Static and dynamic uniaxial compression tests on coal rock considering the bedding directivity
Static and dynamic uniaxial compression tests on coal rock considering the bedding directivity
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考虑层理方向性的煤岩静动单轴压缩试验
DOI：
10.1007/s12665-015-4106-3
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发表时间：
2015-05-01
影响因子：
2.8
通讯作者：
Liu, Jianfeng
中科院分区：
文献类型：
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作者：
Liu, Xiaohui;Dai, Feng;Liu, Jianfeng
煤岩在静态和动态加载速率下的力学性能和行为在煤炭开采实践中非常重要。本研究考虑煤岩层理方向性，分别使用MTS液压伺服控制试验机和分体式霍普金森压力棒（SHPB）对煤岩进行准静态和动态单轴压缩试验。静态测试获得的应变率范围为 10−5 至 10−2s−1，动态 SHPB 测试获得的应变率范围为 20 至 100 s−1。对于动态测试，利用脉冲整形技术实现动态力平衡，从而验证准静态数据缩减。 SHPB测试中使用高速摄像机来捕捉失效过程。研究了失效模式、断裂强度、能量耗散和分形维数的特征。揭示了煤岩显着的应变率相关行为，抗压强度、弹性模量和能量消耗随着应变率的增加而增加。静态应变速率下层理对煤体行为的影响比动态应变速率下的煤体行为更显着。沿不同层理方向的测量强度表现出明显的变化，具有显着的各向异性。此外，对回收碎片的筛分统计分析显示出明显的分形；断裂维数可以与分形能量耗散相关。
The mechanical properties and behavior of coal rock under both static and dynamic loading rates are of importance in the coal mining practices. In this study, both quasi-static and dynamic uniaxial compression tests are conducted on coal rock, considering the bedding directivity of coal rocks using a MTS hydraulic servo-control testing machine and split Hopkinson pressure bar (SHPB), respectively. The attained strain rates range from 10−5to 10−2s−1for static tests and 20 to 100 s−1for dynamic SHPB tests. For dynamic tests, pulse-shaping technique is utilized to achieve dynamic force balance and thus validate the quasi-static data reduction. A high-speed camera is used to capture the failure process in SHPB tests. The characteristics of failure mode, fracture strength, energy dissipation, and fractal dimension are investigated. A significant strain-rate-dependent behavior of coal rock is revealed, and the compressive strength, elasticity modulus and energy consumption increase with increasing strain rate. The bedding effect on the coal behavior at static strain rate is more prominent than that at dynamic strain rate. The measured strengths along different bedding directions exhibit distinct variations, featuring significant anisotropy. In addition, a sieving statistics analysis of the recovered fragments depicts obvious fractal; and the fracture dimension can be correlated to the fractal energy dissipation.