DEM investigations of the effects of intermediate principal stress ratio and particle breakage on the critical state behaviors of granular soils

Abstract

Three dimensional discrete element (DEM) analyses were performed in Particle Flow Code (PFC3D) to study the effects of intermediate principal stress ratio and particle breakage on the critical state behaviors of granular materials. The variation of intermediate principal stress ratio is achieved by increasing intermediate and major principal stresses at different ratios. The breakage of calcareous sand particles is simulated in DEM with clumped particles using the octahedral shear stress crushing criterion. The macroscopic behaviors of crushable and uncrushable particles during shearing and at the critical state are compared. It is found that intermediate principal stress ratio and particle breakage affect the dilation and peak strength but have different effects on the critical stress ratios of the assemblies. The evolutions of micromechanical parameters such as redundancy factor, fabric and force anisotropies are examined to explain the difference between the behaviors of crushable and uncrushable assemblies under different stress paths.