浅埋暗挖隧道开挖对既有隧道衬砌结构的影响

Influence of shallow tunneling excavation on lining structure of existing tunnel

浅埋暗挖隧道开挖会引起周边既有构建筑物变形,严重时会导致其变形过大而破坏。以某地下轨道交通工程为依托,利用仿真软件以及实地勘探,对既有隧道衬砌结构受力变形情况、实际施工过程中地表的下降情况、暗挖隧道位移和既有隧道衬砌结构位移情况进行研究。研究结果表明:1)采用隧道错距开挖的方式会造成隧道的沉降量变大;2)在隧道开挖后,既有隧道衬砌结构受新隧道影响,其左侧部分竖向位移整体大于右侧部分,竖向最大位移处在隧道初始位置,竖向最小位移处在隧道末端;3)对于浅埋暗挖上跨施工,当开挖距离大于新建隧道中轴线35m时,开挖新隧道对上跨既有隧道衬砌结构横向位移影响较小;4)当开挖深度到达一定距离后,拱底、左拱腰和右拱腰的应力基本保持不变;5拱底的应力不随开挖距离的深入而发生变化。

The excavation of shallow buried and hidden tunnels will cause deformation of surrounding existing structures,which will cause excessive deformation and damage.Based on an underground rail transit project,the mechanical deformation of the existing tunnel lining structure,the decline of the ground surface in the actual construction process,the displacement of the shallow tunneling and the displacement of the existing tunnel lining structure are studied by using simulation software and field exploration.The results show that:1)The staggered tunnel excavation will cause the settlement of the tunnel to increase;2)After tunnel excavation,the existing tunnel lining structure is affected by the new tunnel,and the vertical displacement of the left part is greater than that of the right part,and the maximum vertical displacement is at the initial position of the tunnel,and the minimum vertical displacement is at the end of the tunnel;3)For the construction of the upper span of sallow tunneling,when the excavation distance is greater than 35 m of the central axis of the new tunnel,the excavation of the new tunnel has little impact on the lateral displacement of the lining structure of the existing tunnel in the upper span;4)When the excavation depth reaches a certain distance,the stress of the arch bottom,the left arch waist and the right arch waist basically remain unchanged;5)The stress at the bottom of the arch does not change with the depth of the excavation distance.