ISRM-suggested method for determining the mode i static fracture toughness using semi-circular bend specimen

M. D. Kuruppu, Y. Obara, M. R. Ayatollahi, K. P. Chong, T. Funatsu

Research output: Contribution to journalArticlepeer-review

557 Citations (Scopus)


The International Society for Rock Mechanics has so far developed two standard methods for the determination of static fracture toughness of rock. They used three different core-based specimens and tests were to be performed on a typical laboratory compression or tension load frame. Another method to determine the mode I fracture toughness of rock using semi-circular bend specimen is herein presented. The specimen is semi-circular in shape and made from typical cores taken from the rock with any relative material directions noted. The specimens are tested in three-point bending using a laboratory compression test instrument. The failure load along with its dimensions is used to determine the fracture toughness. Most sedimentary rocks which are layered in structure may exhibit fracture properties that depend on the orientation and therefore measurements in more than one material direction may be necessary. The fracture toughness measurements are expected to yield a size-independent material property if certain minimum specimen size requirements are satisfied.

Original languageEnglish
Pages (from-to)267-274
Number of pages8
JournalRock Mechanics and Rock Engineering
Issue number1
Publication statusPublished - Jan 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Geotechnical Engineering and Engineering Geology
  • Geology


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