瓦斯渗流场作用下煤层抽放钻孔弹塑性解  

Elastic-plastic analytical solution of drill boreholes in coal seam under the gas seepage field

作　　者：吴爱军[1] 蒋婉筱 吴大伟[1] 胡文义 杨再高[1] 

机构地区：[1]西南科技大学环境与资源学院621010绵阳

出　　处：《应用力学学报》2015年第2期233-238,352,共6页Chinese Journal of Applied Mechanics

基　　金：西南科技大学博士基金(12zx7112)

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。A radial steady-state flow equation of gas is developed in the coal seam around gas drill boreholes by assuming steady-flow forming. Mechanics balance equations are established and analytical solution of elastic stress is obtained by considering the gas seepage field and introducing the stress adjustment coefficient. Furthermore, analytical formulae of plastic stress and plastic radius are obtained by applying Mohr-Coulomb yield criterion. An example is analyzed and the result shows that plastic radius of coal seam increase along with the negative pressure of suction increment in boreholes, the increase value is small, and the influence on the radial stress and tangential stress is very small. In a certain negative pressure, the plastic radial increase along with the original gas pressure in coal seam increase. Simultaneously, the stress absolute value of coal seam that further away from the boreholes increases, and more and more deviates from the classic elastic solution without considering gas seepage field. It is evident that it is more consistent with the actual situation by considering effect of gas seepage field.

关 键 词：瓦斯渗流场 抽放钻孔 弹塑性解 径向应力 切向应力 

分 类 号：TD713[矿业工程—矿井通风与安全]