Abstract: 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, types Ⅰ and Ⅱ dispersants are employed. The results show that the type Ⅱ dispersant has a better effect and is selected for the cutterhead treatment, which can effectively soften the mud cake and guarantee the smooth shield tunneling.

Key words: slurry shield, cutterhead mud cake, tunneling parameters, dispersant