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Tittel:Possibility for using drainage as mitigation to increase the stability of the Åknes rock-slope instability, Stranda in western Norway
Ansvar:editor: Gustav Pless ; authors: Gustav Pless, Lars Harald Blikra and Lene Kristensen
Forfatter:Pless, Gustav / Blikra, Lars Harald / Kristensen, Lene
Materialtype:NVEs utgivelser
Utgitt:Oslo : NVE, 2021
Omfang:74 s. - ill. (noen kol.)
ISBN/ISSN:978-82-410-2147-3 / 1501-2832
Serie:NVE Rapport ; 2021:22
Emneord:Drenering / Skred
Geografiske emneord:Stranda / Åknes
Note:Dokumentet foreligger kun elektronisk
Har bibliografi
Innhold:Sammendrag: The Åknes unstable rock slope in Stranda municipality, western Norway, is identified as a high-risk object. The objective of the Åknes Drainage Project was to obtain sufficient knowledge about the geological and hydrogeological conditions at the Åknes rockslide, and to assess the feasibility and impacts of drainage as a mitigative measure.
Extensive data were collected and analysed. Modelling clearly indicates that if
groundwater levels are lowered, either by redirecting surface runoff above the
backscarp or draining the slope through drainholes from the surface or by tunnels,
this is likely to have significant positive effect on the velocity of the slope. The Åknes Drainage Project has demonstrated that although there are uncertainties associated with an attempt, drainage is a feasible method of further stabilizing Åknes. Sufficient knowledge about geological and hydrological conditions at the Åknes rockslide has been obtained to support the initiation drainage trials, combined with careful monitoring and further modelling and investigations.
The total initial investment cost for drainage of Åknes is, in early estimates, in the
order of 300-350 million NOK, depending on the chosen solution. NVE is suggesting
a phased approach that is tied to observed effects to better control costs. The benefit to cost ratio for such a project will be remarkably high.