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Über dieses Buch

This book includes a numerical investigation of shear localization in granular materials within micro-polar hypoplasticity, which was carried out during my long research stay at the Institute of Soil and Rock Mechanics at Karlsruhe University from 1985 to 1996. I dedicate my book to Prof. Gerd Gudehus from Germany, the former head of the Institute of Rock and Soil Mechanics at Karlsruhe University and the supervisor of my scientific research during my stay in Karlsruhe, who encouraged me to deal with shear localization in granular bodies within micro-polar hypoplasticity. I greatly - preciate his profound knowledge, kind help constructive discussions, and collegial attitude to his co-workers. I am thankful to the both series editors: Prof. Wei Wu from Universität für Bodenkultur in Austria and Prof. Ronaldo Borja from Stanford University in USA for their helpful suggestions with respect to the contents and structure of the book. I am also grateful to Dr. Thomas Ditzinger and Mrs. Heather King from the Springer Publishing Company and SPS data processing team for their help in editing this book. Gdansk, Jacek Tejchman June 2008 Contents 1 Introduction......................................................................... 1 2 Literature Overview on Experiments........................................... 11 3 Theoretical Model.................................................................. 47 3.1 Hypoplastic Constitutive Model............................................. 47 3.2 Calibration of Hypoplastic Material Parameters........................... 60 3.3 Micro-polar Continuum……………………………………………….. 67 3.4 Micro-polar Hypoplastic Constitutive Model………………………… 72 3.5 Finite Element Implementation……….……………………………..... 75 4 Finite Element Calculations: Preliminary Results……………………….

Inhaltsverzeichnis

Frontmatter

Introduction

Abstract
This chapter describes shortly the phenomenon of shear localization in dry and cohesionless granular materials. It presents the main problems in granular bodies related to this phenomenon. In addition, it summarizes different continuum approaches capable to properly describe shear localization using a finite element method and enhanced constitutive models. A micro-polar hypoplastic constitutive model is briefly described to numerically investigate shear localization in dry and cohesionless granular materials during mainly monotonic deformation paths. The differences between hypoplastic and conventional elasto-plastic continuum models are stressed. The outline of the book is given.
Jacek Tejchman

Literature Overview on Experiments

Abstract
This chapter describes several laboratory experiments on shear localization in dry and cohesionless granular materials during different boundary values problems. These experiments include plane strain compression, triaxial compression, wall friction tests, biaxial compression, earth pressures on a retaining walls, strip foundation, pull-out tests and silo flow. The experiments were carried out with different initial densities and mean grain diameters of sand, and wall roughness. During tests, attention was paid to load-displacements diagrams, shear zone thickness and shear zone spacing.
Jacek Tejchman

Theoretical Model

Abstract
This chapter describes shortly the theory of micro-polar hypoplasticity including a characteristic length of micro-structure in the form of a mean grain diameter. First, a non-polar hypoplastic constitutive model formulated at Karlsruhe University by Gudehus (1996) and Bauer (1996) for mainly monotonic deformation paths is summarized. Some results of so-called element tests (oedometric compression, triaxial compression, cyclic simple shearing) by a hypoplastic constitutive model are presented for different initial void ratios and pressure levels. Next, the calibration procedure for hypoplasticity to determine material parameters given by Bauer (1996) and Herle and Gudehus (1999) is outlined. Later, the micro-polar (Cosserat) continuum is presented. The advantages of the micro-polar theory with respect to a conventional (non-polar) continuum to capture shear localization are outlined. The equations of a micro-polar constitutive law proposed by Tejchman (1997) are given which were obtained by enhancement of a non-polar hypoplastic constitutive law of Gudehus (1996) and Bauer (1996) by micro-polar quantities. Finally, the FE implementation of a micro-polar model in a quasi-static regime is depicted.
Jacek Tejchman

Finite Element Calculations: Preliminary Results

Abstract
This chapter presents preliminary numerical results of different quasi-static boundary value problems in granular bodies including shear localization. Calculations were carried out with the finite element method on the basis of a micro-polar hypoplastic model. The following problems were considered: plane strain compression test, monotonic and cyclic shearing of an infinite layer, biaxial compression test, strip foundation, earth pressure, direct and simple shear test, wall direct shear test and contractant shear zones. Attention was paid to the thickness and spacing of shear zones. Numerical solutions were compared with corresponding laboratory tests.
Jacek Tejchman

Finite Element Calculations: Advanced Results

Abstract
This chapter presents advanced numerical results of different quasi-static boundary value problems in granular bodies including shear localization. Calculations were carried out with the finite element method on the basis of a micro-polar hypoplastic model. The following problems were considered: sandpiles, direct symmetric cyclic shearing under constant normal stiffness condition, wall boundary conditions, deterministic and statistical size effects, non-coaxiality and stress-dilatancy rule and textural anisotropy. Attention was paid to the thickness and spacing of shear zones. Numerical solutions were compared with corresponding laboratory tests.
Jacek Tejchman

Epilogue

Abstract
The presented FE results of different boundary value problems for dry cohesionless granular materials in a quasi-static regime show that shear localization is a fundamental phenomenon. It can occur in the interior domain in the form of a spontaneous shear zone as a single shear zone, a multiple or a regular pattern of zones or it can be also created in the form of an induced single shear zone along walls of structures. Thus, it has to be taken into when modeling the behaviour of granular bodies.
Jacek Tejchman

Backmatter

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