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利用双轴伺服试验机开展花岗岩巷道岩爆模拟试验,采用声发射系统获取岩爆全过程的波形信号。基于频谱分析理论,研究岩爆孕育、发生全过程的声发射信号主频特性。研究结果表明:双轴加载条件下花岗岩巷道岩爆声发射主频分布区间为0.4~110 kHz,其中99%以上的主频值集中在35~65 kHz。声发射信号主频的分布随岩爆演化可分为3个阶段:(1)岩爆孕育前期,大部分主频值集中在35~65 kHz和15~25 kHz区间,且有一定数量接近0.4 kHz的低频值出现,极少出现接近110 kHz的高频值;(2)岩爆孕育中期,主频值集中在35~65 kHz区间,接近0.4 kHz的低频值基本消失,少量接近110 kHz的高频值开始出现;(3)岩爆发生阶段,35~65 kHz区间内的主频数量骤减,接近0.4 kHz的低频值极少出现,接近110 kHz的高频值密集出现。研究结果为优选声发射监测频段提供了方法和依据,且对巷道岩爆的监测预警工作具有重要理论意义。
The rock burst simulation experiment of granite roadway is carried out by using the biaxial servo testing machine. The acoustic emission system is used to obtain the waveform signal of the whole process of rock burst. Based on the theory of spectrum analysis, the frequency characteristics of acoustic emission signals during the whole process of rock burst are studied. The results show that the main frequency distribution of rock burst acoustic emission in granite roadway under biaxial loading is 0.4 ~ 110 kHz, of which 99% of the main frequency is concentrated in 35 ~ 65 kHz. The distribution of the dominant frequency of acoustic emission signal can be divided into three stages with the evolution of rock burst: (1) In the early stage of rock burst, most of the dominant frequency values were concentrated in the interval of 35-65 kHz and 15-25 kHz with a certain number close to 0.4 (2) In the mid-term of rock burst, the dominant frequency values are concentrated in the range of 35-65 kHz. The low frequency values close to 0.4 kHz basically disappear and a small amount of frequencies close to 110 kHz (3) In the rockburst stage, the frequency of 35 ~ 65 kHz decreases sharply, the low frequency near 0.4 kHz rarely appears, and the high frequency near 110 kHz appears densely. The results provide the method and basis for optimizing the monitoring range of acoustic emission monitoring, and have important theoretical significance for the monitoring and early warning work of rockburst.