Research On Coal Spontaneous Combustion Law And Control Technology Of Crack Coal In The Roadway Pressure Relief Borehole

Coal seam drilling pressure relief is one of the effective methods to solve the rock burst.The annular fracture area formed after drilling has developed cracks and obvious air leakage,resulting in a high risk of coal spontaneous combustion.In this paper,uniaxial compression and temperature-programmed experiments are carried out for the prevention and control of coal spontaneous combustion in the fractured area of pressure reliefboreholes.Combined with onsite observation and numerical simulation,the dangerous range of coal spontaneous combustion is determined.Through the uniaxial compression test of the porous briquette sample,the stress-strain curve of the sample during the compression process was obtained.The crack dynamic evolution process of the sample is analyzed,and the failure process is divided into five stages,and four failure critical stress values of the sample are obtained.During the failure of the sample,a crack was formed through the borehole and the upper and lower ends of the sample,and there were normal shear cracks around the borehole.The radial displacement of the upper and lower ends of the sample borehole and the circumferential displacement of the left and right ends have the largest deformation,and the displacement and deformation increase with the increase of the hole diameter.The influence area of the fissure field in the fissure area of the pressure relief borehole and the factors of coal spontaneous combustion were analyzed,and the characteristic parameters of coal spontaneous combustion in Yingpanhao Coal Mine were measured by temperatureprogrammed experiments.When the sulfur content is between 0.76 and 2.23,the higher the phase sulfur content is,the more obvious the coal-oxygen composite reaction is.When the oxygen concentration is higher,the coal oxidation reaction is more severe.The law of oxygen seepage in the fracture area of the pressure relief borehole was studied by on-site observation and numerical simulation,and the gas distribution inside the borehole was analyzed by burying the bundle tube in the fracture area along the 2202 working face auxiliary transportation.The internal oxygen concentration fluctuates with time,ranging from 5.83%to 12.63%;the fluctuation range of oxygen concentration inside the bundle tube 7#～12#in the fracture area after grouting is 5.63%～9.65%,and there is no grouting in the fracture area of the relief hole There is obvious air leakage.The gas concentration distribution in the fracture area of the pressure relief borehole was simulated,and it was comprehensively determined that the risk of coal spontaneous combustion in a single pressure relief borehole was an elliptical area with a depth of 30 m and a surrounding area of 0.63 m.A comprehensive prevention and control method of " sealing,gel plugging,monitoring and early warning" in the fracture area of pressure relief drilling is proposed.The method of sealing the hole with the bag-type chemical inhibitor filling material,the gel isolation inside the borehole and the external grouting combined with the plugging method was studied to block the circulating air leakage,and real-time monitoring and early warning of the dangerous range of the fracture area.The project demonstration was carried out in the 4108 working face of Shuiliandong Coal Mine in the fissure area of the pressure relief hole with the return air along the groove,which effectively controlled the spontaneous combustion of coal in the fissure area of the pressure relief hole.