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兰州轨道交通下穿黄河段地层以富水卵石层为主,施工中采用泥水平衡盾构法施工,为国内盾构隧道首次下穿黄河,盾构下穿黄河阶段所面临可能出现隧洞涌水、涌砂、掌子面坍塌、河底击穿、隧道管片上浮事故,高承压水、砂卵石地层、盾构穿越黄河过程中可能出现孤石或漂石等重大风险,这些潜在风险可能会在盾构施工中造成高承压下盾尾密封失效、高水压下主轴承密封失效、管片上浮或下沉、管片错台、管片破损、止水条挤压变形破损、漏水、刀盘与刀具的磨损、更换刀具、掌子面压力不稳定造成河底击穿、盾构机不能保压等后果,严重影响盾构正常安全施工。结合兰州轨道交通建设中的实际问题,对盾构下穿黄河过程中如何实现对这些风险的有效管控进行探讨,并提炼出盾构下穿大江大河时可借鉴与实施的风险控制方案,供轨道交通工程建设作为参考。
The strata beneath Lanzhou Railway under the Yellow River section are mainly water-rich gravel layers. The project uses a slurry-balanced shield construction method to construct a shield tunnel for the first time across the Yellow River. The tunnel may face water inflow under the Yellow River during the shield tunnel. Collapse of sand, face collapse, river bottom breakdown, tunnel segment floating accident, high pressure water, sand and gravel stratum, the shield may cross the Yellow River during the process may be a rock or boulder and other serious risks, these potential risks may be in Shield shield construction caused by the shield under the high pressure failure, the main bearing seal failure under high water pressure, the tube up or sinking, the tube is wrong Taiwan, the tube is damaged, the water seal squeeze deformation damage, leakage, knife Disc and tool wear and tear, replace the tool, the pressure on the palm face instability caused by the breakdown of the river bottom shield machine can not hold pressure and other consequences seriously affect the normal safety shield construction. Based on the practical problems in the construction of rail transit in Lanzhou, this paper discusses how to effectively control these risks in the process of the Yellow River shield crossing the Yellow River, and draws out the risk control scheme Traffic engineering as a reference.