基坑开挖对邻近地铁区间隧道结构安全的影响分析

Influential Analysis of Foundation Pit Excavation on the Structural Safety of Adjacent Metro Tunnel

为研究基坑开挖卸荷对邻近地铁区间隧道所带来的附加变形及附加应力的变化规律,以青岛某邻近地铁基坑施工项目为例,对基坑开挖和主体结构施工工况进行模拟分析,得到不同施工步骤下地铁隧道的位移变化情况和受力状况.研究结果表明:既有区间隧道结构各向位移随基坑开挖深度的增加而增大,最大达2.14 mm,为水平侧向位移;主体结构施工后,由于外部荷载的及时补充,隧道结构各向变形得到抑制,减小至1.91 mm,满足规范控制要求.该基坑开挖期间施工工况不影响地铁的正常运营,但施工过程中应注意各施工步骤间的衔接.

In order to study the additional deformation and stress caused by the unloading of foundation pit excavation on the adjacent subway tunnels,a subway excavation project in Qingdao was taken as an example,and the finite element simulation software was used.Through the simulation analysis of the excavation and the construction of the main structure,the displacement variation and the stress state of the subway tunnel under different construction steps are obtained.The results show that the axial displacement of the existing tunnel increases with the depth of excavation,and the maximum horizontal lateral displacement is 2.14 mm.Due to the timely supplement of external load,the deformation of tunnel structure is restrained to 1.91 mm,which meets the control requirements of the code.The construction conditions of this structure can meet the normal operation of the subway during the excavation of the foundation pit,but attention should be paid to the connection between the construction steps during the construction process.