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Mechanics of reinforced soil1

This book deals with the stress analysis of reinforcedsoils. Its six chapters are entitled: 1) Introduction; 2) Prop-erties of reinforced soil constituents; 3) Interaction betweenthe soil and reinforcement; 4) Composite models of rein-forced soil; 5) Limit states; and 6) Stresses and strains in re-inforced soil. An approach that treats the mixture of soil andreinforcement as a composite material with anisotropic prop-erties is adopted to analyze the mechanics of reinforcedsoils. This approach is different from the discrete materialmethod that explicitly considers the characteristics of eachelement in a reinforced soil structure. In this book, the rein-forced soil denoted as RS is defined as a composite con-struction material consisting of a soil matrix strengthenedwith sufficient reinforcement layers, such as layers of metalstrips or geosynthetics. By this definition reinforced soilwalls, slopes, and abutments may be considered as RS; how-ever, reinforced embankments cannot be treated as RS sincethey typically have only one reinforcement layer betweenthe embankment and the subsoil. Thus, this book deals withreinforced soil walls and slopes.

Chapter 1 introduces the concept of reinforced soil and abrief literature review of research on reinforced soil walls.The differences between the conventional retaining wallsand reinforced soil walls are highlighted. Subsequently, theauthor discussed the fundamental mechanisms of reinforcedsoil followed by a brief summary of design considerationsrelated to the internal failure mechanisms for reinforced soilwalls. Chapter 2 deals with the basic behaviour of granularsoils and reinforcement materials and the interfaces betweensoil and reinforcement. The rheological behaviour ofgeosynthetic reinforcement is examined based on experi-mental data and a number of simple rheological models arerecommended. A mechanical model is formulated in Chapter3 for the interpretation of pull-out test data and the effects ofreinforcement creep, soil confining, and interface stiffnesson the soil-reinforcement interaction are discussed. Chapter4 presents the theoretical formulation of an elastic-plasticsoil-reinforcement composite model and transformation ofthe constituents’ yield surfaces into the stress space of the

composite material. The composite model is extended to al-low for creep of the reinforcement by incorporating an ap-propriate rheological model for reinforcement. However, thequestion as to how much reinforcement in a soil matrix (i.e.,the number of reinforcement layers) is required in order toapply composite models remains open, with a trial and errorapproach being recommended by the author. Chapter 5 ap-plies the limit plasticity theory and slip-line method to theanalysis of the stability of reinforced soil composites de-scribed in Chapter 4. Bearing capacity equations for rein-forced subsoil, reinforced soil walls, and slopes areformulated using the composite continuum approach. Thelower bound and upper bound of the collapse load of rein-forced soil walls are evaluated based on limit statestheorems. Using these equations, a number of examples aregiven to illustrate the author’s approach to the design of re-inforcement beneath footings, within reinforced soil walls,and slopes. Chapter 6 presents a method of analyzing thestress and strain in reinforced soil walls at different con-struction stages. The equations used to calculate the rein-forcement stress and strain are derived and a number ofexamples are given wherein the force and strain in the rein-forced soil are estimated. There is no discussion or compari-son of the pros and cons for the proposed method of analysisversus other more widely used methods. It is recommendedthat the proposed method should be adequately verifiedagainst full-scale (field) test data.

This book is of potential interest to students, engineers,and researchers in that it provides an alternative approach tothe analysis of reinforced soil by treating it as a compositematerial.

A.L. LiGeoEngineering Centre at Queen's RMCDepartment of Civil EngineeringQueen's UniversityKingston, ON K7L 3N6, Canada(e-mail: alli@post.queensu.ca)

Can. Geotech. J.38: 1366 (2001) © 2001 NRC Canada

1366

DOI: 10.1139/cgj-38-6-1366

Received January 10, 2001. Accepted May 24, 2001. Published on the NRC Research Press Web site at http://cgj.nrc.ca on January10, 2002.

1Andrzej Sawicki. A.A. Balkema, Rotterdam.

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