Towards A Unified Soil Mechanics Theory The Use Of Effective Stresses In Unsaturated Soils Third Edition

Towards A Unified Soil Mechanics Theory demonstrates mathematical models for saturated and unsaturated soils by defining the effective stress equation. Chapters present hydraulic models that simulate water distribution in pores. Parameters from these models are then used to demonstrate the use of an effective stress equation to understand the mechanics of soils that have different material constitutions. Key Features: -Sequentially explains soil modeling techniques for easy understanding -Demonstrates the use of an effective stress equation based on data from porous-solid models. -Explains how porous-solid models can simulate the soilwater retention curves of materials. -Establishes an elastoplastic framework for the volumetric behavior of unsaturated soils that is used to simulate the phenomenon of collapse upon wetting and the behavior of expansive soils. -Explains the practical application of fully a coupled hydro-mechanical (critical state) soil model -Includes scientific references for further reading The third edition includes additional information on retention curves in deforming curves, the application of a coupled hydro-mechanical model simulating undrained tests and the behavior of soils during static compaction, and the use of a porous-solid model to develop a fully analytical equation for the relative hydraulic conductivity of soils. The new chapters also cover the experimental parameters used to derive the models. This edition also updates material from previous editions, and adds new scientific references. Towards A Unified Soil Mechanics Theory paves the way for a universal theory of soil mechanics that has a wide range of applications. The book is a valuable reference to civil engineers, geotechnical engineers, earth scientists and hydrologists interested in soil mechanics at both academic and professional levels.

"With the application of the effective stress concept, the strength and volumetric behavior of saturated materials was clearly understood. For the case of unsaturated materials, a universally accepted effective stresses equation is still under debate. Howe"

With the application of the effective stress concept, the strength and volumetric behavior of saturated materials was clearly understood. For the case of unsaturated materials, a universally accepted effective stresses equation is still under debate. However, the use of the effective stress concept to develop constitutive models for unsaturated soils is becoming increasingly popular not only because the hydro-mechanical coupling observed in these materials is implicit in the formulation but also because simpler and more precise models can be established. Towards A Unified Soil Mechanics Theory demonstrates that the same strength and volume change equations used in saturated soil mechanics can be used for the case of unsaturated soils. In other words, the constitutive models developed for saturated soils can be used for unsaturated materials once the effective stress equation has been defined. In this book, an analytical equation for the effective stress for unsaturated soils is established. This equation requires the knowledge of the superficial area of solids affected by the capillary phenomenon. In other words, we need to know how water distributes in the pores of the soil. This distribution can be modeled using a solid-porous model built on a regular network. However, the size of the network required to correctly simulate the structure of a small soil sample cannot be managed with a common PC. For that reason, a probabilistic porous-solid model is developed. This model uses the pore size distribution in the form of a probabilistic function which in addition to the Laplace equation and the principle of continuity can be expressed as the probability of a pore of certain size to be filled or dry at suction during a wetting or drying path, respectively. In this way, the soil-water retention curves can be simulated and the effective stress at any suction during wetting or drying processes can be determined. Based on this approach, it is shown that unsaturated soils behave under the same principles for strength and volumetric behavior as saturated soils. This revised edition brings additional information about an elastoplastic framework for expansive soils, hydro-mechanical coupling and a fully coupled model. The additional chapters also cover the experimental parameters used to derive the models. An updated set of references and a list of abbreviations is also included in this edition. Towards A Unified Soil Mechanics Theory paves the way for a universal theory of soil mechanics. The volume will be a valuable reference to civil engineers, earth scientists and hydrologists interested in soil mechanics at both academic and professional levels.

Water inside the earth, the groundwater and the invisible resource is the most important source of survival of mankind on this globe. Part of the hydrological cycle between entry (percolation and recharge) and exit (natural or forced extraction and discharge), the groundwater fascinates all: engineers, hydrogeologists, agriculturists, environmentalists, scientists, academia, resource managers and domestic and industrial users. This book is the outcome of efforts of those eminent authors who despite their fascination were able to write upon some important facet of groundwater flow and the transport of pollutants with it. The dimensions covered range from simple descriptive narratives; to expose of analytical methods; to complex mathematical treatment; to numerical simulations and computer modeling. All areas have been touched upon for the sake of general readers, students, professional engineers and scientists.

