两明挖隧道基坑先后开挖对其下地铁隧道的影响评价

Assessment of the Impact of Subway Tunnel under the Two Open-excavated Tunnel after Foundation Pit Excavation

基坑开挖会对下卧运营地铁隧道的围岩应力造成重分布,进而可能引发隧道结构产生变形及内力变化,影响地铁隧道的正常运行。故一个合理的施工方案以及充足的保护措施对基坑开挖和隧道保护显得尤为重要。以广州某工程为例,利用有限元软件Midas GTS模拟实际施工工况,动态分析了两明挖隧道基坑先后开挖对其下卧地铁5号线隧道的影响。分析结果表明:两明挖隧道基坑先后开挖所引起的叠加效应会对地铁5号线隧道结构造成影响,但应力变化量均很小,不足以对地铁隧道的结构安全性造成影响。其分析成果可为优化设计和施工提供有益的参考,为类似工程提供借鉴。

Foundation pit excavation will cause surrounding rock stress redistribution of the tunnel construction under the metro line, which could change deformation and internal force of the tunnel construction, thus affecting the normal operation of the subway tunnel. Therefore, a rational construction scheme and adequate protection of foundation pit excavation is of great significance as well as the tunnel protection. Taking a project in Guangzhou as an example in this paper, the model simulated the practical construction process and then also dynamic analysis on the affection of two open-excavated tunnels excavating successively on the tunnel construction under the metro line 5 by using large finite element software Midas-GTS. The results show that additive effect caused by the two open-excavated tunnels excavating successively will influence the force and deformation of the tunnel construction under the metro line 5, but its varieties of stress are very small, not enough to affect the structural safety of subway tunnel. The result provides valuable reference for design and construction. It is helpful to other similar projects.