地下连续墙对叠合墙式地铁车站结构地震反应的影响研究

Effect of diaphragm wall on earthquake responses of an underground subway station

针对现行地铁地下车站结构的常见叠合墙式结构设计方法和抗震分析方法中不考虑地下连续墙存在的现实情况,基于数值计算方法,建立了土–地下连续墙–地下结构静动力耦合非线性相互作用有限元分析模型,分析了地下连续墙存在时对地铁地下车站主体结构地震反应的影响规律。研究结果表明:地下连续墙的存在对地铁车站主体结构的抗水平侧移能力有一定的提高作用,使得其顶底间的最大相对位移有显著减小。从这一结果出发,似乎可以认为地下结构抗震分析中不考虑地下连续墙时可看作是地下结构的地震安全储备。但是,地下连续墙的存在明显改变地下结构的整体变形性态,进而导致地下结构的内力发生重分布,尤其使得大震时车站结构的顶、中、底板一些关键部位的地震损伤程度明显比不考虑地下连续墙时要严重;同时,地下连续墙对车站结构顶底板表面与土体间的相对摩擦剪力也产生明显的影响。

At present, the diaphragm wall is always used as the partial side wall of the underground subway station. However, the diaphragm wall is always neglected in the seismic design of an underground structure for that it is looked as a reserved safety for its earthquake resistance. To verify this opinion, a finite-element model is established to simulate the static and dynamic coupling interaction among the soil, the diaphragm wall and the underground subway station. The effects of the diaphragm wall on the earthquake responses of the underground subway station are investigated and analyzed. As a result, the diaphragm wall can increase the lateral deformation stiffness of the underground structure, which reduces the relative lateral seismic deformation of the underground structure. From this point, the seismic design method for the underground structure is conservative. However, the diaphragm wall may also change the seismic deformation characteristics of the underground structure, which will aggravate the earthquake-induced tension damages of the plates of the underground structure under strong earthquakes. Moreover, the diaphragm wall may affect the friction responses on the interaction surfaces between the soils and the underground structure.