备注
The deep blasting hole can increase the permeability coefficient of coal gas,decrease slowly gas pressure and gas content,thereby reducing gas compression energy,improving the mechanical strength of coal body,reducing or eliminating the hazard of coal and gas outburst.At the same time contribute to the coal body original stress concentration zone and high pressure gas zone is shifted to deep coal,which increases the pressure relief zone width,reducing gas drainage time,so as to improve the speed of working face mining.But for the loose controlled blasting pressure relief,control hole dynamite blasting hole was not arranged in the surrounding,control hole in the blasting process controlled the blasting direction and compensation effect of blasting cracks space.Because the control oriented role to control the hole,the hole around the inside of the media have a columnar compression through blasting crack surface grinding ring and a along the blasting hole and control hole center line direction.Control hole exists is equivalent to the increase in the auxiliary free surface around the blast hole blasting resistance,relatively narrow line length,the blasting fragmentation circle is more favorable to form a wider band and loose belt.After blasting hole formed near the fracture zone and fractured zone,greatly undermined the integrity of coal and rock mass,can eliminate the large span roof hanging in the process of extraction and rotation sinking on the influence of gob,while improving the permeability of protected seam,improve drainage borehole pre pumping rate,effectively release stress,eliminate the danger of coal and gas outburst.As one of Twelve mine mine depth of KM,Ji15-31010 working face was took the outburst prevention measures,greatly improving the rate of the drainage borehole pre pumping,the gas stress and the stress was released,effectively control coal and gas outburst,and optimized the left lane area stress field,ensured the normal safety protection layer mining.