基于设定地震场地相关反应谱的高土石坝抗震安全评价

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

结合最新颁布的《水电工程水工建筑物抗震设计规范》(NB35047—2015)中关于甲类设防重大土石坝工程设计反应谱的规定,重点研究了基于设定地震的场地相关反应谱和一致概率反应谱确定的动参数下高土石坝的动力反应特征。通过240m高长河坝高心墙堆石坝在两种不同反应谱下设计和校核地震动下的计算分析发现一致概率谱得到的坝顶动力响应加速度、动位移、永久变形、坝坡安全系数和塑性滑移等关键安全评价指标均高于场地相关反应谱的结果,进而探讨了两种反应谱对长河坝高土石坝工程极限抗震能力的影响,计算结果表明采用基于设定地震的场地相关反应谱得到的坝体的极限抗震能力明显高于一致概率谱,采用一致概率谱得到的地震动参数进行长河坝抗震设计和抗震加固措施研究易得到较保守的结果。

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.