- Client / design: statens vegvesen Region vest, Askedalen 4, 6863 leikanger ID 971 032 081, Norway
- Contractor: Joint venture Metrostav – Bertelsen&Garpestad AS.
- Contrctual time period: 09/2015 – 07/2017
- Contrctual price: 352 422 365 NOK excluding VAT 35 million EUR (Approx.)
Project description
Prevention of road Rv.13 from avalanches and stone falls included excavation of a 2035 m long tunnel and 800 m of roads on the surface. The first 100 m from the eastern portal was dug using the NATM method with the implementation of its key principles: face sequencing; face stabilisation with bolts and sprayed concrete; primary lining of lattice girders, wire mesh, and sprayed concrete; pipe-roof umbrellas; geotechnical monitoring of tunnel, surface, and portal wall. The NATM excavation was done in glacial moraine with isolated inflows of water with a phyllite rock base. The rest of the tunnel, 1935 m, mostly comprised of gneiss and phyllite, was gouged using the Drill & Blast method. Water and frost insulation was made of a 45 mm PE-foam and an 80 mm shotcrete layer with PP microfibers. In the NATM section, reinforced concrete secondary lining and the intermediate membrane were constructed.
Project data
| Tunnel length: | 2.035 m |
| Tunnel profile: | T9,5 (70,4 m2) |
| Emergency bay profile: | T12,5 (94,0 m2) |
| Excavated volume: | 170.800 m3 |
| Pipe-roofing: | 2500 m |
| Sprayed concrete: | 9.160 m3 |
| Insulation: | 29.500 m2 |
| Portals: | 2 pcs(5m+40 m) |
| Blasting on surface: | 12.000 m3 |
| Earth moving: | 140.000 m3 |
| Backfills: | 155.000 m3 |
Extraordinary of the project
- The project was specific mainly by the implementation of the NATM method as it was the very first planned use of that method in Norway.