Fracture toughness of stripa granite cores

There is a growing interest in the study of fracture parameters of rock material, but to date no standard testing method for measuring the fracture toughness of rock exists. Three round specimen configurations, namely the notched beam, the compact specimen, and the short rod were used in this work and different fracture toughness measures evaluated for Stripa granite. Then a comparison with an apparent fracture toughness, K (sub Qm) , obtained from pre-cracked specimens, showed that low K (sub m) values arise because the microcrack growth that precedes crack extension is neglectedGodkänd; 1986; 20071107 (ysko)