基坑开挖卸载对地铁区间隧道影响的数值模拟

Numerical modeling of affection of foundation pit excavation on metro tunnel

上海新金桥广场基坑工程位于地铁区间隧道的正上方,坑底距隧道顶的最小距离仅为 4 m。基坑开挖对该地铁区间隧道影响的分析与计算成为该工程的关键。为此建立了该基坑工程的数值分析模型,模型充分考虑了设计中隧道周围土体加固、充分利用时空效应开挖土方等重要措施,并采用了能反应应力路径的上海软土卸荷模量。数值模型对实际施工工况进行模拟,动态地分析了施工过程中开挖卸荷对地铁隧道的影响。为优化设计和施工提供了有益的参考。

The foundation pit of new Jingqiao square in Shanghai is located on above of metro tunnel. And the minimum distance between the foundation pit ‘s bottom and tunnel’s top is just 4 meters. The key of the foundation pit project is know how the excavation of the foundation pit affect the metro tunnel. The paper made a numerical model of the foundation pit project, which considered the measures adopted in design, such as the reinforcement of soil where around the tunnel, and excavation plan in terms of the time-space effecting of excavation. The unloading modulus of the Shanghai soft clay relating the unload stress path is adopted. The model simulated the practical construction process and then dynamically analyzed the affection of excavating on metro tunnel. The result provided valuable reference to design and construction.