10. Non-linear Shear Strength Reduction Method for Slope Stability Based on the HB Criterion

Existing numerical modeling of three-dimensional (3D) slopes is mainly performed by the shear strength reduction (SSR) technique based on the linear Mohr-Coulomb (MC) criterion, whereas the non-linear failure criterion for rock slope stability is seldom used in slope modeling. However, it is known that rock mass strength is a non-linear stress function and that, therefore, the linear MC criterion does not agree with the rock mass failure envelope very well. In this research, therefore, a non-linear SSR technique is proposed that can use the Hoek-Brown (HB) criterion to represent the non-linear behavior of a rock mass in FLAC^3D program to analyze 3D slope stability. Extensive case studies are carried out to investigate the influence of convergence criterion and boundary conditions on the 3D slope modeling. Results show that the convergence criterion used in the 3D model plays an important role, not only in terms of the calculation of the factor of safety (FOS), but also in terms of the shape of the failure surface. The case studies also demonstrate that the value of the FOS for a given slope will be significantly influenced by the boundary condition when the slope angle is less than 50°.