SOURCES OF ERROR IN JOINT SURVEYS

BECAUSE OF THE SIGNIFICANT INFLUENCE OF JOINTS ON IMPORTANT ENGINEERING PROPERTIES OF HARD UNWEATHERED ROCK, A DESCRIPTION OF SUCH ROCK IS INADEQUATE FOR ENGINEERING PURPOSES UNLESS IT INCLUDES REASONABLY COMPLETE AND ACCURATE INFORMATION CONCERNING THE SPACING AND ORIENTATION OF THE JOINTS. SUCH INFORMATION CAN BE OBTAINED BY MEANS OF A JOINT SURVEY BASED ON THE EXAMINATION OF OUTCROPS, OF TUNNEL WALLS , AND OF BOREHOLE PHOTOGRAPHS, PROVIDED THAT ADEQUATE PRECAUTIONS ARE TAKEN TO ELIMINATE THE SERIOUS ERRORS LIKELY TO OCCUR IN THE INTERPRETATION OF THE RESULTS OF SUCH A JOINT SURVEY. THESE ERRORS ARISE FROM FAILURE TO TAKE ACCOUNT OF THE FACT THAT THE ORIENTATION OF DRILL HOLES AND OF TUNNELS, AS WELL AS THAT OF EXPOSED ROCK SURFACES WITHIN A SMALL AREA, COMMONLY LACK SUFFICIENT VARIETY TO ENSURE A RELIABLE ESTIMATE OF THE RELATIVE ABUNDANCE OF JOINTS OF THE SEVERAL SETS PRESENT IN THE AREA. THE ERRORS CAN GENERALLY BE REDUCED TO A TOLERABLE LEVEL BY CORRECTING FOR THE EFFECTS OF NON-RANDOM ORIENTATION OF EXPOSED ROCK SURFACES, BY MAKING OBSERVATIONS IN AN ADEQUATE NUMBER OF APPROPRIATELY ORIENTATED BOREHOLES, AND BY PLOTTING THE RESULTS OF THE SURVEY IN POLAR DIAGRAMS WHICH ARE CORRECTED FOR THE EFFECT OF THE ANGLE OF INTERSECTION BETWEEN THE JOINTS AND THE DRILL HOLES OR EXPOSED ROCK FACES. /RRL/A/

  • Availability:
  • Supplemental Notes:
    • Vol15, No3, PP287-304, 12FIG, 15REF
  • Corporate Authors:

    Road Research Laboratory /UK

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  • Authors:
    • Terzaghi, R D
  • Publication Date: 0

Media Info

  • Serial:
    • GEOTECHNIQUE
    • Volume: 4
    • Issue Number: 3
    • Publisher: Thomas Telford Limited
    • ISSN: 0016-8505

Subject/Index Terms

Filing Info

  • Accession Number: 00228759
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Aug 15 2004 2:37AM