冻结法在盾构接收端头土体加固中的应用

摘要

Research purposes: In the process of shield construction of metro, the end area is the place where the shield machine departs and arrives and where the accidents easily happen. The reinforcement of the end area is crucial to the departure and arrival safety of the shield machine . In the loose unstable alluvial layer, the water - containing rock layer with the pore development, the slush layer, the soft mud stone layer, the saturated layer and the layer with high water head, how to well use the freezing method and conducting the reinforcement monitoring are the key elements to guarantee successful construction of shield tunnel.Research conclusions: The difference between reinforcing the soil on the ends with freezing method and reinforcing the ordinary foundation is that the former has the requirement of the freezing temperature. Only when the freezing temperature is guaranteed can the soil strength on the ends be guaranteed and the risks of sand and water bursting be effectively controlled. In order to avoid the appearance of accident, the relative measures should be taken such as using small propulsive force, slow cutting and avoiding the freezing of the cutter head when the shield machine passes through the soil on ends.%地铁盾构法施工过程中,端头区是盾构机始发、到达事故多发地带,其加固关系到盾构的始发与到达的安全问题.针对松散不稳定的冲积层和裂隙发育的含水岩层以及淤泥、松软泥岩以及饱和含水和水头特别高的地层.如何合理运用好冻结法施工方法和必要的加固监测,是保证盾构法隧道顺利施工的重要环节.研究结论:对于含水量大于10％的松散、不稳定地层,均可采用冻结加固；采用冻结法加固,以温度控制强度是施工成败的关键；冻结法端头土体加固与一般地基加固的不同之处是有冻结温度要求,只有保证冻结温度,才能保证端头土体强度,涌沙涌水风险才能得到有效控制；盾构机穿越端头土体时,为避免发生事故,需采取慢速,小推力,慢切削和防刀盘被冻死等措施.