顶管上跨施工期间地铁隧道变形特征

Deformation Characteristics of the Existing Subway Tunnels During Overpassing Construction of Pipe Jacking

毛家湾污水处理厂进厂干管施工主要采用顶管法,顶管施工过程中上跨地铁,必然导致地铁变形。采用GeoMos监测系统对地铁变形进行监测。结合施工日志,对地铁变形的时间、空间特征进行分析。研究表明:顶管施工期间,地铁会持续变形;始发井恢复期间,地铁变形值增加最快;顶管施工过程中地铁整体位移与顶管方向一致,但局部区域位移方向与顶管方向相反。地铁顶部竖向位移沿纵向呈“V”字形对称分布;对于同一横断面,顶拱位移下降,而底部位移向上,这是由顶管顶进过程中的挤压效应引起。可在顶管施工过程中采用钢管或球墨铸铁管上跨地铁施工,顶管机头出洞后先恢复接收井的方式减少顶管施工对地铁的扰动作用。

The trunk sewer of Maojiawan Sewage Disposal Plant is mainly constructed through pipe jacking.It overpasses subway,which will induce deformation of subway.The deformation is monitored utilizing GeoMos monitoring system.Combined with the construction log,the time and space characteristics of the deformation are analyzed.The result shows that the subway deformation steadily increases during the pipe jacking.The deformation of the subway increases the fastest during the starting shaft recovering.The general displacement of the existing subway is in the direction with the pipe jacking,but the displacement in local region is in opposite.The deformation distribution is similar to letter“V”along the longitudinal direction.The displacement at top of the arch points down and the displacement at bottom of the arch points up.The phenomenon is induced by extrusion effect of the soil driven by pipe jacking.The disturbance action of subway caused decreases by pipe jacking using steel pipe or ball mill cast iron pipe and recovering receiving shaft firstly after pipe jacking.