盾构近距离下穿对已建地铁隧道的位移影响及施工控制

Effect of nearby undercrossing tunneling on the deformation of existing metro tunnel and construction control

通过对盾构近距离下穿杭州地铁1号线已建隧道施工过程进行监测,针对盾构近距离、小角度下穿对已建隧道位移的影响过程和特点,研究了盾构机与已建地铁隧道相对位置关系不同时,已建隧道的隆沉、水平位移及收敛位移变化规律。对盾构参数进行实时记录,通过反馈的已建隧道位移监测进一步优化盾构施工参数,合理盾构参数的设置可以有效控制既有隧道变形在允许范围内。已建隧道变形规律显示,盾构隧道在距离已建隧道20 m以外工况下,对上部已建隧道影响很小;盾构整个过程中已建隧道穿越交叉点竖向和水平位移变化过程大致经历5个阶段。

Construction process of shield undercrossing the existing metro tunnel No.1 is monitored. Based on monitored data, the heave/subsidence, horizontal and convergence displacement of the existing tunnel structure are analyzed with the change of the relative position of the shield machine to the existing tunnel. Shield driving parameters have been recorded during the tunneling process. The parameters of shield machine are optimized further through the feedback of line 1 monitoring results, and the existing tunnel deformation is controlled within the permitted value according to the reasonable set of shield parameters. Based on the deformation of built tunnel, it is found that the displacement of existing tunnel is negligible when the cross tunneling is more than 20 meters away. The shield process had a major impact on the left side of the existing tunnel. The results indicate that the displacement process of the interaction of existing tunnel and new tunnel can be divided into five phases.