受载煤样渗透率与应变的关联性研究  

Correlation between permeability and strain of coal samples under loading

作　　者：祝捷[1] 唐俊[1] 王琪 兰天翔 林立 姜耀东[1] ZHU Jie;TANG Jun;WANG Qi;LAN Tianxiang;LIN Li;JIANG Yaodong(School of Mechanics&Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《煤炭学报》2019年第S02期566-573,共8页Journal of China Coal Society

基　　金：国家重点研发计划资助项目(2016YFC0801401);中央高校基本科研业务费专项资金资助项目(2010QL02)。

摘　　要：为了研究受载煤岩渗透率与变形的关联性,利用含瓦斯煤热-流-固耦合三轴伺服渗流装置,对取自开滦赵各庄煤矿9号煤层的原煤样品,设计完成了围压不变、降低气体压力以及围压、气体压力同步降低的2种实验方案下煤样径向应变、轴向应变和渗透率测试。实验气体分别为氦气和二氧化碳气体。实验结果表明:采用无吸附性气体(氦气)实验时,煤样体应变与气体压力之间基本为线性关系;与含氦气的煤样相比,当其他实验条件相同时,含二氧化碳气体的煤样产生了显著的膨胀体应变,该膨胀体应变是二氧化碳气体的吸附作用导致的。实验显示,相同气体压力下,围压不变、降低气体压力对应的煤样吸附膨胀体应变大于围压、气体压力同步降低时的吸附膨胀体应变,但二者相差小于5.4%,可见本文实验的外部应力降低对煤样吸附应变影响很小。随着气体压力的降低,实验结果显示煤样的宏观变形为体积收缩,但是其渗透率逐渐升高。原因在于煤样的渗透率同时受到有效应力导致的煤体变形和吸附气体解吸引起的煤基质变形的影响,渗透率的变化特征不仅与煤样表面测得的宏观体积变形有关,而且与煤基质变形导致的煤样内部孔裂隙结构变化密切相关。仅依据煤样表面测得的应变不足以解释煤样渗透率与变形的内在联系。考虑到煤样渗透率受有效应力和气体吸附的叠加作用,将含二氧化碳气体煤样的应变分解成两部分,即有效应力导致的应变和气体吸附引起的应变。以S&D渗透率模型为基础,推导了表征煤样渗透率与有效应力导致的应变变化量、气体吸附引起的应变变化量之间关联性方程,该关联性方程为指数函数形式,对实验数据的拟合相关系数大于0.9,拟合效果良好。In order to study the correlation between coal permeability and deformation under loading,the radial strains,axial strains and permeability of coal samples from No.9 coal seam of Zhaogezhuang Coal Mine in Kailuan mining area were measured with the triaxial servo-controlled seepage device.The experiments were carried out in two different conditions.One condition was to reduce the inlet gas pressure while the confining stress was constant.The other condition was to reduce the gas pressure and confining stress synchronously.The experimental results showed that the strains of coal samples containing non-adsorbing gas(helium)were linear with gas pressures.Compared with coal sample containing helium,the swelling of coal samples containing carbon dioxide gas was remarkable under the same experimental conditions.The swelling was resulted from the adsorption of carbon dioxide gas in coal samples.The experimental results showed that under the same experimental conditions of gas pressure,the strain of coal sample adsorbed by constant confining pressure and decreasing gas pressure was larger than that by decreasing confining pressure and gas pressure synchronously,and the difference between them was less than 5.4%.The decrease of external stress in this test had little effect on the adsorption strain of coal sample.With the decrease of gas pressure,the experimental results showed that the macroscopic volume of coal sample shrank,but the permeability increased.The pores and fractures of coal sample were not narrowed with the shrinkage of coal samples.The reason was that the permeability of coal sample was affected by the deformation of coal caused by effective stress and the deformation of coal matrix caused by gas desorption.The change characteristics of permeability were not only related to the macroscopic deformation measured on the surface of coal sample,but also related to the change of pore and fracture structure in coal sample caused by the deformation of coal matrix closely.The strain change measured on the surface of

关 键 词：渗透率 有效应力 体应变 气体吸附 气体压力 

分 类 号：TD712[矿业工程—矿井通风与安全]