水底大型泥水盾构盾尾密封失效的应对技术

Countermeasures for Failure of Tail Sealing of Large Underwater Slurry Shield

水底大型盾构法隧道常因地层透水性强、水压高而采用泥水平衡盾构机施工,盾尾密封失效事故发生概率较低,但一旦发生其后果较为严重,甚至是灾难性的,风险等级评价为3C,即三级需要决策采取措施的风险。针对杭州市庆春路过江隧道盾构掘进过程中盾尾密封失效导致漏水漏浆的险情,分析了其盾尾密封失效的原因,研究提出了大型泥水盾构盾尾密封失效情况下采用液氮冷冻措施形成盾尾冻土环帷幕止水,在冻土帷幕止水保护下对盾尾管片拆、复拼并检查、更换、增补盾尾刷综合治理技术,经工程实践证明该技术是安全、有效、合理的。

Slurry balance shield machines are often chosen for large underwater shield tunnels in order to counter high permeability and high water pressure.The probability of shield tail sealing failure is comparatively low,but in the event of its consequences it is usually more serious and even catastrophic,so the risk rating is of 3C,namely the third class of risk which requests decision-making and the corresponding measures.Based on the accident of leakage of water and slurry caused by the failure of shield tail sealing in the advancing process of Qingchun-Street Tunnel in Hangzhou,this paper analyzes the reasons for the failure of shield tail sealing and studies the proposed comprehensive management technology under the circumstances of shield tail sealing failure： using frozen liquid nitrogen to freeze the ground and eventually form a frozen ring curtain at the end of the shield,which is taken as water sealing measure,then replacing and re-assembling the segments at the end of the shield,and then inspecting,replacing,and adding the brush at the end of the shield,the whole remedial process is taken under the protection of the frozen curtain.The engineering practice has proved that the proposed comprehensive remedial technology is safe,effective and reasonable.