Effective stress

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Fundamentals of soil behavior

Abstract: Preface. CHAPTER 1: INTRODUCTION. 1.1 Soil Behavior in Civil and Environmental Engineering. 1.2 Scope and Organization. 1.3 Getting Started. CHAPTER 2: SOIL FORMATION. 2.1 Introduction. 2.2 The Earth's Crust. 2.3 Geologic Cycle and Geological Time. 2.4 Rock and Mineral Stability. 2.5 Weathering. 2.6 Origin of Clay Minerals and Clay Genesis. 2.7 Soil Profiles and Their Development. 2.8 Sediment Erosion, Transport, and Deposition. 2.9 Postdepositional Changes in Sediments. 2.10 Concluding Comments. Questions and Problems. CHAPTER 3: SOIL MINERALOGY. 3.1 Importance of Soil Mineralogy in Geotechnical Engineering. 3.2 Atomic Structure. 3.3 Interatomic Bonding. 3.4 Secondary Bonds. 3.5 Crystals and Their Properties. 3.6 Crystal Notation. 3.7 Factors Controlling Crystal Structures. 3.8 Silicate Crystals. 3.9 Surfaces. 3.10 Gravel, Sand, and Silt Particles. 3.11 Soil Minerals and Materials Formed by Biogenic and Geochemical Processes. 3.12 Summary of Nonclay Mineral Characteristics. 3.13 Structural Units of the Layer Silicates. 3.14 Synthesis Pattern and Classification of the Clay Minerals. 3.15 Intersheet and Interlayer Bonding in the Clay Minerals. 3.16 The 1:1 Minerals. 3.17 Smectite Minerals. 3.18 Micalike Clay Minerals. 3.19 Other Clay Minerals. 3.20 Summary of Clay Mineral Characteristics. 3.21 Determination of Soil Composition. 3.22 X-ray Diffraction Analysis. 3.23 Other Methods for Compositional Analysis. 3.24 Quantitative Estimation of Soil Components. 3.25 Concluding Comments. Questions and Problems. CHAPTER 4: SOIL COMPOSITION AND ENGINEERING PROPERTIES. 4.1 Introduction. 4.2 Approaches to the Study of Composition and Property Interrelationships. 4.3 Engineering Properties of Granular Soils. 4.4 Dominating Influence of the Clay Phase. 4.5 Atterberg Limits. 4.6 Activity. 4.7 Influences of Exchangeable Cations and pH. 4.8 Engineering Properties of Clay Minerals. 4.9 Effects of Organic Matter. 4.10 Concluding Comments. Questions and Problems. CHAPTER 5: SOIL FABRIC AND ITS MEASUREMENT. 5.1 Introduction. 5.2 Definitions of Fabrics and Fabric Elements. 5.3 Single-Grain Fabrics. 5.4 Contact Force Characterization Using Photoelasticity. 5.5 Multigrain Fabrics. 5.6 Voids and Their Distribution. 5.7 Sample Acquisition and Preparation for Fabric Analysis. 5.8 Methods for Fabric Study. 5.9 Pore Size Distribution Analysis. 5.10 Indirect Methods for Fabric Characterization. 5.11 Concluding Comments. Questions and Problems. CHAPTER 6: SOIL-WATER-CHEMICAL INTERACTIONS. 6.1 Introduction. 6.2 Nature of Ice and Water. 6.3 Influence of Dissolved Ions on Water. 6.4 Mechanisms of Soil-Water Interaction. 6.5 Structure and Properties of Adsorbed Water. 6.6 Clay-Water-Electrolyte System. 6.7 Ion Distributions in Clay-Water Systems. 6.8 Elements of Double-Layer Theory. 6.9 Influences of System Variables on the Double Layer. 6.10 Limitations of the Gouy-Chapman Diffuse Double Layer Model. 6.11 Energy and Force of Repulsion. 6.12 Long-Range Attraction. 6.13 Net Energy of Interaction. 6.14 Cation Exchange-General Considerations. 6.15 Theories for Ion Exchange. 6.16 Soil-Inorganic Chemical Interactions. 6.17 Clay-Organic Chemical Interactions. 6.18 Concluding Comments. Questions and Problems. CHAPTER 7: EFFECTIVE, INTERGRANULAR, AND TOTAL STRESS. 7.1 Introduction. 7.2 Principle of Effective Stress. 7.3 Force Distributions in a Particulate System. 7.4 Interparticle Forces. 7.5 Intergranular Pressure. 7.6 Water Pressures and Potentials. 7.7 Water Pressure Equilibrium in Soil. 7.8 Measurement of Pore Pressures in Soils. 7.9 Effective and Intergranular Pressure. 7.10 Assessment of Terzaghi's Equation. 7.11 Water-Air Interactions in Soils. 7.12 Effective Stress in Unsaturated Soils. 