Abstract:Double torsion specimens were applied to study the subcritical crack growth of flabby and intricate ore in Jinchuan Ⅲ Mine. The relation between the subcritical crack velocity v and the stress intensity factor KI is obtained, and the fracture toughness KIC and the lower limit of stress corrosion K0 are determined respectively. The results of test show that the curves of lgKI—lgv and KI—lgv can be well linear, and the high discretion of data are caused by mineral composition, particle size and mechanical property of rock itself. In addition, the subcritical crack growth with stress corrosion of the ore is caused by the united function of two mechanisms, one is the tensile stress and the other is the material at the crack tip. Chemical reaction takes place between the materials and the corrosion medium in the environment and makes the chemical bond break. So, the obtained results provide reliable references for predicting the block caving velocity of the ore in Jinchuan Ⅲ Mine under high horizontal stress condition.

Key words: subcritical crack growth; fracture toughness; double torsion specimens; stress corrosion; block caving method