煤岩体振动破坏试验及微震信号特征

通过所搭建的大型振动试验装置和微震监测系统，探究不同激励加速度和频率条件下整体煤岩试件的振动破坏特性。利用希尔伯特-黄变换(HHT)对煤岩体受迫振动过程中的监测信号进行了模态分离和信号重构，并结合振动力学知识着重阐释了共振放大效应产生的机理。研究结果表明：微震传感器监测信号具有明显的载波特征；当激励加速度峰值达到一定水平(0.5g)时，煤岩试件出现有效微震信号，首次破裂发生在煤层中，信号随传播距离的增大而衰减；随着裂隙的产生和扩展，煤岩试件自振频率降低，当激励频率等于煤体自振频率时，试件会产生共振放大效应，微震信号明显增强；激励加速度和激励频率对微震信号均有影响，激励加速度峰值越大、激励频率越接近自振频率，则微震信号越密集、幅值越大，且出现了优势频段向低频转移的趋势；理论分析解释了上述现象产生的原因。

Coal and rock vibration failure and the characteristics of micro-seismic signals

By means of a large vibration apparatus and a micro-seismic observation system，the vibration and failure behavior of coal and rock specimen was analyzed under the conditions of different vibration accelerations and vibration frequencies.Using the Hilbert-Huang Transform (HHT) method，the mode decomposition and signal reconstruction on the monitor signals were made in the process of coal and rock vibration.Combined with the vibration mechanics knowledge，the paper explained the mechanism of resonant amplification effect.The result shows that the monitor signals have obvious carrier characteristics.When the peak acceleration reaches 0.5g，effective micro-seismic signals appear，fractures occur in coal seam for the first time and signals begin to decay with the increase of propagation distance.The natural frequencies are decreased along with the generation and expansion of cracks.When the vibration frequency is equal to the natural frequency，resonant amplification effect happens to specimen and micro-seismic signals grow noticeably.Vibration acceleration and vibration frequency both play roles in the micro-seismic signals.The greater the peak acceleration is，the closer vibration frequency gets to the natural frequency，which makes micro-seismic signals more intensive with the larger amplitude，and has a tendency to shift to low frequency.Theoretical analysis may help reveal the causes of these phenomenon.