Study of Reasonable Grouting Pressure in the Process of Measuring Coal Seam Gas Pressure and Application

Coal seam gas pressure is an important index to evaluatethe riskof coal outbursts. The accuracy of measurement is closely relatedto the quality of hole sealing, and reasonable grouting pressure isone of the key factors to determine the quality of hole sealing. Toobtain a reasonable grouting pressure, a mathematical model for slurryflow was established based on the relationship between the seepagelaw of the slurry and the properties of the borehole surrounding arock. According to the conditions of the working face 11111 of thecoal seam Ji(15-17) in Pingdingshan No. 13 Coal Mine,the reasonable grouting pressure in the process of hole sealing andpressure measurement were simulated by COMSOL multiphysics numericalsimulation software. After comparing the pressure distribution andslurry diffusion characteristics in the borehole under different groutingpressures, it is concluded that the reasonable grouting pressure is4 MPa. When 4 MPa grouting pressure to seal the hole is used duringactual engineering verification, the measured gas pressure is 2.7MPa, which is more accurate than the result obtained under conditionsof sealing with normal pressure grouting.