基坑开挖引起下卧既有电力隧道变形的控制技术研究

Deformation control of operating tunnels induced by deep excavation of overlying metro

基坑工程对周围管线的影响是基坑工程环境土工问题的重要研究内容。上海市轨道交通9号线二期杨高中路站新建出入口上跨于Φ3000 mm的电力隧道正上方,为了预防基坑开挖对下方电力隧道可能带来的过大变形,采用了MJS工法进行坑内外土体加固,分区分块开挖,并借助于有限元分析对基坑开挖造成的隧道变形进行了预测,同时在隧道内安装静力水准仪、表面式测缝计和远程通讯设备开展结构变形实时监测,基于监测数据实现反馈施工,通过这一系列手段实现了对电力隧道结构在上方基坑开挖情况下的变形控制,确保了电力隧道结构的安全。对监测数据的分析表明:利用MJS工法进行土体加固变形控制具有良好的效果,隧道结构变形实时监测系统能及时有效地反映隧道结构状态,为反馈施工提供决策依据。

The excavation-induced deformation of pipelines is one of the top environmental concerns for excavations in urban areas. The foundation pit at the exit to Yanggao Road Station Exit, which is part of the second stage project of Shanghai Metro line No. 9, overlies a Ф3000 mrn-operating power tunnel. To prevent the possible tunnel damage due to the excessive deformation, the soils are strengthened by using the metro jet system （MJS） method, the blocks are constructed by means of the block excavation, and the FEM-based tunnel deformation prediction is adopted. In addition, a real-time tunnel deformation monitoring system consisting of static hydraulic pipes, crack meters and signal transmission equipments is also adopted. The monitoring data indicate that the soil treatment by the MJS method is an effective way for deformation control, and that the state of the tunnel can be captured by the tunnel deformation monitoring system in the very first time, which therefore enables the implementation of feed-back construction strategy.