Combination of Directional Drilling and Coal Seam Drilling to Control Gas in Coal Mining Face
In order to meet the need of gas control in high-intensity coal mining,combined with the site situation of 15303 fully-mechanized caving face,a combination method of kilometer directional drilling and coal seam drilling was proposed to control gas.Based on theoretical analysis and numerical simulation,kilometer directional drilling layout was determined to be 21-45 m,and km directional drilling was carried out synchronously during mining roadway excavation to ensure the completion of pre-mining drilling;the coal seam boreholes were arranged at 2 m spacing in the mining roadway to realize gas pre-drainage in the mining area.After the field application,the gas drainage efficiency of 15303 directional borehole in kilometers of fully-mechanized caving face was higher,and the gas volume fraction in the return air roadway and the return air corner of the mining face was controlled within 0.27%and 0.69%respectively,which ensures the safe production of the mining face.