FE studies of quasi-static mass flow in bins: the polar elasto-plastic approach

The paper deals with numerical modelling of confined flow of granular materials in vertical bins. Quasi-static mass flow of non-cohesive sand with a controlled outlet velocity along the entire silo bottom was numerically studied using a finite element method taking into account an elasto-plastic constitutive law laid down within a Cosserat continuum. The influence of the initial density and the mean grain diameter of the solid, wall roughness, wall stiffness and imperfection, the initial stress state and the pressure level on the stress and deformation states in plane-strain vertical bins was investigated. The numerical results were compared with similar model tests performed with a rectangular vertical bin containing sand. The calculated results were in satisfactory agreement with the experimental ones. The advantages and limitations of the polar elasto-plastic approach to model granular silo flow were outlined.