核电厂楼层谱抗震计算的场地模型及其影响分析

Study on Ground Numerical Models for Floor Response Spectra Analysis of Nuclear Power Plant and Their Influences

结合结构-地基动力相互作用数值分析的最新发展,在集总参数场地动力简化模型的框架内,提出了一种便于非均质场地条件采用的核电站厂房时频域动力分析的新模式。该模式利用谐响应法求解场地真实频域动阻抗曲线,利用混合变量模型保证频域动刚度的时域无损转换,实现楼层谱的全时域计算。最后,以某百万千万级核电站反应堆厂房的抗震分析为例,开展均质与非均质场地条件下动刚度及上部结构楼层谱计算的对比研究,验证了该分析方法的精度与应用效果。计算结果表明,比较均质场地条件,水平成层非均质场地条件下竖直方向楼层谱峰值有较大幅度改变,必须在核电抗震安全评价中加以重视。

In the framework of numerical model of lumped parameters, a time-frequency domain coupled model of ground is presented and recommended in this paper to analyze the dynamic interaction, which solves the soil dynamic impedance based on the harmonic response analysis and maintains the necessary accuracy in the numerical transformation between time and frequency domains by using continued fraction expansion. The proposed dynamic analysis method can be easily utilized in practical engineering with inhomogeneous soil layers, and can play a positive role in enhancing the associated seismic analysis of nuclear power plants in China. Finally, by taking the analysis of dynamic stiffness of soil and the floor response spectra for a certain 1000 MW Nuclear Power Plant as an example, specific numerical comparison analyses are carried out to study the impact influences for various soil models, in which the numerical precision for the new proposed method is well validated.