FAILURE OF AN EMBANKMENT FOUNDED ON VARVED CLAY

During the construction of a 19 ft. high roadway embankment at New Liskear, Northern Ontario, on varved clay, a failure involving half the width of the embankment occurred, extending for a length of 350 ft. A comprehensive investigation was carried out, including continuous sampling and in situ vane tests at 2 ft. intervals to locate the failure zone. Stability analyses were carried out both for the failed and the stable side of the embankment, assuming different values of fill strength and depth of tension cracks. Prior to construction, 30 piezometers and 14 settlement gauges were installed at a section close to the failure region. Extrapolation of the pore-pressures measured at this location to the failure section enabled the stability study to be performed in terms of effective stresses. Analyses were also carried out for the instrumented section both in terms of total and effective stresses. The results of this study show that: (a) The discrepancy between in situ vane and laboratory tests carried out in the varved clay stratum is of the same order of magnitude as those experienced in homogeneous deposits. (b) The phi = 0 analysis gives approximately correct factors of safety in all the cases analysed when both fill strength and effect of tension cracks are taken into account. (c) The factors of safety given by effective stress analysis appear to be too high. The remedial measures subsequently carried out for the failure region are described. /Author/

  • Corporate Authors:

    National Research Council of Canada

    1200 Montreal Road
    Ottawa, Ontario  Canada  K1A 0R6
  • Authors:
    • Lo, K Y
    • Stermac, A G
  • Publication Date: 1965-8

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 234-260
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00264401
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 29 1975 12:00AM