基坑施工对下卧地铁盾构隧道管片变形影响分析

An Analysis of the Influence of Foundation Pit Construction on the Deformationof the Tube Segments of the Underground Subway Shield Tunnel

地铁隧道基坑开挖时,由于卸荷作用会引发隧道变形,进而影响地铁的安全运行。以温州某基坑施工上跨地铁线为例,通过现场监测和数值模拟的方法对下卧盾构隧道管片隆起变形规律进行分析。结果表明:在基坑开挖阶段,第一层开挖时隧道管片受到的扰动较小,第二层开挖时隧道管片受到了扰动。基坑开挖过程中诱发盾构隧道管片竖向隆起位移与管片环数呈正态分布,最大隆起位移出现在基坑中部。此外,第二层开挖时,隧道管片位移增大速率增加明显,因此,应采取适当的加固措施。

During excavation of foundation pit,unloading will cause deformation of subway tunnel,which will affect the safe operation of subway.This article takes the construction of an overpass subway line in a foundation pit in Wenzhou as an example,and analyzes the deformation law of the segment uplift of the underlying shield tunnel through on-site monitoring and numerical simulation methods.The results indicate that during the excavation stage of the foundation pit,the tunnel segments were less disturbed during the first layer of excavation,while the tunnel segments were disturbed during the second layer of excavation.During the excavation of foundation pit,the vertical uplift displacement of shield tunnel segment and the number of segment rings are normally distributed,and the maximum uplift displacement occurs in the middle of the foundation pit.In addition,during the excavation of the second layer,the displacement of the tunnel segments increases significantly,so appropriate reinforcement measures should be taken.