ISRM-Suggested Method for Determining the Mode I Static Fracture Toughness Using Semi-Circular Bend Specimen

• Published in: Rock mechanics and rock engineering Vol. 47; no. 1; pp. 267 - 274
• Main Authors: Kuruppu, M. D., Obara, Y., Ayatollahi, M. R., Chong, K. P., Funatsu, T.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.01.2014; Springer; Springer Nature B.V
• Subjects: Applied sciences; Buildings. Public works; Civil Engineering; Compression tests; Earth and Environmental Science; Earth Sciences; Exact sciences and technology; Fracture mechanics; Fracture toughness; Geophysics/Geodesy; Geotechnics; ISRM Suggested Method; Measurements. Technique of testing; Radioactive wastes; Rock; Rock (material); Rock mechanics; Rocks; Sedimentary geology; Sedimentary rocks; Soil investigations. Testing; Soil mechanics. Rocks mechanics; Fracture testing; Semi-circular bend specimen; In situ environment; Rock fracture mechanics; Sedimentary rock; Mode I fracture toughness; Rock mechanics; Fracture mechanics; In situ; Experimental device; Fracture toughness; Size effect; Test method; Computing method; Static test; Fracture mode
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-013-0422-7

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.