Waveform features and failure patterns of hollow cylindrical sandstone specimens under repetitive impact and triaxial confinements
Waveform features and failure patterns of hollow cylindrical sandstone specimens under repetitive impact and triaxial confinements
复制标题
重复冲击和三轴约束下空心圆柱形砂岩试件的波形特征和破坏模式
DOI：
10.1007/s40948-020-00183-9
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发表时间：
2020-09-30
影响因子：
5
通讯作者：
Khandelwal, Manoj
中科院分区：
文献类型：
--
作者：
Wang, Shiming;Liu, Yunsi;Khandelwal, Manoj
在地下工程实践中，围岩承受着具有不同径向梯度的非均匀应力场。为了揭示岩石在非均匀应力条件下的冲击波形特征和破坏特性，采用空心圆柱形砂岩（HOS）试件进行了一系列常规三轴重复冲击试验。试验采用改进的大直径分离式霍普金森压杆试验系统进行。围压分别设置为5、10、12 MPa。选取平衡应力状态下的试样数据进行分析，结果表明：随着围压的增大，岩石破碎需要更多的循环冲击载荷。HOS试样中出现了三种类型的裂缝，即试样中心孔周围的环状裂缝、位于外圆柱面的轴向裂缝和将岩石破碎成小块的侧向裂缝。HOS试件的破坏程度可以通过反射波的波形特征来判断，在相同的破坏模式下，无论冲击速度和冲击次数如何，反射波的波形特征都是相似的，只影响破坏程度。
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.