上海地铁九号线宜山路站降水引起的沉降分析

随着城市地下空间和轨道交通的开发利用，深基坑工程所伴随的降水沉降问题越来越受到人们的关注。通过对上海地铁九号线宜山路站的室内模型试验、现场监测数据的分析以及数值模拟方法对宜山路站降水引起的沉降问题作了研究。结果表明：①通过对上海轨道交通九号线宜山路地铁站的室内模型试验，在整理和分析试验数据的基础上，得出了不同的地下连续墙深度下降水井水位与地表沉降之间的规律。②借助于精确的测量分层沉降多点位移计测出的沉降曲线，分析出分层沉降曲线有着“分叉性”和“不协同性”规律性，即有些土层发生了向下的膨胀，导致位于较深的土层比较浅的土层产生较大的变形，首次发现了“逆回弹”现象。③运用数值计算软件MODFLOW对“逆回弹”现象的产生机理作了研究。

Analysis of settlements caused by dewatering in Yishanlu metro station in Shanghai

With the development and utilization of urban underground space and rail transportation, more and more attention has been paid to the settlement caused by dewatering during construction of deep foundation pits. The settlement at Yishanlu Metro Station of Line 9 in Shanghai caused by dewatering is studied, based on the laboratory model tests, field monitoring and numerical simulation. The results show that (1) The relations between ground settlements and water level of dewatering well at different depths of diaphragm retaining walls are found according to the analysis of laboratory model tests. (2) Based on the settlement curves calculated by multipoint displacement meters, ‘bifurcation’ and ‘inconsistent’ of the settlement curves are obtained. That is to say, the downward expansion takes place in some soil layers, which causes great deformation in deep soil layer than in relatively shallow soil layer. It is the first time that the ‘reverse rebound’ phenomenon is discovered. (3) Numerical analysis software-MODFLOW is used to study the mechanism of “reverse rebound”.