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结合求水山隧道的暗挖法施工方案,对软土地区浅埋隧道下穿高速公路的施工过程进行了有限元模拟,以用于评价按该施工方案施工时对其上部高速公路的影响。由于该段隧道最小埋深仅4m,且上部还有高速公路车辆荷载,因此,在设计时采用了新奥法结合管棚工法的方案。有限元建模使用平面应变单元,通过引入应力释放分析步和使用追踪单元等方法充分体现了新奥法的特点,并通过设置耦合和弹簧的方法实现了管棚工法的模拟,在计算中还考虑了开挖顺序和支护顺序的影响。研究结果表明:对于上部有荷载的浅埋暗挖隧道,控制衬砌的水平向变形能改善衬砌环的工作状态,因此,可显著减少开挖引起的隧道顶面沉降,新奥法结合管棚工法可较好地控制该类型隧道开挖引起的地表沉降变形。
According to the construction plan of tunneling in Qoushui Mountain Tunnel, the construction process of Shallow Tunnel in soft soil area under the expressway is simulated by finite element method to evaluate the influence on the upper expressway when it is constructed according to the construction scheme. As the minimum depth of the tunnel section is only 4m, and the upper part of the highway vehicle load, therefore, the design of the new Austrian law combined with the pipe shedding method. Finite element modeling using plane strain element, through the introduction of stress release analysis step and the use of tracking unit and other methods fully embodies the characteristics of the new Austrian law, and by setting the coupling and spring method to achieve the shedding method simulation, but also in the calculation The effects of excavation sequence and support sequence are considered. The results show that the horizontal deformation of the control lining can improve the working condition of the lining ring for the shallow burying tunnel with load in the upper part. Therefore, it can significantly reduce the settlement on the top of the tunnel caused by excavation. Can better control the type of tunnel excavation caused by surface subsidence deformation.