Soil Mechanics and Foundation Engineering, 2e

This book presents the principles of soil mechanics and foundation engineering in a simplified, yet elegant style that assumes no prior knowledge of the subject in the student reader. It lines up all the material required for a firm background in the subject in logical order, reinforcing theoretical aspects with sound practical applications. Cover......Page 1 Contents......Page 8 Preface......Page 18 1.1 Introduction......Page 20 1.2 Origin of Soils......Page 21 1.3.1 Physical Weathering......Page 22 1.4.1 Residual Soils......Page 23 1.4.2 Transported Soils......Page 24 1.4.3 Desiccated Soils......Page 25 1.5.3 Laterites and Lateritic Soils......Page 26 1.6.1 Solid Phase......Page 28 1.6.2 Liquid Phase......Page 29 1.7.2 Particle Shape......Page 30 1.8 Inter-Particle Forces......Page 31 1.9.1 Clay Minerals......Page 32 1.9.2 Framework Silicate Minerals......Page 34 1.11.1 Characteristics of Electrolytes......Page 35 1.11.2 Electrochemical Characteristics......Page 36 1.11.5 Characteristics of Heat......Page 37 1.12.1 Structure of Granular Soils......Page 38 1.12.2 Structure of Cohesive Soils......Page 39 Questions......Page 41 2.2 Three-Phase System......Page 44 2.2.2 Porosity (n)......Page 45 2.2.5 Specific Gravity of Soil Solids (G)......Page 46 2.2.6 Water Content (w) or Moisture Content......Page 47 2.2.7 Soil Densities......Page 48 2.2.8 Unit Weights......Page 50 2.2.9 Density Index (ID)......Page 51 2.3.2 Sedimentation Analysis......Page 53 2.3.3 Grain-Size Distribution Curves......Page 58 2.4.1 Atterberg Limits......Page 59 2.4.2 Activity of Clays......Page 63 Worked Examples......Page 64 Points to Remember......Page 78 Questions......Page 79 Exercise Problems......Page 80 3.2 Field Identification of Soils......Page 84 3.2.2 Fine-grained Soils......Page 85 3.3.2 Unified Soil Classification System......Page 86 3.3.3 Indian Soil Classification System......Page 89 3.3.5 Textural Soil Classification System......Page 92 Worked Examples......Page 94 Questions......Page 96 Exercise Problems......Page 97 4.2 Principles of Compaction......Page 100 4.4 Laboratory Compaction......Page 101 4.4.1 Standard Proctor Test......Page 102 4.5 Field Compaction and Equipment......Page 103 4.5.5 Grid Rollers......Page 104 4.5.7 Vibrating Plates......Page 105 4.6.2 Field Control......Page 106 4.7.2 Effect of Compactive Effort......Page 108 4.7.4 Effect of Method of Compaction......Page 109 4.8 Effect of Compaction on Soil Structure......Page 111 4.10 California Bearing Ratio Test......Page 112 Worked Examples......Page 113 Points to Remember......Page 118 Questions......Page 119 Exercise Problems......Page 120 5.2 Water Flow......Page 122 5.3 Darcy’s Law......Page 123 5.4 Range of Validity of Darcian Flow......Page 124 5.5.1 Constant Head Permeameter......Page 125 5.5.2 Falling Head Permeameter......Page 126 5.6 Field Permeability Tests......Page 127 5.6.1 Unconfined Flow Pumping Out Test......Page 128 5.6.2 Confined Flow Pumping Out Test......Page 130 5.7.1 Horizontal Flow......Page 131 5.7.2 Vertical Flow......Page 132 5.9.1 Soil Characteristics......Page 134 5.9.2 Pore Fluid Characteristics......Page 135 5.10 Surface Tension......Page 136 5.11 Capillary Phenomenon in Soils......Page 137 5.12 Shrinkage and Swelling of Soils......Page 139 Worked Examples......Page 140 Points to Remember......Page 150 Questions......Page 151 Exercise Problems......Page 152 6.2 Seepage Forces......Page 156 6.3 General Flow Equation......Page 158 6.4 Significance of Laplace Equation......Page 160 6.5.1 Properties......Page 161 6.5.2 Applications......Page 162 6.6.1 Boundary Conditions......Page 163 6.6.2 Construction Methods......Page 164 