OSLOFJORD CHALLENGE

This article describes the unexpected ground conditions faced during excavation of the 7.2km long Oslofjord subsea road tunnel in Norway; it includes a route map. The Oslofjord crossing will include 26.5km of new highway and open in Summer 2000. Because of its hilly topography, the road will have seven bridges and six tunnels, several of which are specified mainly for environmental reasons. As part of the site investigation, acoustic measurements and reflective and refractive seismic studies were conducted, mainly in 1979-80 and 1985-86. As a result, the present tunnel alignment was designed, which follows a rock threshold in the fjord for about 2.1km. Due to the sensitive environment along the fjord, the rest of the tunnel crosses to portals well away from the shore areas on both sides. Seismic investigations showed three wide channels in the rock, eroded by glaciation; in each channel, major weaknesses were confirmed. The worst problems occurred in the Hurum weakness zone, which consisted of crushed rock and clay, like that found when excavating many other Norwegian subsea tunnels. A working group, representing the client, the contractor, and specialist external experts, was formed to advise on investigating and treating this zone. It decided to apply a stabilisation method, using a freezing operation.

  • Availability:
  • Corporate Authors:

    Miller Freeman

    Calderwood Street
    London,   United Kingdom  SE18 6QH
  • Authors:
    • BACKER, L BLINDHEIM
  • Publication Date: 1999-12

Language

  • English

Media Info

  • Features: References;
  • Pagination: p. 39-42
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00788441
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Mar 3 2000 12:00AM