核岛近区域复杂场地的波动场动力特性研究

Research of dynamic characteristics for wave field of complex site near the nuclear island

核岛场地动力特性对核电站结构的地震响应有重要影响。输入波动场构成了结构-地基动力相互作用分析的完整的地震动输入条件,核岛近区域的复杂场地改变了输入波动场的动力特性。本文从工程抗震角度,以现有大型通用有限元软件ANSYS为基础,进行二次开发,建立全三维(3D)地基模型,并引入人工透射边界条件,模拟地基的辐射效应。采用传递函数的分析方法,输入位移脉冲函数,输出关注位置的位移响应。本文探讨了核电场地近区域存在水平软弱层、夹杂体以及开挖场地的输入波动场的动力特性。结果显示水平软弱层具有明显的放大低频、过滤高频的作用;夹杂体的位置和开挖深度对输入波动场的动力特性也有不同程度的改变。本文方法可为核电厂工程结构的抗震设计提供一定的技术依据。

The dynamic characteristics of the nuclear island foundation has an important influence on the seismic response of nuclear power plant, However, a typical problem as encountered in the design and construction is that the complex site can＇t be represented properly. Most of models and algorithms of soil in the engineering are based on hypothesis that all soil are homogeneity, in fact the effect on the input-wave-field also cannot be ignored. The input-wave-field forms ground motion inputting conditions for structure-soil-interaction analysis. To research the characteristics of complex site where is near the nuclear island, in this paper from the engineering perspective, A detailed discussion, based on the numerical model which is for dynamic analysis of interaction, about dynamic characteristics was made, including soft interlayer, exogenous inclusion and excavation field. Then compared with homogeneous site, the soft layer has obvious functions that amplify low frequency and filter high frequency, and the dynamic characteristics of the inclusion and excavation are different from homogeneous site. Finally, the results in this paper proposed can provide technical basis for the seismic design of nuclear power plant structures.