Micro-structure Evolution in Layered Granular Materials During Biaxial Compression

Biaxial compression tests were conducted to investigate the deformation characteristics of layered granular samples by considering the localized deformation characteristics of sublayers. Layered sample refers to a three-layer granular materials stacked in the order hard-soft-hard. The DEM simulation results show that stress and strain development of layered granular samples are positively correlated with the volumetric fraction, which is consistent with the theoretical and FEM results. Directional distribution of contact normal and force chains follows the same pattern: possibilities of near-horizontal and vertical direction increases (decreases) in hard (soft) layer, while possibilities of diagonal direction decreases (increases) in hard (soft) layer.