In the past decades advances have been made in the research and practice on unsaturated soil mechanics. In 2000 the first Asia-Pacific Conferences on Unsaturated Soils was organized in Singapore. Since then, four conferences have been held under the continued support of the Technical Committee on Unsaturated Soils (TC106) of the International Socie

The concept of effective stress and the effective stress equation is fundamental for establishing the theory of strength and the relationship of stress and strain in soil mechanics and poromechanics. However, up till now, the physical meaning of effective stress has not been explained clearly, and the theoretical basis of the effective stress equation has not been proposed. Researchers have not yet reached a common understanding of the feasibility of the concept of effective stress and effective stress equation for unsaturated soils. Effective Stress and Equilibrium Equation for Soil Mechanics discusses the definition of the soil skeleton at first and clarifies that the soil skeleton should include a fraction of pore water. When a free body of soil skeleton is taken to conduct internal force analysis, the stress on the surface of the free body has two parts: one is induced by pore fluid pressure that only includes normal stress; the other is produced by all the other external forces excluding pore fluid pressure. If the effective stress is defined as the soil skeleton stress due to all the external forces excluding pore fluid pressure, the effective stress equation can be easily obtained by the internal force equilibrium analysis. This equation reflects the relationship between the effective stress, total stress and pore fluid pressure, which does not change with the soil property. The effective stress equation of saturated soils and unsaturated soils is unified, i.e., o ̃=o ̃t –Seuw–(1–Se)ua. For multiphase porous medium, o ̃=o ̃t –u*,u*=Seiui(i=1,2,...,M). In this book, a theoretical formula of the coefficient of permeability for unsaturated soils is derived. The formula of the seepage force is modified based on the equilibrium differential equation of the pore water. The relationship between the effective stress and the shear strength and deformation of unsaturated soils is preliminarily verified. Finally, some possibly controversial problems are discussed to provide a better understanding of the role of the equilibrium equation and the concept of effective stress.

An understanding of the mechanical properties of unsaturated soilsis crucial for geotechnical engineers worldwide, as well as tothose concerned with the interaction of structures with the ground.This book deals principally with fine-grained clays and silts, orsoils containing coarser sand and gravel particles but with asignificant percentage of fines. The study of unsaturated soil is a practical subject, linkingfundamental science to nature. Soils in general are inherentlyvariable and their behaviour is not easy to analyse or predict, andunsaturated soils raise the complexity to a higher level. Evenamongst practicing engineers, there is often lack of awareness ofthe intricacies of the subject. This book offers a perspective ofunsaturated soils based on recent research and demonstrates howthis dovetails with the general discipline of soil mechanics. Following an introduction to the basic soil variables, thephases, the phase interactions and the relevance of soil structure,an up-to-date review of laboratory testing techniques is presented.This includes suction measurement and control techniques intriaxial cell testing. This is followed by an introduction tostress state variables, critical state and theoretical models inunsaturated soils. A detailed description of the thermodynamic principles asapplied to multi-phase materials under equilibrium conditionsfollows. These principles are then used to explore and develop afundamental theoretical basis for analysing unsaturated soils. Soilstructure is broken down into its component parts to developequations describing the dual stress regime. The critical statestrength and compression characteristics of unsaturated soils areexamined and it is shown how the behaviour may be viewed as athree-dimensional model in dimensionless stress-volume space. Theanalysis is then extended to the work input into unsaturated soilsand the development of conjugate stress, volumetric andstrain-increment variables. These are used to examine themicromechanical behaviour of kaolin specimens subjected to triaxialshear strength tests and lead to observations not detectable byother means. Unsaturated Soils: A fundamental interpretation of soilbehaviour covers a rapidly advancing area of study, researchand engineering practice and offers a deeper appreciation of thekey characteristics of unsaturated soil. It provides students andresearchers with a framework for understanding soil behaviour anddemonstrates how to interpret experimental strength and compressiondata. provides engineers with a deeper appreciation of keycharacteristics of unsaturated soils covers a rapidly advancing area of study, research andengineering practice provides students and researchers a framework for understandingsoil behaviour shows how to interpret experimental data on strength andcompression the limited number of books on the subject are all out ofdate

Unsaturated soil mechanics is now increasingly recognized as an integral part of mainstream soil mechanics, and the importance and relevance of unsaturated soil mechanics for the broad field of geotechnical engineering no longer needs to be emphasized. The two volumes making up Unsaturated soils include papers from the 4th Asia Pacific Confere