地铁换乘车站深基坑支护体系测试研究

Study on Test for Supporting System for Deep Foundation Pit of Metro Transfer Station

研究目的:城市地铁换乘车站基坑施工难度大,维护结构安全性和稳定性尤为重要。针对某换乘车站工程地质条件、周边建筑环境和工艺特点,选取合适的围护方案和水平支撑体系。采用现场测试方法,分析基坑围护桩水平位移和钢支撑轴力变化规律,得出城市地铁换乘车站基坑支护有益结论,为相类似工程提供借鉴。研究结论:基坑开挖过程中,围护桩的变形随着开挖深度的增加而增大,由于桩顶设置有冠梁,围护桩变形最大值出现在开挖深度的中下部,随着开挖深度的增加,最大位移值的位置也随之下移。支撑轴力值在开始时增加量很大,随着基坑的开挖和下一道支撑的安装,变化幅度不大;施工过程中各道支撑的实测轴力占设计值百分比均小于70%。

Research purposes： As it is very difficult to construct the deep foundation pit of a metro transfer station, it is very important to maintain the structure safety and stability. According to the engineering geological conditions, the surrounding buildings and the process characteristics of one metro transfer station, the appropriate supporting scheme and the horizontal support system were selected. Based on the field test, the change laws of the horizontal displacement of guard pile for the foundation pit and the axial force of the steel support were analyzed to draw the helpful conclusion on the supporting system for the deep foundation pit of metro transfer station to provide the reference to the similar works. Research conclusions：In the process of the excavation of the foundation, the deformation of guard pile increased with the increase of the excavation depth. The maximum deformation of the guard pile appeared in the middle -low part of the excavation depth. The place in where the maximum deformation appeared shifted down with the increase of the excavation depth. The supporting axial force increased largely at the beginning, but it varied a little with the excavation of the foundation pit and installation of the next support. The tested axial force of the various supports during construction was to the 70% of the design value.