浅埋暗挖法地铁施工引起地表沉降规律研究

Research on surface subsidence caused by subway construction using shallow tunneling method

为研究浅埋暗挖法地铁施工在不同埋深和开挖工序情况下对地表沉降的影响规律,通过建立埋深8 m、12 m和16 m以及正台阶法、上下台阶法和单侧壁导坑法的地铁施工FLAC3D数值计算模型,模拟不同埋深和不同施工方法的地表纵向沉降,与地表现场监测数据进行对比分析。结果表明,模拟数值比实际监测值略偏高20%～30%;地表沉降变形随埋深增大而减小;正台阶法对地表的影响最小,上下台阶法引起地表沉降比其大40%。建议东北地区地铁施工采用正台阶环形开挖法施工较为合理,并选择适当的隧道埋深,以减少地表沉降对周围环境的影响。

In order to investigate the surface subsidence caused by subway construction using shal- low tunneling method under different burial depths and excavation processes, a FLAC30 model for numerical calculation was built, where the burial depths were eight, twelve and sixteen meters for the bench cut method, bench tunneling method and side drift method, respectively. Simulation for the surface longitudinal settlement along the axis direction was conducted, and was compared and analyzed with the in-site field monitoring data. The results from the numerical simulation were about 20% ~ 30% higher than that from the field data, and the surface subsidence decreases when the burial depth increases. The bench cut method has the minimum influence, with which the surface subsidence is 40% less than that with the bench tunneling method. Therefore, it is suggested that the bench cut method should be employed for the subway construction in northeastern area, and proper burial depth should be chosen to reduce the influence of the subsidence on the environment.