Characteristics of Energy Dissipation in the Process of Rock Damage under Cyclic Impact.

Energy absorption and dissipation are mainly involved in the rock breaking process which is affected by many factors, such as impact strength, number of cycles, and rock material characteristics. In this study, a novel method was proposed to reveal the mechanical properties and energy dissipation law of surrounding rock under the cyclic impact. A split Hopkinson pressure bar (SHPB) test device was used to obtain the energy dissipation characteristics of granite samples. The stress-strain evolution process was compared with the energy dissipation process to analyze the characteristics of incident energy, transmitted energy, and reflected energy in each stage of the impact process. A relationship between impact strength and energy dissipation was established. Results demonstrate that under the impact load, the rock is primarily an axial tensile failure, and the dissipated energy is mainly in the form of surface energy in crack propagation. With the increase in impact, the number of active cracks, the ratio of incident energy to strain energy, and the ratio of reflected energy all increase, whereas the ratio of transmitted energy decreases. The larger the impact load, the larger the proportion of strain energy absorption, and the average value increases from 28.49% to 30.51%. The proportion of single strain energy absorption under cyclic impact conditions is far less than 40.57% of single impact failure. This study contributes to the optimization design of blasting engineering and the production safety improvement in metal mining. [ABSTRACT FROM AUTHOR]