EFFECTS OF THE SPECIMEN GEOMETRY ON ROCK FRACTURE TOUGHNESS

Fracture toughness of rock materials is measured with standard test methods suggested by the ISRM. Rock fracture toughness is generally affected by the specimen geometry, like other rock properties, and the toughness values measured employing the NBD, SECRBB, SCB and MHT specimen geometries are substantially different from those measured by the standard test method. Also the dispersion of fracture toughness values due to inhomogeneity in rock material is great according to the test method.

Therefore, it will be reasonable to use fracture toughness values acquired by ample specimens and using statistical analysis than those measured by the standard test method.

Hence, the main content of this research is to compare the fracture toughness values of several rock types measured by various test methods with the standard values, aiming to standardize the test geometries