LANDSLIDE AND ROCKFALL HAZARD MITIGATION IN A MULTIPLE INTRUSIVE PRECAMBRIAN DIABASE SERIES ON US 60 IN SALT RIVER CANYON, ARIZONA

US 60 was constructed in the 1930s through a series of diabase dikes and sills that outcrop in the Salt River Canyon, in Central Arizona. Spheroidal weathering in the diabase has reduced much of the rock mass in the road cuts to core block boulders in a weakly cemented, sandy matrix. In time periods ranging from 3 to 10 years, the matrix ravels from the cut faces due to wetting and drying, freeze/thaw and weathering, which de-couples large blocks, producing rockfall and landslide hazards that require on-going maintenance. Cut slopes for the highway range in height up to 200 ft. At one location on the east side of the Canyon, there have been a series of rockfalls that have blocked the highway. Attempts have been made in the past to mitigate the problem by scaling the slope and, later, by covering the slope with mesh. These efforts temporarily controlled hazardous rockfall from this slope. However, during the winter of 2000, a landslide destroyed the slope mesh and exposed a larger decomposed diabase slope. After renewed rockfalls in early 2001, the Arizona Department of Transportation decided to implement more substantial measures to mitigate the problem. Preliminary designs were prepared for several options, each of which was evaluated on the basis of cost, construction safety, impact on traffic, reduction of risk of future rockfalls, and environmental impacts. The selected design involves realignment of a portion of the highway, using conventional, cantilever retaining walls, creation of an elevated rockfall catchment area with an MSE retaining wall, and erection of a GeoBrugg rockfall containment fence at the top of the retaining wall.

• Supplemental Notes:
  • Unlike most groups and organizations that meet on a regular basis, the Highway Geology Symposium has no central headquarters, no annual fees, and no formal membership requirements. The governing body of the Symposium is a Steering Committee. Recent proceedings may be obtained from the Treasurer of the Symposium, Mr. Russell Glass.
• Corporate Authors:

  Mr. Russell Glass

  100 Wolf Cove Road
  Asheville, NC  United States  28804
• Authors:
  • Priznar, N M
  • Humphries, R
  • Rice, A H
• Conference:
  • Better Highways Through Applied Geology. 53rd Annual Highway Geology Symposium
  • Location: San Luis Obispo, California
  • Date: 2002-8-13 to 2002-8-16
• Publication Date: 2002

Language

• English

Media Info

• Features: Figures; Photos; References;
• Pagination: p. 74-85

Subject/Index Terms

• TRT Terms: Alignment; Embankments; Fences; Landslides; Mechanically stabilized earth; Retaining walls; Rockfalls; Weathered rock
• Uncontrolled Terms: Mitigation measures (Rockfalls); Rockfall catchment areas
• Geographic Terms: Salt River Canyon (Arizona)
• Subject Areas: Design; Geotechnology; Highways; I20: Design and Planning of Transport Infrastructure; I43: Rock Mechanics;

Filing Info

• Accession Number: 00962014
• Record Type: Publication
• Report/Paper Numbers: CD-ROM
• Files: TRIS
• Created Date: Aug 8 2003 12:00AM