Stochastic seismic performance assessment of high CFRDs based on generalized probability density evolution method

摘要

Determining the failure probabilities of high concrete-faced rockfill dams (CFRDs) is an important component of seismic performance assessment, considering the randomness of earthquake ground motions. In this paper, a new efficient methodology that couples the recently developed generalized probability density evolution method (GPDEM) with the spectral representation-random function method is proposed to evaluate the seismic performance of high CFRDs from a stochastic perspective. A set of representative acceleration time histories of non stationary earthquake ground motions with complete probability are generated based on an evolutionary power spectral density model through an iterative correction to produce a good fit between the average response spectrum and the code spectrum in China's hydraulic structure seismic code. Then, a series of deterministic dynamic calculations for a 200-m CFRD based on a generalized plasticity model modified for rockfills and a generalized plasticity interface model are performed to solve the GPDEM equation. A new face-slab damage index that considers double physical parameters (demand capacity ratio and cumulative overstress duration based on stress) is presented and its probability information is determined by constructing a virtual random process. Finally, probability density functions and cumulative distribution functions are obtained under two seismic levels by considering three performance indices corresponding to deformation, stability of dam slope and safety of face-slabs. The failure probability of different failure grades demonstrates that this new method has a good applicability to seismic performance assessment of high CFRDs.