不同高径比煤样巴西劈裂声发射特征及能量演化机制研究  

Study on acoustic emission characteristics and energy evolution of Brazilian splitting tests of coal samples with different height-diameter ratio

作　　者：雷瑞德 粟罗 贺培 胡超 李俊 周林森 LEI Ruide;SU Luo;HE Pei;HU Chao;LI Jun;ZHOU Linsen(National and Local Joint Engineering Research Center of Shale Gas Exploration and Development,Chongqing Institute of Geology and Mineral Resources,Chongqing 4001120,China;Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources,Chongqing Institute of Geology and Mineral Resources,Chongqing 401120,China;School of Civil Engineering,Sichuan University of Science&Engineering,Zigong 643002,China;Key Laboratory of Safety and High-efficiency Coal Mining,Ministry of Education,Anhui University of Science and Technology,Huainan 232001,China)

机构地区：[1]重庆地质矿产研究院页岩气勘探开发国家地方联合工程研究中心,重庆401120 [2]重庆地质矿产研究院自然资源部页岩气资源勘查重点实验室,重庆401120 [3]四川轻化工大学土木工程学院,四川自贡643002 [4]安徽理工大学煤矿安全高效开采省部共建教育部重点实验室,安徽淮南232001

出　　处：《煤炭科学技术》2024年第10期63-77,共15页Coal Science and Technology

基　　金：国家自然科学基金资助项目(52004047);重庆市博士后研究项目特别资助项目(2022CQBSHTB3109);煤矿安全高效开采省部共建教育部重点实验室开放课题资助项目(JYBSYS202306)。

摘　　要：为探究不同高径比对圆盘煤样抗拉强度及能量演化机制的影响,对5组直径相同、高度不同的煤样进行巴西劈裂试验,并同步声发射监测系统及三维形貌扫描技术探究不同高径比煤样的抗拉特性、声发射特征、破断模式及断面形貌特征。结果表明:随着煤样高径比的增加,煤样抗拉强度呈现逐渐减小的趋势,当高径比在0.4∶1至1∶1范围内时,高径比为0.4∶1的煤样抗拉强度最大。圆盘煤样宏观破坏模式逐渐由拉-剪混合裂纹主导的多裂纹复杂破断模式转变为单一断面拉伸裂纹破坏。累积声发射能量逐渐增大,且累积能量曲线的聚丛现象较为显著,呈阶梯式上升趋势。较低应力水平阶段的耗散能占比逐渐增大;当荷载增至弹性极限时,耗散能及其占比逐渐减小;当煤样趋近破裂阶段时,弹性应变能与耗散能占比趋于平稳;当煤样进入峰后破裂阶段时,积聚在煤样内的弹性应变能迅速释放,耗散能占比急剧增加,煤样内部宏观裂纹迅速扩展并贯通。多重分形谱宽度(Δα)逐渐增大,频谱测度子集(Δf)小于零,表明煤样拉伸破裂过程中小破裂尺度信号占主导优势。另外,不同高径比工况下煤样破断面高程的相对频率呈现出拟合度较高的高斯型函数分布,分形维数呈逐渐增大趋势,表明高径比越小,其破裂后断面的复杂程度越低,反之高径比越大的煤样破裂后断面粗糙程度越复杂。In order to explore the influence of different ratios of height-diameter on the tensile strength and energy evolution of disc coal samples,Brazilian splitting tests were carried out on five groups of coal samples with the same diameter and different heights.The tensile behavior,acoustic emission(AE)characteristics,fracture modes and section morphology characteristics of coal samples with different height-diameter ratio are investigated using a synchronous AE monitoring system and three-dimensional morphology scanning technology.The results show that the tensile strength of coal gradually decreases with the increase of the ratio of height to diameter,and the peak strength of coal reaches the maximum when the height-diameter ratio is 0.4∶1.The failure mode of coal samples gradually changed from the complex fracture mode of multiple cracks dominated by tensile-shear mixed cracks to the tension cracks of single section.The cumulative AE energy increases gradually,and the clustering phenomenon is more significant,showing a stepwise upward trend.The proportion of dissipated energy increases gradually at the lower stress level.When the load increases to the elastic limit,the dissipated energy and its proportion decrease gradually.The ratios of elastic strain energy and dissipated energy tend to be stable when the coal sample approaches the failure stage.When the coal sample enters the post-peak stage,the accumulated elastic strain energy releases rapidly,the proportion of dissipated energy increases sharply,and the macroscopic cracks in the coal sample rapidly expand and coalesce.The width(Δα)of the multifractal spectrum gradually increases,and the spectral measure subset(Δf)is less than zero with the increase in height-diameter ratio,which indicates that the small fracture scale signal dominates in the splitting tests.In addition,the relative frequency of broken section elevation of coal samples under different height-diameter ratios presents a good Gaussian function distribution,and the fractal dimension shows a

关 键 词：巴西劈裂 力学特性 声发射 微观裂纹 多重分形 

分 类 号：TU45[建筑科学—岩土工程] TD313[建筑科学—土工工程]