摘要
为探究分形矸石胶结充填体的宏细观力学特性,对骨料粒径分布满足分形理论的胶结充填体开展超声波探测、单轴压缩和微观扫描试验,研究胶结充填体的超声波、强度和变形特性及微观结构特征;建立考虑骨料粒径分布和多种颗粒介质及接触界面的胶结充填体颗粒流模型,探讨胶结充填体承载全程能量、裂纹、力链和颗粒破坏的演化规律,从微细观层面揭示骨料粒径分布对胶结充填体力学特性的影响机制。结果表明:胶结充填体的超声波速度和抗压强度与骨料粒径分布分形维数呈二次多项式关系,而峰值应变与分形维数呈负相关。胶结充填体的最优骨料粒径分布分形维数介于2.4~2.6,其表现出更均匀的微观结构。胶结充填体的峰值应变能随骨料粒径分布分形维数先增大后减小,但分形维数低的骨料粒径分布更有利于强化结构内的摩擦效应。胶结充填体内的裂纹由骨料尖角应力集中处萌生,并沿胶结–骨料界面发育,其在胶结基质内则沿最弱或最薄胶结基质向临近骨料尖角或断裂界面扩展。低骨料粒径分布分形维数的胶结充填体容易发生局部力链断裂,表现出明显的早期局部裂纹积聚和颗粒碎胀,分形维数的增大可以弱化该局部破坏特征,但细骨料含量的增多导致界面过渡区的扩大化,诱发更多的胶结–骨料界面力链断裂。
In order to investigate the macroscopic and mesoscopic mechanical properties of cemented waste rock backfill using fractal gangue,the ultrasonic detection,uniaxial compression and microscopic scanning tests were carried out on cemented waste rock backfill of which the aggregate size distribution satisfies fractal theory. The ultrasonic,strength,deformation and microstructure characteristics of cemented waste rock backfill were studied.A particle flow model considering the aggregate size distribution,multiple particle media and contact boundaries was constructed for simulating cemented waste rock backfill. The evolution laws of the energy,crack,force chain and particle failure of cemented waste rock backfill during the whole loading process were explored. The influencing mechanism of the aggregate size distribution on the mechanical property of cemented waste rock backfill was revealed from the microscopic and mesoscopic views. The results show that the ultrasonic pulse velocity and the compressive strength of cemented waste rock backfill have a quadratic polynomial relationship with the fractal dimension of the aggregate size distribution,while the peak strain is negatively correlated with the fractal dimension. The fractal dimension of the optimal aggregate size distribution for cemented waste rock backfill is between 2.4–2.6,which shows a more uniform microstructure. The peak strain energy of cemented waste rock backfill increases firstly and then decreases with the fractal dimension of the aggregate size distribution,but the low fractal dimension of the aggregate size distribution is more conducive to strengthening the friction effect in the structure. The cracks initiate from the stress concentration of the sharp corners of aggregates in cemented waste rock backfill,develop along the cementing-aggregate boundaries,and propagate along the weakest or thinnest cemented matrix to the adjacent sharp corners of aggregates or fracture interfaces in the cemented matrix. The fractures of local force chains are prone to occur in the cemented waste rock backfill with a low fractal dimension of the aggregate size distribution,showing obvious early local crack accumulation and particle bulking. The increase of the fractal dimension of the aggregate size distribution can weaken this local failure characteristic,but the increase of the fine aggregate proportion causes the expansion of the interfacial transition zone,which induces more force chain fractures of cementing-aggregate boundaries.
作者
吴疆宇
靖洪文
浦海
张新国
孟庆彬
尹乾
WU Jiangyu;JING Hongwen;PU Hai;ZHANG Xinguo;MENG Qingbin;YIN Qian(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China;State Key Laboratory of Mining Disaster Prevention and Control,Co-founded by Shandong Province and the Ministry of Science and Technology,Shandong University of Science and Technology,Qingdao,Shandong 266590,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2021年第10期2083-2100,共18页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(52004272,51734009)
江苏省自然科学基金资助项目(BK20200660)。
关键词
采矿工程
胶结充填体
骨料粒径分布
力学特性
微观结构
细观结构演化
mining engineering
cemented waste rock backfill
aggregate size distribution
mechanical property
microstructure
mesostructure evolution
