About the author:

1. Guangzhou Metro Design & Research Institute Co., Ltd., Guangzhou, Guangdong 510000, China;2. College of Civil Engineering, Tongji University, Shanghai 200092, China

Abstract:

To mitigate safety risks during long⁃distance shield tunnelling of urban utility tunnels under⁃crossing bridge pile groups, this study investigates a complex tunnel section of the Guangzhou centralutility tunnel project. Considering the constraints of high⁃density built environment, complex geo⁃hydrological conditions, and specific construction requirements, 3D numerical simulations and theoreticalanalysis are used to characterize mechanical behavior and risk evolution during the tunnel under⁃crossingprocess. An innovative framework integrating 3D numerical simulation, theoretical analysis, and dynamiccontrol is established, supporting a comprehensive risk⁃control system comprising ground reinforcementgrouting, optimized temporary support, and simultaneous AB slurry grouting technology. Simulation andanalysis accuracy is validated against field monitoring data,yielding a reliable risk⁃control frameworksuitable for complex geological and spatially constrained engineering conditions. The results demonstratethat, the difference ratio between monitored and simulated vertical settlements of bridge piles is less than8%, and the maximum settlement of the directly under⁃crossed pile .􀁋􀁘 is only 2. 57mm, evidencing thereliability of the proposed framework and effectiveness of grouting and support measures. The AB slurrygrouting technology has reduced the initial setting time to 14 minutes and decreased the ground loss rateby 42%, thereby significantly inhibiting surface and pile settlements, decreasing the need for secondarygrouting, and improving tunnelling efficiency.