含瓦斯煤体渗透失稳判别式

Formula of penetration stability failure of coal containing gas

为了研究含瓦斯煤体渗透失稳发生机理,假设煤层以分层形式发生失稳,提出"修正气压梯度"指标。应用总应力法,推导"临界修正气压梯度"的数学表达式,该式表明:"临界修正气压梯度"与煤体抗剪强度成正比、与煤层圆形(矩形)暴露面半径(短边宽度)成反比。结合该式,对煤与瓦斯突出的一些现象及渗透失稳发展过程影响因素进行了分析,得出失稳分层厚度随气压梯度降低而增加,以及失稳推进速度不是常量等结论。

In order to study the occurrence mechanismin of penetration stability failure of coal containing gas,it was supposed that the outburst be a process of coal mass as a form ＂sublayer＂pushing forward. Based on the totall stress method,a simplified calculation formula of the ＂critical improved gas pressure gradient＂was given. According to the formula,the critical ＂improved gas pressure gradient ＂ is directly proportional to shearing strength,and is inversely proportional to the uncovering coal circular section radius or the short side of rectangular width. Based on the formula,some phenomena and influence factors on the process of the outburst were analyzed. Some conclusions were drew that were the thickness of the falure sublayer increasing with the decreasing of the gas pressure gradient and the velocity of the failure sublayer pushing foward no a constant value.