School of Mining, Liaoning Technical University State and Local Joint Engineering Lab of Deep Well Gas Drainage
and Surrounding Rock Control Technology

为研究钻孔瓦斯抽采渗流规律,为钻孔合理布置提供依据,提出了考虑气-水两相流的瓦斯抽采流固耦合模型。在多孔介质的有效应力原理基础上,考虑瓦斯吸附/解吸产生的应力,推导出煤体应力-应变本构关系;分析水和瓦斯运移的气-水两相流过程,以相对渗透率为桥梁,给出水渗流方程和考虑Klinkenberg效应的瓦斯渗流方程;构建作为耦合项的煤层孔隙率和渗透率动态演化方程,结合成庄矿4321工作面进行数值模拟。结果表明:成庄矿4321底抽巷穿层钻孔瓦斯抽采预抽期定为90 d是合理的,抽采过程中瓦斯渗流速度具有阶段性,增大抽采负压对抽采效果影响不明显;穿层钻孔布置方式为终孔间距9 m,钻场间距9 m。工程实践表明,测得的煤层瓦斯压力变化情况与数值模拟结果基本吻合,抽采后煤层瓦斯含量为6.46~7.67 m~3/t,43212巷瓦斯浓度降低了37%,抽采效果良好。

In order to study the gas drainage seepage law of the borehole and to provide the basis to the rational layout of the boreholes, in consideration of the ga s-water two-phase flow, a fluid-solid coupling model of the gas drainage was provided.Based on the effective stress principle of the multi pore medium and in considerat ion of the stress occurred by the gas adsorption and desorption, a coal stress-strain relationship was derived.A gas-water two-phase flow process of the water and gas migration was analyzed.Based on the relative permeability as the bridge, a water seepage equation was provided and the gas seepage equation of the Klinkenberg effe ct was considered.A dynamic evolution of the seam pore rate and permeability was established as the coupling terms and a numerical simulation was conducted on No. 4321 coal mining face in Chengzhuang Mine. The results showed that, it is reasonable to set the pre-drainage period of gas drainage in No.4321 bottom tunnel through t he borehole for 90 days.During the gas drainage process, the gas sewage velocity would have stages and the gas drainage negative pressure increased would not hav e obvious influences to the gas drainage effect. The layout mode of the borehole passed through strata would have the borehole completed space of 9 m and the drilling site space would be 9 m.The engineering practices showed that the measured gas pressure variation condition of the seam was basically fitted to the numerical simulati on results and the gas content of the seam was 6.46 ~ 7.67 m3/t after the gas drainage completed. The gas density from No.43212 gateway was reduced by 37% and th e gas drainage effect was excellent.

国家自然科学基金资助项目(51674132)；国家重点研发计划资助项目(2016YFC0801407-2)；深井瓦斯抽采与围岩控制技术国家地方联合工程实验室开放基金资助项目(G201602)；辽宁省自然科学基金资助项目(2015020614)；