6.7 Anisotropic Soil Conditions......Page 168 6.8 Non-Homogeneous Soil Conditions......Page 171 6.9 Piping......Page 172 6.10 Design of Filters......Page 173 Worked Examples......Page 174 Points to Remember......Page 179 Questions......Page 180 Exercise Problems......Page 182 7.2 Stresses at a Point......Page 186 7.3 Mohr’s Circle......Page 188 7.4 Stress Paths......Page 189 7.5.1 Dry Soil......Page 190 7.5.2 Saturated Soil......Page 191 7.5.3 Partially Saturated Soil......Page 192 7.6 Geostatic Stresses......Page 194 7.6.3 Case 3 – Completely Submerged Soil withWater Table at Ground Surface......Page 195 7.6.4 Case 4 – Completely Saturated by Capacity Action AboveWater Table But No Flow......Page 197 7.7.1 Elastic Half-Space......Page 198 7.7.2 Elastic Properties of Soil......Page 199 7.7.3 Boussinesq’s Theory......Page 200 7.7.4 Pressure Distribution Diagrams......Page 203 7.7.5 Westergaard Equation......Page 204 7.7.6 Types of Surface Loads......Page 205 7.7.7 Contact Pressure......Page 216 7.7.8 Validity of Elastic Theory Application......Page 217 Points to Remember......Page 227 Questions......Page 228 Exercise Problems......Page 230 8.1 Introduction......Page 234 8.2 Rheological Models of Soils......Page 235 8.4 One-Dimensional Consolidation......Page 236 8.5 Consolidation Test......Page 238 8.6.2 Compression Index......Page 240 8.6.5 Degree of Consolidation......Page 241 8.7.1 Normally Consolidated Clay......Page 242 8.7.2 Over-consolidated Clay......Page 243 8.7.3 Under-consolidated Clay......Page 244 8.9.1 Terzaghi’s Theory of One-Dimensional Consolidation......Page 245 8.9.2 Time Factor......Page 248 8.9.3 Determination of Coefficient of Consolidation......Page 249 8.10 Secondary Compression......Page 252 8.11 Consolidation Settlement and its Rates......Page 253 8.11.1 Consolidation Settlement......Page 254 8.11.2 Construction Period Correction......Page 256 8.11.4 Predicting the Rate of Settlement......Page 257 8.12 Acceleration of Consolidation by Sand Drains......Page 258 8.13 Compressibility of Sands......Page 260 Worked Examples......Page 261 Points to Remember......Page 273 Questions......Page 274 Exercise Problems......Page 276 9.2 Stress–Strain Curve......Page 280 9.3 Mohr–Coulomb Failure Criterion......Page 281 9.4 Peak and Residual Shear Strengths......Page 282 9.5.1 Drainage Condition......Page 285 9.5.3 Direct Shear Test......Page 286 9.5.5 Triaxial Shear Test......Page 289 9.5.6 Unconfined Compression Test......Page 294 9.5.8 Choice of Rate of Deformation......Page 296 9.6 Field Measurement of Shear Strength......Page 297 9.6.1 Vane Shear Test......Page 298 9.6.2 Borehole Shear Device......Page 299 9.7.1 Undrained Strength......Page 300 9.7.2 Consolidated–Undrained Strength......Page 302 9.7.3 Strength in Terms of Effective Stresses......Page 304 9.8.1 Theory......Page 305 9.8.2 Measurement of Pore Pressure Coefficients......Page 308 9.9 Sensitivity of Cohesive Soils......Page 309 9.10 Thixotrophy of Clays......Page 310 9.11 Shear Strength of Granular Soils......Page 311 Worked Examples......Page 313 Points to Remember......Page 322 Questions......Page 323 Exercise Problems......Page 325 10.1 Introduction......Page 328 10.2 Test No.1: Preparation of Dry Soil Samples for Various Tests......Page 329 10.3 Test No.2: Specific Gravity of Soil Solids......Page 330 10.4 Test No.3: Water Content Determination by Oven-Drying Method......Page 333 10.5 Test No. 4: In-Place Dry Density of Soil by Core-Cutter Method......Page 334 10.6 Test No. 5: In-Place Dry Density of Soil by the Sand Replacement Method......Page 336 10.7 Test No.6: Grain-Size Distribution by Sieve Analysis......Page 339 10.8 Test No. 7: Grain-Size Distribution by Pipette