Polygons vs. clumps of discs: A numerical study of the influence of grain shape on the mechanical behaviour of granular materials

Krzysztof Szarf; Gaël Combe; Pascal Villard

doi:10.1016/j.powtec.2010.08.017

Polygons vs. clumps of discs: A numerical study of the influence of grain shape on the mechanical behaviour of granular materials

Abstract

We performed a series of numerical vertical compression tests on assemblies 01 20 granular material using a Discrete Element code and studied the results with regard to the grain shape. The samples consist of 5000 grains made from either 3 overlapping discs (clumps - grains with concavities) or six-edged polygons (convex grains). These two grain type have similar external envelope, which is a fund ion of a geometrical parameter alpha. In this paper, the numerical procedure applied is briefly presented followed by the description of the granular model used. Observations and mechanical analysis of dense and loose granular assemblies under isotropic loading are made. The mechanical response of our numerical granular samples is studied in the framework of the classical vertical compression test with constant lateral stress (biaxial test). The comparison of macroscopic responses of dense and loose samples with various grain shapes shows that when a is considered a concavity parameter, it is therefore a relevant variable for increasing mechanical)erformances of dense samples. When a is considered an envelope deviation from perfect sphericity, it can control mechanical performances for large strains. Finally, we present some remarks concerning the kinematics of the deformed samples: while some polygon samples subjected to a vertical compression present large damage zones (any polygon shape), dense samples made of clumps always exhibit thin reflecting shear bands.

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Authors (3)

Krzysztof Szarf dr inż.
- Université de Grenoble, Laboratoire Sols, Solides, Structures, Risques (3SR) UJF, G-INP, CNRS UMR 5521, Domaine Universitaire BP53 38041 Grenoble Cedex 9, France .
Gaël Combe
- Université de Grenoble, Laboratoire Sols, Solides, Structures, Risques (3SR) UJF, G-INP, CNRS UMR 5521, Domaine Universitaire BP53 38041 Grenoble Cedex 9, France .
Pascal Villard
- Université de Grenoble, Laboratoire Sols, Solides, Structures, Risques (3SR) UJF, G-INP, CNRS UMR 5521, Domaine Universitaire BP53 38041 Grenoble Cedex 9, France .

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Category:: Other
Type:: supllement, wydanie specjalne, dodatek
Published in:: POWDER TECHNOLOGY no. 208, edition 2, pages 279 - 288,
ISSN: 0032-5910
Language:: English
Publication year:: 2011
DOI:: Digital Object Identifier (open in new tab) 10.1016/j.powtec.2010.08.017
Verified by:: Gdańsk University of Technology