SOME GEOLOGICAL CRITERIA FOR EVALUATING ENGINEERING PROPERTIES OF ROCK MASSES

THE COMPETENCY OF ROCK MASSES IS DISCUSSED IN TERMS OF THEIR ENGINEERING BEHAVIOR. ATTENTION IS DIRECTED PRIMARILY TO PROPERTIES OF CRYSTALLINE ROCKS IN RELATION TO UNDERGROUND OPENINGS EXCAVATED BY CONVENTIONAL METHODS. ENGINEERING BEHAVIOR OF ROCK IN SUCH OPENINGS IS EXPRESSED MAINLY IN TERMS OF SUPPORT REQUIREMENT AND OVERBREAK. DATA FROM UNDERGROUND OPENINGS SUGGEST THAT THE MOST IMPORTANT GEOLOGICAL PARAMETERS FOR ESTIMATING ROCK BEHAVIOR ARE: 1) THE DEGREE OF ARGILLIC ALTERATION, OR CLAY CONTENT, 2) THE RATIO OF FAULTS TO JOINTS, AND 3) THE ATTITUDE OF THE PLANAR ROCK FABRIC. THE FIRST TWO ARE LARGELY RESPONSIBLE FOR THE SUPPORT REQUIREMENTS, AND THE THIRD EXERTS A SUBSTANTIAL INFLUENCE ON OVERBREAK IN COMPETENT ROCKS. TECHNIQUES FOR EVALUATING THESE PARAMETERS ARE SUGGESTED. SLOPE ANALYSIS MAY SERVE AS A CRITERION FOR ESTIMATING THE COMPETENCY OF LARGE MASSES OF ROCK (DIMENSIONS OF THE ORDER OF A MILE). THE RATIO OF PERCENT OF ROCK EXPOSURE IN AN AREA TO THE TANGENT OF THE AVERAGE SLOPE ANGLE IS TAKEN AS AN INDEX OF AVERAGE COMPETENCY FOR THE ROCK MASS. DATA FOR THE OTHER PARAMETERS MAY BE USED TO SUPPLEMENT AND MODIFY THIS INDEX. /AUTHOR/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 201-12

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Filing Info

  • Accession Number: 00236442
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 3 1973 12:00AM