Abstract:This paper primarily addresses the characteristics of low permeability and difficulty in water injection in coal seams of the mines under Shanxi Xinyuan Coal Industry Co., Ltd. By employing the method of mechanical cavity formation, the permeability of the coal seams is enhanced to achieve the purpose of water injection for dust prevention. Firstly, based on the field conditions, numerical simulations of cavity formation drilling were conducted using the PFC2D5.00 software. The study found that under a 500mm diameter drilling hole, the fractures initially distribute uniformly and then spread in the vertical direction. Within the elastic region, the porosity in the horizontal direction shows an increasing trend, while in the vertical direction, it shows a decreasing trend. Secondly, considering the field environment and relevant regulations, appropriate drilling intervals, cavity formation intervals, and cavity lengths were selected. Finally, suitable water injection pressure, water volume, and injection time were calculated based on empirical formulas. By analyzing the water injection effect of the coal seams after mechanical cavity formation, the results indicate that after ordinary water injection, the average increase in coal body moisture is 1.53% to 2.35%, with an average increase of 0.23% to 1.05%. After implementing mechanical cavity formation, the average coal body moisture measured is 4.83% to 7.02%, with an average increase of 3.53% to 5.75%. Through comparison, it can be seen that mechanical cavity formation significantly increases the moisture content of the coal body. The more thoroughly the coal body is moistened, the greater the increase in moisture, and the larger the average increase in coal sample moisture.
