Summary
A wide variety of specimen types and methods are employed in fracture toughness measurement of rocks, which result in scattered values for the same rock type. In order to provide some consistency to the values, the International Society for Rock Mechanics (ISRM) recommended three suggested methods using core based specimens, the Chevron Bend (CB) test, the Short Rod (SR) test and the Cracked Chevron Notch Brazilian Disc (CCNBD) test. This standardization helped obtain more consistent values but still a variation of 20–30% was observed in the values of fracture toughness obtained with the CB and SR methods. The values obtained with the CCNBD method were found to be consistently lower (30–50%) than those of the other two methods (CB and SR). Many reasons have been offered to explain this deviation. These include size of the specimen, anisotropy of rock, a dimensionless parameter in the fracture toughness calculation equation for the CCNBD test, etc. A comprehensive test program was initiated to identify the cause of these discrepancies between the CB and CCNBD methods. Three brittle rock types were selected for the study and more than 200 tests were conducted to measure the values of fracture toughness.
A rigorous statistical analysis was carried out to determine the confidence level and find the significance of the test results. It was found that the CB and CCNBD methods were very comparable provided the correct equation for fracture toughness calculation was used for the CCNBD method and the size of the specimens was selected carefully. The error in the ISRM 1995 formula of fracture toughness for the CCNBD method could be the major factor responsible for the consistently lower values obtained with the method.
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References
B. K. Atkinson (1987) Fracture mechanics of rock Academic Press London
Barton, C. C. (1982): Variables in fracture energy and toughness testing of rock. In: Proc., 23rd U.S. Symp. Rock Mechanics, AIME, New York, NY, pp 449–462.
R. A. Bearman (1999) ArticleTitleThe use of the point load test for the rapid estimation of mode-I fracture toughness Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 36 257–263
R. D. Dwivedi A. K. Soni R. K. Goell A. K. Dube (2000) ArticleTitleFracture toughness of rock under sub-zero temperature conditions Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 37 1267–1275 Occurrence Handle10.1016/S1365-1609(00)00051-4
R. J. Fowell C. Xu (1993) ArticleTitleThe cracked Chevron notched Brazilian disc test – geometrical considerations for practical rock fracture toughness measurement Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 30 821–824 Occurrence Handle10.1016/0148-9062(93)90029-D
I. Guttman S. S. Wilks J. S. Hunter (1982) Introductory engineering statistics EditionNumber3 Wiley Toronto
ISRM Testing Commission, Brown, E. T. (ed.) (1981, 1985): Rock characterization testing and monitoring ISRM suggested methods. Pergamon Press, Oxford.
ISRM Testing Commission (Ouchterlony, F. Co-ordinator) (1988): Suggested methods for determining the fracture toughness of rock. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 25, 71–96.
InstitutionalAuthorNameISRM Testing Commission R. J. Fowell (1995) ArticleTitleSuggested method for determining mode – I fracture toughness using cracked Chevron notched Brazilian disc (CCNBD) specimens Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 32 57–64 Occurrence Handle10.1016/0148-9062(94)00015-U
K. Matsuki S. S. Hasibuan H. Takahashi (1991) ArticleTitleSpecimen size requirements for determining the inherent fracture toughness of rock according to the ISRM suggested methods Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 28 365–374 Occurrence Handle10.1016/0148-9062(91)90075-W
Nasseri, M. H. B., Mohanty, B., Prasad, U. (2002): Investigation of micro-structural properties of selected rocks and their effect on fracture toughness. In: Hammah et al. (eds), NARMS-TAG 2002, University of Toronto, ISBN 0 7727 6708 4.
F Ouchterlony (1982) ArticleTitleReview of fracture toughness testing of rock SM Archives 7 131–211
F. Ouchterlony (1989) ArticleTitleOn the background to the formulae and accuracy of fracture toughness testing with lSRM standard core specimens Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 26 13–23 Occurrence Handle10.1016/0148-9062(89)90521-4
Ouchterlony, F., Takahashi, H., Matsuki, K., Hashida, T. (1991): Experiences from fracture toughness testing of rock according to the ISRM suggested methods. National Technical Information Service, Springfield, U.S. Department of Commerce, Report No. DS-1991: 2.
R. E. Walpole R. H. Mayers S. L. Mayers (1998) Probability and statistics for engineers and scientists Prentice Hall Upper Saddle River
B. N. Whittaker R. N. Singh G. Sun (1992) Rock fracture mechanics; principles, design and applications Elsevier Amsterdam
C. Xu R. J. Fowell (1994) ArticleTitleStress intensity factor evaluation for cracked Chevron notched Brazilian disc specimens Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 31–32 157–162 Occurrence Handle10.1016/0148-9062(94)92806-1
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Iqbal, M., Mohanty, B. Experimental Calibration of ISRM Suggested Fracture Toughness Measurement Techniques in Selected Brittle Rocks. Rock Mech. Rock Engng. 40, 453–475 (2007). https://doi.org/10.1007/s00603-006-0107-6
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DOI: https://doi.org/10.1007/s00603-006-0107-6