Safety evaluation of high rockfill dams subjected to earthquakes based on site-related response spectra

Based on the provisions of “China's code for seismic design of hydraulic structures of hydropower project” (NB 35047-2015), the detailed effects of seismic parameters determined by use of different design response spectra including site-related response spectra based on scenario earthquake and probability-consistent response spectra on the safety evaluation of class A high rockfill dams located in highly seismic regions are studied. Comparisons of the key indexes such as dynamic response acceleration, permanent deformation, safety of impervious body, factor of safety and sliding displacement of the potential failure surfaces of 240 m-high Changhe core rockfill dam under the above-mentioned seismic parameters are provided. It is shown that the results from the probability-consistent response spectra are higher than those from the site-related ones. In addition, its ultimate seismic capabilities based on the above-mentioned two design response spectra are achieved. It is proved that the probability-consistent spectra adopted in the safety evaluation of high rockfill dams may result in conservative results.