THE SIGNIFICANCE OF STRESS IN ROCK MASSES

THE DETERMINATION OF STRESSES IN A POINT IMPLIES THE MEASUREMENT OF SIX STRAIN COMPONENTS. A NEW TRIAXIAL STRAIN CELL, DEVELOPED BY LEEMAN, FACILITATES THAT DETERMINATION BY MEANS OF 3 STRAIN GAUGE ROSETTES GLUED ON THE BOREHOLE WALL (38 MM DIAMETER) AT 90 DEGREES, 180 DEGREES AND 315 DEGREES. IT MUST BE REALIZED THAT THE MEASURED MAGNITUDES ARE RELATIVE, BUT THE "OVERCORING" TECHNIQUE PERMITS THE DETERMINATION OF "ABSOLUTE STRESSES", PROVIDED THE ROCK MASS IS ELASTIC. TWO EXAMPLES OF PRACTICAL USE OF TRIAXIAL STRAIN CELLS ARE GIVEN, NAMELY THE DETERMINATION OF THE VIRGIN STRESSES IN A QUARZITIC ROCK 1770 M DEEP AND IN A DUNITE ROCK MASS INTERSPERSED WITH SERPENTINE LAYERS 350 M DEEP. IN BOTH CASES, THE 3 NORMAL STRESSES WERE THE PRINCIPAL ONES. THE USE OF STRESSES IN ROCK MECHANICS IS DISCUSSED. SUCH A TERM IS CONVENIENT TO SPECIFY A FAILURE CONDITION, TO DESCRIBE THE LOAD-DEFORMATION BEHAVIOR OF ROCK MASSES AND THE LATERAL ROCK PRESSURE DUE TO GEOLOGICAL TECTONIC SOURCES. THE ELASTIC PART OF THE STRAIN MUST BE TAKEN INTO ACCOUNT. A CLEAR DISTINCTION MUST BE MADE BETWEEN THE PLASTIC BEHAVIOR AND PLASTIC DEFORMABILITY. /RRL/

Media Info

  • Features: Figures; References;
  • Pagination: p. 263-71

Subject/Index Terms

Filing Info

  • Accession Number: 00235242
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: TRIS
  • Created Date: Apr 23 1972 12:00AM