A Micro-mechanical Study for Constant Shear Drained Behaviour of Granular Material

Abstract

Soil liquefaction has been often reported in undrained condition (lack of drainage), in which pore water pressure is continuously generated until flow deformation. However, it has been also found that the flow deformation may happen in drained condition due to lateral stress relief. Such phenomenon, also known as constant shear drained (CSD) response, is not uncommon, but the knowledge about CSD condition is still not fully understand. A discrete element method (DEM) is used to investigate the CSD condition by performing stress-controlled simulations on 3D specimens of ellipsoid particles. After consolidation, the specimens were sheared in drained condition. Then, shear stresses ($\tau$) were kept constant and the normal effective stresses ($\sigma_{\text{N}}^{{\prime }}$) reduced until failure. It was found that the specimens started to fail when the effective stress paths approached the critical state line. At the point of failure, the axial and volumetric strains have abrupt changes. The study will also provide more in-sights in the micro-mechanical quantities such as soil fabric, which was believed to control the overall observed behavior of soils.