Experimental Study On Laminar Spallation And Dynamic Evolution Characteristics Of Coal Body During Coal And Gas Outburst

Coal and gas outburst is an extremely serious underground power accident,and the laminar spallation phenomenon in the process of coal and gas outburst has been the basic problem in the study of outburst evolution mechanism.Therefore,in order to reveal the experimental research on the evolution characteristics and dynamic characteristics of laminar spallation of coal body in the process of coal and gas outburst,based on the uniaxial mechanical experiments of coal samples and the adsorption experiments of different gases,this paper independently designed a coal and gas outburst simulation experiment system,and carried out coal and gas outburst simulation experiments with different geostress,different adsorption gases,and different coal body strengths,The laminar spallation evolution and dynamic characteristics of coal in the outburst cavity during the outburst process,and the outburst intensity and distribution characteristics of coal powder after the outburst are analyzed.The following research results have been achieved:1)The elastic modulus and uniaxial compressive strength of coal specimen increase with the increase of humic acid sodium concentration.The adsorption performance of CO₂ gas on coal is greater than that of CH₄ gas and N₂ gas.2)The laminar spallation of coal body mainly appears from the weak structural plane behind the coal body and develops to the front,and its location is mostly concentrated in the middle and rear of the outburst cavity.The fracture thickness of coal body presents a trend of increasing with time.The fracture of coal body develops rapidly in the early and middle stages of spallation,and develops slowly in the later stages.The coal body is accelerated first and then decelerated,and the acceleration time is less than the deceleration time.The closer the coal body is to the outburst,the faster the coal body moves and the longer the distance.The development time of coal seams,the total thickness of coal seams,and the migration distance of coal seams increase with the increase of stress,increase with the enhancement of gas adsorption performance,and decrease with the increase of coal strength.3)After the outburst,the gas pressure of the coal body changes with time,and the decay rate is from fast to slow.The evolution law of coal gas pressure under different adsorbed gases is slightly different,which shows that the stronger the adsorption performance of gas on coal,the slower the decline rate of gas pressure in the early stage of outburst,and the longer the disturbance time of gas in the outburst cavity.The coal seam stress also shows a decay trend with time,and the decay rate is from fast to slow.The stronger the adsorption of gas to coal,the faster the decline rate of coal seam stress in the prophase of outburst;The greater the coal strength is,the slower the decline rate of coal seam stress in the early stage of outburst is.4)Stress,adsorbed gas and coal body strength have great influence on coal and gas outburst strength.The outburst strength increases with the increase of stress,increases with the increase of gas adsorption performance,and decreases with the increase of coal body strength.Compared with the other two,the adsorption gas has a greater impact on the outburst strength.The mass distribution of outburst pulverized coal presents a trend of vibration attenuation along the way,and more pulverized coal is distributed in the middle of the pipeline.The stronger the adsorption property of gas,the farther the protrusion distance;The greater the coal strength is,the smaller the coal outburst distance is.Figure[44]Table[12]Reference[89]...