Abstract:

To prevent protected gas flooding to protective working face, cause its top corner and return air roadway gas overrun , based on gas migration rule in “three zones” of goaf overling strata, took use of high drilling to draiage prssure relief gas from proteccted seam; Through practical application in Yangdong mine 8458 working face, adop theoretical calculation and numerical simulation to determine the height of the fracture zone and desingn high drilling parameter; Results show that every drilling of the working face pure gas drainaging quantity increased from 0.5 m3 / min to 0.8 m3 / min, gas concentration of return air roadway reduced from 0.9% to 0.4% and gas concentration of the upper corner reduced from 1.2% to 0.6%, improved gas drainnage rate, ensured the safety and efficiency of recovery.

Key words: protective layer mining, protected layer, high drilling, crack development area, gas drainage