利用强震记录识别场地的总体非线性动力特性

Using strong earthquake recordings to estimate overall nonlinearity of sites

提出了一个以场地强地震动估计为目的的场地总体非线性动力特性识别方法。方法以一已知参考场地为基础,假定参考场地和待识别场地具有相同的基岩露头运动,根据参考场地和待识别场地地表强震和弱震记录,识别场地的总体非线性动力特性。以天津地区相邻的两个实际场地(一个作为参考场地,一个作为待识别场地)为例对场地总体非线性动力特性进行了识别。研究表明,方法能有效识别场地的总体非线性动力特性,识别的总体非线性动力特性可以实现场地强地震动的准确估计。

Estimation of nonlinear soil properties （the relation of dynamic shear modulus and damping ratio with shear strain） from downhole array recordings has been paid attention in recent years.However,because of the difficulty of downhole instrumentation,these studies have some limitation in their engineering application.For the purpose of prediction of strong earthquake ground motion of an engineering site with unknown soil properties （called unknown site）,this paper,as an alternative,proposes a method of estimating the overall nonlinearity of an unknown site,in which,an adjacent reference site with known linear and nonlinear soil properties is introduced,and both the unknown site and the reference site are assumed to have the same bedrock outcrop motion,and only the weak and strong earthquake recordings at the surface of the unknown site and the reference site are used for the estimation.It is shown that the method can accurately estimates the overall nonlinearity of sites and predicts strong seismic ground motion,and the method can be directly applied to engineering practice.