A criterion for crack initiation and propagation in intact rocks under creep condition

This paper presents a study on the criterion of crack initiation and propagation under creep conditions, which were investigated using specimens collected from outcropped sandstone rock formations. Beam specimens under three points bending were used in this investigation. The experimental result shows that due to creep deformation, rock crack will inevitably initiate and propagate after a time interval of sustained loading under a load of K I , which is less than fracture toughness K IC but not less than a constant marked as K IC2 . K IC2 indicates the ability of rock to resist crack initiation and propagation under creep conditions and it is defined as creep fracture toughness.