下卧运营地铁隧道基坑开挖方案优选

Optimization of excavation scheme of the foundation pit over pperational subway

采用Midas GTS有限元软件动态模拟施工风险最大位置处的基坑开挖过程,分析深圳前海交易广场项目基坑开挖对区间隧道结构的影响规律。研究结果表明:采用施工方案二"竖井分块开挖方案"可有效控制基坑开挖过程中下卧区间隧道的变形;采用竖井分块开挖方案应重点控制隧道上方竖井开挖过程;采用竖井分块开挖方案,每个竖井中土体开挖完成后应及时施作1.5 m厚混凝土板,同时可考虑增大基底混凝土板厚度、混凝土板与围护桩连接等措施进一步有效控制施工对区间隧道的影响。

Finite element software of Midas GTS is adopt to simulate excavation process of the foundation pit where the construction risk is the largest,and effects of excavation of the foundation on the tunnel is analyzed. Result obtained in this paper shows that： deformation of the interval tunnel could be controlled effectively by using the construction scheme 2 that called shaft block excavation. Excavation process of the shaft above the tunnel should be controlled when the scheme of shaft block excavation is adopt. By taking the scheme of shaft block excavation,1. 5 m thick concrete slabs should be made. Meanwhile,measures of increasing thickness of the basement concrete and strengthening connection between concrete slabs and enclosure piles could be taken into account,so as to further control effect of foundation pit excavation on the interval tunnel.