不同应变率下煤岩冲击动力试验研究

利用75 mm的分离式霍普金森压杆（SHPB）实验系统，对煤岩进行不同应变率下冲击压缩试验。实验结果表明：煤岩微细观特征复杂，离散性强；煤岩在低应变率下多呈轴向劈裂破坏，高应变率下呈现出压碎破坏；冲击过程中能量随着应变率的增大而增大，耗散能与应变率基本呈弱幂函数关系或线性分布关系；煤岩破碎块度分维与应变率呈线性相关，分形维数在1.7~2.2范围内，应变率越大，块度越小，分形维数越大，煤岩耗散能量越大。

Dynamic test study of coal rock under different strain rates

The impacting compression test of coal rock was made by 75 mm Split Hopkinson Pressure Bar (SHPB) under different strain rates.The results show that the characters of coal rock are complicated and dispersed.Under lower strain rate，the specimens presents an axial cleaving failure mode，while under higher strain rate，the specimens presents an crushing failure mode.Dissipation energy of specimens during process of the impacting increases with increase of strain rate，and relationship between them is a weak power function or linear distribution.The fractal dimension of the fragmented coal rock ranged from 1.7 to 2.2，and there is a linear correlation between the fractal dimension and the strain rate.The larger the strain rate，the smaller the fragmentation size，the larger the fractal dimension and the greater the dissipation energy.