In underground engineering practice, the surrounding rocks are subjected to a nonuniform stress field with various radial gradients. In this study, a series of conventional triaxial repetitive impact tests using hollow cylindrical sandstone (HOS) specimens were conducted to reveal the impact waveform features and failure properties of rocks under nonuniform stress conditions. The tests were conducted using a modified large diameter split Hopkinson pressure bar testing system. The confining pressure was set as 5, 10 and 12 MPa. The data of specimens under equilibrium stress states were chosen and analyzed, and the results showed that more applied numbers of cyclic impact loads were needed to break rocks with the increase of confining pressure. Three types of cracks, i.e., ring-shaped cracks around the hole in the center of specimens, axial cracks located in the outer cylindrical surface, and lateral cracks fracturing rock fragments into small pieces appeared in HOS specimens. The failure degrees of HOS specimens could be judged by the waveform features of the reflected wave, and the waveform features of reflected wave are similar in the same failure mode, regardless of the impact velocity and the number of impacts, which only affect the failure degree.

在地下工程实践中，周围的岩石受到具有各种径向梯度的非均匀应力场。在这项研究中，使用空心圆柱砂岩（HOS）试样进行了一系列常规三轴重复冲击试验，以揭示在非均匀应力条件下岩石的冲击波形特征和破坏特性。使用改进的大口径霍普金森压力棒测试系统进行测试。围压设定为5、10和12MPa。选择和分析了处于平衡应力状态下的试件数据，结果表明，随着围压的增加，需要更多次施加周期性冲击载荷才能破碎岩石。三种类型的裂纹，即试样中心孔周围的环形裂纹，在HOS试件中出现了轴向裂纹，位于圆柱外表面，横向裂纹将岩石碎片破碎成小块。可以通过反射波的波形特征来判断HOS试样的破坏程度，并且在相同的破坏模式下，反射波的波形特征是相似的，而与冲击速度和冲击次数无关，仅影响破坏程度。