基坑开挖对盾构隧道影响的三维数值分析

Three Dimensional Numerical Analysis of the Influence of Foundation Pit Excavation on Metro Shield Tunnel

当开挖基坑位于隧道附近,由于基坑开挖导致影响范围内的土体应力释放,打破了土体原有的应力平衡,致使基坑底部隆起,进而使基坑开挖范围内的土体发生位移,从而带动周围隧道产生移动。以武汉地铁7号线北延工程天阳路站至腾龙大道站区间风井基坑为例,采用三维有限元数值模拟的方法,模拟了基坑开挖引起的盾构隧道变形和内力的变化,分析得出了采取分段分区施工方案能够明显改善基坑开挖引起的盾构管片的水平、竖向位移以及内力变化,结合现场实际穿越过程中的监测数据,与数值模拟结果基本一致,说明施工方案合理可行。

When the excavated foundation pit is located near the tunnel,the stress of the soil within the influence range is released due to the excavation of the foundation pit,which breaks the original stress balance of the soil,resulting in the uplift of the bottom of the foundation pit,thus causing the displacement of the soil within the excavation range of the foundation pit,thus driving the surrounding tunnels to move.Taking the air shaft foundation pit of Tianyang Road Station Tenglong Avenue station on QianChuan line of Wuhan Metro as an example,this paper uses the three-dimensional finite element numerical simulation method to simulate the changes of shield tunnel deformation and internal force caused by foundation pit excavation.It is analyzed that the construction scheme of subsection and zoning can significantly improve the changes of horizontal and vertical displacement and internal force of shield segments caused by foundation pit excavation,Combined with the monitoring data in the actual crossing process,it is basically consistent with the numerical simulation results,indicating that the construction scheme is reasonable and feasible.