Study On Time-frequency Characteristics Of Acoustic Emission And Electromagnetic Radiation Signals In The Evolution Process Of Coal And Gas Outburst

Coal and gas outburst are a kind of dynamic disaster in coal mine production,which will cause huge casualties and property losses.How to effectively warn coal and gas outburst has become one of the difficulties in curbing the safe production of coal mines.Electromagnetic radiation and acoustic emission technology have been widely used in coal and gas outburst warning,and have achieved certain results,but lack of research on the time-frequency characteristics of acoustic and electrical signals and the prominent precursor information in the process of prominent evolution.In view of this,this paper carried out the experiment of coal body loading and rupture,using characteristic parameters and waveform spectrum method,analyzed the time series and frequency series characteristics of acoustic and electrical signals in the experimental process,selected the acoustic parameters of acoustic signals,and carried out the coal mining roadway induction.Coal and gas outburst sound and electricity monitoring experiments,the characteristics of time-frequency,waveform and power spectrum of acoustic and electrical signals in the process of evolution are studied,and the precursor information of acoustic and electrical signals is obtained.Based on theoretical analysis and experimental research,when acoustic signals are selected Based on the frequency characteristic parameters,an early warning model of coal and gas outburst butterfly mutation in coal roadway face was constructed,and a butterfly-type mutation fuzzy warning method was proposed.The research results obtained in this paper mainly include:(1)The energy value,counting and centroid frequency of the acoustic and electrical signals are sensitive to the damage of the coal body during the experimental process of coal loading and fracture.It can be used as the characteristic parameter of acoustic and electrical monitoring.The peak frequency of the acoustic and electrical signals is broken by the coal body.Poor responsiveness.(2)The energy value and count of the acoustic and electrical signals have a good response to the deformation and rupture of the coal body during the process of coal mine roadway induced excavation,and the upward trend of the excavation footage is increasing.The peak frequency of the acoustic signal is basically unresponsive to the fracture of the coal body during the excavation process;the centroid frequency of the AE signal is sensitive to the large-scale fracture and protrusion of the coal body.The centroid frequency of the EMR signal is sensitive to small-scale micro-fracture of the coal body during the excavation process and is not sensitive to large-scale rupture.The sudden increase behavior of the AE signal energy value,the count,the centroid frequency,and the energy value of the EMR signal before the protrusion can be used as precursor information for the coal body to protrude.(3)The waveform and power spectrum of the acoustic and electrical signals induced by the excavation process of coal roadway are sensitive to the time series and frequency domain of coal rupture,and the trend is more obvious.The waveforms of the acoustic and electrical effective signals in the process of coal roadway excavation and accentuation are divided into strong period,decay period and gentle period;the waveform amplitude of the acoustic and electric effective signal increases with the advancement of the excavation;the waveform wavelength of the AE effective signal is continuously shortened.A "spike" type of sudden decrease occurs near the protrusion;the wavelength of the waveform of the EMR effective signal is continuously increased.(4)The power spectrum of the AE effective signal in the process of coal roadway induced excavation is divided into rising period and quiet period.The power spectrum of EMR effective signal is more turbulent,and the peaks of both are increasing with the advancement of excavation.The energy carried by the main frequency band of the AE effective signal continues to rise throughout the tunneling process,and the energy carried in other frequency bands only rises in the vicinity of the protrusion.The energy carried by each frequency band of the EMR effective signal is greatly increased during the whole process of tunneling induction.During the prominent experiment,the main frequency band of the acoustic and electrical effective signal is always in the range of 0~10kHz,indicating that this frequency band is sensitive to micro-fracture of coal.40~50kHz and 25~34kHz are sensitive frequency bands of acoustic and electric effective signals respectively,which are sensitive to the large-scale rupture of nearby coal bodies.(5)Combining the catastrophe theory and the fuzzy mathematics theory,the AE intensity,EMR intensity,AE centroid frequency and EMR centroid frequency are selected as the control variables,and the coal and gas outburst risk are taken as the state parameters,and the coal and gas are constructed.The butterfly-type mutation model was highlighted,and a fuzzy warning method for the butterfly-type mutation of coal and gas outburst was established.The research results have certain theoretical basis and experimental basis,which can reveal the time-frequency characteristics of AE and EMR signals in the process of coal and gas outburst evolution,fully obtain prominent precursor information,accurately warn coal and gas outbursts,and reduce false positives and false negatives of prominent events.And the warning method has a wide range of application prospects.