Liquefaction behavior of inherently anisotropic sand under cyclic simple shear: Insights from three-dimensional DEM simulations

Abstract

Inherent fabric anisotropy has been widely recognized to have significant effects on the liquefaction behavior of sand. A discrete element method (DEM) study was conducted to investigate the liquefaction behavior of inherently anisotropic sand under cyclic simple shear conditions. In the DEM model, the under-compaction method was modified to generate uniform and inherently anisotropic specimens. A series of DEM simulations of undrained cyclic simple shear tests were performed to investigate the effects of bedding plane angles with a full spectrum ranging from −90° to +90°. The relative magnitudes of the three effective normal stress components were compared and analyzed. The internal structure evolution was quantified through a contact-normal-based fabric tensor that could describe the load-bearing structure of granular specimens. The simulation results show that the effect of bedding plane angle on the liquefaction resistance of anisotropic sand is not monotonic. For example, as the bedding plane angle of specimen increases from 0° to 90°, the liquefaction resistance first decreases and then increases, with the most detrimental scenario occurs at 45°. This could be explained by correlating the magnitudes of shear modulus with the discrepancy between the loading direction and the direction of fabric during each cycle.