The Effect of Nonlinear Strength of Rockfill Material on Dam's Stability

The material parameters of rockfill dams over 100m in height are collected in China, including nonlinear strength of rockfill material and linear strength of core wall material. The distribution type, mean value, standard deviation and variation coefficient of material parameters are obtained for main rockfill, secondary rockfill and core wall by mathematical statistical method. Simple Bishop method is used to calculate the safety factor under static condition. Particle Swarm Optimization (PSO) is applied to search the most critical slip circle. And First-Order Second-Moment (FOSM) method is used to analyze the reliability. The results show that both the safety factor and reliability index decrease with the increase of height under the same slope ratio. They also decrease with the increase of slope ratio under the same height. Based on the computed results, six fitting equations are given to fast estimate safety factor and reliability index.