Research On Physics Explode Model And Forecast Indexes Of Coal And Gas Outburst

Coal and gas outburst is a gas dynamics phenomenon which is affected synthetically by stress,gas pressure and the coal structure. It has a serious threat to coal mine safety production. coal and gas outburst mechanism and outburst prediction indexes research are important theoretical and technical basis of setting out outburst risk forecast and prevention measures of coal and gas outburst effect test indexes system. The article uses synthetically methods of theoretical analysis, laboratory experiment, and on-site measurement and verification to study systematically the mechanism of coal and gas outburst, fixing method of prediction indexes and critical value, testing instrumentation and engineering application, then a technical system theory from the mechanism - forecast indexes- critical value - prediction instrument– to application of project system is formed, which improves the reliability and accuracy of coal and gas outburst prediction.Basing on the full analysis of coal and gas outburst factors and its function, the article discussed the power sources and energy conversion of coal and gas outburst. in the process of coal and gas outburst, stress is the main force to destroy the coal , while the main energy of coal and gas outburst comes from gas expansion energy, so a certain amount of gas expansion energy is the necessary condition which coal and gas outburst happen and develop.The preparation occur and development of coal and gas outburst can be divided into three continuous processes:①Coal is pressure relief destructed by the aiction of stress nearly the work face;②The gas that accumulated in the coal gap poured out Sharply and coal explosion shattered;③a large amount of gas poured out and coal and gas mixed flow was produced, which transits coal and formats air Shockwave;according to plastic and elastic mechanics, aerodynamics theory, the article studied the coal seam pressure relief destruction, coal explosive fragmentation, the mechanical and energy conditions of gas and coal mixture flow in details, and put forward the physical explosion model of coal and gas outburst.According to the physical explosion model of coal and gas outburst, analyzed the impact factors of coal and gas outburst;①C oal pressure relief is the motivating factor of coal and gas outburst occur, the greater the stress, the lower seam strength, the relief wave velocity is greater,and large-scale fast relief destruction become easier for coal. it's favorable for the occurrence of gas outburst;②t he faster Coal cracks formed, the more favorable breakdown of gas bubbles and forming coal and mixed flow;the strength of coal reduces that is propitious to gas bubble break and the occurrence of outburst;it proposed that gas expansion energy greater than coal moving power is a necessary condition of moving mixture of coal gas flow. Gas expansion energy should be greater than small-sized coal and gas outburst moving power. the gas expansion energy critical value is 76.96 kJ/t, it provided a theoretical basis for determination the critical value of coal and gas outburst prediction indexs.According to outburst physical explosion model of coal and gas outburst, analyzed the relationship between prediction indexs and gas expand energy,selected region risk prediction indexes and work face outburst prediction indexes. combined with laboratory testing, technical route, process of prediction index critical value determination methods and reliability evaluation method is proposed. and provided a theoretical basis and technical approach for coal and gas outburst prediction indexs and the critical value research.According to Darcy's law of gas flow, studied the relationship of initial rate of gas emission in drilling hole q, gas pressure, test time and other factors, and put forward the technical requirements which test instrument should meet with. analyzed the shortage of test instrument of initial rate of gas emission in drilling hole q, developed WY-Ⅰtype gas q value test meter, which improves the test accuracy of initial rate of gas emission in drilling hole q.According to the relationship of gas expansion energy and prediction indexes, put forward gas desorption index Q3 ,using laboratory tests and filed measurement methods, studied the relationships of gas desorption index Q3 ,gas initial desorption quantity V1, gas pressure P and gas content X,which are good correlation.gas desorption index Q3 can be used to predict outburst rick.Through Xin'an coal filedⅡ1 coal seam gas Geological rule and laboratory studying, proposed regional prediction methods and indexes,and took a regional outburst of prediction of Xi'anⅡ1 coal seam. The result is consistent with the actual production.Through laboratory research and on-sit testing, analyzed the relationship between work face outburst prediction indexes and gas content. and also analyzed the impact factors and sensitivity of prediction indexes. Through field industrial experiment and reliability assessment, determined the Coal and gas outburst forecast prediction indexes and their critical value of Gaocheng Coal mine advancing work face, coal face and Mengjin exposing outburst seam by crosscut. and the reliability of Outburst Prediction is improved.