可液化地层中地铁隧道地震响应数值模拟及其试验验证

饱和砂土地层中的地下结构在地震作用下可能因地基液化而发生破坏。采用动力固结两相体有限元程序DIANA SWANDYNE-II对可液化地层中地铁隧道结构的地震响应进行了模拟,并与动力离心模型试验结果对比以验证其效果。选用广义塑性模型Pastor-Zienkiewicz III模拟可液化土的动力特性,基于Biot方程的u–p形式建立有限元方程,进行饱和土动力固结的耦合计算。计算表明,该数值模型可较合理地模拟地下结构的地震反应特性,计算结果与试验现象基本相符。地基液化引起的结构附加内力及隧道上浮主要受地基液化时土水压力变化的影响,截断墙的设置可有效减轻隧道结构的上浮。

Numerical modeling of subway tunnels in liquefiable soil under earthquakes and verification by centrifuge tests

Underground structure in saturated sandy soil might be subject to severe damage due to seismic liquefaction.Numerical simulation for earthquake response of subway tunnels in liquefiable soil was conducted by use of finite element program DIANA SWANDYNE-II and the numerical model was verified by some centrifuge test results.A generalized plasticity model,Pastor-Zienkiewicz III,was used to model the dynamic behavior of saturated soil.Finite element procedure based on the u-p form of Biot equations was employed to perform the coupling analysis.It was shown that the numerical model could simulate the earthquake response of subway tunnels in liquefiable soil reasonably.Liquefaction induced ternal force in tunnel segments and its uplift were mainly influenced by the excess pore pressure and the earth pressure increment during earthquakes.Cut-off walls could reduce the uplift of subway tunnels effectively.