Micro-modelling of shear localization during quasi-static confined granular flow in silos using DEM

Abstract

The paper deals with the quasi-static confined flow of cohesionless sand in a plane strain model silo with parallel walls and a slowly movable bottom. Numerical modelling was carried out by the discrete element method (DEM) using spheres with contact moments to approximately capture a non-uniform shape of sand particles. Different initial void ratios of sand and silo wall roughness grades were employed. Regular triangular grooves (asperities) with the same inclination and a different height were used to describe the varying wall surface topography. The emphasis was on the formation and evolution of both wall and internal shear zones during sand flow. DEM simulation outcomes were compared with corresponding model experiments and theoretical solutions. In addition, the particle displacements, particle rotations, normal contact forces, void ratios and wall stresses were evaluated. The numerical findings enhance the understanding of shear localization at the grain level during confined flow in silos and its strong impact on the magnitude, distribution and oscillation of wall stresses.