Stochastic seismic response and stability reliability analysis of a vertical retaining wall in front of the pumping station of a nuclear power plant using the probability density evolution method

Abstract

Vertical retaining walls are widely used to protect the water intake and drainage structures of nuclear power plants (NPPs); in particular, they are built as the inlet in front of the pumping station pool. It is of great significance to investigate the seismic behavior of the vertical retaining walls considering the uncertain nature of earthquakes according to the nuclear safety design requirements. The probability density evolution method (PDEM), which is a new and efficient methodology, is proposed here to study the stochastic seismic response and stability reliability of a vertical retaining wall in front of the pumping station pool of a NPP. Firstly, a set of representative acceleration time histories of non-stationary earthquake ground motions are generated by the spectral representation random function method according to the RG1.60 spectra for the NPP project design. Then, a series of deterministic stochastic seismic response analysis of a 26-m-high vertical retaining wall are performed. Finally, the probability information and seismic reliability of the vertical retaining wall under two seismic levels (SL-1 (operating-basis earthquake) and SL-2 (safety shutdown earthquake)) are obtained based on two physical parameters: the anti-sliding safety factor and anti-overturning safety factor. The results demonstrate that the proposed method of investigating the stochastic responses and seismic reliability of vertical retaining walls can provide more objective indices to evaluate the seismic safety during SL-1 and SL-2 seismic events. Furthermore, the proposed method can effectively investigate the ultimate seismic capacity of vertical retaining walls and other geo-structures in NPPs.