SLOPE FAILURES IN FOLIATED ROCKS, BUTTE COUNTY, CALIFORNIA

THE SLOPE FAILURES DISCUSSED OCCURRED DURING RELOCATION OF HIGHWAY 40A AND THE WESTERN PACIFIC RAILROAD AROUND THE PROPOSED OROVILLE DAM AND RESERVOIR NEAR OROVILLE, BUTTE COUNTY, CALIF. THE RELOCATIONS ARE ROUTED ALONG THE EDGE OF THE SACRAMENTO VALLEY AND THROUGH THE RUGGED FOOTHILLS OF THE SIERRA NEVADA, WHERE 8 1/2 MILES OF THE RELOCATIONS PASS THROUGH METAMORPHIC ROCK OF THE CALAVERAS GROUP. MOST SLOPE FAILURES OCCURRED IN A ROCK TYPE CALLED PHYLLITE, WHICH HAS BEEN TIGHTLY COMPRESSED AND INTENSELY FOLDED DURING METAMORPHISM. DESIGN CRITERIA CALLED FOR NUMEROUS 3/4'1 CUT SLOPES, SOME IN EXCESS OF 100 FT IN HEIGHT. BENCHES WERE USED IN MANY OF THE DEEPER CUTS, HOWEVER, SOME LARGE CUTS WERE CONSTRUCTED WITHOUT BENCHES. SLOPE STABILITY PROBLEMS WERE MOST SERIOUS WHEN CUTS WERE MADE IN DIRECTIONS PARALLEL OR NEAR PARALLEL TO THE DIRECTION OF FOLIATION OF THE ROCK. VERY LITTLE WAS ENCOUNTERED WHEN CUTS WERE MADE AT RIGHT ANGLES TO THE FOLIATION. THE NATURE OF THE FAILURES WITH RESPECT TO GEOLOGIC STRUCTURE, THE TYPE AND CONSISTENCY OF CRACKING ON FOLIATION, AND THE DIRECTION OF THE DISPLACEMENT ALONG THE PLANES OF FOLIATION SUGGEST THAT STRESS RELIEF WAS PART OF THE MECHANISM CONTRIBUTING TO ULTIMATE FAILURE OF THE SLOPES. /AUTHOR/

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  • Supplemental Notes:
    • No 17, pp 40-42 Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
  • Authors:
    • Oneill, A L
  • Publication Date: 1963

Media Info

  • Monograph Title: Stability of rock slopes - 5 reports
  • Serial:

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Filing Info

  • Accession Number: 00233640
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Dec 12 1994 12:00AM