地铁车站基坑围护结构变形监测与数值模拟

以某城市大型地铁车站基坑为研究背景,对基坑围护结构及其变形监测方案进行了设计,并对基坑围护结构变形的现场监测数据进行了分析,重点分析了基坑施工过程中围护结构的水平变形随基坑开挖深度和时间的变化规律。建立了弹塑性有限元模型,并对地铁车站深基坑开挖进行施工仿真模拟计算,将获得的围护结构变形结果与监测结果进行了对比分析,再引用多种围护形式对基坑变形进行敏感性因素分析。结果表明:钢支撑+围护桩的围护形式对基坑土体的侧向变形有较好的限制作用,有限元数值计算结果与现场实测结果比较一致,有限元计算的结果是可信的,改变钢支撑的施作位置对限制基坑的侧向变形有重要作用。随着围护桩入土深度的增大,土体向基坑内侧变形的趋势有所减缓。

Monitoring and numerical simulation of deformation of retaining structure in subway station foundation pit

Based on some urban subway station foundation-pit project, retaining structure of the foundation pit and its deformation monitoring program are designed; in-situ monitoring data of the retaining structure deformation in the foundation pit are analyzed. The laws of the horizontal deformation of the retaining structure changing with the excavation depth and time are studied. Elastoplastic finite element model is built to do construction simulation calculation of the station foundation pit; FEM results and in-situ monitoring results of retaining structure deformation are compared; and sensitivity factors analyses of the foundation pit deformation are done with a variety of retaining structure form. The results showed that: the retaining form with steel support and supporting pile has good limit to the lateral deformation of the foundation pit soil. The results calculated by FEM are consistent with the in-situ monitor results; it is shown that the results of finite element analysis is credible; it plays an important role in limiting lateral deformation by change the position of steel support; with the increase of supporting pile insertion depth; the soil deformation trending to the foundation pit inside is slowed down somewhat.