Before the rock mass in the engineering is broken under load, it is usually in a state of varying degrees of damage. Aiming at the fracture characteristics of damaged sandstone under impact load, this paper adopts a method of the cyclic static load to cause the sandstone specimens to have varying degrees of damage. Then, the wave velocity of sandstone before and after the damage is measured using the nonmetallic acoustic velocimeter, and the change rule of damage factor is analyzed. Finally, the split Hopkinson pressure bar (SHPB) is used to test the impact dynamics of sandstone with different damage degrees. The broken rock block is screened by a vibrating screen, and the crushing characteristics are analyzed. The results show that not only the damage factor of damaged sandstone but the growth rate increases, with the raising upper limit of stress. Under the impact load of the same incident energy, the fragmentation degree of the damaged sandstone increases with the increase of the upper stress limit, while the average diameter of the broken rock block decreases gradually, and the reduction rate increases first and then decreases.

中文翻译：

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冲击载荷下受损砂岩的断裂特征和几何分形

在工程中的岩体在载荷作用下破碎之前，它通常处于不同程度的损坏状态。针对冲击载荷作用下受损砂岩的断裂特性，本文采用循环静载荷的方法使砂岩试件受到不同程度的破坏。然后，利用非金属声速计测量了损伤前后砂岩的波速，分析了损伤系数的变化规律。最后，使用裂开的霍普金森压力棒（SHPB）来测试不同破坏程度的砂岩的冲击动力学。用振动筛筛分碎石块，并分析其破碎特性。结果表明，不仅破坏砂岩的破坏因素，而且增长速度加快，随着压力上限的提高。在相同入射能量的冲击载荷下，破损砂岩的破碎度随应力上限的增大而增大，而破碎岩块的平均直径逐渐减小，减小率先增大后减小。