河南小浪底大坝的设计地震动参数

DESIGN GROUND MOTION PARAMETERS FOR THE XIAOLANDI DAM IN HENAN PROVINCE

本文基于以坝址为中心,320公里范围内地质构造、历史地震和地震活动性的分析结果,研究了地震活动性模型,给出了影响小浪底大坝场地地震的空间和震级的分布,采用中国东部地区中强地震动记录和历史地震烈度观测资料,研究了地震动的衰减公式,并考虑了近场和远场震源的烈度与加速度之间的关系。在地震危险性分析中,应用概率方法,确定以10^(-4)年超过概率作为大坝地震危险性评定准则,可得到坝址场地地震动峰值加速度。考虑了各潜在震源离坝址的距离、最大震级和近场或远场震源等场地特征,选取大坝场地反应谱和地震动加速度时程曲线的包络线。最后,应用非随机过程的数学模型逐渐逼近目标谱的方法,得到近场和远场的每一组10条地震动时程曲线。这些人造地震动时程曲线可作为大坝的设计地震动的工程参数。

Based on the analysis results of geological tectonics, historical earthquake and the seismicity within a radius of 320km from the dam site in this paper, a seismicity model is studied. the spatial and magnitude distribution of earthquake affected the Xiaolandi dam site has been given. The attenuation formula has been developed by using the data of moderate earthquake motion and the observation of historical earthquake intensity in eastern China. And the relationship between acceleration and intensity of the source in the near and far field has been considered. The probabilistic method is used in seismic risk analysis to determine the peak acceleration of 10-4 annual probability, of exceedance. which is chosen as a criterion for the safe level earthquake of the dam. Considering the distance from the dam for every potential seismic sources, the maximum magnitude. near source. far source and the characteristic of the dam site, the envelop curve of the site spectra and acceleration time history of the ground motion has been selected. Finally, the mathematical model of nonstationary random process is used to match the target spectra. to generate 10 time history curves of the ground motion in each set of the near and far source. And those artificial ground motiom time history curves are the parameters of the design ground motion for the dam.