基于饱和多孔介质的复杂自由场地震响应分析

Seismic Response Analysis of Complicated Soil Site Based on Saturated Porous Media

摘要:

采用不可压缩饱和多孔介质的广义Biot理论模型，导出流体饱和两相多孔介质振动问题的有限元方程，并对港珠澳工程沉管隧道段自由场进行数值模拟计算.计算结果表明，相对于传统的单相介质自由场而言，饱和两相多孔介质自由场地表加速度峰值有所降低；实际场地的地形地貌对孔隙水压力有显著影响；多孔材料的渗透系数增大，可能会导致其孔隙水压力降低；同时输入地震作用的大小也会影响场地地震液化的评估.由此可见，基于不可压缩饱和多孔介质的数值模拟方法在场地地震液化分析中可行，其结论可以应用在其他工程场地分析中.

Abstract:

Based on the generalized Biot theory model of incompressible saturated porous media model, a finite element formulation for dynamic transient of fluid saturated two phase porous media is presented, the numerical simulation model directly aiming at the soil site of Hong Kong, Zhuhai and Macau long immersed tube tunnel project. The result of numerical simulation indicates that: PGA of the saturated two phase porous medium free field reduces in comparison with traditional single phase medium free field; the topography of complicated soil site has a significant influence on the peak of pore water pressure; a greater permeability coefficient of porous materials may result in a lower pore water pressure; also the magnitude of input seismic action will affect the assessment of earthquake induced site liquefaction. Therefore, the numerical simulation method based on incompressible saturated porous medium is feasible in the analysis of earthquake induced site liquefaction and the conclusion can be applied to other soil site projects.