Dynamic Fracture Experiment of Fractured Rock under Dynamic Loading

Table 5

Crack propagation process of Specimen a2 at the loading rate of 10.6 m/s.

High-speed images	Crack sketch	Stress (MPa)	Loading time (μs)	Crack propagation process
		33.64; Prepeak	68.0	Microcracks occurred from the vertex of prefabricated fracture of the specimen
		40.48; At peak	102.3	Cracks occurred at the vertex of specimen fracture propagated from left to right, leading to a few of branching cracks
		30.26; Postpeak	137.6	Cracks gradually propagated with increased width, and cracks began to occur at the ends of the specimen