7.13 Concluding Comments. Questions and Problems. CHAPTER 8: SOIL DEPOSITS-THEIR FORMATION, STRUCTURE, GEOTECHNICAL PROPERTIES, AND STABILITY. 8.1 Introduction. 8.2 Structure Development. 8.3 Residual Soils. 8.4 Surficial Residual Soils and Taxonomy. 8.5 Terrestrial Deposits. 8.6 Mixed Continental and Marine Deposits. 8.7 Marine Deposits. 8.8 Chemical and Biological Deposits. 8.9 Fabric, Structure, and Property Relationships: General Considerations. 8.10 Soil Fabric and Property Anisotropy. 8.11 Sand Fabric and Liquefaction. 8.12 Sensitivity and Its Causes. 8.13 Property Interrelationships in Sensitive Clays. 8.14 Dispersive Clays. 8.15 Slaking. 8.16 Collapsing Soils and Swelling Soils. 8.17 Hard Soils and Soft Rocks. 8.18 Concluding Comments. Questions and Problems. CHAPTER 9: CONDUCTION PHENOMENA. 9.1 Introduction. 9.2 Flow Laws and Interrelationships. 9.3 Hydraulic Conductivity. 9.4 Flows Through Unsaturated Soils. 9.5 Thermal Conductivity. 9.6 Electrical Conductivity. 9.7 Diffusion. 9.8 Typical Ranges of Flow Parameters. 9.9 Simultaneous Flows of Water, Current, and Salts Through Soil-Coupled Flows. 9.10 Quantification of Coupled Flows. 9.11 Simultaneous Flows of Water, Current, and Chemicals. 9.12 Electrokinetic Phenomena. 9.13 Transport Coefficients and the Importance of Coupled Flows. 9.14 Compatibility-Effects of Chemical Flows on Properties. 9.15 Electroosmosis. 9.16 Electroosmosis Efficiency. 9.17 Consolidation by Electroosmosis. 9.18 Electrochemical Effects. 9.19 Electrokinetic Remediation. 9.20 Self-Potentials. 9.21 Thermally Driven Moisture Flows. 9.22 Ground Freezing. 9.23 Concluding Comments. Questions and Problems. CHAPTER 10: VOLUME CHANGE BEHAVIOR. 10.1 Introduction. 10.2 General Volume Change Behavior of Soils. 10.3 Preconsolidation Pressure. 10.4 Factors Controlling Resistance to Volume Change. 10.5 Physical Interactions in Volume Change. 10.6 Fabric, Structure, and Volume Change. 10.7 Osmotic Pressure and Water Adsorption Influences on Compression and Swelling. 10.8 Influences of Mineralogical Detail in Soil Expansion. 10.9 Consolidation. 10.10 Secondary Compression. 10.11 In Situ Horizontal Stress (K 0 ). 10.12 Temperature-Volume Relationships. 10.13 Concluding Comments. Questions and Problems. CHAPTER 11 STRENGTH AND DEFORMATION BEHAVIOR. 11.1 Introduction. 11.2 General Characteristics of Strength and Deformation. 11.3 Fabric, Structure, and Strength. 11.4 Friction Between Solid Surfaces. 11.5 Frictional Behavior of Minerals. 11.6 Physical Interactions Among Particles. 11.7 Critical State: A Useful Reference Condition. 11.8 Strength Parameters for Sands. 11.9 Strength Parameters for Clays. 11.10 Behavior After Peak and Strain Localization. 11.11 Residual State and Residual Strength. 11.12 Intermediate Stress Effects and Anisotropy. 11.13 Resistance to Cyclic Loading and Liquefaction. 11.14 Strength of Mixed Soils. 11.15 Cohesion. 11.16 Fracturing of Soils. 11.17 Deformation Characteristics. 11.18 Linear Elastic Stiffness. 11.19 Transition from Elastic to Plastic States. 11.20 Plastic Deformation. 11.21 Temperature Effects. 11.22 Concluding Comments. Questions and Problems. CHAPTER 12: TIME EFFECTS ON STRENGTH AND DEFORMATION. 12.1 Introduction. 12.2 General Characteristics. 12.3 Time-Dependent Deformation-Structure Interaction. 12.4 Soil Deformation as a Rate Process. 12.5 Bonding, Effective Stresses, and Strength. 12.6 Shearing Resistance as a Rate Process. 12.7 Creep and Stress Relaxation. 12.8 Rate Effects on Stress-Strain Relationships. 12.9 Modeling of Stress-Strain-Time Behavior. 12.10 Creep Rupture. 12.11 Sand Aging Effects and Their Significance. 12.12 Mechanical Processes of Aging. 12.13 Chemical Processes of Aging. 12.14 Concluding Comments. Questions and Problems. List of Symbols. References. Index.

