Silt

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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.

Nomenclature Based on Sand-silt-clay Ratios

Abstract: Following a canvassing of sedimentationists an attempt is made to standardize nomenclature of sediment types relative to sand, silt, and clay content. A triangle diagram with boundaries between types, which met with general approval, is submitted and compared with other systems which have been used for the purpose. The new system uses old well established names and has a simplicity and symmetry which make it easily remembered. The boundaries appear to be well located for description of sediments such as those that have been analyzed in large volume from the investigations of the northern Gulf of Mexico (API Project 51), but it is inadequate in describing well sorted sediments with median diameters near the boundaries of sand and silt or silt and clay. The nomenclature suggested applie only to sediment grade sizes so that other names should be used depending on other characteristics of the sediments. Furthermore, the nomenclature should not be applied to sediments containing large percentages of gravel.

A Statistical Exploration of the Relationships of Soil Moisture Characteristics to the Physical Properties of Soils

Abstract: Stochastic modeling of soil water fluxes in the absence of measured hydraulic parameters requires a knowledge of the expected distribution of the hydraulic parameters in different soil types. Predictive relationships describing the hydraulic parameter distributions must be developed based on the common descriptors of the physical properties of soils (e.g., texture, structure, particle size distribution). Covariation among the hydraulic parameters within these relationships must be identified. Data for 1448 soil samples were examined in an evaluation of the usefulness of qualitative descriptors as predictors of soil hydraulic behavior. Analysis of variance and multiple linear regression techniques were used to derive quantitative expressions for the moments of the hydraulic parameters as functions of the particle size distributions (percent sand, silt, and clay content) of soils. Discriminant analysis suggests that the covariation of the hydraulic parameters can be used to construct a classification scheme based on the hydraulic behavior of soils that is analogous to the textural classification scheme based on the sand, silt, and clay content of soils.

The Distinction between Grain Size and Mineral Composition in Sedimentary-Rock Nomenclature

Abstract: A system of grain-size nomenclature of terrigenous sediments and sedimentary rocks is introduced wherein fifteen major textural groups are defined on the ratios of gravel, sand, silt, and clay. Further subdivision of each class is based on the median diameter of each size fraction present. Next, the mineral composition of terrigenous sedimentary rocks is considered. A triangular diagram is used to define eight rock types (orthoquartzite, arkose, graywacke, and five transitional types) based on the mineralogy of the silt-sand-gravel fraction and ignoring clay content. The writer contends that the current practice of calling all clayey sandstones "graywackes" is not valid, inasmuch as it represents a confusion of texture with composition. It is suggested that sedimentary rocks may be best defined by the use of a tripartite name, based on the following pattern-(grain size): (textural maturity) (mineral composition).

The capacity of soils to preserve organic C and N by their association with clay and silt particles

Abstract: Although it has been recognized that the adsorption of organics to clay and silt particles is an important determinant of the stability of organic matter in soils, no attempts have been made to quantify the amounts of C and N that can be preserved in this way in different soils. Our hypothesis is that the amounts of C and N that can be associated with clay and silt particles is limited. This study quantifies the relationships between soil texture and the maximum amounts of C and N that can be preserved in the soil by their association with clay and silt particles. To estimate the maximum amounts of C and N that can be associated with clay and silt particles we compared the amounts of clay- and silt-associated C and N in Dutch grassland soils with corresponding Dutch arable soils. Secondly, we compared the amounts of clay- and silt-associated C and N in the Dutch soils with clay and silt-associated C and N in uncultivated soils of temperate and tropical regions. We observed that although the Dutch arable soils contained less C and N than the corresponding grassland soils, the amounts of C and N associated with clay and silt particles was the same indicating that the amounts of C and N that can become associated with this fraction had reached a maximum. We also observed close positive relationships between the proportion of primary particles 20 μm was not correlated with soil texture. Cultivation decreased the amount of C and N in the fraction > 20 μm to a greater extent than in the fraction < 20 μm, indicating that C and N associated with the fraction < 20 μm is better protected against decomposition. The finding of a given soil having a maximum capacity to preserve organic C and N will improve our estimations of the amounts of C and N that can become stabilized in soils. It has important consequences for the contribution of different soils to serve as a sink or source for C and N in the long term.