超近距离基坑施工对交叠地铁的影响及响应

随着城市发展,既有地铁车站及隧道结构不可避免地会与邻近新建工程相互影响。针对此问题,本文以北京某邻近地铁6号线车站及区间隧道的超近距离基坑工程实测资料为基础,运用MIDAS/GTS软件建立了三维数值分析模型,对基坑施工进行了全过程动态模拟。通过数值分析和实测分析等手段,研究了既有交叠地铁车站及隧道对超近距离基坑施工的影响及响应。结果表明:由于既有结构刚度大于土体刚度,会影响基坑开挖产生的土体位移场,使既有结构侧土体隆起明显小于无结构侧、隆起减小速度明显大于无结构侧;既有结构的存在同样会影响围护桩的变形,使既有结构侧的桩侧移量小于无结构侧;随着平面内与基坑距离和平面外与基坑竖向距离的变化,既有结构的位移响应会有所不同;平面内与基坑距离和截面刚度变化,既有道床和轨道也会有不同的响应。研究成果可为类似超近距离施工及交叠隧道工程提供参考。

Influence and Response of Construction of Ultra-close Foundation to Overlapping Metro

With the development of the cities, it is inevitable that metro station and tunnel structure will interact with adjacent new projects. Aiming at this problem, this paper is based on a foundation engineering ultra-close to the station and tunnel of Beijing Metro line 6. Using MIDAS/GTS software to build three-dimensional numerical analysis model, we dynamically simulate the whole construction process of foundation. Through numerical analysis, the influence and response of the overlapping metro station and tunnel to the construcion of the ultra-close foundation are studied. The results indicate as following: due to the stiffness of existing structure is greater than soil, it will affect the displacement field produced by excavation of foundation. It is obvious that the upheaval of the existing structure side is less than the unstructured side and the upheaval of the existing structure side is reduced faster than the unstructured side significantly. The existing structure will also affect the deformation of the pile, so that the pile lateral displacement of the existing structure side is less than the unstructured side. The displacement response of the existing structure is different with the change of the vertical and in-plane distance from the foundation. The track and track bed will also response diffenently when in-plane distance from the foundation and stiffness of the section change. The results can be used to provide reference for similar ultra-close-distance construction and overlapping tunnel engineering.