地基土参数对核电厂地震动响应的敏感性分析

An Analysis of the Sensitivity of Parameters of Ground Soil for the Ground Motion Response of Nuclear Power Plant Structures

基于两种规范方法计算得到的地基阻抗函数,分析计算CPR1000安全壳结构的地震反应,量化了RCC-G和ASCE4-98两种规范方法计算的地基阻抗函数差异对核电厂结构反应产生的影响,同时考虑地基阻抗函数敏感性,研究了地基土剪切波速、泊松比及地基土密度3种影响因素变化情况下核电厂结构的反应规律.结果说明:ASCE4-98计算地基阻抗函数的方法较RCC-G方法保守;地基土密度对核电厂结构响应的影响较小,地基土泊松比对核电厂结构响应的影响可以忽略;一定条件下地基土对核电厂结构响应起到了隔震效应;随着地基土剪切波速的增大,核电厂结构响应变化幅度降低,当剪切波速从1900m/s增加至2200m/s时,安全壳结构最高点水平向加速度变化幅度约2%,竖向加速度峰值随剪切波速的变化已经出现拐点,考虑到整个计算过程的不确定性,本文建议当地基土剪切波速大于等于1900m/s时,CPR1000安全壳结构可不考虑地基与结构的相互作用.

Based on impendence functions of foundation that were calculated by two methods of different regulations,we analysied the ground motion response of CPR1000 nuclear power plant （NPP）and gave the difference of ground motion response of NPP structures by impendence functions of RCC-G and ASCE4-98. Considering the sensitivity of the impendence functions of soil parameters,we studied the response behavior of three parameters of the ground, which were shear wave velocity, Poisson＇s ratio, and soil density. The computational results were summarized as follows. The impendence function of ASCE4-98 was conservative compared with the function in RCC-G. The density of soil had little impact on the response of NPP. The influence of Poisson＇s ratio could be neglected to the response of NPP. The ground soil could reduce the response of earthquakes under some conditions. With the increasing of the shear wave velocity of ground,the response variation of NPP would decrease, and when the shear wave velocity varies from 1900m/s to 2200m/s,there was only 2% difference for the horizontal peak acceleration responses of the highest point in the safety crust structure. Considering the uncertainty of the computation,we suggested that the effect of soil-structure interaction could be neglected when the shear wave velocity was greater than or equal to 190（O/s.