DISCUSSION OF DRAINED STRENGTH CHARACTERISTICS OF SAND

MAISAL BELIEVES THE SUBJECT PAPER IS A VALUABLE CONTRIBUTION TO THE STUDY OF GRANULAR SOILS. THE DRAINED SHEAR STRENGTH OF SANDS IS ANALYZED IN AN ATTEMPT TO EXPLAIN THE COMPLEX PHENOMENA OF THE STATISTICAL NATURE UNDERLYING THE BEHAVIOR OF COHESIONLESS SOILS. THE PROPOSED WORKING HYPOTHESIS PERMITS THE PRESENTATION OF THE FOLLOWING REMARKS: (1) THE SHEAR STRENGTH OF A GRANULAR MATERIAL IS GIVEN BY THE STRESS CURVE DEFINED BY THREE POINTS IN A PRESENTED FIGURE, AND THE CURVE WILL BE CLOSE TO THE MOHR'S ENVELOPE, (2) THE INTRINSIC SHEAR STRENGTH IS PROVIDED BY SLIDING FRICTION ALONG THE GRAIN PATHS, (3) CONSTANT VOLUME TRIAXIAL TESTS COMPLY WITH MOHR-COULOMB THEORY, ALTHOUGH THE ANGLE OF THE ENVELOPE DOES NOT COINCIDE WITH THE AVERAGE VALUE OF INTERPARTICLE FRICTION, AND (4) TO EXPLAIN THE PEAK AND RESIDUAL STRENGTH THAT OCCUR IN DENSE GRANULAR SOILS TESTED UNDER LOW CONFINING PRESSURES, IT HAS TO BE RECOGNIZED THAT SLIP PLANES DEVELOP AFTER REACHING THE PEAK STRENGTH. A METHOD WILL BE REQUIRED FOR PRACTICAL APPLICATIONS TO DETERMINE THE FLOW PATTERN OF GRAINS IN THE PROTOTYPE AND TO ESTIMATE THE AVERAGE NORMAL STRESSES. MESSRS ROWE AND BARDEN CONGRATULATE THE AUTHORS ON THEIR COMPREHENSIVE STUDY OF SANDS IN THE DRAINED STATE OVER AN EXCEPTIONALLY WIDE RANGE OF PRESSURE. THE DIFFICULTY OF REACHING THE CRITICAL VOID RATIO STATE OF CASAGRANDE IS DISCUSSED. HE LATER INTRODUCED AN ARBITRARY DEFINITION OF THE LOWER CRITICAL VOID RATIO WHICH IS ASSOCIATED WITH ZERO OVER-ALL VOLUME CHANGE AT DEVIATOR STRESS. HE FOUND THAT THIS DECREASES WITH INCREASE IN CONFINING PRESSURE. THIS LOWER RATIO PROVIDED A CONSERVATIVE ESTIMATE OF THE TRUE CRITICAL VOID RATIO IN THE SENSE THAT SANDS COMPACTED TO THE LOWER CRITICAL VOID RATIO WOULD STILL BE SAFE AGAINST LIQUEFACTION. THE DATA INDICATE THAT THE AUTHORS HAVE USED THE LOWER CRITICAL VOID RATIO FOLLOWING TAYLOR. THE SIGNIFICANCE IS DISCUSSED OF THE DIFFERENCE BETWEEN ESSENTIALLY CONSTANT VOLUME AND ACTUAL CONSTANT VOLUME AT THE LOWER AND TRUE CRITICAL VOID RATIO RESPECTIVELY. AN EQUATION IS DERIVED WHICH PRESENTS TAYLOR'S DEFINITIONS OF CRITICAL VOID RATIOS. THE BISHOP AND ROWE EQUATIONS ARE DERIVED AND PRESENTED FOR DILATANCY EFFECTS. REFERENCES: CLASSIFICATION AND IDENTIFICATION OF SHALES, LLOYD B. UNDERWOOD, ASCE, (PROC. PAPER 5560), NOVEMBER 1967.

  • Supplemental Notes:
    • Vol 95, No SM1, PP 349 - 359, 6 FIG, 4 REF, 2 APP
  • Corporate Authors:

    N/A

    ,   United States 
  • Authors:
    • Marsal, R J
    • ROWE, P W
    • Barden, L
  • Publication Date: 0

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00229693
  • Record Type: Publication
  • Report/Paper Numbers: No SM5, Proc Paper 490
  • Files: TRIS
  • Created Date: Aug 15 2004 2:39AM