INACCURATE CONTOUR-BORING RESULT IN EXCESSIVE ROCK VOLUMES /IN NORWEGIAN/

THE NECESSITY OF LOCATING BOREHOLES AT A "CONTOUR-ANGLE", WITH THE MAIN DIRECTION OF THE TUNNEL WHEN TUNNELLING IN ROCK BY BLASTING, IS DISCUSSED. THE USE OF EXCESSIVE CONTOUR-ANGLES RESULTS IN EXCESSIVE QUANTITIES OF CONCRETE IN THE LINING AND BROKEN ROCK TO BE REMOVED. MEASUREMENTS OF ACTUAL CONTOUR ANGLES RESULTING FROM DIFFERENT TYPES OF DRILLING MACHINES ARE CARRIED OUT AND THE RESULTS ARE PRESENTED IN A TABLE GIVING THEORETICAL AND ACTUAL CONTOUR ANGLES AND THE CORRESPONDING EXCESSIVE VOLUMES OF ROCK AS A PERCENTAGE OF THEORETICAL TUNNEL VOLUME. THE INVESTIGATIONS SHOW THAT THE ACTUAL CONTOUR ANGLE IS USUALLY 2 TO 3 TIMES GREATER THAN THE THEORETICAL ANGLE. A NOMOGRAM FACILITATING THE ESTIMATION OF PERCENTAGES OF EXCESSIVE ROCK VOLUME ON THE BASIS OF CONTOUR ANGLE, LENGTH OF BOREHOLES, TUNNEL PERIMETER OF CROSS SECTION AREA IS ALSO PRESENTED. /SVV/RRL/

  • Supplemental Notes:
    • Vol 18, No 7, PP 43-44, 2 FIG
  • Corporate Authors:

    Bygg, Oslo /Norway

    ,    
  • Authors:
    • Fossheim, J
    • Amundsen, C
  • Publication Date: 1970-8

Subject/Index Terms

Filing Info

  • Accession Number: 00234980
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: TRIS
  • Created Date: May 26 1971 12:00AM