Experimental study on dynamic mechanical properties of anthracite under different impact loading conditions

In this study, impact loadings with different velocities were conducted on coal samples with different bedding directions (perpendicular/parallel/45 degrees oblique intersection with the bedding) from Zhaogu No. 2 Coal Mine with the aid of the Hopkinson impact test system. Furthermore, the responses of impacted coal samples with different bedding directions to impact loadings with different velocities were investigated according to the changes of mechanical parameters such as stress, strain and strain rate. The following conclusions were drawn. The peak pressures of impacted coal samples are closely correlated to the impact velocity and exhibit significant impact mechanical anisotropy. The stress-strain curve of coal sample after impact can be divided into two types according to the impact speed: the stress-strain curve with impact speed less than or equal to 1.61 m/s and the stress-strain curve with impact speed greater than 1.61 m/s. After experiencing elastic deformation, the stress-strain curve has a strengthening deformation process similar to that of steel, and it has an obvious strain-hardening section, showing notable plastic characteristics. The damage values of coal samples display evident impact velocity correlation and impact directionality, and a higher impact velocity corresponds to a greater difference in the impact damage values of coal samples with different bedding directions.