UNDRAINED CREEP IN A SENSITIVE CLAY

WHEN SUBJECTED TO SUSTAINED LOAD, AN UNDRAINED TRIAXIAL SPECIMEN OF CLAY EXHIBITS A STEADY TIME-DEPENDENT INCREASE IN BOTH PORE PRESSURE AND AXIAL STRAIN, CONTINUING UNDRAINED CREEP MAY OFTEN RESULT IN A COLLAPSE OF THE SAMPLE AFTER LONG PERIODS OF TIME HAVE ELAPSED. THIS PAPER ANALYZES THE OBSERVED BEHAVIOR IN TERMS OF EFFECTIVE STRESS-STRAIN RELATIONSHIPS. TYPICAL UNDRAINED CREEP DATA FROM TESTS ON LEDA CLAY ARE PRESENTED, AND IT IS SHOWN THAT DURING CREEP THE EFFECTIVE STRESS STATE OF THE SAMPLE SHIFTS WITH TIME TOWARDS THE FAILURE ENVELOPE FOR THE CLAY. A SIMPLIFIED THEORETICAL ANALYSIS OF THE PROBLEM ENABLES TWO EQUATIONS TO BE DERIVED WHICH SUGGEST THAT CREEP IN PORE PRESSURE IS PROPORTIONAL TO MEAN EFFECTIVE STRESS, AND THAT CREEP STRAIN AND PORE PRESSURE ARE DIRECTLY RELATED. THE GENERAL FORM OF THESE RELATIONSHIPS IS SUPPORTED BY EXPERIMENTAL DATA, ALTHOUGH FURTHER WORK IS NECESSARY TO EVALUATE PRECISELY THE FUNCTIONAL FORMS INVOLVED. THE PRACTICAL SIGNIFICANCE OF UNDRAINED CREEP IS OUTLINED WITH PARTICULAR REFERENCE TO THE CONSTRUCTION AT NEW LISKEARD OF A HIGHWAY EMBANKMENT ON A THICK DEPOSIT OF SENSITIVE CLAY. PIEZOMETER READINGS INDICATED THAT AFTER THE COMPLETION OF CONSTRUCTION, A SIGNIFICANT BUILD-UP IN PORE WATER PRESSURE OCCURRED, THIS BEING ACCOMPANIED BY INCREASING SETTLEMENTS THROUGHOUT THE CLAY MASS. THESE OBSERVATIONS APPEAR TO BE COMPATIBLE WITH THE PRESENTED CONCEPTS OF UNDRAINED CREEP, AND IT IS EMPHASIZED THAT DESIGN PARAMETERS SUCH AS PORE PRESSURE COEFFICIENTS AND STRESS-STRAIN MODULI SHOULD BE CHOSEN TO INCORPORATE THE EFFECTS OF THE CREEP PROCESS. /A/RRL/

  • Availability:
  • Supplemental Notes:
    • Vol 19, No 4, PP 515-529, 12 FIG, 3 TAB, 31 REF
  • Authors:
    • Walker, L K
  • Publication Date: 1969-12

Media Info

  • Serial:
    • GEOTECHNIQUE
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00234886
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Jun 22 1970 12:00AM