Karrech, Ali (2007) Behaviour of granular materials under vibration : application to the ballast of rail way platforms. PhD thesis, ENPC p.212.

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Abstract

Granular materials are discrete solid particles which are large enough to avoid any thermal fluctuations. These materials are widely encountered especially in construction, transportation and pharmaceutical industries. The behavior of these materials is generally out of the scope of the statistical and continuum mechanical approaches. In the first part of this thesis, we focus on the description of the discrete element model that we use, the effect of the simulation parameters on the sample quality and their response under quasistatic axial loading. The second part is dedicated to the settlement of granular materials under periodic loading. An experimental study is conducted to investigate the effects of the physical factors on the settlement speed. These results are confronted and completed by numerical results based on the molecular dynamics. Moreover, the settlement mechanism, the effect of granular shape, the interaction and mode of confinement on this phenomenon are described in details. At this level, we also introduced a computational method for the prediction of bed response under long term dynamic loading. The suggested approach uses sequentially a molecular dynamics scheme, a time averaging technique, and a relaxation method in order to simulate long term granular materials settlement.

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