Clogging Prevention of Slurry–Earth Pressure Balance Dual-Mode Shield in Composed Strata with Medium–Coarse Sand and Argillaceous Siltstone

The slurry–earth pressure balance dual-mode shield has an earth (EPB) and slurry functions. Based on a tunnel project of Guangzhou Metro Line 12 in China, this study investigates the clogging prevention composed stratum with medium–coarse sand argillaceous siltstone. results show that mode was not applicable to excavated soil accumulated easily chamber, causing clogging. total thrust force increased significantly, tunneling speed gradually decreased 0, torque cutterhead slightly after clogged. fluctuation force, torque, also significantly. EPB is recommended for strata dispersible foam agent water needed be used conditioning. injection amount determined according status mud discharged by screw conveyor. Water absorption can characterize capacity particles larger than 0.15 mm. ideal state consistency index smaller mm less 0.5 prevent from particle should removed when calculating index.