Contractor Limak has successfully completed the first tunnel to be driven by tunnel boring machine (TBM) in Austria with the breakthrough the 6.7km Moglicë head race tunnel on the Devoll Hydropower Project.
The project is also the first in Europe to use a Robbin’s Crossover TBM and successfully bored the 6.2m diameter tunnel through varied ground conditions including ophiolite, sandstone, breccia and siltstone flysch.
The tunnel is a key part of a new 242MW hydroelectric scheme being developed for Norwegian power producer Statkraft, which will increase Albania’s electricity production by 17%.
“The cutterhead and cutters have achieved outstanding performance,” said Limak TBM manager Engin Gur. “The TBM achieved rates as high as 648m per month in April 2018 and as much as 37.4m in one day.”
Limak reports that the TBM did not encounter high-pressure water, which was expected during the 18 month tunnel drive, and made it possible to work in hard rock double shield mode throughout tunnelling.
Grouting of the unlined tunnel is now underway and it is expected to be operational by late spring next year.