The overload phenomenon in dynamic Brazilian disc: Insights from Voronoi-based discontinuous deformation analysis

The tensile strength of rocks is a critical information in the design of operational blasting and support systems in rock engineering. However, it is important to note that in rock dynamic, the measured tensile strength in the BD test may be higher than the real value due to the overload effect. In this study, the overload effect and dynamic tensile strength correction are investigated by comparing the DDA simulation of BD tensile test with laboratory results from split Hopkinson pressure bar (SHPB) tests. A calibration flow for Voronoi-based DDA is implemented to quantitatively evaluate the dynamic tensile strength properties of rocks. To replicate the rate effect observed in dynamic tensile tests, a modification strategy is proposed, which considers the influence of the loading rate on the strength meso-parameters. To obtain the accurate dynamic tensile stress of rocks, it is crucial to adjust the dynamic BD tensile stress using the overload correction. Additionally, the failure modes of BD sample shifts as the loading rate increases. Overall, the numerical results demonstrate that the Voronoi-based DDA is a powerful tool for quantitatively analyzing the overload effect in dynamic Brazilian disc and may provide valuable insights into the dynamic fracture mechanism of rock.