Application of the technique of quasi-parallel cutting blasting inhalf-coal tunnel drivage

In order to improve speed of half-coal tunnel drivage in Jinhuagong coal mine, technique of quasi-parallel cutting blasting was applied.On account of the rock distribution characteristic of the half-coal tunnel, new blasting scheme with the technique of quasi-parallel cutting blasting was designed.Results of the application indicate that:average blasting footage cycle is 1.82 m, and average blast holes utilization factor is 91%, increases by 15% compared to pre-application; specific charge is reduced by 30% compared to pre-application; the rates of half-hole marks are all up to 81%, increases by 41% compared to pre-application, and contour outline of half-coal tunnel is very good.