Fragmentation Characteristics Analysis of Sandstone Fragments for Impact Rockburst Under Different Dynamic Loading Frequency

This study used a self-developed rockburst-inducing system to apply dynamic load at different frequencies to true triaxially loaded sandstone specimens pierced by a central hole. After failure, the sandstone fragments generated were collected, as were those generated by a similar compression experiment where only static load was applied. The quantity of fragments falling within coarse, medium, fine and micro-scale size ranges and the mass distribution were analyzed. Image processing software was then used to process images of the medium grains, and the measurements obtained were used to calculate the fractal dimensions of the granularity–quantity, perimeter length–quantity and area–quantity relationships. The experimental results show that fine and micro-grains make up a higher proportion of the fragmented mass when the dynamic loading frequency is higher. Fractal analysis of medium grains shows that the fractal dimension increases with an increase in dynamic loading frequency. The degree of crushing in impact rockburst experiments is found to be higher than in the compression experiment.