Forepoling ("Umbrella Drilling")
Today’s demand to improve infrastructures requires increasing number of new tunnels to be constructed also in ground conditions , which are not perfectly suitable to such purpose. The excavation of tunnels in loose soils, through fault zones, and in unstable formations require preventive actions in ground consolidation - especially for the arch but sometimes also the excavation to face of the tunnel.
Injection casings are drilled to the crown (arch) of the tunnel in order to enable safe tunnel excavation underneath the protective roof. Overlapping casings make it possible to advance drilling even in long tunnels. Tunnel portals can also use heavy load carrying pipe roofs where casings are drilled into solid rock through the loose overburden or landslide material.
PPV Finland provides a solution for all major forepoling applications. We can offer ring bit systems delivered with or without the casings. Please contact us for further information.