基于有限元法的地铁隧道下穿既有输水隧洞安全影响研究

The safety evaluation of existing water conveyance tunnel during excavation of nearly undercrossing subway tunnel based on finite element method

新建地铁隧道下穿输水隧洞,会引起既有结构的变形及附加应力,可能影响其运行安全。针对某地铁隧道下穿南水北调输水隧洞进行安全影响评价,通过建立三维有限元模型对施工过程进行仿真分析,预测输水隧洞及地表的沉降,分析不同工况下地铁隧道施工对既有输水隧洞的安全影响,提出地铁隧道下穿输水隧洞的变形控制指标,并结合监测数据进行验证。结果表明:地铁隧道下穿输水隧洞施工主要引起既有输水隧洞轴线方向的不均匀沉降,进而引起输水隧洞的轴线方向附加应力,应控制输水隧洞轴线方向应力不超过允许应力,进而间接确定变形控制指标,必要时可根据计算结果进行加固方案的设计。研究成果对类似穿越工程的设计、施工参数及监控量测控制指标的确定等具有参考价值。

The water conveyance tunnel passing through a new building subway can result in displacement and stress of existing structure, which may affect its safety in operation. The safety evaluation of water con- veyance tunnel during excavation of subway tunnel is studied in the paper. Based on a 3-D finite element model, the engineering construction process is simulated, and the displacement of water conveyance tunnel is predicted. Besides, the impact of excavation under different working conditions of subway tunnel on safety of existing water conveyance tunnel is analyzed. Finally the deformation controlling indices is proposed and the corresponding monitoring data is verified. The results indicate that the subway tunnel construction mainly leads to the uneven settlement and stress of the existing water conveyance tunnel in axis direction. The defor- mation controlling indices is determined by controlling the stress in axis direction. Then the design of rein- forcement scheme can be carried out according to the calculation above. The research results are of valuable reference for the determination of design and construction parameters and monitoring and measurement con- trolling indices in similar crossing projects.