The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

207 / 2018-07-04 17:24:18

Study on evolution rule of gas migration dominant channel in fully-mechanized coal mining face under dip angle of different seams

mining-induced overlying strata fissure; dominant channel; angle of coal seams; mining working face; high-level boreholes

Gas of Coal Mine & Coal and Gas Outburst > Gas of Coal mine

To investigate the mechanisms underlying evolution of mining-induced pressure-relief gas dominant channel in overlying strata fissure at fully-mechanized mining working face, similar physical simulation tests were conducted resembling the mining process of a coal mine at Heshun, Shanxi, and profiles of the dominant channels were mathematically modeled based on the theory of elliptical belt of mining-induced fissure, using angle of coal seams of working face as the key parameter. The impacts of angle of coal seams on evolution of pressure-relief gas dominant channel in overlying strata fissure at the main mining working face were comprehensively analyzed. Results suggested that increased angle of coal seams caused reduced height of the three belts and enlarged average weighting intervals, and dominant channels were formed at lower positions in the overlying strata, and presented lower height, width, caving angle and range. In addition, with the increase of the dip angle, the rate of separation and penetration of the dominant channel gradually increase, and the fractal dimension of the dominant channel is 0°<15°<30°, which shows the trend of dimensionality increase. In conducting the on-site high-level boreholes tests, parameters of the high-level boreholes were optimized according to coal seam inclination angles, and gas extraction through the high-level drilling field reached 49.94%~89.88% of the total gas emission. Accordingly, average gas concentrations at the upper corners and outtake airflow road were maintained below 0.27% and 0.32% respectively, which ensured production safety and efficiency of the mining working face. The present study contributed to theoretical basis for identification of pressure-relief gas enrichment areas in overlying strata under different angle of coal seams.