RESEARCH ON CONSTRUCTION TECHNOLOGY OF LARGE-DIAMETER SHIELD TUNNEL IN SHALLOW COVER SECTION OF RED STRATA GEOLOGY

Abstract

This paper is based on the construction of the Haizhuwan Tunnel in Guangzhou, which passes through predominantly mudstone and sandstone red strata geology. Excavation is carried out using a slurry balance shield tunneling machine with both atmospheric pressure and pressurized cutterheads, and real-time excavation parameters recorded by the shield equipment are collected and statistically analyzed. Discovery: In the initial shallow-buried excavation section, the total thrust of the shield machine increased as the tunneling distance increased. By continuously adjusting the excavation parameters during construction, the shield machine gradually tended towards a stable operating state, leading to a gradual reduction in the range of thrust fluctuations. East Line: After excavating the reinforcement area, the increase in cutterhead torque is significant, leading to a more pronounced adaptation process for the shield machine.  The cutterhead torque fluctuates more on rings 20 to 65 on the East Line, showing greater variability.  This situation is related to the wear of the cutterhead and the condition of the shield machine equipment on the East Line. West Line: After excavating the reinforcement area, the cutterhead torque is initially reduced, with a slow and continuous increase in torque from rings 20 to 65, eventually stabilizing at around 12 MN·m. Throughout the excavation process, the shield machine on the East Line maintained a relatively high excavation speed within the reinforced soil at the face, with an average of 7.76 mm/min. As the machine excavated beyond the reinforcement area, the overall excavation speed of the shield machine slowed down. The excavation speed from ring 21 to ring 65 was primarily controlled between 2 to 6 mm/min, with an average of 4.49 mm/min, showing a relatively stable overall change.