Study On The Regulation Of Stress Distribution In Coal Seam Slotted By Pulsed Water Jet During The Process Of Coal Roadway Excavation

Advancing hole is commonly used in the outburst mine to prevent outburst, but theinfluence scope of drilling is limited, which results more drillings and a longerconstruction time. Slotting technology by pulsed water jet can improve the influencerange of single-hole, but little research in the influence range of the drilling afterslotting lead to a unreasonable layout of drilling, it has a negative effects on preventingoutburst and advance in coal. Coal stress have a certain impact on ground stress and gas,so there is meaningful to study the regulation of coal stress in order to determine theinfluence range of drilling after slotting.This paper presents the analysis about the relief stress influence on the distributionof coal stress which is caused by the pulsed water jet slotting, and the ground stress andgas pressure in the various distribution of coal stress. Simulation is applied to researchthe influence of impact regulation of coal stress by ground, depth of slotting, width ofslotting, distance of slotting and arrangement of slotting. Optimized layout of drillingand field test has been done to evaluate the simulation results. There researchconsequences are as follows: The main conclusions are stated as follows:â‘ An elliptic pressure relief zone is formed around the slotting which is cut by thepulse water jet. Ground stress is reduced and gas is easy to emissions in this area, at thesame time, the pressure relief of pulsed water jet slotting can increase the width of therelief area on coal tunneling surface stress field, reducing the possibility of coal and gasoutburst.â‘¡The variation of coal stress in the pressure relief zone is demonstrated, thefarther from the slotting, the lower destressing rate. When coal buried depth increasedfrom200m to1000m, the relief volume and plastic zone gradually increasing and theinfluence scope also increased. While depth of slotting increased from1.0m to3.0m, therelief volume increased exponentially and relief effects increased significantly. But theinfluence of width of slotting is not obvious in the effectiveness of pressure relief. Withthe increasing of slotting distance from2m-6m, the relief volume is in inverted "V"shape distribution, Optimal depressurization efficiency can not be reached when slottingdistance is neither too small nor too much. Parallel and cross arrangement of the samelevel can make cross range wider and more stress concentration factor. There is afeasible method to relief stress the coal. Relief range of slotting can be drawn through the uniform design by the linear regression formula.â‘¢T The influence scope of pulse jet slotting technology can reach2.5m on theå·±_16-17-22302working face. The layout of drilling is optimized Based on the numericalsimulation and the experiment results. The pulsed jet slotting technology is applied ontheå·±_16-17-22302working face. Residual gas content is less than8m³/t and thedepressurization efficiency has been successfully reached. Compared with thetraditional drilling technology, the number of drill holes is decreased from10to5in asingle cycle, which the amount is50%of former method, the execution time of outburstprevention measures decreased from8classes to5classes, reduced by37.5%.