孔隙压力循环加卸载下煤岩渗流演化机制研究  

Study on coal seepage evolution mechanism under cyclic loading and unloading of pore pressure

作　　者：叶平平 李波波[1,2,3] 吴学海 宋浩晟 成巧耘 许江 YE Pingping;LI Bobo;WU Xuehai;SONG Haosheng;CHENG Qiaoyun;XU Jiang(College of Mining,Guizhou University,Guiyang Guizhou 550025,China;National&Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas,Guizhou University,Guiyang Guizhou 550025,China;Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources,Guiyang Guizhou 550025,China;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China)

机构地区：[1]贵州大学矿业学院,贵州贵阳550025 [2]贵州大学喀斯特地区优势矿产资源高效利用国家地方联合工程实验室,贵州贵阳550025 [3]贵州省非金属矿产资源综合利用重点实验室,贵州贵阳550025 [4]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400044

出　　处：《中国矿业大学学报》2023年第4期739-749,共11页Journal of China University of Mining & Technology

基　　金：贵州省省级科技计划项目(黔科合基础-ZK[2021]重点052);国家自然科学基金项目(52274183,52064007)。

摘　　要：为探究孔隙压力周期性变化对煤岩变形和渗流特性的影响,采用含瓦斯煤热-流-固耦合三轴伺服渗流试验装置,开展孔隙压力循环加卸载下煤岩的变形及渗流试验.基于基质-裂隙相互作用的重要性,引入内膨胀系数以量化气体吸附对裂隙体积模量的影响,并进一步修正Betti-Maxwell互易定理,构建气体吸附效应控制下的煤岩渗流模型.结果表明:当有效应力恒定时,煤岩轴向应变、径向应变和体积应变随孔隙压力的增大而减小;相同孔隙压力下,随循环次数增大,煤岩体积应变和径向应变呈减小趋势,而轴向应变呈增大趋势.在孔隙压力加载的过程中,煤岩渗透率先迅速减小后趋于平缓,而卸载时煤岩渗透率有所恢复,但均小于加载阶段;相同孔隙压力下,随循环次数增大,煤岩渗透率呈减小趋势.新建模型所呈现的渗透率演化过程与试验测试结果基本保持一致,表明该模型可较好地描述孔隙压力循环加卸载下煤岩渗流演化过程.探讨不同循环次数下内膨胀系数演化规律,并发现在孔隙压力加载过程中,内膨胀系数随循环次数的增大而增大;而孔隙压力卸载过程中,内膨胀系数随循环次数的增大而减小.研究结果可为合理布置瓦斯抽采钻孔提供理论指导,对井下瓦斯高效抽采和瓦斯灾害防治具有重要意义.In order to study the influence of the periodic change of pore pressure on the deformation and seepage characteristics of coal,the triaxial servo-controlled seepage equipment for the thermofluid-solid coupling of coal containing methane was used to carry out the deformation and seepage test of coal under cyclic loading and unloading of pore pressure.Based on the importance of matrix-fracture interaction,the internal swelling coefficient was introduced to quantify the influence of gas adsorption on fracture bulk modulus,and the Betti-Maxwell reciprocal theorem was further modified to build a coal permeability model controlled by gas adsorption effect.The results show that when the effective stress is constant,the axial strain,radial strain and volumetric strain of coal decrease with the increase of pore pressure;under the same pore pressure,with the increase of cycle times,the volume strain and radial strain of coal decrease,while the axial strain increases.In the process of pore pressure loading,the permeability of coal firstly decreases rapidly and then tends to be flat,while the permeability of coal recovers when unloading,but it is smaller than the loading stage;under the same pore pressure,the permeability of coal decreases with the increase of cycle times.The permeability evolution process presented by the new model is basically consistent with the test results,which indicates that the model can well describe the evolution process of coal permeability under cyclic loading and unloading of pore pressure.The evolution law of internal swelling coefficient under different cycle times is discussed,and it is found that the internal swelling coefficient increases with the increase of cycle times during pore pressure loading.In the process of pore pressure unloading,the internal swelling coefficient decreases with the increase of cycle times.The research results can provide theoretical guidance for rational arrangement of gas drainage boreholes,and have important significance for efficient underground gas drainage a

关 键 词：煤岩 孔隙压力 渗透率 互易定理 循环加卸载 

分 类 号：TD712[矿业工程—矿井通风与安全]