To deeply understand the failure characteristics of defective rock under actual stress condition, impact tests were conducted on prismatic granite containing two rectangular holes with different axial static pre-stresses by a modified split Hopkinson pressure bar (SHPB), and uniaxial compression tests were also carried out for comparison. Combined with digital image correlation (DIC), the dynamic damage and fracture process of specimens were observed by low-speed and high-speed cameras. Moreover, the energy evolution characteristics of specimens were analyzed to further understand the failure mechanism. The results indicate that the pre-stress has dual effects on the dynamic mechanical behavior of rock specimens, and the transition mechanism of the effect of pre-stress can be revealed by the elastic deformation limit. Observations show that the failure of specimens under different loads is caused by the growth of secondary cracks at hole corners. However, with the increase in pre-stress, the crack mode tends to shear and the strain localization tends to concentrate on sidewalls, resulting in severe rock bursting and extensive fracturing. Four coalescence modes around two rectangular holes were summarized: diagonal shear coalescence under static load, no coalescence under dynamic load, shear coalescence inside the middle rock bridge area under the pre-stress of 25–55% UCS, and indirect coalescence outside the rock bridge area under the pre-stress of 75% UCS. The specimen with the pre-stress of 75% UCS releases the internal strain energy during dynamic failure process, while the specimen with lower pre-stress absorbs the external impact energy. Finally, some insights are provided for deep rock engineering based on the test results.

为了深入了解缺陷岩石在实际应力条件下的破坏特性，采用改进的剖分式霍普金森压力棒（SHPB）对包含两个具有不同轴向静态预应力的矩形孔的棱柱形花岗岩进行了冲击试验，并进行了单轴压缩试验进行比较。结合数字图像相关技术（DIC），通过低速和高速相机观察样品的动态损伤和断裂过程。此外，分析了标本的能量演化特征，以进一步了解破坏机理。结果表明，预应力对岩石试件的动力力学行为具有双重影响，而预应力作用的转变机理可以通过弹性变形极限来揭示。观察表明，在不同载荷下，试样的破坏是由孔角处二次裂纹的增长引起的。但是，随着预应力的增加，裂纹模式趋于剪切，应变局部化趋于集中在侧壁上，从而导致严重的岩石破裂和大范围的破裂。总结了两个矩形孔周围的四种聚结模式：静载荷下的斜向剪切聚结，动载荷下的无聚结，在25-55％UCS预应力下中岩桥区域内的剪切聚结以及岩桥外的间接聚结。 UCS预应力为75％的区域。UCS预应力为75％的试样在动态破坏过程中释放内部应变能，而预应力较低的试样则吸收外部冲击能。最后，