Research and application of water gel explosive grain on coal mine gas extraction in coal seam deep hole blasting

Aimed at high gas and low permeability coal seam,initial peak pressure of blasting shockwave,incident pressure propagating to hole wall and projective pressure from coal surface of hole wall were theoretically discussed when water gel explosive grain of coal mine gas extraction was used in coal seam deep hole blasting.The dynamic stress field around the coal seam was built,and the radial crack area and expansion radius in blasting source were analyzed.Finally,the crack area radius was applied to distribution parameter design of coal seam blasting holes and extraction,the reasonable blasting span between deep hole presplitting explosion and gas extraction in high gas and low permeability coal seam was put forward,which was applied to engineering practice.The results show that the method supplies an effective solution for antireflection of high gas and low permeability coal seam and for solving gas extraction in coal seam.