可液化土中地铁结构的地震响应

Earthquake induced liquefaction response of subway structure in liquefiable soil

在饱和土耦合作用与土和结构相互作用理论基础上,以地铁车站为例,用有限元法研究地下结构在地震液化作用下的响应。所采用的软件为动力两相体非线性有限元软件 Dyna-Swandyne-II,该软件可以应用先进的 Pastor-Zienkiewicz III 广义塑性模型模拟可液化土的动力特性,应用 u-p 形式的 Biot 方程,在有限元分析中充分考虑孔隙水与土之间的耦合,同时考虑地下结构与饱和土在动力作用下的非线性相互作用。分析了地铁车站的动力响应,包括地铁内力、加速度以及地铁位移。研究结果表明,地铁结构在地震液化作用下会产生较大的上浮,从而对结构造成比较严重的破坏;地铁结构在地震作用下的最大内力位于结构的交接处。因此,结构交接处的配筋应该格外小心。

Based on the theories of coupled interaction in saturated soil and dynamic soil-structure interaction, the response of subway structure in fully saturated liquefiable soil under earthquake excitation is investigated using the effective-stress based finite element program Dyna-Swandyne-II. A generalized plasticity model, Pastor-Zienkiewicz III model, is used to model the cyclic behavior of soil; and finite element procedure based on the u-p form of Biot theory is employed to conduct the coupled analysis. The nonlinearity of the interaction between soil and subway structure is fully considered. The dynamic response of subway structure, including the internal forces, the acceleration, and the vertical and horizontal displacements, are analyzed. The results showed that the subway structure may uplift due to the earthquake induced liquefaction, which shall lead to severe damage in the structure; and that the maximum seismic internal forces occurred at the connections of the structure elements and their reinforcement must be carefully designed.