Research on key technologies of thick slurry filling chamber method for earth pressure balance shield in karst areas

Due to the presence of numerous karst cavities, fractures, and fissure water, karst strata exhibit significant air leakage during pressurized chamber opening. This leads to a large gas replenishment volume, substantial formation water inflow, and the inability to conduct pressurized chamber opening operations normally. To address this issue, this study focuses on the shield tunneling project in the first standard section and second work area of the Shenzhen Metro Line 16 utility corridor. Based on the engineering characteristics of highly developed karst strata, the technical mechanism of the thick-slurry chamber-filling method for pressurized chamber opening is analyzed. The slurry mix design parameters, filling parameters, grouting parameters, working pressure for pressurized chamber opening, construction technology, and control measures are systematically summarized. Consequently, a chamber-opening technology using the thick-slurry chamber-filling method for Earth Pressure Balance (EPB) shield tunneling in karst formations is proposed. The results indicate that the thick-slurry chamber-filling method is an effective approach for chamber opening in EPB shield tunneling through karst formations. It can successfully mitigate issues related to formation air leakage during chamber opening, thereby ensuring operational safety, enhancing efficiency, and reducing costs.