Influence of component shear strength on rock failure

Mohr-Coulomb strength criteria is a conventional method for judgment of rock failure. Shear stress τ on the slip surface of rock is often calculated with principal stresses σ1 and σ3, and it is used to compare with the ultimate strength τf to evaluate the situation of rock. However, the position of slip surface, shear stress τ and ultimate strength τf calculated with a set of parameters σz, σx and τzx are found different from the conventional Mohr-Coulomb method in this paper. A case is studied by numerical simulation and theoretical analysis, the results showed that when the component shear strength τzx is positive, the ultimate strength τf on the slip surface is bigger than that of the conventional method, but the rupture angle is smaller; when the component shear strength τzx is negative, the results are inverse. Therefore, the component shear strength τzx must be considered in rock failure judgment.