饱和多孔介质中外源振动输入方法的研究

Study on the External Excitation Input Methods for Porous Medium

通过建立数值模型研究外源振动下结构-地基体系的动力响应时,往往涉及到半无限地基的模拟以及外源振动的输入.常见的外源振动输入方法主要包括波动法、人工边界子结构法和区域缩减方法(DRM)等.文中首先结合FLAC 3D和Matlab比较了人工边界子结构法和DRM方法对单相介质波动问题的适用性,发现DRM方法得到的自由场响应与一维精确解一致;进一步将人工边界子结构法和DRM方法推广到饱和多孔介质中,分别提出了将外源振动转化为节点等效力和等效流量的表达式;最后通过垂直入射地震波动作用下弹性半无限饱和地基响应算例比较了两种方法的可行性.结果表明,DRM方法得到的自由场响应与一维精确解完全一致,而人工边界子结构法得到的响应值偏小.

The numerical methods have been widely used to solve the structure-foundation interaction problems in which the semi-infinite medium simulation and the external excitation input method are of most concern.The commonly used external excitation input methods include the wave method,the artificial boundary substructure method and the domain reduction method(DRM),etc.Firstly,the applicability of different wave input methods for single-phase media e are compared by virtue of FLAC 3D and Matlab,and the results show that the free field response obtained by the DRM method match well with the one-dimensional analytical solution.Further,the artificial boundary substructure method and DRM method are applied to porous medium,respectively,and the formula to transfer external excitation into equivalent force and equivalent discharge are proposed.Finally,the feasibility of two methods are compared and verified with the elastic semi-infinite saturated foundation response under the effect of vertical seismic wave.The results indicate that the free field response value obtained by the DRM method is consistent with the one-dimensional analytical solution,however,the response value obtained by the artificial boundary substructure method is much smaller.