基于无限元和波场分离法的地震响应数值分析

Numerical Analysis of Seismic Response Based on Infinite Element and Wave Field Separation Method

用无限元模拟远场地基,有限元模拟近场区域,并在有限元和无限元接触处施加等效荷载以输入地震作用,从而求解半无限地基的地震响应.通过算例对边界和地震输入方式进行验证,研究剪切波作用下,重力和土与结构相互作用对场地地震响应的影响.结果表明:基于无限元和波场分离法的地震输入,能够有效仿真波动在半无限地基中的传播过程;重力对水平地震运动无影响;土与结构相互作用效应使短周期段加速度反应谱值降低,而长周期段加速度反应谱值增加;土与结构相互作用对岩石地基水平位移无影响,但使结构底部地基的最大主应力和最小主应力幅值增大.

The infinite element is adopted to model the far field and the finite element to model the near field of foundation, and the equivalent load is artificially applied to the interface between the finite element and the infinite element meshes to replace the seismic action. The seismic responses of semi-infinite foundation are then simulated. An example is performed to verify the boundary and seismic input, simultaneously effects of gravity and soil-structure interaction on the seismic response of field under incident shear wave are investigated. Numerical results show that the proposed method based on the infinite element and wave field separation method is feasible and it can effecti,;,ely simulate the process of wave propagation in semi-infinite foundation. Gravity has nothing to do with horizontal earthquake. Furthermore, the influence of soil-structure interaction reduces the acceleration response spectrum in a short period, while increasing the acceleration response spectrum at long period. Finally, the influence of soil-structure interaction has nothing to do with horizontal displacement of rock foundation, however, it augments the max and min principal stress of groundwork just beneath the structure.