加载速率对煤样单轴压缩宏细观破裂特征的影响  

Macro-mesoscopic fracture characteristics of coal samples under different loading rates

作　　者：沈铭华 刘晨辉 方士正 李永亮[2] 黄海鹏 刘晓明 SHEN Minghua;LIU Chenhui;FANG Shizheng;LI Yongliang;HUANG Haipeng;LIU Xiaoming(Ningxia Coal Industry Co.,Ltd.,CHN Energy Group,Yinchuan 751400,China;School of Energy and Mining Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China;School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]国家能源集团宁夏煤业有限责任公司,宁夏银川751400 [2]中国矿业大学(北京)能源与矿业学院,北京100083 [3]北京科技大学土木与资源工程学院,北京100083

出　　处：《煤炭工程》2023年第12期147-154,共8页Coal Engineering

基　　金：国家自然科学基金项目(52174095,51804310)。

摘　　要：为研究煤样单轴压缩宏细观破裂特征的加载速率效应,对煤样进行了0.06、0.3及3 mm/min三种加载速率的单轴压缩试验,结合声发射及数值计算方法,分析了加载速率影响下煤样的力学性质、声发射特征、裂隙扩展与宏观破坏模式。研究结果表明,加载速率越高煤样的单轴抗压强度与峰值应变越大;累计振铃计数与声发射定位事件随加载速率增大不断减小;微观裂隙破坏由张拉破坏向剪切破坏过渡;宏观破坏模式由低加载速率的少量拉剪混合微裂纹破坏转变为高加载速率的单一贯穿的剪切裂纹破坏;数值模拟结果印证了室内试验结论,并揭示了煤样加载破坏实质是力链体系失稳,峰值应力前,轴向应力的增加使得局部力链强度差异增大,强弱力链断裂产生煤样的宏观破坏。In order to study the effect of loading rate on the macro-mesoscopic fracture characteristics of uniaxial compression of coal, coal samples were tested with uniaxial compression at the loading rates of 0.06, 0.3 and 3 mm/min. Combining with acoustic emission and numerical calculation methods, the influence of loading rate on mechanical properties, acoustic emission characteristics, crack propagation and macroscopic failure modes of coal samples were analyzed. The results show that the higher the loading rate, the greater the uniaxial compressive strength and peak strain of the coal;the accumulated ringing counts and acoustic emission localization events keep decreasing with increasing loading rate;the microscopic fracture damage transitions from tension damage to shear damage;the macroscopic damage mode changes from a small amount mixed tensile-shear micro-crack damage at low loading rate to a single penetrating shear crack damage at high loading rate;the numerical simulation results effectively support the indoor test conclusions and reveal that, the damage of coal samples is essentially the destabilization of the force chain system, the increase of axial stress before the peak stress enlarges the difference of the local force chain strength, and the fracture of the strong and weak force chains produces the macroscopic damage.

关 键 词：加载速率 力学特性 声发射 力链演化 破坏模式 

分 类 号：TD323[矿业工程—矿井建设]