Abstract: When an earth pressure balance shield tunneling in a longdistance section with high quartz content, the screw conveyor jammed and hysteretic mucking occurred. Hence, the causes for screw conveyor malfunction are analyzed, countermeasures are proposed for hysteretic mucking, and corresponding repairing methods are determined, resulting in a good effect. Furthermore, according to the hard rock conditions, an optimized scheme for hydraulic system and treatments for screw conveyor jamming are proposed, and the suitable driving technological parameters and rational bentonite ratio are obtained through test. The countermeasures recommended successfully release the screw conveyor and guarantee the highefficient operation of the equipment onsite.

Key words: shield machine, hard rock formations, screw conveyor, hysteretic mucking, longdistance boring