不同加载速率含水煤样力学响应及宏微观破坏机制研究  

Mechanical response and macro and micro failure mechanism of water-bearing coal samples with different loading rates

作　　者：许庆钊 史文豹[1] 常聚才[1] 苗壮 闫澳运 李传明[1] 齐潮 XU Qing-zhao;SHI Wen-bao;CHANG Ju-cai;MIAO Zhuang;YAN Ao-yun;LI Chuan-ming;QI Chao(School of Mining Engineering,Anhui University of Science and Technology,Huainan,Anhui 232001,China)

机构地区：[1]安徽理工大学矿业工程学院,安徽淮南232001

出　　处：《岩土力学》2025年第3期881-893,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52104117,No.52174105,No.52174103);安徽省高校优秀科研创新团队项目(No.2023AH010023)。

摘　　要：为探明工作面注水防冲解危后,回采速率对含水煤体裂隙结构发育的影响,对不同含水率煤样(Dr、Se、Sa)开展不同加载速率单轴压缩试验研究,分析加载速率效应影响下含水煤样力学特性及声发射特征,通过分形维数及扫描电子显微镜(scanning electron microscope,简称SEM),揭示不同加载速率含水煤样微观结构破断机制。研究结果表明:含水率的增加弱化煤样峰值强度,诱导声发射振铃计数和能量信号滞后出现,水的润滑作用降低煤样张拉裂纹占比,颗粒发生水化作用的同时是降低其脆性属性和改变断口特征的主要原因,断口由脆性断裂向塑性断裂、穿晶断裂向沿晶断裂方向转变;加载速率的增加抑制煤样内部裂纹充分扩张,增强煤样峰值强度和弹性模量,减弱加载初期的累计损伤,导致声发射振铃计数和能量信号逐渐靠近峰值处显现,声发射累计能量从长时缓增-短时突增向短时缓增-短时突增转变;加载速率越快,lg(ML_(eq)/M)-lg L_(eq)(M为碎块总质量,ML_(eq)为小于等效边长L_(eq)的碎屑质量,L_(eq)为等效边长)曲线k值斜率越小,分形维数越大,煤样破碎程度越小,增强煤样脆性属性改变煤样断口形貌。研究成果可为工作面快速安全高效生产提供一定试验基础。To investigate the influence of mining rate on the development of fracture structures in water-bearing coal after implementing water injection for rockburst prevention in the working face,uniaxial compression tests at various loading rates were conducted on coal samples with different moisture contents(Dr,Se,Sa).The mechanical properties and acoustic emission characteristics of these water-bearing coal samples were analyzed under different loading rates.Using fractal dimension and scanning electron microscope(SEM),the fracture mechanism of the microstructure of these coal samples was revealed.The results show that an increase in water content weakens the peak strength of coal samples,induces a delay in acoustic emission ringing count and energy signals,and the lubrication effect of water reduces the proportion of tensile cracks in coal samples.Particle hydration is the primary reason for the reduction in brittleness and the alteration of fracture characteristics,with fractures transitioning from brittle to plastic and from transgranular to intergranular.An increase in loading rate inhibits the full propagation of internal cracks in coal samples,enhances their peak strength and elastic modulus,and reduces cumulative damage during the initial loading stage,resulting in acoustic emission ringing counts and energy signals gradually approaching their peak values.The cumulative energy of acoustic emissions shifts from a pattern of long-term slow increase followed by short-term sudden increase to a pattern of short-term slow increase followed by short-term sudden increase.The faster the loading rate,the smaller the slope of the k-value on the lg(ML_(eq)/M)-lgL_(eq)curve(where M is the total mass of the fragments,ML_(eq)is the mass of fragments smaller than the equivalent side length L_(eq)),the larger the fractal dimension,the less fragmented the coal sample,and the brittleness of the coal sample is enhanced,altering its fracture morphology.The research results can provide a solid experimental basis for rapid,safe,and e

关 键 词：加载速率 含水率 声发射 分形维数 SEM 

分 类 号：TU457[建筑科学—岩土工程]