瓦斯渗流场作用下煤层抽放钻孔弹塑性解

发布时间：2018-12-08 08:28

【摘要】：为研究瓦斯渗流场作用下的煤层抽放钻孔周围应力分布情况,假定钻孔周围煤体中瓦斯的流动为稳定径向流动状态,建立了渗流力学模型,给出了瓦斯径向稳定渗流方程;在考虑瓦斯渗流场作用下,推导了钻孔周围煤体的微元体力学平衡方程,并引入应力调整系数,求解出其弹性应力解析解;再应用Mohr-Coulomb屈服准则,求解出钻孔周围煤体的塑性应力和塑性半径的解析表达式。通过实例分析表明:钻孔内的抽放负压对钻孔周围煤体应力、塑性区的半径等参数影响较小;在一定的抽放负压(15k Pa)下,随着煤层原始瓦斯压力的增大,钻孔周围煤体的塑性区半径随之增大,距钻孔足够远处的弹性区煤体的应力也随之增大,这比不考虑瓦斯渗流场作用时的经典弹塑性解更加符合实际情况。
[Abstract]:In order to study the stress distribution around the coal seam drainage borehole under the action of gas seepage field, the gas flow around the borehole is assumed to be a stable radial flow state, the seepage mechanics model is established, and the gas radial stable seepage equation is given. Considering the effect of gas seepage field, the micro-element mechanical equilibrium equation of coal body around the borehole is derived, and the stress adjustment coefficient is introduced to solve the analytical solution of elastic stress. Then the Mohr-Coulomb yield criterion is applied to solve the analytical expressions of plastic stress and plastic radius of coal body around the borehole. The analysis of examples shows that the negative pressure in the borehole has little effect on the coal stress and the radius of the plastic zone around the borehole. Under a certain suction negative pressure (15k Pa), with the increase of the original gas pressure of coal seam, the radius of the plastic zone of the coal body around the borehole increases, and the stress of the coal body in the elastic area far away from the borehole also increases. This is more in line with the actual situation than the classical elastoplastic solution without considering the gas seepage field.
【作者单位】：西南科技大学环境与资源学院;
【基金】：西南科技大学博士基金(12zx7112)
【分类号】：TD712

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