Experimental and numerical study on determination of indirect (splitting) tensile strength of rocks under various load apparatus

Komurlu E. , KESİMAL A. , DEMİR S.

CANADIAN GEOTECHNICAL JOURNAL, vol.53, no.2, pp.360-372, 2016 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 53 Issue: 2
  • Publication Date: 2016
  • Doi Number: 10.1139/cgj-2014-0356
  • Page Numbers: pp.360-372


The indirect tensile strengths (ITSs) of more than 200 disc specimens for 19 different rock and rock-like materials were determined by considering the concept of fracture toughness under different loading conditions. Steel loading arcs with various contact angles and flat platens were used in experiments to investigate whether they can be used as alternatives for the standard Brazilian jaw. Many of the disc specimens tested under the standard jaw did not fail with ideal tensile cracking at the centre, whereas simple splitting cracks were obtained along the vertical diameter of most of the discs tested under the flat platens. However, flat platens caused cracks to initiate in the compressive zone just under the loading points. This is an important outcome for criticizing the validity of the test because tensile failure is expected to occur along the vertical diameter of the disc. Friction conditions between the disc and jaw have important roles in the failing load. Moreover, fracture toughness is an additional parameter for investigating the ITSs of rock materials. According to the experimental results, fracture toughness values were found to increase with an increase in contact angle. In addition to the experimental study, finite element analyses were performed on several types of rock discs under various loading conditions. As a result, a comparison between all loading conditions was made to determine the best ITSs of the rocks. Both experimental and numerical analyses concluded that deciding the best loading type depends on the rock type. Therefore, the standard jaw is not recommended to use for determination of the ITS values of all rock types.