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In this study, the damage characteristics of the slit charge pack along the rock slitting and the vertical slitting directions were investigated using green sandstone as the subject. Split-Hopkinson pressure bar (SHPB) experiments were performed on green sandstone, and the dynamic mechanical properties of rock specimen were analyzed in the slitting and vertical slitting directions. Based on the SHPB experiments of the rock specimens in different damage zones along the rock slitting and the vertical slitting directions combined with the fractal theory, the distribution pattern of rock fracture fragmentation was investigated at different positions in the kerf direction and vertical kerf direction. The results of this study show that the dynamic strength of the rock corresponds to the damage degree of the rock, which is greater in the direction of the slit than that in the perpendicular direction of the slit. In addition, the core at 150 mm distance from the blast hole perpendicular to the slit direction could easily bear the blast loads. The lumpiness distribution of rock specimens under impact load shows good statistical self-similarity. The evolution law of fractal dimension shows that with increasing distance from the core to the blast hole, the fractal dimension of the specimen after failure increases. The fractal dimension of the specimen perpendicular to the slit direction is greater than that of the specimen along the slit direction at the same distance.

Defects have a significant effect on the dynamic fracture characteristics of the medium. In this paper, the dynamic fracture experiment of specimens with bias precracks is designed by utilizing the digital laser dynamic caustics system, and the effect of defect eccentricity on the dynamic fracture behavior is studied. Research shows that crack propagation can be divided into four stages: crack initiation stage, attraction stage, repulsion stage, and specimen fracture stage. The change of defect eccentricity has no obvious effect on the crack propagation behavior in the crack initiation stage and penetration stage but has a significant effect on the attraction stage and specimen fracture stage. In the process of the interaction between defect and crack, mode I stress intensity factor decreases at first and then increases. The decrease of mode I stress intensity factor reduces with the increase of defect eccentricity. The value of mode II stress intensity factor changes from negative to positive. With the increase of defect eccentricity, the symbol of mode II stress intensity factor no longer changes. The fractal dimension and the deflection angle of crack trajectory both decrease with the increase of defect eccentricity. In addition, a numerical simulation of the experiment is conducted by ABAQUS, which provides results that are in good agreement with the experimental results.

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