Discrete numerical analysis of drained cyclic loading on a model sand
Résumé
Discrete element method (DEM) is adopted in this work to characterize the behaviour of Fontainebleau sand NE34 under cyclic stress. For that YADE, an open-source software, is used where a linear contact model is utilized. The effect of anisotropic particle shape is modelled by a rolling resistance moment. The model parameters are first calibrated to reproduce experimental data from drained monotonic triaxial tests on NE34. Then, a series of drained cyclic triaxial tests is carried out on an elementary volume sample in homogeneous conditions where the cyclic stress ratio and the density index ID of the sample vary between different tests. The small strains properties, shear modulus G and damping ratio D, are then evaluated and compared with experimental data from the literature. The accumulation of irreversible deformations is also characterized. Finally, a micromechanical analysis of fabric evolution and force transmission allows to link the observed macroscopic behaviour to phenomena at the grain scale, depending on the stress level and ID initially set.
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