泥水盾构掘进砂卵石夹黏土地层泥饼处置技术研究

Mud Cake Disposal Technology for Slurry Shield Tunneling in Sandy-Pebble and Clay Mixed Strata

为解决泥水盾构在含黏性土的地层中掘进时,因刀盘易结泥饼而引发的刀具切削能力下降、渣土滞排等降低盾构掘进效率的问题,依托北京南水北调配套工程泥水盾构施工实例,结合富水砂卵石夹黏土地层中的盾构掘进参数和地层岩性变化趋势,分析刀盘出现结泥饼的具体表现,提出将刀盘转矩与贯入度、推力与贯入度的比值作为判别刀盘是否结泥饼的指标;开展双氧水、Ⅰ型和Ⅱ型分散剂泥饼浸泡试验,最终比选出效果较好的Ⅱ型分散剂进行刀盘泡舱处理,有效地软化了泥饼,使得盾构得以顺利掘进。

When slurry shield tunneling in the cohesive soil layer,muck cake on cutterhead would cause the decrease of tool cutting ability,and the muck stagnation would lower shield tunneling efficiency.Accordingly,a case study is conducted on the slurry shield tunneling of the supporting project of Beijing South-to-North water diversion project.Based on the shield tunneling parameters in the water-rich sandy-pebble and clay mixing strata and the formation lithology variation trend,the specific performance of the cutterhead mud cake is analyzed,and the ratio of cutterhead torque to penetration degree and that of thrust to penetration degree are taken as the indexes to judge mud cake formation.Finally,the mud cake soaking tests in hydrogen peroxide,typesⅠandⅡdispersants are employed.The results show that the typeⅡdispersant has a better effect and is selected for the cutterhead treatment,which can effectively soften the mud cake and guarantee the smooth shield tunneling.