Experimental study on relationship between surface fracture distribution and gas adsorption as well as emission characteristics of outburst coal seam

Abstract

Gas absorption and emission characteristics are very important for the prediction, inspection and prevention of coal and gas outburst disasters, which are related to the structural distribution characteristics of coal fractures closely. In this paper, the coal samples of No.2, No.4, No.8 and No.9 coal seams in Dongqu Coal Mine are selected, and the fractal dimension is used to quantitatively characterize the distribution of coal surface fractures. The relationship is studied between the characteristic parameters of fracture distribution and gas absorption and emission. The results show that the fractal dimension parameters of the fracture distribution on the coal surface are solved by fitting based on the fractal theory. The value range of the fractal dimension parameters is 1.4-1.5, and the development degree of primary fractures is No.9 coal seam>No.4 coal seam>No.8 coal seam>No.2 coal seam. The isothermal adsorption constants of coal and the initial velocity of gas emission are analyzed through the gas adsorption and emission experiment. The value range of adsorption constants a is 34.180-36.920 m3/t, while the value range of initial velocity of gas emission is 12-18 mL/s, which is consistent with the fractal dimension value. The correlation between fractal dimension parameters and gas adsorption and emission parameters of coal in Dongqu Coal Mine are statistically analyzed. It shows that there is a significant positive correlation between them. The fractal dimension value can characterize the values and capabilities of gas adsorption and emission of coal in this coal mine.

Keywords

• outburst coal seam
• surface cracks
• fractal dimension
• adsorption constant
• initial velocity of gas emission