Research And Application Of Gas Drainage Technology In High Gas And Super Long Fully Mechanized Caving Face

Because of China's coal seam with low concentration, low pressure,low permeability of the "three low" characteristics, coal mine gas source from the source of governance has three aspects, the coal gas control,goaf gas control and adjacent layer gas control. But because of fully mechanized caving mining has the advantages of large output, low cost and good benefits, widely used in China, with the large amount of coal left in goaf, the gas concentration in goaf is more serious, which not only affects the production but also endangers the safety of employees. Gas drainage of coal mine gas can solve the problem fundamentally. The goaf problem is an effective way to save costs by changing the ventilation method. Therefore this paper based diffusion equation in the derivation of the coalbed gas migration, with the help of COMSOL Multiphysics numerical simulation software to simulate the different drainage time,drainage hole, drainage pressure, drainage hole spacing, rock pressure or drainage effect of porosity and permeability, to find suitable gas drainage parameters; influence the ventilation mode of goaf gas concentration ratio; simulated high pumping height and theoretical formula of calculating roadway. Finally, the monitoring values in engineering practice are compared.The extraction effect of pumping time before 180d is better than that of later, the extraction hole is 120mm, The negative pressure is lOkPa,and the hole spacing is 5m. The problem of gas overrun in the upper corner and the working face is solved by changing the ventilation mode,to simulate the change of gas concentration in goaf, it is determined that the Ventilation way is "Y" and high pumping lane. Through the calculation of the periodic weighting step distance is 8.8m-11.7m, the three zone in the goaf caving zone height of 11.8m-18.1m, numerical simulation the height is 15.5m, determine the UDEC numerical simulation software to simulate the excavation distance of 20m, the three zone height and formula contrast match. Monitoring values in real applications the maximum Kmax value of gas desorption index is 0.38;The maximum Smax value of drilling cuttings is 2.4 kg/m; The gas content of W is less than 8m^3 /t, meet the standard requirements.