Experimental study on dynamic fracture of rock-mortar specimens with different interface trajectories

•When the inner angle of the triangle rock changes from 60° to 120°, the direction of crack expansion at the interface will deviate from the initial crack expansion direction, and the rock will not be penetrated by the interfacial crack.•When the loading rates are the same, the interfacial types of MS-II and MS-III series specimens have a more significant attenuation of the interfacial crack extension speed compared to the MS-I series specimens.•At a loading rate of 919 GPa/s, the specimens from the MG-II and MS-II series have a much better dynamic fracture toughness than the specimens from the MG-IV series.•Tensile stress and shear stress coexist at the interface of models, and tensile stress plays a dominant role in the crack initiation process.•Comparing the parameter K1 values of these BSCT specimens, one can find that the MG-IV series specimens have the best initial fracture toughness.