The strength and dilatancy of sands

Abstract: Extensive data of the strength and dilatancy of 17 sands in axisymmetric or plane strain at different densities and confining pressures are collated. The critical state angle of shearing resistance of soil which is shearing at constant volume is principally a function of mineralogy and can readily be determined experimentally within a margin of about 1°, being roughly 33° for quartz and 40° for feldspar. The extra angle of shearing of ‘dense’ soil is correlated to its rate of dilation and thence to its relative density and mean effective stress, combined in a new relative dilatancy index. The data of o′max – o′crit in triaxial or plane strain are separately fitted within a typical margin of about 2°, though the streneth of certain sands is underpredicted in the 1000–10000 kN/m2 range owing to the continued dilation of their crush-resistant grains. The practical consequences of these new correlations are assessed, with regard to both laboratory and field testing procedures. L'auteur analyse de nombreuses d...

Role of fluid pressure in mechanics of overthrust faulting: I. Mechanics of fluid-filled porous solids and its application to overthrust faulting

Abstract: Promise of resolving the paradox of overthrust faulting arises from a consideration of the influence of the pressure of interstitial fluids upon the effective stresses in rocks. If, in a porous rock filled with a fluid at pressure p, the normal and shear components of total stress across any given plane are S and T, then are the corresponding components of the effective stress in the solid alone. According to the Mohr-Coulomb law, slippage along any internal plane in the rock should occur when the shear stress along that plane reaches the critical value where σ is the normal stress across the plane of slippage, τ 0 the shear strength of the material when σ is zero, and ϕ the angle of internal friction. However, once a fracture is started τ 0 is eliminated, and further slippage results when This can be further simplified by expressing p in terms of S by means of the equation which, when introduced into equation (4), gives From equations (4) and (6) it follows that, without changing the coefficient of friction tan ϕ , the critical value of the shearing stress can be made arbitrarily small simply by increasing the fluid pressure p. In a horizontal block the total weight per unit area S zz is jointly supported by the fluid pressure p and the residual solid stress σ zz ; as p is increased, σ zz is correspondingly diminished until, as p approaches the limit S zz , or λ approaches 1, σ zz approaches 0. For the case of gravitational sliding, on a subaerial slope of angle θ where T is the total shear stress, and S the total normal stress on the inclined plane. However, from equations (2) and (6) Then, equating the right-hand terms of equations (7) and (8), we obtain which indicates that the angle of slope θ down which the block will slide can be made to approach 0 as λ approaches 1, corresponding to the approach of the fluid pressure p to the total normal stress S . Hence, given sufficiently high fluid pressures, very much longer fault blocks could be pushed over a nearly horizontal surface, or blocks under their own weight could slide down very much gentler slopes than otherwise would be possible. That the requisite pressures actually do exist is attested by the increasing frequency with which pressures as great as 0.9 S zz are being observed in deep oil wells in various parts of the world.

An Introduction to Geotechnical Engineering

Abstract: This manual presents data on soil behaviour, with emphasis on practical and empirical knowledge, required by geotechnical engineers for the design and construction of foundations and embankments It deals with: index and classification properties of soils; soil classification; clay minerals and soil structure; compaction; water in soils (capillarity, shrinkage, swelling, frost action, permeability, seepage, effective stress); consolidation and consolidation settlements; time rate of consolidation; the Mohr circle, failure theories, and stress paths; shear strength of sands and clays Four appendices deal with the following: application of the "SI" system of units to getechnical engineering; derivation of Laplace's equation; derivation and solution of Terzaghi's one-dimensional consolidation theory; pore pressure parameters (TRRL)