Study of the Relationship between Mode I Fracture Toughness and Rock Brittleness Indices

Mode I fracture toughness (KIC) and rock brittleness are important properties that influence many engineering applications. Due to the difficulties in determining KIC experimentally, previous studies have investigated relationship between indices. However, only indices (based on strength parameters) obtained from Chevron Bend Short Rod test methods were considered. In this paper, regression analysis was carried out investigate using literature data collected different types core under level static conditions. Rock assessed ten based pre-peak elastic parameters. The results showed elastic-based not good predictors of KIC, while strength-based correlated well with KIC. A comparison revealed correlations significantly sensitive type, i.e., soft or hard, method. a index, both parameters, found be best index predict because its lower sensitivity method type.