Research on gas extraction technology of directional long drilling for roof plate of coal face in high gas mine

In order to study the construction parameters of long directional drill holes in 1213 working face, it was determined through theoretical analysis that the drill holes were arranged vertically in the fissure zone (12.9～42.3 m) and horizontally 9～50 m away from the back-air lane, and by simulating the distribution of the gas concentration and the flow field in the four kinds of different final spacing of the holes, it was found that the final spacing of the holes in the normal direction was 2m, and the horizontal spacing of the holes in the normal direction was 3m with optimal extracting effect. Three groups of directional drilling holes were arranged in the top plate of the return-airway, and the pure amount of gas extracted from the drilling site and the gas concentration in the upper corner showed a stable stage and a decay stage, with the highest gas concentration in the upper corner being about 0.42%. The results of field application show that the top directional drilling extraction effect is better, and can effectively solve the problem of over-limit of gas concentration in the working face.