基坑开挖对邻近既有隧道结构安全性的影响

Effect of Excavation of Foundation Pits on Structure Safety of Adjacent Metro Tunnels

天津黄河医院三期项目,深度超过5 m,紧邻天津市地铁二号线。基于该基坑的施工过程,使用有限元软件MIDAS/GTS进行数值模拟,评估该项目基坑工程对地铁二号线区间结构安全性的影响。结果表明,基坑周围土体和地铁隧道管片的位移随着土体开挖过程而增大,而受楼面载荷的影响较小。此外,地铁隧道管片的竖向位移主要受基坑降水影响,其轴力和弯矩在施工过程中保持稳定,裂缝验算结果在允许范围内。研究成果可以为该项目工程影响评估提供有效的参考依据。

The depth of the dip in the third phase engineering project of Huanghe Hospital that adjoining Tianjin Metro Line 2 exceeds 5m. Based on the procedure of this engineering, the finite element method software Midas/GTS was adopted for numerical simulation aiming at conducting assessment on the effect of excavation of dip on the structure safety of Metro Line 2. The results indicates that the displacement of soils around the dip and the tunnel segments increase as the excavation proceeding but are not sensitive to the loading representing the architecture. Besides the vertical displacement of tunnel segments is dominated by excavation perviousness. Furthermore as the axial force and bending moment of the segments change little during the whole process, the results of crack checking is in a permissible range. The conclusion can provide effective reference for the construction influence assessment.