The Research On The Effect Of Guiqing Coal Mine Hydraulic Hole And Coal Unloading Quantity On Improving Permeability

This article mainly researches on the problems of soft coal quality,low permeability,and unreasonable quantity of hydraulic hole expanding coal and hole parameters in Guiqing coal mine,by using the methods of field tests,theoretical analysis,numerical simulation and track inspection.Analyzing the characteristic of M9coal seam outburst hazard with combinations of the feature of coal seam,microstructure and diffusion experiment.Elaborating hydraulic hole mechanism and analyzing the stress redistribution conditions around the borehole after punching,to get the relationship of depressurization zone radius,the plastic zone radius and the radius of the hole size.Under the condition of considering Klinken-berg effect,on the basis of the equation of gas seepage and permeability variation,a fluid-solid coupling model of coal containing gas is established to study the regularity of different hydraulic hole showing different punching coal amount and the effect of penetration improvement and the pressure releasing.Through the application and effect investigation,the reliability of the mathematical model was verified.The thesis mainly made the following findings:(1)It is concluded the relationship between the radius of plastic zone and depressurization zone around borehole and equivalent holes size.Increasing the equivalent hole can increase the radius of depressurization zone and plastic zone,improve the gas permeability of coal seam around borehole,and shorten the time of gas pre-drainage.(2)Considering the boundary layer molecular diffusion Klinken-berg effect under the condition of low pressure,combined with the gas seepage equation and permeability variation equation and equation of deformation control of coal and rock,established the flow-solid coupling model of coal body's deformation and gas flow.(3)Using Comsol Multiphysics numerical simulation software to simulate the stress variety around borehole and the effective influence radius when the punching coal amount is0.5,1.0 and 1.5 t/m in different time.Through studying the regularity of penetration improvement and the pressure releasing around borehole,It came to a conclusion that the relationship between effective influence radius of the extraction and single-bore per meter expanding coal quantity accords with power function r(28)Am~B.As far as Guiqing mine coal is concerned,Determined that cross layer borehole hydraulic hole punching coal amount is 1t/m,boreholes space of hydraulic flushing is 5m,space at the bottom of borehole is 5m,and extraction time is 3 months.(4)According to the result of numerical simulation about the effect of punching coal amount on hydraulic hole increasing permeability,carry out the application and effect investigation of the measure of hydraulic hole at Guiqing coal mine and Luoboan coal mine that is similar conditions with it.The residual gas content meets the effective index for outburst control.The extraction rate is improved from 12.2%,9.62%to 12.2%,12.2%respectively.In addition,the average driving speed per month of Luoboan coal mine increased from 10-15 m to 46 m,about 2.1-3.6 times,verified the reliability of the mathematical model.