Tunnel Grjóta, Iceland
Hraunaveita-KAR-25, excavation works on the tunnel Grjóta
The tunnel presents a part of the Kárahnjúkar Hydroelectric Project, specifically Hraunaveita part.
Landsvirkjun /National Power Company/
ÍSTAK hf, Iceland
August 2008 – October 2008
- tunnel Grjóta is an aqueduct of the water tank and dam Grjóta
- tunnel was excavated at the same time from two sides
- tunnel has two portals – P6 and P7
Excavation works were carried out by drilling and blasting works (NMT – Norwegian Tunnelling Method). Drilling works were executed by using of 2-arms drilling jumbo Tamrock Axera Data T08 with power of drill hammers 22kW. Blasting works were executed by using of emulsion explosive – slurry type and Mini-SSE charging device. Loading and mucking was carried out by wheel loader Volvo L180 with side tipping and lorries MB Actros 4131.
- driving of tunnel tube, profile 20 m2, length 301 m
- rock support by sprayed steel fibre reinforced shotcrete and rockbolts