Abstract:The strength of layered rocks possesses anisotropic (or transversely isotropic) characteristics. When Mohr-Coulomb criterion is used to describe the shear failure of this kind of rocks,it should be considered that c, are varied with the layered directions. The empirical expressions of c, for layered rocks are proposed and compared with the test results given by the former researchers. It is found that both of them are agreeable well to each other. Based on the proposed expressions,the influences of the change rule of c, ,the stress state and the inclination of layer loading direction on the shear failure orientation of layered rocks are calculated and analyzed.