大坝抗震分析中地震动输入方式研究

Study on earthquake ground motion input for seismic analysis of dams

大坝、核电厂结构、桥梁等重要建(构)筑物的地震响应分析均要考虑结构和无限地基的动力相互作用问题。对一般文献中常用的3类地震输入模式的合理性进行了讨论,即等价惯性力地震动输入模型、基础边界地震动输入模型、与上部结构互动的地震动输入模型。研究结果表明,前两个模型忽略的条件较多,应用范围及受到一定的局限,准确性受到一定影响;而后一种模型既考虑了建坝对原自由场地震动的影响,又考虑了坝与无限地基动力相互作用的空间耦合及时间耦合的影响,具有较好的适用性及准确性。

The effect of dynamic structure and unbounded foundation interaction should be considered in the seismic analysis of critical structures such as dams, nuclear power plant structures, bridges, so on. The rationality of three typical modes of earth-quake ground motion inputs in literatures, input model of equivalent inertial force, earthquake input model at foundation bounda-ry, input model with interaction of upper structure, is reviewed and discussed. The analysis results show that the first two models have some application restrictions as they ignore some conditions, and the last one has better rationality as it not only considers influence from dam construction on ground motion of free field, but also give consideration to dynamic interaction between dam structure and infinite foundation.