undrained Shear Strength Other Methods for Determining Undrained Shear Strength Strength Anisotropy in Clay Sensitivity and Thixotropy of Clay Empirical Relationships Between Undrained Cohesion (c u ) and Effective Overburden Pressure (o-') Shear Strength of Unsaturated Cohesive Soils 426 Problems 427 s References 431

6 xi TEN LATERAL EARTH PRESSURE Earth Pressure at Rest Rankine's Theory of Active Pressure Theory of Rankine's Passive Pressure Effect of Wall Yielding Diagrams for Lateral Earth Pressure Distribution Against Retaining Walls Lateral Pressure on Retaining Walls from Surcharges Based on Theory of Elasticity Coulomb's Earth Pressure Theory Graphic Solution for Coulomb's Active Earth Pressure Approximate Analysis of Active Force on Retaining Walls Effect of Wall Friction on Passive Pressure Properties of a Logarithmic Spiral Passive Earth Pressure Against Retaining Walls with Curved Failure Surface Braced Cuts Determination of Active Thrust on Bracing Systems of Open Cuts in Granular Soil Determination of Active Thrust on Bracing Systems for Cuts in Cohesive Soil Pressure Variation for Design of Sheetings, Struts, and Wales 492 Problems 495 References 500 ELEVEN DYNAMIC LATERAL EARTH PRESSURE Active Force on Retaining Walls with Earthquake Forces Location of the line of Action of the Resultant Force, P oe Design of Retaining Wall Based on Tolerable Lateral Displacement 11.4 Dynamic Earth Pressure Distribution Behind a Wall Rotating About the Top P ae for c-<f> Soil Backfill Passive Force on Retaining Walls with Earthquake Forces 515 Problems 518 References TWELVE SOIL-BEARING CAPACITY FOR SHALLOW FOUNDATIONS Ultimate Soil-Bearing Capacity for Shallow Foundations Terzaghi's Ultimate Bearing Capacity Equation Effect of Groundwater Table Factor of Safety General Bearing Capacity Equation 536

7 XII 12.6 A Case History for Evaluation of the Ultimate Bearing Capacity 12.7 Ultimate Load for Shallow Foundations Under Eccentric Load (One-Way Eccentricity) Foundations Subjected to Two-Way Eccentricity Plate Load Test A Field Test Bearing Capacity of Sand Based on Settlement Bearing Capacity of Foundations on a Slope General Comments 560 Problems 561 References THIRTEEN SLOPE STABILITY Factor of Safety Stability of Infinite Slopes without Seepage Stability of Infinite Slopes with Seepage Finite Slopes General Analysis of Finite Slopes with Plane Failure Surfaces (Culmann's Method) Slopes with Water in the Tensile Crack Analysis of Finite Slopes with Circular Failure Surfaces General Mass Procedure Slopes in Homogeneous Clay Soil with </> = Mass Procedure Slopes in Homogeneous Soil with < > Ordinary Method of Slices Bishop's Simplified Method of Slices Stability Analysis by Method of Slices for Steady State Seepage Bishop and Morgenstern's Solution for Stability of Simple Slopes with Seepage Morgenstern's Method of Slices for Rapid Drawdown Condition Spencer's Solution for Stability of Simple Slopes with Seepage Fluctuation of Factor of Safety of Slopes in Clay Embankment on Saturated Clay Case Histories of Slope Failure 618 Problems 621 References 626 FOURTEEN LANDFILL LINERS AND GEOSYNTHETICS Landfill Liners Overview GeosynthetTcs Geotextiles Geomembranes Geonets Single Clay Liner and Single Geomembrane Liner Systems i 14.7 Recent Advances in the liner Systems for Landfills

8 XIII 14.8 Leachate Removal Systems 14.9 Closure of Landfills General Comments 641 References FIFTEEN SUBSOIL EXPLORATION Planning for Soil Exploration Boring Methods Common Sampling Methods Sample Disturbance Correlations for Standard Penetration Test 15.6 Other in situ Tests Rock Coring Soil Exploration Report 668 Problems 670 References APPENDICES APPENDIX A: Conversion Factors 672 APPENDIX B: Braced Cuts 675 APPENDIX C: Factor of Safety for Slopes 677 APPENDIX D: Rankine Active and Passive Earth Pressure Answers to Selected Problems 698 Index

Introduction to Soil Mechanics

Introduction to Soil Mechanics Sela Sode and Colin Jones WILEY Blackwell Contents Preface Dedication and Acknowledgments List of Symbols Soil Structure 1.1 Volume relationships 1.1.1 Voids ratio (e) 1.1.2