A Novel Polyaxial Strength Criterion for Rock Materials Under General Stress Condition

Yielding or failure of rocks under the action of external loading is complicated due to the dependence on pressure sensitivity and Lode angle. In this study, a generalized hyperbolic strength criterion is proposed to describe the strong nonlinear characteristics of rocks over a wide range of confining pressures. The relationship between failure stress and instantaneous friction angle of rocks is analyzed based on nonlinear Mohr strength envelope. In order to reflect the influence of intermediate principal stress on the strength of rock materials, the generalized hyperbolic criterion has further been extended to complicated stress state. The failure criterion allows the possibility of transitions from an equilateral triangle to circle, which greatly improves the durability and applicability to describe the strength characteristics of various rocks under complicated stress state. The validity of the proposed criterion is verified by comparing predictions with experimental results of rocks.