Testing study of subcritical crack growth velocity and fracture toughness of marble

摘要

Subcritical crack growth of double torsion specimens made of marble was studied using Instron1342 type electro hydraulic servo test machine. The relations of the mode-I stress intensity factor K_I versus the subcritical crack growth velocity V and the fracture toughness K_(Ic) were obtained by the double torsion constant displacement load relaxation method. The behavior of subcritical crack growth was analyzed. The results show that lgK_I-lgV relations of marble measured by this method accord with linear rule, i.e. the relations between subcritical crack growth velocity V and stress intensity factor K_I have a power law, which is in good agreement with Charles theory. The testing results provide a basis for time-dependency of rock engineering stability.