A plastic-damage model for rock-like materials focused on damage mechanisms under high pressure

Abstract The purpose of this study is to present a plastic-damage model that can well capture the mechanical behaviors of rock-like materials. To this end, a three-invariant yield function combined with a cap function is employed to concurrently consider the physical mechanisms due to the presence of microcracks and pores as well as their combinations. The major contribution falls into the establishment of three damage mechanisms with clear physical backgrounds, including hydrostatic damage due to pore collapse, shear damage due to shear-induced microcracking, and tensile damage due to tensile microcracking. Particularly, the hydrostatic damage that can accumulate under even purely hydrostatic loading is proposed to account for the material properties degradations due to pore collapse. Results show that pore collapse under high pressure will cause a great loss of material properties. Without consideration of this will cause overestimation of the residual strength and modulus of materials. The validation examples demonstrated that the proposed hydrostatic damage can well accommodate the degradations of material strength and modulus due to pore collapse, which, however, has not been considered in most of the existing material models.