Abstract:

The running tunnel from Qiushui Square to West Zhongshan Road on line 1 of Nanchang Metro is the first tunnel crossing Ganjiang river. The launching and arriving of the shield machine are both located in waterrich sandy strata. In the launching of the shield machine, mortar leakage occurs at the shield tail. High quality bentonite slurry is injected into the excavation chamber to seal the tunnel face and cement mortar is injected at the shield tail to seal the ground water system. Proper thrust cylinder stroke is selected on basis of the segment width and the tail seal positions so as to dismantle the segments. The gap between the grouting pipeline and the grease injection pipeline and the tail skin at the three rows of tail seal brushes is sealed by means of plug welding. In this way, the tail seal is repaired and the problem of mortar leakage at the shield tail is solved successfully. The paper can provide reference for other tail seal repairing in the future.

Key words: waterrich sandy strata, shield, tail seal repairing