Method......Page 341 10.9 Test No. 8: Grain-Size Distribution by the Hydrometer Method......Page 348 10.10 Test No. 9: Liquid Limit of Soil......Page 353 10.11 Test No. 10: Plastic Limit of Soil......Page 356 10.12 Test No. 11: Shrinkage Factors of Soil......Page 357 10.13 Test No. 12: Linear Shrinkage of Soil......Page 360 10.14 Test No. 13: Permeability Test......Page 361 10.15 Test No. 14: Free Swell Index of Soils......Page 365 10.16 Test No. 15: Moisture Content – Dry Density Relationship (Standard Proctor Compaction Test)......Page 366 10.17 Test No. 16: Density Index of Non-Cohesive Soils......Page 370 10.18 Test No. 17: Consolidation Test......Page 372 10.19 Test No. 18: Unconfined Compression Test......Page 378 10.20 Test No. 19: Direct Shear Test......Page 381 10.21 Test No. 20: Triaxial Shear Test......Page 384 10.22 Test No. 21: California Bearing Ratio (CBR) Test......Page 392 Points to Remember......Page 398 Questions......Page 400 11.1 Introduction......Page 402 11.3 Earth Pressure at Rest......Page 403 11.4 Rankine’s States of Plastic Equilibrium......Page 405 11.5 Rankine’s Earth Pressure Theory......Page 408 11.5.1 Effect of Level Backfill Surface......Page 411 11.5.2 Effect of Surcharge Load on Backfill Surface......Page 412 11.5.3 Effect of Water Table on a Backfill......Page 414 11.5.5 Effect of c–φ Soils as Backfill......Page 416 11.6 Coulomb’s Earth Pressure Theory......Page 419 11.7 Culmann’s Graphical Method......Page 421 11.8 Poncelet’s Graphical Method......Page 423 11.9 Arching of Soils......Page 424 Worked Examples......Page 426 Points to Remember......Page 437 Questions......Page 438 Exercise Problems......Page 440 12.2 Gravity-Type Retaining Walls......Page 444 12.2.1 Proportioning Retaining Walls......Page 445 12.2.3 Stability Requirements......Page 446 12.2.4 Backfill Materials and Drainage......Page 448 12.2.5 Joints in Retaining Walls......Page 449 12.3 Sheet Pile Walls......Page 451 12.3.1 Cantilever Sheet Pile Walls......Page 452 12.3.2 Anchored Sheet Pile Walls......Page 458 12.4 Braced Excavations......Page 464 12.4.2 Failure of Braced Cuts......Page 466 12.4.3 Heave of the Bottom of a Clay Cut......Page 467 Worked Examples......Page 469 Points to Remember......Page 482 Questions......Page 483 Exercise Problems......Page 485 13.2 Causes of Slope Failures......Page 490 13.4.1 Basic Types of Landslides......Page 492 13.4.2 Multiple and Complex Slides......Page 493 13.4.3 Rates of Land Movement......Page 494 13.5 Factor of Safety......Page 495 13.7 Infinite and Finite Slopes......Page 497 13.8.1 Infinite Dry or Moist Cohesive Slope......Page 499 13.8.2 Infinite Cohesive Slopes with Seepage......Page 501 13.9.1 Planar Failure Surface......Page 502 13.9.2 Circular Failure Surfaces......Page 505 13.9.3 Non-circular Failure Surfaces......Page 517 13.10 Selection of Shear Strength Parameters and Stability Analysis......Page 519 13.11 Slope Protection Measures......Page 520 Worked Examples......Page 522 Points to Remember......Page 527 Questions......Page 528 Exercise Problems......Page 530 14.1 Introduction......Page 534 14.3 Modes of Shear Failure......Page 535 14.3.1 General Shear Failure......Page 536 14.3.3 Punching Shear Failure......Page 537 14.4 Terzaghi’s Bearing Capacity Theory......Page 538 14.5 Foundation Pressures......Page 544 14.6.1 Foundations with Eccentric Loading......Page 545 14.6.2 Foundation Subjected to Inclined Load......Page 547 14.6.4 Foundations on Stratified Soil......Page 548 14.6.6 Foundations on Desiccated Soil......Page 549 14.6.7 Foundations on Rock......Page 550 14.7.1 Modified Bearing Capacity Formulae (IS: 6403, 1981)......Page 552 14.7.2 Skempton’s Bearing Capacity Theory......Page 