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/

Superior contractor

ÍSTAK hf, Iceland

Construction period

August 2008 – October 2008

Objects description:

  • 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

Construction technology:
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.

Executed works:

  • driving of tunnel tube, profile 20 m2, length 301 m
  • rock support by sprayed steel fibre reinforced shotcrete and rockbolts