THE INFLUENCE OF THE MEMBRANE RESTRAINT ON THE MEASURED STRENGTH OF A SOIL SAMPLE FAILING ALONG A SINGLE SHEAR PHASE IN THE TRIAXIAL TEST

The rubber membrane surrounding a soil sample in the triaxial compression apparatus imposes a restraint on the deformation of the sample and introduces an error in the measured stress. The author discusses corrections that can be introduced to compensate for this error. All these methods of correction are considered to start from the same basic idea: a series of triaxial tests is performed at various cell pressures on a dummy sample in which a slip plane has been formed at an angle of 45-55 degrees and which is surrounded by the rubber membrane or by both the membrane and the filter paper drain. Some means (grease, ball bearings) is provided on the slip plane to eliminate friction. The deviator stress is measured at various displacements and this is subtracted from the uncorrected deviator stress measured in the actual triaxial test on the soil sample, at the corresponding displacement and cell pressure. The normal and shear stresses on the slip plane are then calculated from the corrected deviator stress and the ambient stress which is considered to remain unchanged. This note is intended to show that correcting only the deviator stress for membrane effects is not sufficient, but that a correction should also be applied to the ambient stress in the plane in which relative movement of the two parts of the sample takes place. /TRRL/

Media Info

  • Features: Figures; References;
  • Pagination: p. 226-230
  • Serial:
    • GEOTECHNIQUE
    • Volume: 26
    • Issue Number: 1
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00138969
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Nov 17 1976 12:00AM