Dynamic experiments were conducted on single cleavage drilled compression（SCDC） specimens of sandstone using large-diameter split Hopkinson pressure bar to obtain the whole dynamic fracturing process of Mode-I crack.A crack propagation gauge was used to measure the key moments of dynamic initiation

propagation

arrest and re-initiation

respectively.A fractal model of crack extension was applied to analyze the propagation speed of a tortuous crack.Finally

we determined the dynamic initiation toughness

dynamic propagation toughness

dynamic arrest toughness

and dynamic re-initiation toughness using the experimental-numerical-analytical method.The results demonstrate that the crack propagation path is torturous in the process of crack propagation.For this irregular curve path

the value of the universal function

which was characterized by the crack propagation velocity

was smaller than that with a straight path.It is found that the dynamic propagation toughness obtained by the fractal model was close to its real value.The dynamic initiation toughness was greater than the dynamic arrest toughness

and the dynamic initiation toughness was slightly greater than the dynamic re-initiation toughness.The reason probably was that the naturally formed crack at the second re-initiation was sharp

while the artificial notch for the first dynamic initiation was blunt at a certain degree.