Effects of wall inclinations and wall imperfections on pressures during granular flow in silos

Abstract

The effects of wall inclinations and wall imperfections at the onset of granular flow in a silo are numerically studied. The calculations were carried out for the onset of quasi-static mass flow in a silo with a controlled outlet velocity along the entire bottom. In the analysis, a finite element method and a polar hypoplastic constitutive law were used. A polar hypoplastic law describes the salient properties of granular bodies. FE calculations were performed with a plane strain silo with parallel walls, slightly convergent walls, slightly divergent walls, and parallel and convergent walls. The influence of a wall imperfection directed inwards and a wall imperfection directed outwards in a silo with parallel walls was also analysed. The FE results showed a large sensitivity of stresses in bulk solids due to the change of the direction of shear deformation along the silo wall.