APPLICATION AND CONSIDERATION OF PIPE-ROOF METHOD IN SHALLOW-BURIED MINED-TUNNEL PASSAGES

This paper investigates the application efficiency and key technical points of the pipe-roof method in shallow-buried tunnel-excavation passage projects. Taking the mined-tunnel passage for Exit No. IV of Fenghuang Xincun Station on Guangzhou Metro Line 8 as an engineering case, this study systematically reviews the whole implementation process of the pipe-roof method, covering design, construction and troubleshooting. Combined with literature review and field engineering practice, this paper documents typical construction problems including jacking difficulty, abnormal soil discharge and rock-stratum obstruction, and illustrates the countermeasures adopted, such as replacing large-tonnage jacks, optimizing drill-bit types, adjusting pipe-roof parameters and implementing reinforcement grouting. The results demonstrate that the pipe-roof method can effectively control ground surface settlement and deformation of surrounding structures. All monitoring data remained below warning thresholds, which guaranteed construction safety. It is concluded that the pipe-roof method delivers remarkable supporting performance and environmental-friendly advantages under complex geological conditions. Its successful application, however, relies on refined parameter design, dynamic construction adjustment and rigorous process control. The experience obtained provides important guidance for subsequent similar projects.