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.

本研究的目的是提出一种可以很好地捕捉类岩石材料力学行为的塑性损伤模型。为此，采用结合帽函数的三不变屈服函数来同时考虑由于微裂纹和孔隙及其组合的存在而导致的物理机制。主要贡献在于建立了三种具有明确物理背景的损伤机制，包括孔隙坍塌引起的流体静力损伤、剪切致微裂纹引起的剪切损伤和拉伸微裂纹引起的拉伸损伤。特别是，即使在纯静压载荷下也可以累积静压损伤，以解释由于孔隙坍塌导致的材料性能退化。结果表明，高压下的孔隙坍塌会导致材料性能的极大损失。如果不考虑这一点，就会高估材料的残余强度和模量。验证实例表明，所提出的静水压损伤可以很好地适应由于孔隙坍塌引起的材料强度和模量的退化，然而，在大多数现有材料模型中并未考虑到这一点。