CONSOLIDATED-UNDRAINED PLANE STRAIN SHEAR TESTS ON BOSTON BLUE CLAY

RESULTS OF CONSOLIDATED-UNDRAINED PLANE STRAIN ACTIVE AND PASSIVE TESTS ARE REPORTED ON K SUB ZERO CONSOLIDATED SAMPLES OF RESEDIMENTED BOSTON BLUE CLAY AT OVERCONSOLIDATION RATIOS (OCR) OF ONE, TWO, AND FOUR. THE PLANE STRAIN EQUIPMENT, DEVELOPED AT M.I.T., USES A SAMPLE WITH DIMENSIONS OF 3.5 X 3.5 X 1.4 INCHES. THE VERTICAL AND HORIZONTAL STRESSES CAN BE VARIED INDEPENDENTLY. THE MAGNITUDE OF THE CELL PRESSURE DURING CONSOLIDATION YIELDS VALUES OF K SUB ZERO, AND PRESSURE TRANSDUCERS IN THE FIXED END PLATENS YIELD VALUES OF K SUB ZERO AND INTERMEDIATE PRINCIPAL STRESS. THE APPARATUS GIVES RELIABLE STRESS--STRAIN DATA FOR ACTIVE TESTS; FOR PASSIVE TESTS THE DATA BECOME UNRELIABLE BEYOND 2--4% AXIAL STRAIN BECAUSE OF NECKING AND VARIOUS SOURCES OF "FRICTION." HOWEVER, A FAILURE CRITERION BASED ON THE MAXIMUM OBLIQUITY OF PRINCIPAL STRESSES GAVE FAIRLY RELIABLE UNDRAINED STRENGTH PARAMETERS FOR PASSIVE CONDITIONS. THE ACTIVE AND PASSIVE TEST DATA SHOW THAT BOSTON BLUE CLAY HAS HIGHLY ANISOTROPIC UNDRAINED STRENGTH PROPERTIES. FOR NORMALLY CONSOLIDATED CLAY, THE RATIO 0.5 (SIGMA 1 - SIGMA 3): SIGMA VC, WHERE SIGMA 1 AND 3 ARE MAJOR AND MINOR PRINCIPAL STRESSES, RESPECTIVELY, AND THEIR DIFFERENCE IS MAXIMUM; AND WHERE SIGMA VC IS VERTICAL CONSOLIDATION STRESS, IS 0.34 FOR THE ACTIVE AND 0.19 FOR THE PASSIVE CONDITION; THE CORRESPONDING RATIOS AT AN OCR OF FOUR ARE 0.95 AND 0.67. THESE STRENGTH RATIOS HAVE BEEN VERIFIED BY UNDRAINED MODEL FOOTING BEARING CAPACITY TESTS. A COMPARISON OF PLANE STRAIN AND TRIAXIAL TEST DATA SHOWS THAT UNDRAINED TRIAXIAL COMPRESSION TESTS AFTER K SUB ZERO CONSOLIDATION YIELD RESULTS VERY SIMILAR TO THOSE OBTAINED BY THE ACTIVE TESTS. HOWEVER, TRIAXIAL EXTENSION TESTS UNDER THE SAME CONDITIONS WILL UNDERESTIMATE THE UNDRAINED PASSIVE STRENGTH. /AUTHOR/

  • Supplemental Notes:
    • Phase Rpt NO 15, SOILS PUB 273, RES REPT R71-13, 243 PP,
  • Corporate Authors:

    Massachusetts Institute of Technology

    Soil Mechanics Division
    Cambridge, MA  USA 
  • Authors:
    • Ladd, C C
    • Bovee, R B
    • Edgers, L
    • Rixner, J J
  • Publication Date: 1971-10

Subject/Index Terms

Filing Info

  • Accession Number: 00235308
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 20 1971 12:00AM