553 14.7.3 Meyerhof’s Bearing Capacity Theory......Page 554 14.7.4 Brinch Hansen’s Bearing Capacity Theory......Page 556 14.8 Bearing Capacity of Soils from Building Code......Page 559 14.9 Permissible Settlements......Page 561 14.10 Allowable Bearing Pressure......Page 563 14.11.1 Bearing Capacity Based on Standard Penetration Test......Page 565 14.11.2 Bearing Capacity Based on Cone Penetration Test......Page 566 14.11.3 Bearing Capacity Based on Plate Load Test......Page 568 Worked Examples......Page 570 Questions......Page 580 Exercise Problems......Page 582 15.2 Design Criteria......Page 586 15.3.4 Mat Foundations or Footings......Page 587 15.4 Selection of the Type of Foundation......Page 589 15.5.2 Adjacent Structures......Page 590 15.7 Settlement of Shallow Foundations......Page 592 15.7.1 Immediate Settlement......Page 593 15.7.2 Consolidation Settlement......Page 598 15.7.3 Evaluation of Settlement from Field Tests......Page 599 15.8 Design Steps for a Shallow Foundation......Page 602 15.9 Proportionating Footing Size......Page 603 15.10.2 Trapezoidal Combined Footing......Page 604 15.10.3 Combined Strap Footing......Page 607 15.11.2 Bearing Capacity of Mat Foundations......Page 608 Worked Examples......Page 610 Questions......Page 614 Exercise Problems......Page 616 16.2.1 Material Composition......Page 618 16.2.3 Ground Effects......Page 621 16.2.4 Function as Foundation......Page 622 16.3 Pile-Driving Equipment......Page 624 16.4 Bearing Capacity of Single Pile......Page 626 16.4.1 Pile Capacity from Statical Methods for Driven Piles......Page 627 16.4.3 Pile Capacity from Pile-Driving Formulae......Page 631 16.4.4 Pile Capacity from Wave Equation......Page 633 16.4.6 Pile Capacity from Pile Load Test......Page 634 16.4.7 Negative Skin Friction......Page 636 16.5 Under-Reamed Piles......Page 637 16.6.1 Pile Group Capacity......Page 640 16.6.2 Pile Group in Filled Ground......Page 642 16.6.3 Pile Group Settlement......Page 644 16.7.1 Uplift of Single Pile......Page 645 16.8.1 Causes of Lateral Forces......Page 646 16.8.2 Short and Long Piles......Page 647 16.10 Pile Cap......Page 648 Worked Examples......Page 649 Questions......Page 655 Exercise Problems......Page 657 17.2.1 Uses......Page 660 17.2.3 Bearing Capacity of Drilled Piers......Page 661 17.2.4 Settlement of Drilled Piers......Page 664 17.2.5 Construction Procedures of Drilled Piers......Page 665 17.3.1 Uses......Page 669 17.3.4 Construction Procedure of Caissons......Page 670 17.4.1 Types of Wells......Page 674 17.4.3 Design of Wells......Page 675 17.4.4 Stability Analysis of Well Foundations (Approximate Solution)......Page 680 17.4.5 Stability Analysis of a Heavy Well......Page 682 17.4.6 Construction of Well Foundations......Page 684 17.4.7 Shifts and Tilts......Page 685 Points to Remember......Page 686 Questions......Page 687 Exercise Problems......Page 688 18.1 Introduction......Page 690 18.3 Types of Soil and Rock Samples......Page 691 18.4.1 Geophysical Methods......Page 692 18.5.2 Rotary Drilling......Page 696 18.6 Direct Methods of Sub-Surface Exploration......Page 698 18.6.2 Sample Disturbance......Page 699 18.6.3 Types of Samplers......Page 700 18.6.4 Accessible Explorations......Page 702 18.6.5 Undisturbed Sampling of Soils......Page 704 18.7.1 Standard Penetration Test (SPT)......Page 707 18.7.2 Cone Penetration Test (CPT)......Page 708 18.7.3 Vane Shear Test......Page 709 18.7.4 Groundwater Observations......Page 711 18.8 Recording of Field Data......Page 712 Points to Remember......Page 713 Questions......Page 714 Exercise Problems......Page 716 19.1 Introduction......Page 718 19.3 Surface Compaction......Page 719 19.4.1 Well-Point Systems......Page 720 19.4.2 