Abstract

Studying the characteristics of tensile and shear cracks in a rockburst event is crucial for understanding the rockburst mechanism. In this study, several specimens were tested under biaxial compression, and the released acoustic emissions (AEs) of the resulting tunnel rockburst event were recorded. Based on the AE energy and dominant frequency parameters, the different AE characteristics and dominant frequency evolution law of tensile and shear cracks during the rockburst were analysed. According to the results, there are four types of AE signals in a rockburst event: low-frequency and low-energy signals, low-frequency and high-energy signals, medium-frequency and low-energy signals and high-frequency and low-energy signals. The low-frequency and low-energy signals are mainly generated by tensile cracks, and the low-frequency and high-energy signals originate from both tensile and shear cracks. The medium-frequency and low-energy signals and high-frequency and low-energy signals are often generated by tension cracks. The rockburst process can be classified into four stages: calm period, small-grain ejection period, sheet-like peeling period and violent ejection period. Before the occurrence of rockburst, both tensile and shear cracks produce low-frequency and high-energy signals. The low-frequency and high-energy (amplitude) AE signals are crucial for monitoring and early warning procedures for rockburst events.

摘要

研究岩爆事件中拉伸和剪切裂缝的特征对于理解岩爆机制至关重要。在这项研究中，几个试样在双轴压缩下进行了测试，并记录了由此产生的隧道岩爆事件的释放声发射 (AE)。基于声发射能量和主频参数，分析了岩爆过程中拉剪裂缝不同声发射特征和主频演化规律。结果表明，一次岩爆事件中的声发射信号有四种类型：低频低能信号、低频高能信号、中频低能信号和高频低能信号。能量信号。低频低能量信号主要由拉伸裂纹产生，低频和高能信号来自拉伸裂纹和剪切裂纹。中频低能信号和高频低能信号往往是由张力裂纹产生的。岩爆过程可分为四个阶段：平静期、小颗粒喷出期、片状剥落期和剧烈喷出期。在岩爆发生之前，拉伸裂缝和剪切裂缝都会产生低频和高能信号。低频和高能（振幅）AE 信号对于岩爆事件的监测和预警程序至关重要。平静期、小颗粒喷射期、片状剥离期和剧烈喷射期。在岩爆发生之前，拉伸裂缝和剪切裂缝都会产生低频和高能信号。低频和高能（振幅）AE 信号对于岩爆事件的监测和预警程序至关重要。平静期、小颗粒喷射期、片状剥离期和剧烈喷射期。在岩爆发生之前，拉伸裂缝和剪切裂缝都会产生低频和高能信号。低频和高能（振幅）AE 信号对于岩爆事件的监测和预警程序至关重要。