| Gas extraction of borehole is the most effective technical measures of controlling gas disasters,while the key to gas extraction effect is the sealing quality of borehole.But the stress filed of the borehole is changing,so the boreholes always happens the buckling failure,which affect the effect of the gas extraction.The original coal body is simplified as a viscoelastic body in this paper,then analysing the deformation and gas leakage mechanism of drilling hole.according to the nonlinear Darcy.Seepage law,and combing the visco elastoplastic model around the drilling hole,established the fluid solid couping model of the coal containing gas,considering the gas pressure and adsorption effect of coal seam.By using COMSOL Multiphysics multi field numerical simulation software,the dynamic laws of stress,gas pressure and dynamic permeability around the borehole are studied respectively by numerical simulation.By using COMSOL Multiphysics multi physics field numerical analysis software,the construction process of new sealing technology is simulated.Through the simulation analysis of roadway stress distribution on the influence of gas pressure distribution,the characteristics of variation of junction stress around the roadway junction and gas pressure has greatly changed,for determining the appropriate range of sealing depth;through the simulation permeability difference of sealing section,studying the effect of different sealing hole technology to the sealing effect and support effect of the drill hole,verifying different sealing process for gas drainage.Finally,according to the sealing depth of the borehole in last paragraph,The actual extraction efficiency of two sealing techniques is tested in a mine,Through monitoring for three months,it is proved that the sealing technology of superfine cement can effectively improve the sealing effect and realize the long-term stable extraction of pumping boreholes. |
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