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Communication Dans Un Congrès Année : 2011

PARTICLE SHAPE DESCRIPTORS AND THEIR INFLUENCE ON THE MECHANICAL BEHAVIOR

Résumé

ABSTRACT: The present study is a part of a collaborative French national research project CEGEO/shape (Change of Scale in GEOmaterials). The purpose of benchmark collaborative numerical tests performed, using CD (Contact Dynamics) or MD (Molecular Dynamics) methods, is to quantify the non-circular shape of particles, by their degree of distortion relative to the disk, and to analyse their influence on the local and the macroscopic mechanical properties of granular materials. This contribution points out the compact collection of rigid octagonal shaped particles, built in accordance with our specific shape index. It also deals with the first investigations of realistic 3D particles. The following five biaxial compressions tests (which bring difficulties such as little deformations and multiple localizations) are numerical simulations, using NSCD (Non Smooth Contact Dynamic) method and LMGC90 software. The macroscopic behavior is studied in terms of solid fraction and internal angle of friction. We show that the internal angle is influenced by the increased anisotropy of friction forces and the contact orientations with the shape indicator. The variation of the initial assembly density (area of solids over total area) and the final density in the critical state is modelled using the number of particle edges, in order to explain the higher peak shearing resistance of assemblies with smaller initial void ratio or higher coordination number. Besides unilateral contact and Coulomb friction, other parameters relevant to the shape and contact anisotropy, which influence the anisotropy of stress transmission, as the ratio of edge-to-edge or vertex-to-edge active contacts, the stick-slip phenomenon, and the friction mobility, (ratio of tangential and normal contact forces) are quantified. Finally, different approaches have been proposed for the change of scale of kinematic variables. Analysis of local kinematics, and relation between the global strain and the local relative displacements at the contacts is studied.

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Génie civil
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Dates et versions

hal-00941044 , version 1 (03-02-2014)

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  • HAL Id : hal-00941044 , version 1

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Marie Chaze. PARTICLE SHAPE DESCRIPTORS AND THEIR INFLUENCE ON THE MECHANICAL BEHAVIOR. The 2d International Symposium on Computational Geomechanics (ComGeo II), Apr 2011, Cavtat-Dubrovnik, Croatia. ⟨hal-00941044⟩
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