Tying Back a Landslide

by Stephen J. Klein, (M.ASCE), Assoc.; Woodward-Clyde Consultants, Oakland, CA,

Serial Information: Civil Engineering—ASCE, 1992, Vol. 62, Issue 12, Pg. 40-43

Document Type: Feature article


A slope covered with landslide debris is never the most desirable site on which to build, but sometimes it is the only one available. For the Forks of Butte hydroelectric power project, this meant stabilizing a slope that showed threatening signs of movement during construction of a water tunnel into the hillside. The solution, presented by Woodward-Clyde Consultants, Oakland, Calif., was to tie the landslide debris back with steel cables anchored into the bedrock beneath the slope and reinforced concrete bearing pads on the surface. The design had to take into account the tenuous stability of a nearby earthquake measuring up to 6.0 on the Richter scale. The $2 million project permanently increased the landslide's factor of safety from about 1.0 to 1.5, allowing work to resume after three months of expensive delays.

Subject Headings: Cables | Hydro power | Landslides | Debris | Slope stability | Reinforced concrete | Water tunnels | Tunnels

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