An energy-driven model for granular materials with crushing, contraction and dilation

Crushable granular materials exhibit complex mechanical behaviour due to the interplay between crushing, contraction and dilation. Traditional constitutive models often struggle to capture these coupled effects and rely heavily on employing more fitting parameters. To address these gaps, this study presents a novel energy-based constitutive model for addressing the crushing–contraction–dilation coupling issues of crushable granular materials. A novel formulation for gradation-dependent bounds on void ratio is first described, followed by the proposal of a novel dissipative framework to incorporate the effect of dilation. Subsequently, a convex and gradation-density-dependent yield criterion is developed, which further assists in structuring the gradation-dependent critical state lines to enable the classification of dilative and contractive regimes under different gradations. Next, plastic and crushing flow rules are also constructed, ensuring the strict non-negativity of total dissipation. Last, the model is validated against experimental data under varied loading paths, stress levels, initial densities and materials.