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Etude numérique des propriétés mécaniques et des processus de déformation et d'endommagement des matériaux granulaires

Abstract : The understanding of structural and mechanical properties of granular assemblies remains an open issue. The numerical modeling of granular media, using the Molecular Dynamic approach, brings some answers to critical problems. At first, we are studying the effects of mixture parameters on the degree of order and on the stress distribution in these arrangements of grains. Next, we are interested in the acoustic properties of these media, which are very nonlinear in comparison to continuous elastic solids; ours simulations serve to clarify the deficiencies of Effective Medium Theory, which only partially account for the dependency of elastic moduli with pressure. We show that relaxation of grains, following an infinitesimal deformation is an essential component of the shear modulus. There is clearly a need for an alternative formulation and the traditional elasto-plastic approach is faced with new theories. If the numerical simulations led in this study, which measure the response function of granular media (stress field generated by a point force), show an elastic scaling, it also accounts for important relaxation process. The deformation mechanisms of granular materials were also study by simulating bixial compression tests, which reproduce qualitatively well the classical mechanicals data (stress peak, compaction/dilatancy transition), and also localization of the deformation; while at low pressure, grains rotations accommodate the deformation, at high pressure, the mobilization of friction is more pronounced. Finally, we propose a probabilistic model of damage of granular rocks, which predicts a dependency of damage both with the cementation heterogeneity and with the sample size. These predictions are confirmed by simulations, which also highlight two successive damage behaviors, diffuse at first and then concentrated in clusters.
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Contributor : Nicolas Gland <>
Submitted on : Monday, August 9, 2004 - 11:39:37 PM
Last modification on : Thursday, October 29, 2020 - 3:01:17 PM
Long-term archiving on: : Wednesday, September 12, 2012 - 5:25:11 PM


  • HAL Id : tel-00006671, version 1



Nicolas Gland. Etude numérique des propriétés mécaniques et des processus de déformation et d'endommagement des matériaux granulaires. Mécanique []. Université Paris Sud - Paris XI, 2003. Français. ⟨tel-00006671⟩



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