Underground hydroelectric power Kárahjúkar I., Iceland


Landsvirkjun (National Power Company), Iceland

Superior Contractor

FOSSKRAFT J.V., Reykjavík, Iceland

Construction period

November 2003 – December 2004

Objects description:

  • Kárahjúkar Powerstation KAR 15 with service capacity 690 MW
  • company realized excavation works at construction of underground objects of the underground powerhouse and associated galleries

Construction technology:
Excavation works were realized by drilling and blasting. Drilling was carried out by drilling set Tamrock Axera T 11, T 08 with extended feed that allowed to drill up to advance lenght 5 m. Putzmeister WKM 133 was used for stabilizing by shotcrete. Mucking was realized by wheel loader Volvo L 180 E with side tipping. Mucking from tunnel was carried out by lorries 6×4 Mercedes DB 3331.

Executed works:

  • cable tunnel for conduction of electric power from underground transformer station, length 960 m, profile 68,8 m2
  • tailrace tunnel for tail water from turbines, length 1 400 m, profile 68,8 m2
  • air tunnel for aeration of underground engine room, length 92 m, profile 5,5 m2
  • underground powerhouse with dimensions: length 119 m, width 14 m, height 35 m
  • underground transformer hall with dimensions: length 103 m, width 13,5 m, height 16 m
  • penstock tubes to turbines with cross-section from 16 m2 to 5 m2 with total length 225 m
  • draft tubes from turbines to tailrace tunnel with section 14,3 m2 with length 310 m
  • primary support was realized by shotcrete reinforced with steel fibers and SN anchors