CONSIDERATION OF SLIP SURFACE GEOMETRY OF LANDSLIDES IN DESIGNING STABILIZATION MEASURES

IRREGULAR, BASAL SLIP SURFACES ARE COMMON IN LANDSLIDES IN MASSIVE CLAYEY ROCKS AND MAY BE SIGNIFICANT ENOUGH IN LARGER LANDSLIDES TO WARRANT SPECIAL SUBSURFACE EXPLORATION AND DESIGN STUDIES. SPECIAL EXPLORATION USUALLY REQUIRES MORE BUCKET AUGER BORINGS THAN ARE NORMALLY MADE SO THAT DETAILED IN SITU GEOLOGICAL INSPECTION OF THE SIP SURFACE CONFIGURATION CAN BE MADE. THE MOST COMMON IRREGULARITIES IN SLIP SURFACE GEOMETRY ARE TANDEM ARCS AS SEEN IN CENTER OF MASS SECTIONS, AND GROOVES ALIGNED PARALLEL OR SUB-PARALLEL TO THE PRINCIPAL DIRECTION OF MOVEMENT. SLOPES ON THE ACTUAL SLIP SURFACE MAY DEVIATE AS MUCH AS 27 DEGREES FROM SLIP SURFACE CURVES PROJECTED FROM SCARP TO TOE FOR STABILITY ANALYSES. GROOVES WITH A RELIEF OF 15 FEET HAVE BEEN MEASURED. THESE IRREGULARITIES HAVE PROBABLY BEEN CAUSED, AT LEAST IN PART, BY CONDITIONS OF EXTREME SATURATION, 14,000 - 18,000 YEARS AGO. THE COMMONLY EMPLOYED CONCEPTS OF REMOVAL OF MATERIAL FROM THE HEAD OF THE LANDSLIDE AND/OR PLACEMENT OF FILL AT THE TOE SHOULD BE MODIFIED TO INCLUDE STRATEGIC PLACEMENT OF STABILIZATION TRENCHES OR SHEAR KEYS WITHIN THE LANDSLIDE MASS, OR GRADING DESIGNED TO ELIMINATE AREAS WHERE SLIP SURFACE SLOPES ARE STEEPEST, IN PLACE OF COMPACTED FILL BUTTRESSES AT OR NEAR THE TOE, OVERALL GRADING COSTS FOR ANCIENT LANDSLIDE STABILIZATION MAY BE LOWERED BY AS MUCH AS ONE-THIRD. /AUTHOR/

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Filing Info

  • Accession Number: 00235819
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 26 1971 12:00AM