Objective. County-level socioeconomic and demographic data were used to construct an index of social vulnerability to environmental hazards, called the Social Vulnerability Index (SoVI) for the United States based on 1990 data.

Methods. Using a factor analytic approach, 42 variables were reduced to 11 independent factors that accounted for about 76 percent of the variance. These factors were placed in an additive model to compute a summary score—the Social Vulnerability Index.

Results. There are some distinct spatial patterns in the SoVI, with the most vulnerable counties clustered in metropolitan counties in the east, south Texas, and the Mississippi Delta region.

Conclusion. Those factors that contribute to the overall score often are different for each county, underscoring the interactive nature of social vulnerability—some components increase vulnerability; others moderate the effects.

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Social Vulnerability to Environmental Hazards

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Global environmental change and sustainability science increasingly recognize the need to address the consequences of changes taking place in the structure and function of the biosphere. These changes raise questions such as: Who and what are vulnerable to the multiple environmental changes underway, and where? Research demonstrates that vulnerability is registered not by exposure to hazards (perturbations and stresses) alone but also resides in the sensitivity and resilience of the system experiencing such hazards. This recognition requires revisions and enlargements in the basic design of vulnerability assessments, including the capacity to treat coupled human–environment systems and those linkages within and without the systems that affect their vulnerability. A vulnerability framework for the assessment of coupled human–environment systems is presented.

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A framework for vulnerability analysis in sustainability science

Recent advances in theory and experimen- tation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a com- prehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoret- ical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining stat- ic; both can deform in a slow, tranquil mode character- ized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompress- ible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (mea- sured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibra- tional energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ;10 m 3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris be- hind surge fronts is nearly liquefied by high pore pres- sure, which persists owing to the great compressibility and moderate permeability of the debris. Realistic mod- els of debris flows therefore require equations that sim- ulate inertial motion of surges in which high-resistance fronts dominated by solid forces impede the motion of low-resistance tails more strongly influenced by fluid forces. Furthermore, because debris flows characteristi- cally originate as nearly rigid sediment masses, trans- form at least partly to liquefied flows, and then trans- form again to nearly rigid deposits, acceptable models must simulate an evolution of material behavior without invoking preternatural changes in material properties. A simple model that satisfies most of these criteria uses depth-averaged equations of motion patterned after those of the Savage-Hutter theory for gravity-driven flow of dry granular masses but generalized to include the effects of viscous pore fluid with varying pressure. These equations can describe a spectrum of debris flow behav- iors intermediate between those of wet rock avalanches and sediment-laden water floods. With appropriate pore pressure distributions the equations yield numerical so- lutions that successfully predict unsteady, nonuniform motion of experimental debris flows.

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The physics of debris flows

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...

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The strength and dilatancy of sands

The book is intended to develop an understanding of the factors determining and controlling the engineering properties of soil, the factors controlling their magnitude, and the influences of environment and time. The two-part book contains the following chapters: Part 1 - the nature of soils; bonding, crystal structure and surface characteristics; soil mineralogy; soil formation and soil deposits; determination of soil composition; soil water; clay-water-electrolyte system; soil fabric and its measurement; Part 2 - soil behavior; soil composition and engineering properties; effective, intergranular and total stress; soil structure and its stability; fabric, structure and property relationships, volume change behavior; strength and deformation behavior; and, conduction phenomena. /TRRL/

Fundamentals of soil behavior

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.

Fundamentals of Soil Behaviour

The understanding of soil behavior during the last 300 years has centered on mechanical principles, geological processes, and later on, mineralogy and the relevance of colloidal chemistry. More recently, research in biology and earth science has enabled important advances in understanding the crucial involvement of microorganisms in the evolution of the earth, their ubiquitous presence in near surface soils and rocks, and their participation in mediating and facilitating most geochemical reactions. Yet, the effect of biological activity on soil mechanical behavior remains largely underexplored in the geotechnical field. The purposes of this paper are to introduce microbiological concepts, identify and illustrate their potential roles in soils and rocks, and stimulate interest in seeking improved understanding of their importance and potential for advancing the states of knowledge and practice in geotechnical engineering. It is shown that microorganisms play an important part on the formation of many fine grained soils, can alter the behavior of coarse grained soils (including hydraulic conductivity, diffusion and strength), accelerate geochemical reactions by orders of magnitude, promote both weathering and aging, and alter the chemical and mechanical properties of specimens after sampling. While extensive research is needed to delineate the full impact of biomass and biomediated reactions on soil behavior, it is anticipated that a proper understanding of biological principles will lead to improved soil characterization, enhanced understanding of soil behavior, and even alternative geotechnical engineering solutions.

Biological Considerations in Geotechnical Engineering

Volume and pore water pressure variations that develop in saturated soils due to temperature changes are expressed in terms of the thermal expansion of the soil components, compressibility of the soil and physico-chemical effects. While the compression index of remolded illite was found independent of temperate, the higher the temperature the lower the void ratio at any given consolidation pressure. The magnitude of pore pressure change accompanying temperature change under undrained conditions is controlled primarily by the compressibility of the soil and thermal expansion of pore water. Results are useful for assessing the effects of temperature variations on properties of soils, the assessment of necessary laboratory temperature control during undrained tests, and the study of physico-chemical phenomena in soils.

James K. Mitchell

Papers

Fundamentals of soil behavior

Fundamentals of soil behavior

Fundamentals of Soil Behaviour

Biological Considerations in Geotechnical Engineering

Influence of Temperature Variations on Soil Behavior