Stability Charts for Rock Slopes Subjected to Water Drawdown Based on the Modified Nonlinear Hoek-Brown Failure Criterion

Because of the change in hydraulic gradient of a fully or partially submerged rock slope caused by a drop in the external or internal water level, enhanced seepage forces may lead to slope instability and collapse. Based on the Hoek-Brown failure criterion, a three-dimensional stability analysis on submerged rock slopes was conducted using the kinematic approach. Emphasis was given to applications of the equivalent Mohr-Coulomb parameters method and the generalized tangent technique and the adoption of the Hoek-Brown failure criterion to the stability analysis. The accuracy of the two methods for safety factor calculation was investigated and compared with the computational results. Stability analysis of a rock slope subjected to different hydraulic conditions was performed using the generalized tangential technique, and safety factors are presented in the form of stability charts for convenient practical use. The obtained results demonstrate the applicability of the nonlinear Hoek-Brown failure criterion in rock slope stability analysis. It was found that an increase in water level differences reduces slope stability, and different water drawdown conditions lead to various changing rules for obtained safety factors.