盾构井开挖及暗挖法施工对既有地下隧道安全分析

盾构隧道下穿既有隧道或构筑物时,为降低对其地基、桩基础等产生不利影响,可采用先行暗挖施工,然后盾构空推的方案。依托穗莞深城际深圳机场至前海段区间隧道下穿桂湾一路地下市政隧道安全评估项目,通过Midas GTS NX有限元分析软件模拟注浆加固、PHC桩基切除、暗挖隧道施工等工序,得出了隧道施工监控数据要求等。结果表明:该方案施工地下隧道结构安全、位移指标选取合理。同时可为隧道开挖、桩基切除、二衬施工中的结构受力模型转换等工况提供建议和指导。

Analysis of the Influence of Shield Shaft Excavation and Subsurface Excavation on Safety of Built Underground Tunnel

When the shield tunnel goes through the built tunnel or buildings,the construction scheme of subsurface excavation before shield tunneling can be applied to reduce the adverse effect on foundation and pile foundation.The tunnel crosses Guiwan 1 st Road which is the section of Shenzhen Airport-Qianhai in Guangzhou-Shenzhen Intercity Railway.Taking the safety assessment of underground municipal tunnel of the project as an example,its grouting reinforcement,pile foundation of PHC cutting and construction of mined tunnels are simulated by MIDAS GTS NX finite element analysis software and got the construction monitoring data.The result shows that the underground tunnel structure is safe and the selection of displacement index is reasonable by the scheme.At the same time,the scheme provides suggestion for tunnel excavation,pile foundation cutting and structural stress model transformation during secondary lining construction.