Based On The Acoustic Emission Of Coal And Gas Outburst Experimental Study

With the development of coal mining, frequent occurrence of minedisasters poses a great threat to the safety production of mining. There are fivemain categories of mine disasters occurring in coal mines, including coal andgas outburst, heavy coal dust and mine explosion, mine fire, mine flood androof accident. Among these disasters, the foremost dangerous coal and gasoutburst, is not only threatening safe production of coal mines, but also causingconsiderable loss to national property, especially it being a potential factorinfluencing the safety of miners who works underground. Long repeatedpractices and explorations discovered that although coal and gas outburstdisaster happened suddenly, it had obvious precursor before and after thedisaster happening. Based on previous academic research, this thesis carried outthe simulation of coal and gas outburst collected from the coal mine, exploredthe internal acoustic emission activities of coal and gas outburst using acousticemission detection technology and meanwhile conducted a contrastiveexperiment to investigate the physical properties of coal and the characteristicsof adsorption and desorption of coal containing gas, which could improve theaccuracy of acoustic emission technique to predict coal and gas outburst disasters and also had its unique guiding significance.The thesis includes five chapters and two experimental parts, as follows:Chapter1introduces the domestic and overseas energy situation, analyzesthe risk of coal and gas outburst disasters, as well as prediction and preventionmethods of coal and gas outburst prevention and proposes research direction.Chapter2expounds the generation mechanism of coal and coal bedmethane, competitive adsorption mechanism and the molecular layer adsorptiontheory, which provides strong theoretical guidance for coal and gas outburstexperiments, and also makes experiments for the adsorption and desorption ofcoal.Chapter3outlines the mechanism of acoustic emission and elaborates thismechanism including the introduction of composition and parameters oflaboratory equipment in the process. The discussion and analysis of thefeasibility of applying acoustic emission technology to the prediction of coal andgas prominent are presented in this chapter. According to different acousticemission sensor arrangement positions, three different experiments areconducted to testify this feasibility in order to explore the best plan to arrangeacoustic emission sensor.Chapter4systematically discusses acoustic emission experiments of coaland gas outburst under triaxial loading, including experimental background, thespecimen, debugging of experimental equipment, experimental methods, andprocedures. Chapter5analyzes and compares the experimental results, which manifeststhat all internal activities of experimental coal and gas outburst can be detectedin three programs conducted in six experiments, a whole process from internalcoal crushing at the beginning of the experiment to outburst. Changes inexperiment1,2and3show different results obtain in different experiments ofacoustic emission of ringing launch count, acoustic emission energy, amplitude,average frequency, the cumulative number of events and the energy accumulatedover time.