Numerical Investigation into the Mechanical Behaviours and Energy Characteristics of Hard Coal Subjected to Coupled Static-Dynamic Loads

In practical engineering, coal burst is usually caused by the combination of high geo-stress and dynamic loading. To study response in conditions, numerical models a coupled static–dynamic split Hopkinson pressure bar (SHPB) test system were established, based on which impact tests for specimens at different speeds static pre-stress levels conducted. The mechanical properties, energy characteristics failure patterns under loads analyzed. results show that when constant, peak stress, maximum strain kinetic increase significantly with speed. Nevertheless, they are less affected pre-stress, increasing linearly level lower but becoming stable higher speeds. addition, weak may trigger instability specimen condition. Overall, both speed have influence behavior loads, outweighs pre-stress.