GEOLOGICAL INFLUENCES ON THE STABILITY OF CLAY SHALE SLOPES

THE SUSCEPTIBILITY OF CLAY SHALE SLOPES TO FAILURE IS DEPENDENT ON THE FOLLOWING NATURAL FACTORS: (1) LIGHOLOGY, (2) EROSION, (3) STRUCTURAL RELAXATION, (4) WEATHERING, (5) LOCAL TOPOGRAPHY, (6) PRECIPITATION AND GROUNDWATER, (7) ROCK STRUCTURE, AND (8) ROCK FABRIC. THESE INFLUENCES ARE ANALYZED WHICH MATERIALLY AFFECT THE HEIGHTS AND THE ANGLES AT WHICH SLOPES ARE STABLE, THE TIME PERIODS FOR WHICH THEY ARE STABLE, AND THE LOADS THAT SUCH SLOPES ARE ABLE TO MAINTAIN. THE MAJOR FACTORS ARE CONSIDERED TO BE THE VARIOUS ASPECTS OF LITHOLOGY, STRUCTURE, AND GROUNDWATER. THE IMPORTANCE OF INDIVIDUAL FACTORS VARIES FROM PLACE TO PLACE, SOMETIMES OVER SHORT DISTANCES. LANDSLIDES AT THE PACIFIC PALISADES, LOS ANGELES, CALIFORNIA ARE CONTROLLED LARGELY BY THE DIRECTION IN WHICH THE DIP OF BEDDING IS EXPOSED IN SLOPES AND BY THE PENETRATION OF GROUNDWATER. ANDERSON LAKE IN CALIFORNIA CONFIRMS THE CONTROL THAT INTERNAL STRUCTURE HAS ON SLOPE STABILITY. ALONG FORT RANDALL RESERVOIR IN SOUTH DAKOTA, THE PERCENTAGE OF SODIUM- MONTMORILLONITE IN MEMBERS OF THE PIERRE SHALE SEEMS TO AFFECT THE SLOPE ANGLES THAT DEVELOP. HIGH SODIUM- MONTMORILLONITE CONTENT IS EQUATED WITH LOWERING OF THE POTENTIAL SLOPE ANGLES. SANDSTONE BEDS WITHING A CLAY SHALE IN WYOMING WERE USED TO DEVELOP A STEEP SLOPE EVEN UNDER UNFAVORABLE CONDITIONS OF DIP. UNDER EXTREME CONDITIONS OF EROSION IN THE PERIVIAN ANDES, SLOPE ANGLES AND CLAY SHALES ARE 20 TO 55 DEGREES AND HEIGHTS ARE AS GREAT AS 300 FEET. FAILURES ARE MOSTLY CONTROLLED BY STRUCTURE.

Media Info

  • Serial:
    • Issue Number: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00229739
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 9 1970 12:00AM