Investigation on the correlation of mode II fracture toughness of sandstone with tensile strength

A series of tests with centrally cracked Brazilian disc and un-cracked Brazilian disc specimens were conducted to investigate the relation between the mode II fracture toughness KIIC and tensile strength σt of sandstone under different treatment conditions. The results indicated that there was a good linear relation between these two rock parameters. Further, this conclusion was also validated by theoretical analysis based on the generalized maximum tangential stress criterion. Moreover, an empirical formula KIIC = 0.2159σt was obtained using linear regression analysis, which can be confidently used to estimate the mode II fracture toughness with tensile strength of rocks.