Theoretical shear damage characterization of intact rock under compressive-shear stress considering energy dissipation

Investigation into rock damage is of great significance for evaluating and predicting the stability of underground rock applications, such as deep mining or tunneling structures. Considering the energy dissipation properties during rock deformation, this paper proposes a novel theoretical characterization of the damage induced by compressive-shear stress and its evolution in intact rocks. The linear energy dissipation (LED) law is derived from shear stress and deformation data of rocks resulting from the preset angle shear experiment. Based on the LED law, two damage variables are separately constructed from the theoretical and experimental aspects. Several sets of experimental data are subsequently utilized to validate the two constructed damage variables. Results show that both damage variables grow first slowly and then rapidly with shear displacement or shear stress in nonlinear relations. By comparison, however, it is found that the theoretical damage variable outperforms the experimental damage variable, which can accurately reflect the stress and deformation data during progressive rock damage with favorable continuity. This study contributes to a novel theoretical approach to quantifying the pre-peak damage in intact rocks subject to compressive-shear stress.