In this study, the effect of loading rate on shale fracture behaviors was investigated under dynamic and static loading conditions. Cracked straight through Brazilian disc (CSTBD) shale specimens were tested with a split Hopkinson pressure bar (SHPB) setup and INSTRON1346 servo-testing machine under pure mode I loading conditions. During the test, the crack propagation process was recorded by high-speed (HS) camera, and the acoustic emission (AE) signal generated by the fracture was collected by acoustic emission (AE) system. At the same time, crack propagation gauge (CPG) was used to measure the crack propagation velocity of the specimen. The results show that the crack propagation velocity and fracture toughness of shale have a positive correlation with the loading rate. The relationship among the crack propagation velocity, the fracture toughness and the loading rate is established under the static loading condition. In addition, the characteristics of AE signals with different loading rates are analyzed. It is found that the AE signals generated by microcrack growth decrease with the increase of loading rates. Meanwhile, the turning point of cumulative counting moves forward as the loading rate increases, which shows that the AE signal generated by shale fracture at low loading rate mainly comes from the initiation and propagation of microcracks, while at high loading rate it mainly comes from the formation of macro large-scale cracks. The fracture mechanism that causes shale fracture toughness and crack propagation velocity to vary with loading rate is also discussed based on the analysis results of AE signals.

在这项研究中，研究了加载速率对动态和静态加载条件下页岩断裂行为的影响。在分开的Hopkinson压力杆（SHPB）装置和INSTRON1346伺服测试机上，在纯模式I加载条件下，测试了直通巴西圆盘​​（CSTBD）的页岩样品。在测试过程中，通过高速（HS）摄像机记录了裂纹的传播过程，并通过声发射（AE）系统收集了由裂缝产生的声发射（AE）信号。同时，使用裂纹扩展仪（CPG）测量试样的裂纹扩展速度。结果表明，页岩的裂纹扩展速度和断裂韧性与加载速率呈正相关。裂纹扩展速度之间的关系，在静态载荷条件下建立断裂韧性和载荷率。另外，分析了不同负载率的声发射信号的特性。发现随着裂纹扩展速率的增加，裂纹扩展产生的声发射信号减小。同时，随着加载速率的增加，累积计数的转折点向前移动，这表明低加载速率下页岩裂缝产生的声发射信号主要来自微裂纹的萌生和传播，而高加载速率下则主要来自微裂纹的产生和传播。宏观大裂纹的形成。基于声发射信号的分析结果，探讨了导致页岩断裂韧性和裂纹扩展速度随加载速率变化的断裂机理。