Study on application of D-type energy gathering blasting tube on gob-side entry retaining

In order to obtain reasonable blasting parameters for D-type energy gathering tube, combined with conditions of the roadway along the No.22204 entry of No.1 coal mine of Yunmei, the influencing factors affecting the pre-splitting blasting effect, including the charge amount, sealing length, charging structure and the blasting hole spacing, etc. were studied and the down-hole blasting test was carried out,. An interval blasting method was put forward,and the non-blasting holes were used to connect the cracks in adjacent blasting holes, and the borehole observation technology was used to monitor the blasting effect. Finally, the reasonable pre-splitting blasting parameters of D-type energy gathering tube were determined in gob-side entry retaining of No.1 coal mine of Yunmei. The single hole charge of the blasting hole is 9 m in depth,48 mm in hole diameter and 15 degree inclination, the charge quantity of single hole is advised no less than 450 g/m, the length of sealing hole should not be less than 2 m and the interval space between two blasting holes is no more than 800 mm. It has a certain engineering reference value for for the selection of the pre-splitting blasting parameters under the same conditions.