The Protodyakonov index is stated as being a simple rock characteristic which has the possibility of practical application, particularly in predicting rock drillability in percussive drilling. However, the accuracy of the index as determined by the standard procedure is considered to be susceptible to certain defects, and in this note the authors present a critical appraisal of the index. The scope of the work and experimental procedure is described and the results discussed. The conclusions reached are given as: 1. The mass of assays has no influence on the index; 2. The size of chunks also has little effect for a size range of 15-22mm. But for lower sizes the index varies, thus necessitating close size control; 3. The number of impacts affects the index to some extent, and there is no way short of an actual trial by which the number of impacts for different rocks can be estimated in order to get comparable values of the index; 4. For this reason specific energy is felt to be a more consistent rock strength index, since it gives a constant value irrespective of mass of assay, size of chunks and number of impacts over a wide range. /TRRL/

  • Availability:
  • Corporate Authors:

    Pergamon Press, Incorporated

    Headington Hill Hall
    Oxford OX30BW,    
  • Authors:
    • Misra, G B
  • Publication Date: 1976-8


  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00145374
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Apr 13 1977 12:00AM