Research on impact fracture of rock based on fractal theory

Impact experiments were made on the sericite-quartz schist samples and on the sandstone samples respectively by using the apparatus of split Hopkinson pressure bar with a diameter of 100 mm, and the fragment-size distribution of fragmental rocks was obtained through sieving and statistics calculating of rock samples. Fractal dimensions of sericite-quartz schist and sandstone were calculated by using fractal geometric method and the relationship between the dynamic compressive strength and the fractal dimensions of the two kinds of rocks was analyzed. The experimental results indicate that the values of fractal dimensions of sericite-quartz schist range from 1.9 to 2.4 and those of sandstone range from 2.5 to 3.0. The fractal dimensions of the two kinds of rocks increase linearly with the increase of impact speed. The dynamic compressive strength of sericite-quartz schist has no obvious correlation with the fractal dimensions, however the dynamic compressive strength of sandstone increases with the increase of fractal dimensions. Thus using the fractal dimensions to describe the dynamic compressive strength of rocks may provide a new approach to investigate the inherence rule between fractal characteristics and impact mechanical properties of rock materials.