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利用深部岩爆模拟试验系统对花岗岩进行室内瞬时岩爆模拟试验,同时利用声发射系统采集试验过程中声发射信号,得到试验全过程应力和声发射波形信息时域图。结合声发射累计能量曲线特征,找到5个关键拐点,即花岗岩初始加载能量激增后产生的第一个拐点A、岩爆发生前两次明显的上升台阶处拐点B和C、岩爆发生时的能量突跃点D、最终峰值点E。将关键点处波形信号从全时域波形中提取出来并进行快速傅里叶变换,得到各关键点二维功率谱图,结果表明:花岗岩声发射主频值在加载初期时为106 k Hz,随着荷载的增加,频率由低频向高频过渡,频带变宽且由单峰向多峰转化,频率成分复杂预示多种破裂模式的发生。岩爆前和最终岩爆时刻频带又变窄并恢复单峰,主频值降低至与初始加载时一致,约为106 k Hz,预示着岩爆时刻花岗岩岩石高能量的释放。
The deep rockburst simulation test system was used to simulate the instantaneous rockburst in granite. At the same time, the acoustic emission signal during the test was collected by the acoustic emission system to obtain the time-domain information of stress and acoustic emission waveform during the whole experiment. According to the cumulative energy curve of acoustic emission, five key inflection points are found, that is, the first inflection point A generated after the granite initial energy surge. The two obvious inflection points B and C at the ascending step before rock burst and the energy at the time of rock burst Sudden jump point D, the final peak point E. The waveform signal at the key point is extracted from the full-time waveform and the fast Fourier transform is performed to obtain the two-dimensional power spectrum of the key points. The results show that the main frequency of granite acoustic emission is 106 k Hz at the initial stage of loading, With the increase of load, the frequency transition from low frequency to high frequency, broadening the band and transforming from unimodal to multimodal, and the complex frequency components predict the occurrence of multiple modes of rupture. The frequency bands before and after the rockburst are narrowed again and single peaks are recovered, and the main frequency value is reduced to be consistent with that at initial loading, which is about 106 k Hz, which indicates the release of high energy of granite rocks during rockburst.