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Tunnel construction in shallow soft rock using the pipe shed support
1Institute of Architecture and Civil Engineering, Yulin University, No. 51 Chongwen Road, Yulin, 719000, Shaanxi, China.
Scientific Reports
|February 9, 2024
Summary
Shallow buried soft rock tunnel excavation impacts highways. New deformation control indices like deformation difference rate help manage rock deformation and prevent surface cracks, ensuring highway safety.
Area of Science:
- Geotechnical Engineering
- Tunnel Engineering
- Highway Engineering
Background:
- Shallow buried tunnels in soft rock pose risks to overlying infrastructure.
- Understanding excavation impacts on existing highways is crucial for safety.
- Pipe shed reinforcement mechanisms require detailed study.
Purpose of the Study:
- To clarify the impact mechanism of shallow buried soft rock tunnel excavation on an upper existing highway.
- To investigate the mechanism of pipe shed reinforcement.
- To establish safety control measures for tunnel construction over highways.
Main Methods:
- Combined theoretical analysis and on-site monitoring.
- Studied the Diantou Tunnel Crossing project on the Dayong Expressway.
- Introduced a new deformation control index: deformation difference rate.
Main Results:
- Lateral rock deformation influence extends up to twice the tunnel diameter.
- Surrounding rock deformation stabilizes approximately twice the tunnel diameter beyond the excavation face.
- Effective rock deformation control relies on cumulative settlement, change rate, and difference rate.
Conclusions:
- For V-class tunnels, cumulative deformation < 50 mm, change rate < 3 mm/day, and difference rate < 5 mm/m prevent surface cracks.
- Proposed surface subsidence control standards for similar shallow buried tunnel projects.
- Deformation difference rate is a key indicator for controlling tunnel-induced ground movement.
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