Following evident settlements with the opening of joints in the rock mass, widespread problems of instability of rock portions as well as a structural insufficiency of the external upright, some extraordinary maintenance interventions of the natural tunnel “Passo Predil” were necessary. The interventions in the project aimed to secure the tunnel, stabilizing the wall rock mass and the wallsabove the entrances. Interventions for the reinforcement/restoration of the support and lining structures inside the tunnel were also implemented. Among the main interventions, it is highlighted:
- Nailing of the section with n. 9 nails (in B450C steel and fiberglass) for the stabilization of the mass at the natural tunnel
- Waterproofing of the external surface of the artificial tunnel, as well as the creation of a curb with a micropile trestle for the stabilization of the section.
- Cleaning and scaling of the walls, with stitching in passive B450C steel bars, doubletwist metal nets, and subhorizontal drainages.
- Sealing of cracks with polyurethane resins or shotcrete
