High-pressure water jet slotting and influence on permeability of coal seams

Based on pressure relief and permeability increase technology used by high-pressure water jet slotting,researched the changes of slotted coal seam permeability.Analyzed the effect of stress and pressure on gas permeability of coal.According to the actual slotted process to set model,using FLAC simulation software,simulated the change characteristics of the relief effect scope of slotted coal.Adopted a similar method of physical modeling experiments and established similar model to measure permeability variation when the process of slotted coal seam pressure relief changes;and conducted field trials.The results show that the pressure relief around coal after slotting,coal permeability increases with the impact of pressure relief after slotting.Field test results show that after slotting,coal seam permeability increases to 113 times of the original,effective influence on extraction expands to 2 times of the original radius.