<p>In the process of underground cavern excavation and resource exploitation, cohesion and internal friction angle of disturbed rocks vary with increasing plastic strain. Some scholars have established relevant evolution models of cohesion weakening and friction strengthening for isotropic rocks. However, the evolution of cohesion and internal friction angle of bedded shale after disturbance exhibits significant anisotropy. Therefore, based on the laboratory test data of shale specimens in the related literature, this research introduces an equivalent plastic internal variable to unify the critical equivalent plastic strain of specimens under different confining pressures. The evolutions of cohesion and internal friction angle for different bedding dip angles with the equivalent plastic internal variable are analyzed, and a modified anisotropic cohesion weakening–friction strengthening (A-CWFS) model is established. The established model is integrated into FLAC^3D numerical simulation software for verification. By comparing the simulation results with the laboratory test data, it is found that the simulation results can effectively express the characteristics of each plastic deformation stage of the specimens. This shows that the modified A-CWFS model can describe the evolutions of cohesion and internal friction angle of bedded shale with different bedding dip angles and the proposed method can be used for the analysis of the other bedded rocks in future.</p>