ROCK FRAGMENTATION - MODERN TUNNELLING TECHNIQUE

The author discusses advances in methods of rock fragmentation and defines terms used in their comparison. The usefulness of each method is said to depend on many factors including (a) capital cost, (b) durability of equipment, (C) ease of supplying power to excavation face, (D) health hazards, (e) effect of method on support requirements and, (F) ease of removing fragmented material. Methods examined are explosive, mechanical and novel fragmentation methods. Of these methods, explosive fragmentation is said to be the most economical using the lowest specific energy. The main disadvantage of the technique, is the slow rate of advance and the damage suffered by the surrounding rock. Mechanical methods such as peripheral sawing results in an improved rock condition when used with explosives. Other mechanical methods include tunnel borers, raise boring and reaming, boom excavators, cutter bits and discs, and impact hammers or picks. Many of the novel methods are still in the laboratory stage and use flame or electrical power to induce thermal stresses in rock in order to offer easier excavation. Other techniques use hydraulic power in the form of a water cannon, chemical methods using aluminium chloride instead of water, and projectile impact in which 90 mm and 105 mm guns, fire concrete and steel projectiles at a rock face. /TRRL/

  • Corporate Authors:

    Foundation Publications Limited

    7 Ongar Road
    Brentwood CM15 9AU, Essex,   England 
  • Authors:
    • STERLING, R
  • Publication Date: 1976

Media Info

  • Features: Figures; Photos; References;
  • Pagination: p. 36-42
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00142129
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jul 19 1977 12:00AM