预制裂隙煤样损伤破坏力学及声发射特征分析
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摘要
为研究裂隙倾角对煤样损伤破坏力学机制及声发射特征的影响,应用电液伺服岩石三轴实验机与AE21C声发射仪对不同倾角预制裂隙煤样进行了单轴压缩声发射试验。试验结果表明:煤样破坏时表面裂纹分布特征具有明显的不同,从完整试样的劈裂破坏演变为从预制裂隙末端开始顺着岩桥扩展直至形成贯通裂纹;预制裂隙对煤样峰值强度有明显的影响,不同倾角预制裂隙煤样其峰值强度随着裂隙倾角的增加呈现出先降低再增加的趋势;完整煤样的声发射事件在压密阶段和弹性阶段前期都比较平静,在弹性阶段末期发展较快,而预制裂隙煤样在弹性阶段前期或中期就产生明显的声发射现象,并且预制裂隙煤样总体的声发射现象相比完整煤样更密集,同时,还呈现出随着裂隙倾角增加其声发射逐渐密集的现象。
In order to study the influence of fracture inclination on the damage and failure mechanism and AE characteristics of coal samples,uniaxial compression acoustic emission tests were carried out on coal samples with prefabricated cracks under different inclination angles by using hydraulic servo rock triaxial tester and AE21 Cacoustic transmitter.The results showed that the characteristics of surface crack distribution were obviously different when coal samples were destroyed,and the splitting failure of the intact specimen evolved from the end of the prefabricated cracks to the extension of the rock bridge until the penetrating crack was formed.Prefabricated cracks had obvious influence on peak strength of coal samples,and the peak strength of prefabricated fractured coal samples with different inclination angles decreased firstly and then increased with the increase of inclination angle.The acoustic emission event of the complete coal sample was calm at the compaction phase and the early stage of the elastic phase,and developed rapidly at the end of the elastic phase.The coal samples with prefabricated cracks produced obvious acoustic emission at the early or middle stage of the elastic phase,and the acoustic emission phenomenon of the coal samples with prefabricated cracks was more dense than that of complete coal samples.It also showed the phenomenon that the acoustic emission was increasing gradually with the inclination angles.
In order to study the influence of fracture inclination on the damage and failure mechanism and AE characteristics of coal samples,uniaxial compression acoustic emission tests were carried out on coal samples with prefabricated cracks under different inclination angles by using hydraulic servo rock triaxial tester and AE21 Cacoustic transmitter.The results showed that the characteristics of surface crack distribution were obviously different when coal samples were destroyed,and the splitting failure of the intact specimen evolved from the end of the prefabricated cracks to the extension of the rock bridge until the penetrating crack was formed.Prefabricated cracks had obvious influence on peak strength of coal samples,and the peak strength of prefabricated fractured coal samples with different inclination angles decreased firstly and then increased with the increase of inclination angle.The acoustic emission event of the complete coal sample was calm at the compaction phase and the early stage of the elastic phase,and developed rapidly at the end of the elastic phase.The coal samples with prefabricated cracks produced obvious acoustic emission at the early or middle stage of the elastic phase,and the acoustic emission phenomenon of the coal samples with prefabricated cracks was more dense than that of complete coal samples.It also showed the phenomenon that the acoustic emission was increasing gradually with the inclination angles.
引文
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[4]王国艳,于广明,高丽燕,等.初始裂隙倾角对岩石损伤断裂特征的影响研究[J].煤炭科学技术,2017,45(6):100-104.
[5]李小帅,唐烈先,张颖,等.节理倾角对岩体破坏特性影响的单轴压缩数值试验[J].辽宁科技大学学报,2015,38(6):463-466.
[6]刘学伟,刘泉声,陈元,等.裂隙形式对岩体强度特征及破坏模式影响的试验研究[J].岩土力学,2015(S2):208-214.
[7]周辉,孟凡震,张传庆,等.不同位置和尺寸的裂隙对岩体破坏影响的试验研究[J].岩石力学与工程学报,2015,34(S1):3018-3028.
[8]孙朝阳.不同裂隙角度对岩体强度影响研究[J].煤炭技术,2015,34(6):113-115.
[9]叶洪涛,孙光华,刘志义,等.单轴压缩作用下砂岩变形规律及声发射特性研究[J].矿业研究与开发,2017(8):52-55.
[10]纪洪广,卢翔.常规三轴压缩下花岗岩声发射特征及其主破裂前兆信息研究[J].岩石力学与工程学报,2015,34(4):694-702.
[11]杨永杰,陈绍杰,韩国栋.煤样压缩破坏过程的声发射试验[J].煤炭学报,2006(5):562-565.
[12]刘京红,姜耀东,赵毅鑫,等.煤岩单轴压缩破坏过程声发射试验研究[J].河北农业大学学报,2012,35(5):105-108.
[13]周天白,杨小彬,韩心星.煤岩单轴压缩破坏PFC~(2D)数值反演模拟研究[J].矿业科学学报,2017(3).
[14]杨永杰,王德超,郭明福,等.基于三轴压缩声发射试验的岩石损伤特征研究[J].岩石力学与工程学报,2014,33(1):98-104.