The full face method, also known as the full-face tunnelling method, is a common and efficient technique for excavating tunnels. This method utilizes a large, specialized machine called a tunnel boring machine (TBM) to excavate the entire cross-section of the tunnel in one pass.
How it Works:
- Excavation: The TBM's rotating cutterhead, equipped with cutting tools, removes rock or soil from the tunnel face. The excavated material is transported away by a conveyor belt system.
- Support: As the TBM advances, a support system is installed behind it to maintain the stability of the tunnel. This support system typically consists of segmental lining, which is prefabricated concrete or steel segments that are assembled into a ring to support the tunnel walls and roof.
- Advancement: The TBM moves forward, repeating the excavation and support process.
Advantages of the Full Face Method:
- High Excavation Rates: The full face method allows for faster excavation compared to other methods.
- Improved Safety: The TBM provides a controlled and enclosed environment for workers, reducing the risk of accidents and hazards.
- Reduced Disturbance: The method minimizes surface disturbance, making it suitable for urban areas or environmentally sensitive regions.
- Improved Accuracy: The TBM's precision allows for accurate tunnel alignment and dimensions.
Applications of the Full Face Method:
The full face method is widely used for various tunnel projects, including:
- Subway Tunnels: Building underground railway systems.
- Highway Tunnels: Connecting roadways through mountains or under rivers.
- Water Tunnels: Transporting water for irrigation or municipal water supply.
- Power Tunnels: Carrying power cables or pipelines.
Examples:
- The Channel Tunnel, connecting England and France, was constructed using the full face method.
- The Seikan Tunnel, the longest undersea tunnel in the world, located in Japan, was built using the full face method.
Conclusion:
The full face method is a highly effective and efficient tunnelling technique that offers numerous advantages. It is widely used in various projects worldwide, making it a crucial tool for modern infrastructure development.
