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采用多重分形理论研究了冲击破坏过程不同阶段微震波形的多重分形及其时变响应特征,提出了将最大多重分维数D_(maxq),多重分形谱参数Δα和Δf(α)作为煤矿微震波形多重分形特征量.研究表明:冲击诱发微震波形的多重分形特征明显强于冲击前后的常规微震波形;D_(maxq)和Δα能够反映微震波形的非均匀性和波动程度,D_(maxq)和Δα越大,微震波形的非均匀性和波动性越强,多重分形特征越明显;Δf(α)是反映微震波形信号中大小峰值所占比例的度量,Δf(α)越小表示微震波形中大峰值所占比例越大,即微震波能量越大.冲击破坏前微震波形多重分形特征量D_(maxq),Δα和Δf(α)的时变响应具有明显的规律性,当D_(maxq)或Δα超过其下临界值并持续增加接近其上临界值时,或当Δf(α)小于其上临界值并持续降低接近其下临界值时,特别是当上述3种时变响应特征同时发生时,极易发生大的冲击破坏事件;微震波形多重分形特征量D_(maxq),Δα和Δf(α)的时变响应特征能够作为有效的前兆信息对冲击地压进行监测预警.
Multifractal theory is used to study the multifractal and time-varying response characteristics of microseismic waveform in different stages of impact damage process. The multi-fractal dimension D maxq, multifractal spectrum parameters Δα and Δf α are proposed as the microseismic waveform The results show that the multifractal characteristics of shock-induced microseismic waveforms are significantly stronger than those of conventional microseismic waveforms before and after shocks. D maxmax and Δα can reflect the non-uniformity and fluctuation of microseismic waveforms, D maxq and Δα The larger the nonuniformity and volatility of the microseismic waveform, the more obvious the multifractal feature is. Δf (α) is a measure of the proportion of the peaks in the microseismic waveform. The smaller Δf (α) The larger the peak value is, the larger the microseismic energy is. The time-varying responses of the multifractal characteristics D maxq, Δα and Δf (α) of the microseismic wave before impact failure have obvious regularity. When D maxq or Δα exceeds its lower critical value and continues increasing above its upper critical value, or when Δf (α) is less than its upper critical value and continues to decrease close to its lower critical value, especially when the above three time-varying response characteristics occur simultaneously Very easy to happen The impact failure event; multifractal microseismic waveform feature amount D_ (maxq), when Δα and Δf (α) varying in response to the impact pressure characteristics can be monitored as an effective precursor warning information.