Crack monitoring is an important issue in coal and rock hydraulic fracturing (HF). In this study, we conducted experimental coal HF acoustic emission (AE) monitoring tests under true triaxial stress by using a self-developed experiment system. The results showed that the AE signal statistical parameters had a good positive correlation with the water pressure curve. Based on the STA/LTA, improved AIC and simplex algorithm, we developed a new method for AE event automatic identification and source location for coal HF. By using this new method, we were able to detect and locate more accurately the AE events induced by HF. Hydraulic crack propagation and temporal-spatial AE event distribution were located with high accuracy. According to the AE event temporal-spatial distribution of AE events, coal hydraulic crack propagation was not uniform. In the middle and late HF stages, especially when hydraulic cracks approach the coal sample boundary, the hydraulic crack propagation speed was accelerated significantly. The important factors that affected hydraulic crack initiation, propagation, steering, and acceleration included the triaxial stress state, original joints and cracks, and local stress disturbance caused by hydraulic cracks. These results offer a reference for designing optimized, safe and effective HF programs, which are important in preventing coal/rock dynamic disasters and ensuring safe and efficient mining.

裂缝监测是煤炭和岩石水力压裂（HF）的重要问题。在这项研究中，我们通过使用自行开发的实验系统在真实的三轴应力下进行了煤HF声发射（AE）监测实验。结果表明，声发射信号统计参数与水压曲线具有良好的正相关性。基于STA / LTA，改进的AIC和单纯形算法，我们开发了一种用于煤HF的AE事件自动识别和源定位的新方法。通过使用这种新方法，我们能够更准确地检测和定位由HF诱发的AE事件。高精度定位了水力裂缝的传播和时空AE事件的分布。根据AE事件的时空分布，煤水力裂缝扩展不均匀。在HF的中后期，尤其是当水力裂缝接近煤样边界时，水力裂缝的传播速度明显加快。影响液压裂纹萌生，扩展，转向和加速的重要因素包括三轴应力状态，原始接缝和裂纹以及由液压裂纹引起的局部应力扰动。这些结果为设计优化，安全和有效的高频程序提供了参考，这些程序对于防止煤/岩动态灾害和确保安全有效的采矿非常重要。加速度包括三轴应力状态，原始接缝和裂纹以及水力裂纹引起的局部应力扰动。这些结果为设计优化，安全和有效的高频程序提供了参考，这些程序对于防止煤/岩动态灾害和确保安全有效的采矿非常重要。加速度包括三轴应力状态，原始接缝和裂纹以及水力裂纹引起的局部应力扰动。这些结果为设计优化，安全和有效的高频程序提供了参考，这些程序对于防止煤/岩动态灾害和确保安全有效的采矿非常重要。