Some industrial activities in mines, such as underground coal mining, destress blasting for preventing rockburst, and ground blasting for mining, can cause microseismic occurrence. The microseismic waveform contains abundant information on the hypocenter and propagation path, which is valuable to study the microseismic mechanism and propagation. Therefore, this study adopts the multifractal detrended fluctuation analysis (MF-DFA) and the Hilbert–Huang transform (HHT) method to study the nonlinear and time–frequency–energy characteristics of different types of microseismic waveforms. The microseismic waveform induced by mining and destress blasting has a higher dominant frequency (above 100 Hz) and shorter duration (less than 0.5 s) than ground blasting-induced microseismic waveforms (dominant frequency below 25 Hz and duration more than 3 s). Furthermore, for destress blasting-induced microseismic waveforms, the waveform is characterized by rich spectrum, complex energy attenuation, developed coda wave, and clear multifractal characteristics, which indicate that the waveform is more complex and variable. The complex underground geological environment and the superposition effect of blasting stress and mining stress are the main reasons. Moreover, the propagation distance and source energy of microseismic waveforms also greatly affect waveform characteristics. The results show that the waveform information of destress blasting-induced microseismic waveforms can describe the release process of blasting stress and mining stress. Based on this, a blasting efficiency index Be was proposed to evaluate the effect of pressure relief, and the classification system was developed. Then, the evaluation index was successfully applied to 63 rounds of destress blasting in the Yutian coal mine. The research results can provide a certain reference for some work such as the identification of different microseismic, rock dynamic failure process analysis, and evaluation of the destress blasting effect.

In underground coal mines, the deep-hole blasting (DHB) technology is generally adopted for thick hard-roof control. This technology uses the energy released by explosives to weaken the energy storage capacity of hard roof so as to prevent hard-roof rock burst disasters. In this paper, a numerical simulation model of roof DHB was established based on particle flow and the damage range of single-hole blasting with concentrated cylindrical charge was studied. The temporal and spatial evolutions of overlying strata, the distribution of the force chain structure, and the working resistance of hydraulic pressure in the mining process before and after the application of DHB were contrastively analyzed. The following beneficial conclusions were drawn. The blasting-induced single-hole damage range is generally characterized by annular zoning. After the application of DHB, overall the collapse morphology of the key strata in the mining process changes from long-distance instantaneous slipping instability to stratified short-arm stepped synergistic subsidence. The density and strength of force chains in the overburden are notably reduced; the peak value of compressive force chain strength in the key strata in the mining process falls by 17.85% as a result of DHB. The monitoring results of the working resistance of hydraulic support reveal that the DHB technology can effectively shorten the step distance of periodic weighting and reduce the variation amplitude of overburden load during weighting. In summary, the mechanism of hard-roof rock burst control by DHB is reflected by both static load reduction and dynamic load reaction.

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