A concrete shaft is a vertical or steeply inclined excavation that is reinforced with a concrete lining. In tunnelling, shafts are essential for:
Support: Providing structural support, often serving as a starting or retrieval point for the TBM, and can be used in conjunction with tunnel segments to provide additional strength and durability for the entire infrastructure project.
Access: Providing entry and exit points for workers, materials, and machinery (like the Tunnel Boring Machine, or TBM).
Ventilation: Allowing fresh air into the underground network.
