A constitutive model for the state-dependent behaviors of rockfill material considering particle breakage

The particle breakage during specimen compaction had more significant influence on the position of the breakage critical-state line （BCSL） of Tacheng rockfill material （TRM） in the e-lnp＇ plane than the particle breakage during shearing, based on the large-scale triaxial compression tests on TRM in a wide range of densities and pressures. The state-dependent dilatancy and the plastic modulus were correlated to the breakage index, based on the formulations of the BCSL of TRM in the e-lnp＇ plane. The state-dependent model considering particle breakage was proposed for TRM within the framework of the generalized plasticity theory. The proposed model contained fourteen material constants. The test data of TRM from Group A were adopted to determine these material constants, while the test data from Group B were used independently to validate the model predictive capacity. The comparisons between model simulations and test data illustrated that the model with consideration of particle breakage could well represent the stress-strain behaviors of TRM, e.g., the strain hardening and volumetric contraction behaviors at a loose state and the strain softening and volumetric expansion behaviors at a dense state, and also the particle breakage behaviors of TRM.