基于宁波软土地区某位于地铁隧道上方的大面积道路及管沟工程,介绍了减少对下卧地铁隧道影响的设计及施工关键措施.管沟基坑采用钢板桩结合钢支撑支护,围护桩与隧道竖向净距、水平净距分别控制在 3.0m、5.0m以上;管沟施工采取依次开挖、分段施工、地铁隧道 4.0m 范围内钢板桩静压振拔等措施,道路施工采取地铁隧道 6.0m范围内静压、分段开挖和回填等措施.建立三维有限元模型,研究管沟与道路施工对下卧地铁隧道的影响,结果表明:管沟及道路开挖引起地铁隧道产生水平位移和隆起,回填后位移回落;地铁上方管沟基坑主要引起隧道产生隆起,旁侧管沟基坑卸载引起隧道产生水平位移.管沟同时施工引起地铁隧道产生较大隆起,建议依次开挖;道路一次性开挖对地铁隧道影响较大,建议分段施工长度不大于 50 m.
Analysis and Control Measures of the Influence of Pipe Trench and Road Construction on the Underlying Subway Tunnel
This study examines a large-scale road and pipe trench project located above a subway tunnel in the soft soil region of Ningbo.It presents key design and construction measures aimed at minimizing the impact on the underlying subway tunnel.The foundation pit of the pipe trench is supported by a combination of steel sheet piles and steel supports,maintaining vertical and horizontal clearances of over 3.0 meters and 5.0 meters,respectively,between the retaining piles and the tunnel.Pipe trench construction adopts sequential excavation,segmented construction,and the application of static pressure with vibratory extrac-tion of steel sheet piles within a 4.0-meter radius of the subway tunnel.Road construction utilizes static pressure support,seg-mented excavation,and backfilling within a 6.0-meter radius of the subway tunnel.A three-dimensional finite element model is developed to assess the impact of trench and road construction on the underlying subway tunnel.The results indicate that trench and road excavation induce horizontal displacement and uplift of the subway tunnel,which reduce after backfilling.Specifically,the pipe trench foundation pit directly above the subway tunnel primarily causes tunnel uplift,while the unloading of the pipe trench foundation pit adjacent to the tunnel results in horizontal displacement.Simultaneous construction of the pipe trench leads to significant uplift of the subway tunnel,suggesting that se-quential excavation is preferable.Additionally,one-time road excavation exerts considerable influence on the subway tunnel,recommending that segmented construction sections do not exceed 50 meters in length.
万方数据
维普
