Evaluation of indentation method in determining fracture toughness of rocks

Document Type : Original Article

Authors

1 1. Fatigue and Fracture Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology,

2 . Fatigue and Fracture Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, m.ayat@iust.ac.ir

Abstract

Fracture toughness is an important parameter in some applications related to rock masses like fracture of rock, hydraulic fracturing process, design and manufacturing of tunneling apparatus. Different methods have been proposed for determining fracture toughness of quasi-brittle materials including the indentation test. In this research, the properties of some rocks with different textures (grain size and shape) are examined in the indentation test. Then applicability of the indentation method in determining fracture toughness of rocks is evaluated. It is shown that rocks exhibit two different types of behavior in the indentation test. For forces less than a critical force, rocks behave in accordance with other brittle materials, while for loads more than the critical force, the rocks behave completely in contrast with other brittle materials. This difference makes the indentation method an unsuitable option for determining fracture toughness of rocks. The main reason for this difference could be the presence of inherent defects in rocks.

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References

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Scientific Quarterly Journal of Iranian Association of Engineering Geology
Volume 6, Number 3 & 4
March 2013
Pages 59-68

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History

  • Receive Date: 11 December 2012
  • Revise Date: 19 September 2012
  • Accept Date: 28 December 2013

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