Study on gas emission mechanism and prevention technology of extra-thick fully mechanized caving face

To improve gas management in small coal pillars,comprehensive gas drainage was implemented in the extra-thick coal seams of the 8204 working face at Tashan Coal Mine. Numerical simulations, combined with field measurements and quantitative gas source analysis, were used to examine the distribution and behaviour of gas in the working face. The study introduced ground vertical well extraction as a control method and identified the best times for gas extraction. Results showed that fractures within the small coal pillar formed channels for gas flow, causing convection between the 8206 goaf and the 8204 working face. This process made the 8206 goaf the primary gas source for the 8204 working face,contributing 62. 0% of the total gas. The best gas extraction effect was achieved within the range of 20 meters ahead of the working face to 120 meters behind the working face. The use of ground vertical shaft extraction effectively maintained gas concentrations well below the critical threshold of 0. 8%. This approach significantly reduced gas levels and offers practical guidance for managing gas in similar mining conditions.