Abstract: Abstract: For the treatment of thick coal seam with large mining height fully mechanized caving face gas "far field", in Tashan mine 8214 working face as the research background, the use of "O" ring theory, analysis the study found that gas flow characteristics in the goaf overburden fissures in the ground, "L" type hole end the horizon is located in the "far field" gas enrichment zone, therefore, by using the "L" type drainage technology governance "far field gas, comparative analysis of the implementation of the" L "type ground drainage" far field gas before and after the studies show that the variation of gas concentration, the roof roadway, implementation the "L" type after drilling, the gas concentration of the roof roadway is significantly reduced, and the gas concentration of roof roadway tends to be gentle, modest, remained at about 2.5%, therefore, the ground of "L" type drilling well shared roof roadway drainage Mining pressure to ensure the safe production of coal mine.

Key words: "L", type drill ground