饱和软土层地铁列车运行引起的环境振动研究

我国沿海地区大量的地铁隧道都修建在饱和软土地层，饱和软土地层中地铁列车运行引起的环境振动逐渐成为社会关注的问题。以上海2号线某地铁区间隧道为研究对象，采用循环运动模型本构模型和水土耦合动力分析方法，分析了饱和软土中地铁列车运行引起的地表振动加速度以及振动位移响应规律，采用加速度振级对地表的振动强度进行了评价，分析了单次列车通过时引起的隧道下卧土层超孔隙水压力（EPWP）响应规律。计算结果表明，饱和土的振动响应比干土要小得多，地表水平向与竖向的振动规律明显的不同，超孔隙水压力沿隧道下方沿向是不断减少的，在距离隧道中心的纵断面上是先增加后减少。分析饱和土中地铁运行引起的环境响应规律，可为地铁沿线建筑物减隔振设计及沉降控制提供一定依据。

Research on environmental vibration response of soft saturated soil due to moving metro train

Environmental vibration induced by underground moving metro trains has aroused much attention of the society as more and more subway tunnels are constructed in saturated soft soils in the coastal area of China. Taking the Shanghai metro line 2 for example, response of saturated soft soil layers induced by subway train in the shield tunnel is analyzed by using cyclic mobility constitutive model and water-soil coupled method, including ground surface vibration acceleration and dynamic displacement, as well as the dynamic response of excess pore water pressure(EPWP). The acceleration level of ground surface is adopted to evaluate the intensity of ground surface vibration. Numerical results show that dynamic response of saturated soil is much smaller than that of dry soil, vibration on the ground surface also presents distinct differences in the horizontal direction and vertical direction. As for excess pore water pressure, it diminishes along vertical tunnel axial direction, whereas it increases first and then decreases in the vertical profile several meters away from tunnel center. The results can provide guidance for vibration mitigation design and settlement control measures for nearby structures.