Forepoling is a pre-support technique widely used in tunnelling and underground excavation to stabilise the ground ahead of the tunnel face. The method consists of installing a series of steel pipes, bars or spiles at a shallow angle above the excavation profile, creating a protective canopy that supports the surrounding ground during excavation.
These elements are installed before the advance of the tunnel face and form a structural arch that distributes loads and reduces the risk of ground collapse. The system is particularly effective in weak, fractured or loose ground conditions where conventional excavation support methods may not be sufficient.
Forepoling systems are frequently combined with shotcrete, rock bolts and other reinforcement techniques to create a comprehensive ground support strategy during tunnel construction.
Typical applications include:
- Tunnelling in weak or heterogeneous ground
- Portal stabilisation in tunnel entrances
- Urban tunnelling with limited ground stability
- Sequential excavation method (NATM)
- Underground infrastructure projects
