Study on sandstone fragments from impact rockburst experiments

Impact rockburst is induced by the combined static and dynamic loads after excavation.There are two types of impact rockburst experiments，one is induced by changing the static load and another is induced by changing the amplitude of dynamic load.The sandstone fragments after these two experiments were collected.Meanwhile，the sandstone fragments generated from the similar compression experiment under static load were collected too.And the mass， length，width and thickness of each fragment has been measured respectively.The quantities and mass distribution of fragments with coarse，medium，fine and micro grains in different size ranges，and size distribution were further analyzed.The crushing level and shape characteristic of fragments were obtained.Then the fractal dimensions were calculated.The results show that the degree of crushing level of fragments from impact rockburst is higher and with obvious slice shape；the ways of combined static and dynamic loads have a little effect on the crushing level and scale characteristic of fragments from impact rockburst experiments；energy dissipation from impact rockburst experiments is higher than that of similar compression experiment.