The Micro-seismic Respond Characteristics Of Coal-rock Signals Propagation And Dynamic Disasters

Based on the micro-seismic signal is the carrier of the internal information of coal and rock damage,which indirectly reflects the changes of the internal structure and stress of coal and rock mass,a micro-seismic monitoring system was constructed to explore the propagation and attenuation characteristics of blasting mining micro-seismic signals in the different propagation media and the micro-seismic dynamic response characteristics about blasting mining,coal outflow and coal wall collapse.The aspect of propagation and attenuation characteristics of blasting mining micro-seismic signal indicates that: through the combining analysis of the micro-seismic signal received by 12 channels and a total of 10 detectors,we can see that blasting mining micro-seismic signal shows the following characteristics of propagation and attenuation in the roof and coal seam.The average velocity and acceleration of blasting mining micro-seismic signals received by the rock roof are higher than that received by the coal seam,the acceleration of blasting mining micro-seismic signal in the two media is proportional to the amount of charges and negatively correlated with propagation distance and the density of medium.The energy and signal duration of blasting mining micro-seismic signal shows index and linear attenuation with the propagation distance,the energy and signal duration in the coal seam is higher than that in the roof near the explosive center,but the energy and signal duration in the roof is higher than that in the coal seam after a certain propagation distance.The propagation distance of blasting mining micro-seismic signal is limited,and the effective propagation distance in the roof is higher than that in the coal seam,the amount of charges is linearly and positively correlated with the effective propagation distance.The quality factors of the low frequency part of the blasting mining micro-seismic signal are higher than that of the high frequency part,and quality factors of the rock roof are higher than that of the coal seam.The aspect of micro-seismic respond characteristics of impact damage of coal and rock under blast mining: through detailed analyze the three types of micro-seismic signals of blasting mining,coal outflow and coal wall collapse and combined field data,the conclusion could be drawn that coal outflow has a non-linear distribution with micro-seismic response events,and the degree of instant destruction shows an increasing trend in the continuous coal outflow events;The blasting effect will greatly reduce the stability of the coal wall ahead of the working surface,which is the primary induction factor of coal wall collapse,and the period of coal body adaptive stress adjustment is a key to prevent coal and rock shocks;These three types of micro-seismic signals show that their peak durations,times consuming from micro-seismic signals arrive at detectors to restore stability,and released energy are ranked in the following order: blasting>coal outflow>coal wall collapse.Moreover,there exhibited different spectrum characteristics for them: the main frequency of the coal outflow micro-seismic signal is 800 Hz,the blasting micro-seismic signal is 400 Hz,and the coal wall collapse micro-seismic signal is 1000 Hz.Meanwhile,the low frequency parts of three types of micro-seismic signals are mainly contributed by the impact damage,and the high frequency part is mainly contributed by the coal body caving.The greater the impact damage,the lower the low frequency bound of its signal.The research conclusions could provide a theoretical basis for non-contact monitoring of coal-rock dynamic disasters,and contribute to the selection of seismic wave propagation medium and layout optimization of detectors,which also provide relevant help to improve the micro-seismic warning of coal and rock power disasters.