单轴压缩下宏观裂纹倾角对煤体特性影响研究  

Research on the coal characteristics of macro-crack dip angles under uniaxial compression

作　　者：李德行[1,2] 王恩元[1,2] 李楠[3] 孔祥国[1,2] 王笑然[1,2] 

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,江苏徐州221116 [2]中国矿业大学安全工程学院,江苏徐州221116 [3]中国矿业大学煤炭资源与安全开采国家重点实验室,江苏徐州221116

出　　处：《岩石力学与工程学报》2017年第A01期3206-3213,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：教育部科学技术研究项目资助(113031A);国家重点研发计划(2016YFC0801401);江苏省自然科学基金青年基金项目(BK20150183)~~

摘　　要：为研究宏观裂纹倾角对煤体特性的影响,采用YAW4306电伺服试验系统和CTA–1声发射采集系统对不同预制裂纹倾角的煤样进行单轴压缩声发射试验,分析试验过程的声发射信号特征,研究裂纹倾角对声发射响应、煤样峰值强度和裂纹扩展方式的影响。试验结果表明:宏观裂纹的存在对试样声发射信号的变化规律有显著影响,且声发射信号变化与载荷变化具有很高的一致性,能够很好地反映含宏观裂纹煤样受压时内部破裂发展情况;裂纹的存在降低煤体的强度,且随着裂纹倾角的减小,峰值强度受影响越来越明显,呈现出逐渐减小的趋势,通过曲线拟合,得出二者近似成二次函数关系;裂纹倾角为0°,15°,30°和45°的煤样,其破坏过程中主要裂纹形态为翼型裂纹,并伴有各方向细微次生裂纹;倾角为60°和75°的煤样,其主要裂纹形式为反翼裂纹;当倾角增至90°时,煤样无表面扩展裂纹,此时煤样的破裂方式为劈裂。To investigate the influence of macro-crack dip angles on the coal characteristics, acoustic emission（AE） tests under uniaxial compression of coal samples with different dip angles pre-existing crack were carried out by YAW4306 electric mechanical test system and CTA - 1 acoustic emission monitor. AE signal characteristics in test process were analyzed, and the effects of macro-crack dip angles on AE response characteristics, peak stress and crack propagation modes were studied. The results show that： the existence of macro-cracks in specimen under uniaxial compression has a significant impact on AE signals, and the response of AE signals is of high consistency with the applied load, so it can well reflect the internal rupture development when macroscopic defects appear under uniaxial compression. The peak stress increase with the dip angles of the cracks, which presents quadratic function relationship by curve fitting. When the dip angle of pre-existing cracks is 0°, 15°, 30° and 45° respectively, the major crack morphology of coal samples in the failure process is wing crack, accompanied by subtle secondary cracks. While the dip angle rises to 60 ° and 75 °, anti-wing cracks appear on the surface of the coal specimen. There is no obvious propagating crack on the surface when the dip angle reaches to 90 °, and the coal samples show a splitting failure mode.

关 键 词：岩石力学 宏观裂纹 声发射 峰值强度 裂纹扩展方式 

分 类 号：TU45[建筑科学—岩土工程]