Research On Water Jet Technology For Increasing Coal Seam's Permeability And Its Application

Gas drainage is the most effective gas prevention and control method,but the traditional gas drainage method for low permeability coal seam is not effective.Therefore,this paper seeks the way to solve this problem through the research and application of water jet gas permeability enhancement technology to improve the gas drainage rate.By analyzing the basic theory of water jet gas permeability enhancement technology,the paper concludes that the main factors affecting water jet coal breaking include jet pressure,nozzle diameter and jet impact distance.After analyzing the core parameters of water jet penetration enhancement effect,a variety of nozzles with different diameters were designed and manufactured.Through the relationship test between nozzle diameter and atomization length and the coal sample cutting test in Rujigou,The test results show that the cutting efficiency and depth were ideal t was 3.0 mm with water pressure was 60 MPa.By using ANSYS/LS-DYNA software to carry out numerical simu.lation,the water pressure-impact depth curves under different jet pressures are obtained.Through analysis,when the jet pressure is 60 MPa,the impact depth tends to be gentle and the effective stress peak value of coal and rock gradually decreases,so the impact efficiency is optimal under this pressure,and the jet impact distanc.e is 75.10 cm.Through scheme design,on-site implementation and observation,on-site tests of water jet gas permeability enhancement technology were carried out at two experimental sites in Rujigou Coal Mine.Th,e test results show that the gas drainage capacity of the boreholes has been greatly increased after the water jet gas permeability enhancement technology was adopted in the two test sites,of which the gas drainage capacity of the test sites has been increased by 6-8 times.And the adoption of water jet gas permeability increasing technology can improve mine production efficiency,alleviate gas hidden danger and win-win economic and social benefits.The analysis,research and application of water jet gas permeability enhancement technology have certain theoretical guiding significance and practical value for solving the important issue of how to improve the gas drainage effect in the safe production of coal enterprises in China.