地铁隧道下穿河流施工遇富水软弱地层的控制技术

以青岛地铁某隧道下穿河段工程为依托,在对地质条件及工程资料进行深入分析的基础上,提出了包含超前深孔注浆、地面复合锚杆桩及洞内小导管补偿注浆等多种注浆加固措施的联合控制方案。通过数值模拟及现场监测,研究了地铁隧道区间下穿河流施工时所遇富水软弱地层的结构及其地表变形特性。结果表明:注浆施工会导致软弱地层膨胀隆起,诱发左、右隧道区间正上方的地层出现“M”型的正曲率变形,地表变形范围约为隧洞跨度的2倍;注浆压力和注浆量对地表隆起的速率和变形量有一定影响,必须及时结合监测资料动态调整注浆工艺和关键参数。该联合施工控制方案具有良好的加固控制效果,能够改善施工作业面前方的地质特性,可有效控制隧道结构及其上部地层的变形。

Construction Control Technology of Metro Tunnel Crossing under River in Water-rich Weak Stratum

Based on the background of a Qingdao metro tunnel crossing under river, through an in-depth analysis of the geological conditions and engineering data, a joint control scheme of grouting reinforcement and auxiliary construction measures is proposed, including advanced deep hole grouting, ground composite anchor pile and small pipe compensation grouting. Through numerical simulation and field monitoring, the structure and surface deformation characteristics of metro tunnel crossing under river in water-rich soft stratum are studied. The results show that the grouting construction can lead to the swelling and uplift of the soft stratum, inducing an "M" type positive curvature deformation of the stratum directly above the left and the right tunnel sections, and the surface deformation range is about twice the span of the tunnel. Since the grouting pressure and grouting amount have certain influence on the surface uplift rate and deformation value, the grouting process and key parameters must be dynamically adjusted in time according to the monitoring data. Since the combined construction control measures have good reinforcement control effect, the geological characteristics in front of the construction face can be improved, and the deformation of the tunnel structure and the upper strata be effectivel controlled.