A reliability-based approach to evaluating the stability of high rockfill dams using a nonlinear shear strength criterion

In recent years, many high rockfill dams have been constructed in China for the purpose of hydropower generation. One of the critical aspects of rockfill dam design is the analysis of slope stability. Triaxial compression tests show that the failure envelopes of rockfills are curved and that nonlinear shear strength criteria yield better predictions of the shear strengths of rockfills than the Mohr–Coulomb criterion. Because the determination of shear strength parameters involves uncertainties, a reliability-based methodology was developed for use in evaluating the failure probability of rockfill dam slopes by integrating Bishop’s simplified method, Duncan’s nonlinear strength criterion and the first-order second-moment reliability method presented in this paper. A computer program, SCU-SLIDE, was developed and its outputs validated by comparison with Monte Carlo simulation results. The approach developed was used to study the stability of the Shuang Jiang Kou rockfill embankment dam, which when completed will be the tallest dam in the world. The results of the stability analysis are discussed and conclusions are presented in this paper.