震害调查表明,当地下结构处于非均匀场地、软土层或在结构侧边存在软土夹层等复杂地质环境条件时,地下结构更易遭到损坏。因此,将对含有软弱饱和土夹层场地中地铁车站的地震响应进行分析。结合已有的单相介质和流体饱和多孔介质动力分析的显式有限无方法,考虑了土层中存在软弱夹层的情况,把软弱夹层模拟为流体饱和多孔介质,建立了适用于含软弱饱和土夹层场地中地铁车站结构地震响应分析的有限元方法;进行建模数值计算,分别给出了3条具有不同频谱特性的实际地震记录以P波彤式入射下地铁车站结构关键位置的地震动响应,并分析了软弱夹层的位置、厚度等因素对地铁车站结构地震动响应的影响。分析结果表明,软弱夹层对地铁车站结构地震动响应具有非常不利的放大作用,且当软夹层位于地铁车站中部时,放大作用最不利。
The statistical data of disasters caused by earthquake show that underground structures are more likely to be damaged when they in complicated geology and geological environment, such as nonuniform stratum, soft soil, soft interlayer nearby, etc. The seismic response of the metro station in the site with saturated soft interlayer is hereby analyzed. On the basis of the explicit finite element methods of dynamics analysis about single-phase and fluid saturated porous media, taking into account soft interlayer existing in the surrounding soil, a seismic response analysis method which can be used in metro station structure-saturated soil coupled system is established. By numerical modeling, the seismic responses of the key positions of metro station structure are shown under three actual earthquake recorders with different spectra characteristics which incident as the plane P wave. The factors, such as the location and thickness of the soft interlayer, are discussed in their influence on the dynamic response of metro station structure. The study results show that the soft interlayer has a very negative amplification on the dynamic response of metro station structure; and the amplification is the most unfavorable when the soft interlayer inside the metro station.