Application of technique of quasi-parallel cutting blasting in Zhengxing coal mine

In order to improve the speed of rock drivage in Zhengxing coal mine,technique of quasi-parallel cutting blasting is applied.New blasting schemes is designed according to the conditions of rock.The test results are as follow:① The number of blast holes makes considerable reduction;② Blasting footage is significantly improved,footage is above 1.84m with each repetition.Utilization ratio of blast hole brings up to 92%;③ There is a 25% decrease in explosive specific charge;④ Contour outline of roadway is better.There is a marked improvement in the rates of half-hole marks.Over-excavation and under-excavation phenomenon are seldom seen.