Client
Nant de Drance SA (ALPIQ, SBB and Canton Wallis), Switzerland
General contractor
GMI Groupment Marti Implenia (Marti Tunnelbau AG, Implenia Bau AG), Switzerland
Construction period
April 2010 – December 2015
Construction technology: Tunnels are driving by using drilling and blasting works, by Norwegian Tunneling Method.
Executed works:
- driving of two access tunnels to the caverns and to the main access tunnel in the total length of 3 854, 5 m and driving of two galleries in the total length of 478 m, profile of 46 m2, slope 12 %,
- driving of two pressure water feeders and driving of the tubes for water feeders from 6 turbines in the total length of 2 x 1 508 m and profile of 63 m2,
- driving of the access gallery and connection from the vertical galleries to the pressure water feeders in the total length 289 m, profile of 54 m2 and driving of the tubes for pressure water feeders for 6 turbines, alongs 8 100 m3,
- driving of two caverns for rise-drilling of the vertical shafts in the total length of 58,4 m, width of 12,5 m, height of 18 m, excavation 24 825 m3,
- driving of the cavern for water accumulation in the total length of 50,3 m, width of 16 m, height of 18 m, excavation 13 500 m3,
- driving of the underground powerhouse cavern for six reversible Francis turbines in the calotte and 8 stages in the bench in the total length of 194,25 m, width of 32 m, height of 52 m, excavation 237 000 m3,
- driving of the construction cavern for connection pressure shafts to the pressure feeders and to the single turbines in the total length of 87 m, width of 11,3 m, height of 11,7 m, excavation 10 500 m3,
- driving of the transformer station cavern in the total length of 132,5 m, width of 18,6 m, height of 14,6 m, excavation 32 250 m3,
- driving of the cavern for the underground workshop and service of machinery in the total length of 52,5 m, width of 25,5 m, height of 16 m, excavation 20 850 m3,
- driving of the cavern for rock crusher, excavation 6 500 m3,
- driving of the cavern for underground concrete plant in the total length of 115 m, width of 26 m, height of 16,9 m, excavation 38 250 m3,
- primary lining by shotcrete with steel fibers and rock bolts SWELEX or mortared SN anchors in the length of 4 – 8 m.