Bears can reach speeds of up to 50km/h if necessary. Therefore, the German word “Buddelbär XL” (literally “digging bear”) is a good choice of name for a tunnel boring machine that digs through hard rock at high speed. The machine was named by elementary school pupils, who live in Fusch, a village in Austria where the “Bärenwerk” hydropower plant is being extended. The construction of an underground headrace tunnel is one of the largest modernization measures.
For the construction of the 2.8-km long tunnel, Herrenknecht delivered a Gripper TBM type tunnel boring machine, which is specialized in fast tunneling in hard rock. With an extraordinarily powerful 1,400-kW high-performance drive for a diameter of 3,830 mm and a competent tunneling team the project advanced in the fast lane: Up to 322 m of tunnel per week and 72 m per day have been excavated with a route gradient of 4.8 percent. The “Buddelbär XL” dug persistently through Phylite slate, quartzite, limestone mica slate and green slate with carboniferous banded limestone. Only five and a half months after the start of tunneling at the end of March 2013, the miners of Marti Tunnelbau AG construction company celebrated the successful breakthrough on Sept. 10, 2013.
The modernization of the “Bärenwerk”, which went into operation in 1924 for the first time, will increase the capacity of the hydropower plant by almost a third to 14.96 megawatts. The operator Salzburg AG will then supply around 19,000 households with electricity from environmentally friendly hydropower. In addition, environmental upgrading measures are being carried out. Decommissioning the old pressure pipelines provides local agriculture with new grazing areas.
In hydropower plants, kinetic and height energy is converted into electrical energy, without releasing any emissions. In Austria, the use of hydropower has a long tradition due to the country’s topography and about 55 percent of the electricity needs are generated by hydropower; globally this share is only about 16 percent of total electricity generation.
Construction companies around the world have already excavated more than 75 km, horizontal or inclined tunnels and vertical shafts for hydropower plants using Herrenknecht technology.