CHANGES AND STRUCTURAL DEFECTS DEVELOPED IN SOME SOUTH AUSTRALIAN CLAYS, AND THEIR ENGINEERING CONSEQUENCES

HIGHLY PLASTIC CLAYS OF FLUVIO-LACUSTRINE (STREAM AND LAKE) ORIGIN OCCUR BENEATH ADELAIDE AND TILMY FLAT, NEAR RENMARK, SOUTH AUSTRALIA. BOTH CLAYS ARE UNDERLAIN BY FREE-DRAINING BEDS WHICH CONTAIN THE MAIN WATER-TABLE. THEY ARE GENERALLY STIFF TO VERY STIFF, CLOSE TO THEIR PLASTIC LIMITS, OVERCONSOLIDATED DUE TO DESICCATION AND UNSATURATED. THE CLAYS WERE DEPOSITED DURING LOWER PLEISTOCENE TIME WHEN THE CLIMATE WAS PLUVIAL, BUT SINCE DEPOSITION HAVE BEEN SUBJECTED TO BOTH ARID AND HUMID CONDITIONS, AS A RESULT OF THEIR HISTORY DURING AND SINCE DEPOSITION, THE CLAYS HAVE DEVELOPED FERRUGINOUS MOTTLED ZONES, CHANGES IN PARTICLE SIZE DISTRIBUTION AND PLASTICITY, AND STRUCTURAL DEFECTS INCLUDING JOINTS, DIKES, TUBES, AND TUBE-CASTS. IN ADDITION, GILGAI ARE DEVELOPED ON THE CLAY SURFACE IN ADELAIDE, AND SINKHOLES ARE DEVELOPED THROUGH THE CLAY AT TILMY FLAT. THE MOST IMPORTANT ENGINEERING CONSEQUENCES ARE REDUCED STRENGTH AND INCREASED PERMEABILITY OF THE CLAYS DUE TO STRUCTURAL DEFECTS, AND SOMEWHAT ERRATIC OCCURENCE OF GROUNDWATER ON AND WITHIN THE CLAY MASS. SOME OBSERVED AND PREDICTED EFFECTS OF THE ABOVE, ON BUILDINGS AND WATER RETAINING STRUCTURES, ARE DESCRIBED, AND REVISIONS TO SOME CURRENT INVESTIGATION, DESIGN, AND CONSTRUCTION PRACTICES, ARE SUGGESTED. /AUTHOR/

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 62-71

Subject/Index Terms

Filing Info

  • Accession Number: 00238249
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Conf Paper
  • Files: TRIS
  • Created Date: Nov 14 1973 12:00AM