Numerical evaluation of degradation evolutions in three constitutive models for bonded geomaterials by distinct element method

An evaluation of the degradation evolutions in three constitutive models for bonded geomaterials is presented by means of the distinct element method (DEM). The models examined are the disturbed state constitutive model (DSC), superloading yield surface model and Nova00092;s model. First, the micromechanics theory for bonded granulates is established according to the bonding behavior at contacts between bonded granulates. Then, a microscopic interpretation of the degradation parameter which is used to describe the degradation evolution in these models is provided based on the micromechanics theory. Finally, a series of isotropic, constant stress ratio and biaxial compression tests on the bonded geomaterials are carried out by a two-dimensional DEM code, and then the degradation evolution observed in the DEM tests is compared with the results predicted by the constitutive models. It is shown that it is available to evaluate the degradation evolution in constitutive models for bonded geomaterials by DEM. The degradation evolution assumed in the DSC model agrees well with the simulated results; as for the Nova model, the predicted results differ significantly from the simulated ones in the biaxial compression tests; while the degradation parameter in the superloading yield surface model can not well describe the degradation evolution observed under three loading conditions.