SOME OBSERVATIONS CONCERNING THE STRENGTH-SIZE DEPENDENCY OF ROCKS

Based on the experimental evidence contained in this report, rock strength as defined conventionally in rock mechanics according to fracture stress, is not a property of the undisturbed rock. Rather it is the property of a rock which has been loaded in a certain way, for a certain size (length, diameter, thickness etc) specimen which in turn creates a certain amount of disturbance within the rock as stress levels increase. In particular this disturbance, which is termed sub-critical crack growth, modifies flaw distributions within a rock so that simple volume-related statistical treatments for the prediction of scale affects are unreliable. While the latter were never able to account for scale effects outside of a statistical argument, the present work gives a physical explanation from which predictions based on a fracture mechanics approach appear possible. One significant result of this explanation is that scale effects need not necessarily be present in certain tests, while occurring in others, the same material being tested on each occasion. With regard to this it is recommended that further work be done to extend the predictive capability of the approach to cover a larger range of specimen sizes and loading types. (TRRL)

  • Availability:
  • Corporate Authors:

    Lulea University

    Department of Rock Mechanics
    S-95187 Lulea,   Sweden 
  • Authors:
    • Swan, G
  • Publication Date: 1980

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Filing Info

  • Accession Number: 00331183
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • Report/Paper Numbers: Tulea 1980:01 Monograph
  • Files: ITRD, TRIS
  • Created Date: Aug 15 1981 12:00AM