Reliability analysis of roller compacted concrete gravity dams subjected to earthquake

Due to the uncertainty of material parameters and randomness of earthquake, the dynamic response of high rolled compacted concrete (RCC) gravity dam is uncertain. Analyses of the seismic failure probability and aseismic reliabilities of gravity dam located at meizoseismal area are difficult. Taking the variability of material parameters and earthquake into account, a quadratic polynomial fitting by using response surface method is used to simulate the limit state equation of RCC gravity dam. The reliability index is calculated by a finite iteration step method. The distribution of effective earthquake forces is ameliorated according to adaptive spectra-based Push-over procedure and used to calculate the gravity dam's reliability. The influences of different failure paths on the reliability of RCC gravity dam are studied by analyzing the dam's ultimate bearing capacity. Probable seismic failure paths and failure modes corresponding to limit load state and normal operation state are analyzed. The failure probabilities for the different failure modes corresponding to dam, rock, sliding of roller compacted layer and floor are further analyzed. Based on system reliability theory, the dynamic system failure probability and reliability index of RCC gravity dam are obtained in terms of the correlated and non-correlated failure modes. The results indicate that the reliability levels have relation to various failure paths. The corporate influence of the different failure paths on the system reliability should be considered.