Dynamic characteristics and damage model for rock under uniaxial cyclic impact compressive loads

Experiments on dynamic mechanical performance of granite are carried out under uniaxial cyclic impact loads by using a modified large diameter split Hopkinson pressure bar (SHPB). The dynamic characteristics of the granite specimens and the laws of the energy absorption are analyzed. The cumulative damage of the granite specimens is calculated by use of the dynamic statistics damage model based on the Weibull random distribution. The laws of the cumulative damage of the granite specimens are also analyzed through the stress-strain curves. The results show that, in the cyclic impact compressive tests, with the increase of repeated action times of impact loads, the deformation modulus of granite decreases, the yield strain increases and the yield stress shows a decreasing trend. The value of cumulative specific energy increases with the increase of impact times, which increases slowly before the failure of the specimen and increases rapidly at its failure. The model curves and the test curves have good consistency, which shows that this model can reasonably reflect the relationship of the stress-strain and stress-strain rate. The value of cumulative damage increases with the increase of impact times, and its increasing rate changes from slowly to rapidly. Before the failure of the specimen, the cumulative damage increases smoothly, and the main increment occurs in the last impact when the specimen is broken.