Research On Simulation Experiments On Coal And Gas Outburst In Various Particle Size

Coal and gas outburst is an extremely complex dynamic phenomenon during coal mining, and also is the major threat to China's coal mine safety production. This paper studies the effect of different coal particle size on the coal and gas outburst process, and the coal particle size is the coal's physical and mechanical properties, which belongs to the integrated hypothesis of coal and gas outburst. By using the coal and gas outburst process simulation platform developed by Southwestern Resources and Environmental Disaster Control Engineering of Education Ministry Key Laboratory (Chongqing University), digital cameras, polarized light analysis software, triaxial shear apparatus and other equipments, this research carries out the experiment on the porosity analysis of briquette, the experiment on the basic mechanical properties of coal rock, and the experiment on the coal and gas outburst.Porosity Characteristics analysis of briquette mainly aims at the pores generated in the forming process, and these pores are relatively large. According to Khodot pore classification, these pores belong to large holes, which constitute a strong infiltration of laminar flow, and visible holes and cracks that constitute laminar flow and turbulent mixing infiltration. In the way of digital cameras taking pictures and polarized light analysis software analyzing, the results of coal porosity test show that, under the same shaping pressure, the larger of coal particle size is, the larger porosity of coal sample is; while the less the total pore number is, the bigger average pore radius is. According to the result of fractal dimension analysis, the more the pores are and the more complex the pore distribution of coal is, the greater fractal dimension is. From the results of triaxial compression experiments on briquette of different particle size, it can be concluded that the uniaxial compressive strength of briquette of large particle size is bigger than that of the small one. In the end, the uniaxial compressive strength of briquette samples is fitted with the average coal particle size, and then the corresponding fitting formula is built.After briefly introducing the characteristics and basic operation steps of the self-developed coal and gas outburst process simulation platform, this paper gives an explanation to the process of coal samples production, the distribution of the outburst coal collection areas, the experimental program and the corresponding ancillary equipment. The fatalness of fire and explosive disaster is analyzed in outburst laboratory. At first, by using fault tree analysis, the combination of a variety of reasons for the disaster is qualitatively obtained. Next, by using FLUENT, numerical value simulation of the gas density migration law is carried out in outburst. In the end, the corresponding safety proposal is put forward to increase the nature safety of laboratory.Through the wavelet denoising on the temperature evolution curves during the whole process of gas adsorption and desorption (contains extraction vacuum), it remove the interference and get the smooth and stable temperature signal. By comparison, if coal particle size is smaller, the faster the temperature drops when gas is extracted, the faster the temperature rises when gas is infused, and the faster the temperature drops when outburst happens. Coal particle size significantly affects the outburst strength, and the smaller the coal particle size is, the stronger the outburst strength. In detail, the heavier the outburst coal is, the farther the coal is from the outburst hole. Most of outburst holes look like pear or oval shape with small mouth but big volume, and the smaller the coal particle size is, the larger volume the outburst holes have. Still, this paper uses Pearson correlation coefficient to analyze the internal links among the coal particle size, the outburst strength, uniaxial compressive strength and other factors, chiefly focusing on the relationship between the different coal particle sizes and other factors, such as basic mechanical properties, microstructure, outburst strength, temperature evolution law and so on.