In order to study the influence of gas extraction borehole creep on borehole quality,a numerical simulation software COMSOL was used to establish a fluid-solid coupling model of gas containing coal considering creep.The stress-strain variation law of the coal body around the borehole was studied.At the same time,taking a coal mine as an example,the gas pressure and displacement changes were simulated and calculated under the conditions of Poisson's ratio of 0.2-0.34 and Young's modulus of 2E8-4E8.The influence of Poisson's ratio and Young's modulus on the gas pressure around the borehole and the creep of the borehole were obtained.Research has shown that as the Poisson's ratio and Young's modulus increase,the change in gas pressure gradient decreases,which is more favorable for gas extraction in coal seams.As the horizontal distance from the borehole increases,the displacement first decreases and then increases,but overall shows a decreasing trend.The displacement of the hole wall increases with the increase of Poisson's ratio,decreases with the increase of Young's modulus,and gradually stabilizes over time.The smaller the Poisson's ratio and Young's modulus,the softer the coal rock,and the more obvious the equivalent creep strain of the borehole.The influence of Young's modulus on borehole creep is greater than that of Poisson's ratio.
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