Study On Electromagnetic Radiation Real-time Monitoring And Automatic Early-warning Of Rockburst

China is the country with the most severe rockburst in the world,and its prevention problems seriously restrict the safety and efficient production of mines.As an effective geophysical monitoring method,coal-rock electromagnetic radiation technology has been applied to most mines with serious rockburst in China.The current electromagnetic radiation monitoring of rockburst is mostly mobile monitoring.Although the online electromagnetic radiation monitoring equipment has also been applied to on-site monitoring in recent years,it has been used to access the coal mine KJ safety monitoring system as a sensor,and has not become an independent monitoring system.And there are not deep studies on in-depth analysis of real-time monitoring data,precursor response characteristics,automatic risk identification and Early-warning tips,which limits the effectiveness of monitoring and Early-warning.Therefore,it is of great practical significance and engineering application background to develop independent real-time monitoring of rockburst electromagnetic radiation and automatic warning system and technology.Through the design and development,theoretical analysis,field test and other means,the paper develops the real-time monitoring system of rockburst electromagnetic radiation,reveals the time-space characteristics of electromagnetic precursor of the rockburst hazard at the mining site,and proposes the automatic identification and Early-warning model of the rockburst hazard and applies it on site.The main research results obtained in the research are:(1)Taking the No.7 coal seam mining face with the risk of rockburst as a typical model,a numerical simulation model of mining face was established based on its geological.Mining actual conditions and coal-rock mechanical parameters.And the stress distribution and variation law,stress concentration area,and the influence of stress concentration on rockburst in the mining process of new west-1 and west-1 working face at the No.7 coal seam are obtained;the superposition effect of the coal seam,the upper and lower adjacent goaf and the remaining coal pillars on mining in working face are analyzed theoretically and calculated;on the basis of the results of comprehensive numerical simulation and theoretical analysis,according to the three levels of “Danger Zone,Threat Zone and Safe Mining Zone”,the rockburst risk of four mining faces at No.7 and No.10 coal seams are divided by region,and the key area of rockburst risk is determined.The results provide a theoretical basis for developing a reasonable on-site real-time monitoring scheme for electromagnetic radiation and realizing comprehensive and dynamic monitoring of mining stress concentraiton and rockburst hazard.(2)According to the actual demand of the electromagnetic radiation monitoring of rockburst on the mining site,the real-time monitoring system of rockburst electromagnetic radiation was developed,and the corresponding system software was designed.And the system can realize the high-sensitivity acquisition and orientation of electromagnetic radiation signal,real-time monitoring and depth analysis of monitoring data at the mining site and achieve full coverage of monitoring time and omission of monitoring information.At the same time,the system has anti-interference and noise filtering design,including increasing slot on sensor directional antenna,optimization and selection of monitoring direction and angle,water-repellent envelope,noise suppression design of signal acquisition equipment circuit and filtering algorithm for monitoring abnormal data.These treatments enhance the anti-jamming capability of electromagnetic radiation monitoring,reduce and eliminate the adverse effects of electromagnetic interference sources and signal noise on effective electromagnetic radiation monitoring signals during field operations,and further improve the accuracy and reliability of real-time monitoring and automatic warning.(3)Field tests are carried out to investigate the stress distribution and variation during the mining process of the No.7 and No.10 coal seam working face,and the electromagnetic radiation monitoring law in the stress concentration area.And the electromagnetic radiation response law of increasing rockburst risk and the periodic roof collapse caused by the stress concentration and release of working face are obtained.(4)Based on the combined mobile and online monitoring results,the study analyzes and reveals the time-space characteristics of the electromagnetic radiation precursors before the occurrence of the coal cannon,the stress release,the roof collapse and other dynamic manifestations of the No.7 and No.10 coal seam working faces in Daanshan Mine.The theory of energy dissipation and coal-rock instability and solid fracture are introduced in this study.From the perspective of energy and fracture instability,the response behavior and mechanism of electromagnetic radiation precursors in time and space before the occurrence of rockburst and dynamic disasters are explained.(5)An Early-warning method of impact ground electromagnetic radiation based on dynamic trend and critical value method is proposed.An automatic classification warning model of rockburst based on real-time monitoring of electromagnetic radiation is established.A real-time monitoring and analysis and automatic warning software platform for electromagnetic radiation is developed.The application was carried out at the mining site of Da'anshan Mine.Before the “4.19” rockburst with 2.7 magnitude and some roof collapse events occurred,the automatic identification and Early-warning of danger were successfully carried out,and the effect was obvious.The research results enrich the technical system of rockburst prevention,and provide a basis for the application of real-time monitoring system and automatic Early-warning technology for rockburst electromagnetic radiation.