基坑分块开挖对邻近地铁隧道变形影响实测分析

Field measurement analysis of the influence of block excavation of foundation pit on deformation of adjacent subwaytunnel

基坑开挖引起的土体变形过大会导致周边已运营隧道出现裂缝、错台和渗漏水等病害,严重危害隧道的长期服役性能与运营安全。为研究基坑分块开挖对邻近运营地铁隧道变形的影响,以杭州某邻近已运营地铁隧道的基坑工程为背景,对施工过程中的基坑变形及隧道变形进行实测分析,结果表明:后开挖的分坑需加强第2道支撑的刚度;隧道自身的结构刚度在一定程度上能够减少基坑开挖引起的土体变形;基坑开挖对道床水平和竖向位移的影响效果相同,位移变化在3mm范围内,且随开挖的进行增大;基坑开挖前围护结构的施工对管片收敛变形影响较大。

The soil deformation caused by the excavation of foundation pit will lead to cracks,dislocation and leakage of water and other diseases in the surrounding operating tunnels,which will seriously endanger the longterm service performance and operation safety of the tunnel.In order to study the influence of block excavation of foundation pit on the deformation of adjacent operating subway tunnels,this paper takes the foundation pit project of a nearby operating subway tunnel in Hangzhou as the background,and analyzes the deformation of foundation pit and tunnel during the construction process.The results show that:The post-excavation pit needs to strengthen the stiffiness of the second support;The structural rigidity of the tunnel itself can reduce the soil deformation caused by foundation pit excavation to a certain extent;The effect of foundation pit excavation on the horizontal and vertical displacement of ballast bed is the same,the displacement changes within 3 mm,and it increases with the excavation;The construction of the enclosure structure before the excavation of the foundation pit has a great influence on the convergence and deformation of the segments.