基于瓦斯抽采效果的钻孔塑性区范围优化及应用

Optimization on plastic zone scope of borehole based on gas extraction effect and its application

为获得最佳瓦斯抽采效果,研究不同钻孔孔径与塑性区范围及抽采效果之间关系,基于弹塑性理论,采用Comsol软件模拟嘉禾矿2254底板巷上穿层钻孔周围煤体塑性区范围分布,修正塑性区半径理论推导公式,得到抽采钻孔混合流量、纯流量和浓度,分析钻孔周围煤体不同塑性区范围下瓦斯抽采效果。结果表明:钻孔孔径越大,塑性区范围越大,抽采钻孔卸压范围越大;若不考虑其他因素,钻孔孔径越大,瓦斯抽采效果越好;通过对比塑性区半径模拟值与计算值,修正塑性区半径公式,该公式适用于浦溪煤矿;随钻孔塑性区范围增加,钻孔瓦斯抽采流量逐渐增加,但瓦斯流量相对钻孔塑性区半径差变化率先增大后减小。研究结果可为提高矿井瓦斯抽采效果提供理论参考。

In order to obtain the optimal gas extraction effect,the relationship between different borehole diameters and scope of the plastic zone was studied,and the relationship with the extraction effect was further analyzed.On the basis of elastic-plastic theory,the COMSOL software was used to simulate the distribution of plastic zone scope in the coal body around the crossing borehole of 2254 bottom roadway in Jiahe coal mine,and the theoretical derivation formulas of the plastic zone radius was modified.The data of mixed flow rate,pure flow rate and concentration of extraction borehole were obtained,and the gas extraction effect under different plastic zone scopes in the coal body around borehole was analyzed.The results showed that the larger the borehole diameter,the larger the plastic zone scope,and the larger the pressure relief scope of extraction borehole.When without considering the other factors,the larger the borehole diameter,the better the gas extraction effect.Through the comparative simulation,the obtained plastic zone radius and the modified formula of plastic zone radius were suitable for the Puxi coal mine.With the increase of plastic zone scope of borehole,the gas extraction flow rate of borehole increased gradually,but the change rate of gas flow rate relative to radius difference of plastic zone of borehole increased first and then decreased.The research results have certain reference significance to improve the effect of gas extraction in mine.