An expression for the stiffness coefficient of a rectangular sample of granular material with random packing structure

We established a parallel-column model for a rectangular sample of heterogeneous granular material with random packing structure in a biaxial test. Within the framework of the proposed model, an expression for the stiffness coefficient of the rectangular granular sample is derived. The stiffness coefficient can be predicted using the proposed expression without microscopic analysis of the granular sample. To quantify the amount of grain crushing, the concept of relative breakage is adopted. The relative breakage parameter is then introduced into the proposed expression. Numerical results demonstrate the validity of the derived expression and show the effect of grain crushing on the stiffness coefficient of a granular sample.