What is Tunnel support? Tunnel support, often encountered in the field of civil engineering and construction, refers to a range of techniques and systems designed to stabilize tunnels during their excavation and throughout their operational life. This support system is crucial for maintaining the structural integrity of tunnels, ensuring safety for workers and users, and preventing collapses.
Types of Tunnel Support
1. Temporary Support
- Shields: These are used primarily during tunnel boring operations. They provide a safe working environment by shielding the tunneling crew from potential cave-ins.
- Ground Anchors: These anchors help secure loose or unstable ground around the tunnel perimeter.
2. Permanent Support
- Concrete Linings: After the initial tunnel excavation, concrete is poured into place to form a permanent lining that reinforces the tunnel structure.
- Segmental Lining: Prefabricated segments are assembled inside the tunnel to create a strong, continuous lining.
- Sprayed Concrete (Shotcrete): Often used as part of the New Austrian Tunnelling Method (NATM), shotcrete provides quick application and can be applied directly onto the excavated rock surface.
3. Mechanical Supports
- Steel Girders and Props: Used especially in softer ground conditions where immediate reinforcement is required.
- Bolts: Rock bolts and resin bolts are inserted into drilled holes within the rock walls to reinforce the tunnel's natural stability.
Structural Support:
- Reinforced concrete linings: These are used to strengthen the walls and roof of the tunnel, preventing collapse.
- Steel supports: Such as arches or frames that provide additional strength.
- Rock bolts and anchors: These are inserted into the surrounding rock to hold it in place and prevent movement.
Importance of Tunnel Support
- Safety: Ensures the safety of workers during construction and users post-construction.
- Stability: Prevents collapse and maintains the structural integrity of the tunnel.
- Longevity: Extends the lifespan of the tunnel, reducing maintenance needs over time.
- Cost-Efficiency: Proper support systems minimize long-term costs associated with repairs and potential accidents.
Tunnel support plays a pivotal role in both the construction phase and the operational phase of tunnels, serving as a critical component in ensuring the longevity and safety of these structures.Effective tunnel support design requires a thorough understanding of geotechnical engineering principles and advanced planning to ensure that all safety and functional requirements are met.