软岩铁路隧道上跨既有公路隧道施工变形规律分析

Analysis of Deformation Law in Loess Railway Tunnel Construction Over Existing Highway Tunnel

为研究软岩铁路隧道上跨施工对既有公路隧道结构的影响,本文以某新建铁路隧道工程为依托,采用有限元软件进行数值模拟。结果表明:上跨铁路隧道施工引起的地表沉降主要为开挖瞬间地表瞬时沉降。施工完成后,沿铁路隧道轴线方向地表最大沉降值为3.16mm。既有公路隧道的结构变形主要集中在铁路隧道掌子面抵达公路隧道正上方至开挖结束阶段。既有公路隧道最大拉应力、最大压应力均有所提高。铁路隧道拱顶最大沉降值、水平位移最大值均满足规范要求。

To study the influence of the construction of the upper span of the railway tunnel in soft rock on the structure of the existing highway tunnel,this paper uses the finite element software to carry out numerical simulation based on a new railway tunnel project.The results show that the surface settlement caused by the construction of the over-crossing railway tunnel is mainly the instantaneous surface settlement at the moment of excavation.After construction,the maximum surface settlement along the axis of the railway tunnel is 3.16 mm.The structural deformation of the existing highway tunnel is mainly concentrated in the stage from the railway tunnel face to the top of the highway tunnel to the end of excavation.The maximum tensile stress and maximum compressive stress of existing highway tunnels have been increased.The maximum settlement value and the maximum horizontal displacement of the railway tunnel vault meet the specification requirements.