Numerical Analysis on Apeature of High-Pressure Water Jet Punching Hole to Preventing Outburst

As impacting and cutting role of the small jet, coal around slots occured violent displacement and expansion, increasing coal cracks, which greatly improved gas flow in coal seams and made for gas emission. The original coal stress changed and stress concentration belt moved to coal seams depth constantly. With gradual relief expansion and fracture increased, coal seam permeability coefficient increased, gas pressure decreased. Coal potentiality released, coal crushed and moved, a lot of gas with adsorption state changed free, then gas fully released and gas pressure gradient decreased, which reduced outstanding risk. it was determined that aperture size was 4/15 or so of roadway floor length using ANSYS finite element analysis software, thus roadway fissures developed full, and maintained rock integrity, in favor of speeding up the face driving.