考虑成层地基的黏弹性人工边界模型

Viscoelastic artificial boundary model considering layered foundation

为了将黏弹性人工边界条件用于成层地基模型的计算中,基于波动理论,推导了不同类型地震波的波幅比计算公式,采用延迟法考虑行波效应,完成了成层地基的自由场求解,得到了考虑地震波一次反射透射的等效荷载计算公式,最终建立了考虑成层地基的黏弹性人工边界模型。以SV波垂直入射为例,采用所建立的模型进行了重力坝的动力计算。结果表明,该模型满足工程抗震分析的精度要求,可以解决成层地基条件下,地震波垂直入射时考虑土-结构相互作用的结构动力分析问题。

In order to apply the viscoelastic artificial boundary condition in the computation of a layered foundation model, the formulas for calculating the amplitude ratio of different types of seismic waves are derived in this paper based on the wave theory. The traveling wave effect is considered by the delay method and the free field of the layered foundation is solved, based on which the equivalent load considering the reflection and transmission of seismic waves is obtained. Finally, a viscoelastic artificial boundary model considering layered foundation is established. The vertical incidence of an SV wave is taken as an example to verify the formula and the proposed numerical model is then used in the dynamic calculation of a gravity dam. The results show that the model established in this paper satisfies the accuracy requirement of engineering seismic analysis and it can solve the problem of structural dynamic analysis considering soil-structure interaction when seismic waves spread vertically on the layered foundation.