采动条件下煤体渗流特性试验及应用

Test and Application of Coal Seepage Characteristics Under the Condition of Mining

为准确判断高瓦斯低透气性煤层瓦斯采动卸压抽采的有效区域,进一步提高瓦斯抽采效果,采用渗流试验和理论分析的方法,研究了煤层采动过程中煤体渗透率随应力的变化规律。结果表明:在受采动影响不同阶段,含瓦斯煤体渗透率随应力变化呈现明显的阶段差异性。在煤体弹性变形阶段,煤体渗透率随应力的增加逐步降低;在煤体达到屈服点至煤体破坏阶段,随着应力的升高,煤体发生塑性变形,煤体内产生采动裂隙,渗透率开始缓慢提升;在煤体破坏后,煤体处于卸压状态,煤体渗透率随着应力的降低大幅提升。最后,通过现场本煤层瓦斯抽采效果分析验证了采动煤体渗流特性试验结果的正确性。

In order to accurately judge the effective extraction region of mining-induced pressure relief and extraction in high gas and low air permeability coal seam,and improve gas extraction effect,seepage test and theoretical analysis are adopted to study the impact of stress on coal permeability during mining process. The results show that,the process of coal permeability changing can be divided into three stages with the stress changing caused by mining. In elastic deformation stage,coal permeability will decrease with the increase of stress; when coal body reaches the yield point to coal damage stage,plastic deformation appears and mining-induced fractures form in coal with the increase of stress,coal permeability begins to increase slowly; coal is in pressure relief state after it is destroyed,coal permeability will increase drastically with the decrease of stress. Finally,the accuracy of study results is verified by the coal seam gas extraction effect.