液化场地地铁区间隧道抗震设计研究

Research on seismic design for metro section tunnel in liquefaction region

借鉴建筑结构抗震设计理念及以往工程实践,总结了液化场地条件下地铁隧道抗震概念设计和构造设计的原则,并基于有限差分程序FLAC3D研究了地铁隧道与液化层处于不同相对位置关系时结构的动力反应,从而提出地铁隧道计算设计的抗液化处理原则。研究结果表明:当液化层位于地铁隧道拱顶附近及以上时,如不影响施工,可以不对液化层进行处理;液化层位于隧道拱腰及以上时,地层液化对结构内力及变形将产生一定影响,建议对该部分液化层进行加固处理;隧道周边土体全部为液化层时,地震时结构的内力和地层变形会大幅增加,必须对液化层进行加固处理。不论地铁隧道与液化层相对位置关系怎样,一般均应进行抗浮验算。

According to seismic design concept of building structure and engineering practice, the principle of subway tunnel seismic concept design and structural design in liquefaction region was summarized. The dynamic response of the structures was studied when subway tunnel and the liquefaction sand are in different relative position by using FLAC^3D software and liquefaction resistance principles for the subway tunnel calculation design were put forward. Results showed that the liquefaction stratum should not be handled if the liquefaction layer is located near or above the subway tunnel vault which does not affect the construction, stratum liquefaction has a certain effect on the internal force and deformation of the structure when liquefaction layer is located at or above tunnel arch waist, liquefaction sand of which should be reinforced, internal force and deformation of the structure under the earthquake will be greatly increased when all of the soil around the tunnel is liquefaction stratum, which means liquefaction sand must be reinforced. In general, anti-floating calculation should be made no matter what the relative position relationship between subway tunnel and the liquefacdon sand is.