Development of a standard method for determining the plane strain fracture toughness of rock
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A number of standard methods have been proposed to determine the Mode I plane strain fracture toughness of rock. The semi-circular bend (SCB) specimen has been widely used for fracture toughness determination of geomaterials owing to inherent favourable properties such as its simplicity, minimal requirement of machining and the convenience of testing. However, measurements of Mode I fracture toughness using SCB specimen have shown variability with specimen size. The minimum size requirements suggested by many theories are usually too large for practical applications. This research suggests an approximate, but relatively easily applied method, to satisfy the minimum size requirement. Fracture toughness of Kimachi sandstone was determined using the SCB specimen. By testing specimens of varying size, it was confirmed that the apparent fracture toughness increases with the specimen size. The trend line of the apparent fracture toughness displayed eventual stabilisation giving a value that can be considered as specimen size-corrected fracture toughness. This paper describes the method of determining the SCB specimen size-corrected fracture toughness and also highlights the advantages of using the SCB method over the other suggested standard methods.
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Funatsu, T; Kuruppu, Mahinda (2014)In order to investigate the effect of specimen size on the mode I fracture toughness using Semi-Circular Bend (SCB) specimen, we experimentally studied the fracture toughness using SCB and Short Rod (SR) specimens, both ...
ISRM-Suggested Method for Determining the Mode I Static Fracture Toughness Using Semi-Circular Bend SpecimenKuruppu, Mahinda; Obara, Yuzo; Ayatollahi, Majid; Chong, Ken; Funatsu, Takahiro (2014)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 ...
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