Mechanical response and energy dissipation characteristics of granite under low velocity cyclic impact

Abstract

In the process of metal ore blasting mining, the surrounding rock in the middle and far area will still be affected by the stress wave generated by the explosion, resulting in the damage and strength reduction of surrounding rock. The fracture process of rock under cyclic impact load is a process of energy absorption and dissipation. The research on the mechanical properties and energy dissipation law of surrounding rock under low velocity cyclic impact has a good reference for the research on the damage law of rock under weak impact environment. In this paper, the granite samples collected from Sanshandao Gold Mine in Laizhou City, Shandong Province were subjected to cyclic impact tests by using a 50 mm diameter split Hopkinson pressure bar (SHPB) test device. The stress-strain evolution law and energy dissipation law of the specimen in the process of damage and fracture are mainly studied. The results show that the dynamic process of a large number of void defects (such as voids, dislocations, microcracks, etc.) in granite under cyclic impact load is strengthened, and the damaged core is formed and propagated, leading to tensile fracture; With the accumulation of strain energy, the damage situation intensifies, and then affects the stress propagation, so that the ratio of incident energy to reflected energy increases linearly with the accumulation of strain energy, and the ratio of transmitted energy also decreases linearly.