Deep-Well Drainage......Page 721 19.4.4 De-watering by Electro-osmosis......Page 722 19.5.1 Vibro-Compaction......Page 724 19.5.2 Vibro-Displacement Compaction......Page 726 19.6.1 Pre-loading and Surcharge Fills......Page 731 19.6.2 Vertical Drains......Page 732 19.7 Grouting and Injection......Page 734 19.7.1 Suspension Grouts......Page 735 19.7.2 Solution Grouts......Page 737 19.8.2 Cement Stabilization......Page 738 19.9 Soil Reinforcement......Page 739 19.10.1 Geotextiles......Page 740 19.11.1 Thermal Methods......Page 743 19.11.4 Addition or Removal......Page 744 Questions......Page 745 Exercise Problems......Page 747 20.2 Types of Embankment Dams......Page 748 20.2.3 Zoned Type......Page 749 20.3.2 Casing......Page 750 20.3.4 Other Embankment Details......Page 751 20.4.1 Safety Against Over-Topping......Page 753 20.4.2 Control of Seepage and Pressure in Earth Dams......Page 754 20.4.3 Protection Against Free Passage of Water Through Dams......Page 763 20.4.4 Stability of Earth Dam Slopes......Page 764 20.4.5 Protection of Crest, Upstream, and Downstream Faces......Page 769 Worked Examples......Page 770 Points to Remember......Page 772 Questions......Page 773 Exercise Problems......Page 775 21.2 Earthquakes......Page 778 21.2.2 Magnitude......Page 779 21.4 Theory of Vibrations......Page 780 21.4.2 Free Vibration of a Spring–mass System......Page 781 21.4.3 Free Vibration with Viscous Damping......Page 782 21.4.4 Forced Vibrations with Viscous Damping......Page 783 21.5 Types of Machines and Machine Foundations......Page 785 21.6 Dynamic Bearing Capacity of Shallow Foundations......Page 786 21.7 Design Requirements......Page 787 21.8 Methods of Analysis for Block Foundation......Page 790 21.9 Liquefaction of Soils......Page 792 Points to Remember......Page 793 Questions......Page 794 22.2 Environmental Cycles......Page 796 22.3.1 Oxygen Cycle......Page 797 22.4.3 Acid Rain and Acid Drainage......Page 798 22.4.8 Soil Erosion......Page 799 22.6.1 Identification......Page 800 22.7 Applications......Page 801 Points to Remember......Page 802 Questions......Page 803 23.2 Index Properties of Rocks......Page 806 23.2.3 Permeability......Page 807 23.2.4 Strength......Page 809 23.2.5 Slaking and Durability......Page 810 23.2.6 Sonic Velocity......Page 811 23.3 Classification of Rocks......Page 812 23.4.2 Horizontal Stress......Page 816 23.4.3 Effective Stress in Rock Masses......Page 817 23.4.4 Measurement of In Situ Stresses......Page 818 23.5.2 Behaviour of Rocks in Uniaxial Compression......Page 819 23.5.3 Tensile Strength of Rocks......Page 822 23.5.4 Behaviour of Rocks in Triaxial Compression......Page 825 23.5.5 Failure Theory Applicable to Rocks......Page 826 23.5.6 Shear Strength of Rocks......Page 827 23.5.7 Elastic Properties of Rocks......Page 828 23.5.8 Hardness......Page 829 Points to Remember......Page 830 Questions......Page 831 Exercise Problems......Page 832 24.2 Components of Pavement......Page 834 24.4 Requirements of Pavement Components......Page 835 24.5.2 Embankment and Cutting......Page 836 24.6.1 Design Wheel Load......Page 837 24.6.2 Properties of Subgrade and Pavement Components......Page 838 24.7.1 Group Index Method......Page 839 24.7.2 California Bearing Ratio (CBR) Method......Page 840 24.7.3 Mc Leod Method......Page 842 24.7.4 Burmister’s Method......Page 845 24.8.1 Stresses in Concrete Pavements......Page 847 24.8.2 Westergaard’s Stress Equations......Page 848 24.8.3 Indian Road Congress (IRC) Formula (IRC 15, 1981)......Page 849 Worked Examples......Page 850 Points to Remember......Page 853 Questions......Page 854 Exercise Problems......Page 855 List of Symbols......Page 856 Bibliography......Page 862 Index......Page 876