Energy-Based Analysis of Effect of Inter-particle Friction on the Shear Behavior of Granular Materials

This paper describes a numerical investigation on the effect of inter-particle friction on the shear behavior of granular materials, with an emphasis placed on an energy-based analysis. The numerical simulation results show that the peak friction angle phi(p) increases with the inter-particle friction angle phi(mu), and that the constant-volume friction angle phi(cv) increases with phi(mu) in the low friction region before reaching a plateau stage at the high friction region, with the division point of such two characteristic stages emerging between mu(s) = 0.3 and mu(s) = 0.5. The energy-based analyses indicate that inter-particle friction exerts a profound effect on the energy dissipation and storing of granular assemblies. The inter-particle friction behavior and damping mechanism are the two major means in the consumption of the external work input. Frictional dissipation increases at first with the inter-particle friction coefficient in the low friction region, and then decreases in the high friction region, with the damping consumption exhibiting a reverse variation manner. The mobilized shear strength depends primarily on the energy stored in the normal direction at the contacts, E-pn, which demonstrates the same variation mode as the deviatoric stress and constant-volume friction angle, despite that the energy stored in the tangential direction at the contacts, E-pt, as well as the mobilized friction coefficient mu(b), shows a monotonic increase with the inter-particle friction coefficient.