Influence of mineral mesoscopic structure on rock dynamic fragmentation under compression

Three types of rock were chosen to investigate the effect of mineral mesoscopic structure on rock fragmentation under dynamic compression. The fragments collected from the tested sandstones and granites were studied using an image-processing method, and the relationship between the fractal dimension of rock fragments and the mechanical properties in dynamic compression was established. Four failure patterns (apparently intact, local splitting, fragmentation and pulverisation) were classified according to the stress–strain behaviour and fragment distribution of the rock. Moreover, rock fragments of porous sandstone are blocky in form while they are more elongated in granite, as attributed to the difference in failure mode on the mesoscopic scale. This study is meaningful for the understanding of rock dynamic fragmentation and useful for the optimisation of rock breaking in the development of underground space.