Nailing A Landslide (Available only in the Geo/Environmental Special Issue)

Colarusso, Al; ,

Nailing A Landslide (Available only in the Geo/Environmental Special Issue)

by Al Colarusso, (M.ASCE), Transportation Engineer; California Dept. of Transportation, Construction Branch, Novato, CA,

Serial Information: Civil Engineering—ASCE, 1996, Vol. 66, Issue 11, Pg. 13A-15A

Document Type: Feature article

Abstract:

When mud flows in California threatened to stop traffic on a freeway and erode a street from below, Caltrans worked around the clock to stabilize the slope using soil nailing and shotcrete. The heavily trafficked Marin 101, a State route traversing California, Oregon and Washington, was temporarily blocked in two southbound lanes as a result of a mudslide from its side slope. Also, the structural integrity of Tiburon Boulevard, a county street above the slide, was in jeopardy because of eroding slopes. The California Department of Transportation (Caltrans) removed the mud flow immediately before the start of the heavy, morning rush hour traffic toward the Golden Gate Bridge and San Francisco. When Caltrans realized that repairing the steep slope would require more than simple rip rap or shotcrete, the geotechnical and structures departments worked around the clock preparing a general plan for soil nailing and shotcrete. Soil nailing has been used for soil stabilization in California since the late 1980's. Though the technique has come under scrutiny for the labor, equipment and materials cost, officials at Caltrans believed there was no alternative that would offer comparable anchorage for the steep slope. The shotcrete and soil nailing took seven weeks. The contractor worked between 8 and 12 hours a day, 6-7 days a week�approximately 400 hours. The cost of the project is approximately $580,000. As a result of this project, Caltrans will be ready for this type of emergency project again by using soil nailing and shotcrete technology, and subsurface drains.

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