干燥和饱水裂隙砂岩破坏电磁辐射特征研究  

Electromagnetic radiation characteristics of dry and saturated pre-cracked sandstone during fracturing

作　　者：沈荣喜[1] 李太训 李红儒 薛永生 何顺 侯振海 陈同庆 SHEN Rongxi;LI Taixun;LI Hongru;XUE Yongsheng;HE Shun;HOU Zhenhai;CHEN Tongqing(Key Laboratory of Coal Mine Gas and Fire Control of the Ministry of Education,School of Safety Enginccring,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Wuhushan Mining Co Ltd,Shenhua Group,Wuhai,Inner Mongolia 016040,China)

机构地区：[1]中国矿业大学煤矿瓦斯与火灾防治教育部重点实验室安全工程学院,江苏徐州221116 [2]神华集团乌达五虎山矿业有限责任公司,内蒙古乌海016040

出　　处：《中国矿业大学学报》2020年第4期636-645,共10页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(51574231,51104156);中央高校基本科研业务费专项项目(2019XKQYMS55)。

摘　　要：为研究孔隙水对裂隙岩石破坏过程中电磁辐射(EMR)特征的影响,对含预制平行双裂纹的干燥与饱水砂岩进行了单轴压缩实验,同步采集电磁辐射信号,分析电磁辐射时-频特征,并讨论裂纹扩展与电磁辐射信号之间的关系.结果表明:水岩作用下,裂纹起裂应力水平降低,岩样破坏模式由单一沿岩桥-预制裂纹发生剪切破坏过渡到多裂纹剪切-拉张复合破坏.随着应力的增加,饱水岩样累计电磁辐射脉冲数平稳上升,干燥岩样则呈缓慢-剧烈上升模式且上升幅度明显高于饱水岩样.应力增加过程中,电磁辐射集中分布频段由较低频段逐渐过渡到较高频段,幅值呈现逐渐升高的趋势.相比干燥岩样,饱水岩样在加载前期的主频分布较高,但在加载中后期则较低.裂纹起裂时伴随着电磁辐射脉冲和主频突增现象,可以作为岩样失稳破坏的前兆特征,饱水岩样此特征更为明显.不同加载时期岩样的微观破裂模式和产生电磁辐射的主导机制存在差异,水分对电磁辐射信号的影响由加载前期的增强作用逐渐转变为加载中后期的减弱作用.To study the influence of pore water on the characteristics of electromagnetic radiation(EMR)during the failure of fractured rock,the uniaxial compression experiments of dry and saturated sandstone samples with prefabricated parallel double cracks were carried out,and EMR signals were acquired simultaneously.The EMR time-frequency characteristics of the samples were analyzed and the relationship between crack propagation and EMR signals was discussed as well.The results show that the crack-initiation-stress decreases,and the rock failure mode transforms from a single shear failure along rock bridge-prefabricated crack to multi-crack shear-tension composite failure under water-rock interaction.With the increase of the loading stress,the cumulative EMR pulse number of the saturated rock sample rises steadily,while that of the dried rock sample shows a gentle-rapid rising mode.Moreover,the increased amount of the cumulative EMR pulse number of the dried rock sample is significantly higher than that of the saturated rock sample.As the stress increase,the concentrated frequency band of EMR changes gradually from lower frequency band to higher frequency band,and the amplitude also increases gradually.Compared with the dried rock sample,the saturated rock sample has a higher main frequency distribution of EMR in the early stage,but a lower main frequency distribution in the middle and late stages.The crack initiation accompanies by the sudden increase of EMR pulse and main frequency,which can be regarded as a potential precursory of rock failure,especially for the saturated rock.Because of differences in the micro-fracture mode and the dominant mechanism of EMR in different loading stages,water strengthens the EMR signals of rock sample in the early stage,and then weakens them in the middle and late stages.

关 键 词：饱水岩石 预制裂纹 电磁辐射 裂纹扩展 前兆 

分 类 号：TD76[矿业工程—矿井通风与安全]