Mohr-Coulomb plasticity for sands incorporating density effects without parameter calibration

A simple approach is proposed for enabling the conventional Mohr-Coulomb plasticity to capture the effects of relative density on the behavior of dilative sands. The approach exploits Bolton's empirical equations to make friction and dilation angles state variables that depend on the current density and confining pressure. In doing so, the material parameters of Mohr-Coulomb plasticity become void ratios for calculating the initial relative density and the critical state friction angle, all of which are measurable without calibration. A Mohr-Coulomb model enhanced in this way shows good agreement with experimental data of different sands at various densities and confining pressures. In this regard, the proposed approach permits a significant improvement in the conventional Mohr-Coulomb plasticity for sands, without compromising its practical merits.