China Coal Research Institute Mine Safety Branch, China Coal Research Institute

为了提出一种简单快速求解有效抽采半径的方法,基于周世宁院士提出的瓦斯径向非稳定渗流方程,采用自模拟方法求出近似解析解,即径向流场瓦斯压力分布表达式,以此进一步建立有效抽采半径的数学表达式,研究表明:在无限流场条件下,有效抽采半径与抽采时间的平方根成正比,与抽采负压满足非线性的正相关关系;但不同抽采负压条件下,钻孔周围瓦斯压力分布规律差异较小,因此,可以采用简化的瓦斯压力表达式来近似反映径向流场的瓦斯压力分布规律。该近似解及有效抽采半径的表达式可以用来确定煤层瓦斯抽采的相关参数,通过相关实例验证了有效抽采半径表达式的准确性。

In order to provide a simple and rapid method to solve the effective drainage radius, based on a gas radial unstable seepage equation proposed by Acad emician Zhou Shining, a self simulation method was applied to get the approximate solution, which would be the gas pressure distribution expression of the radial flow f ield. Thus a mathematical expression of the effective drainage radius was further established. The study showed that under the condition of an infinite flow field, the squ are root of the effective drainage radius and the drainage time would be in a direct ratio and the square root of the drainage negative pressure could meet the nonlinear positive correlation. Under the different drainage negative pressure condition, the gas pressure distribution law around the borehole would be small in difference. Theref ore, a simplified gas pressure expression would be applied to approximately reflect the gas pressure distribution law of the radial flow field. The approximate solution an d the effective drainage radius expression could be applied to determine the relevant parameters of the seam gas drainage. The related experiments were verified the a ccuracy of the effective drainage radius expression.