地下结构抗震计算地基弹簧系数取值方法研究

Analysis of methods for determining the spring constant of ground foundation in seismic design of underground structures

荷载-结构模型是地下结构抗震计算中常采用的模型,模型中地基弹簧系数的确定是关键。为了简便、可靠地计算地基弹簧系数,在已有基床系数计算公式的基础上,建立了地基弹簧系数的经验计算公式,以有限元分析结果为数据基础,对公式的系数进行拟合,将公式拓展用于成层土体。选取算例验证了建议公式的合理性和准确性,分别采用建议公式、日本抗震准则公式以及有限元法计算了某地铁区间站结构的地基弹簧系数,并对在此基础上计算所得的地震作用下结构的内力进行了对比分析。

Model of load-structure is widely applied in seismic design of underground structure,and the methods for determining the spring constant of the model is very important.In order to calculate the spring constant of ground foundation conveniently and reliably,empirical formulas are proposed on the basis of the formula of coefficient of subgrade reaction.Coefficients of proposed formulas are fitted by using the results calculated from finite element analysis,and then the formulas are expanded to be used in layered soil.Examples are selected to verify the rationality and accuracy of proposed formulas.Then the spring constant of a subway station structure is calculated respectively by using proposed formula,Japanese seismic code formula and finite element method.Furthermore,on the basis of three different kinds of spring constants,the structural internal forces under earthquake are calculated and compared.