True Triaxial Test and Continuous‐Discrete Coupling Simulation Study on Dynamic Mechanical Properties and Damage Evolution Mechanism of Deep Marble

ABSTRACT This paper investigates the mechanical properties and micro‐fracture activities of marble at depth ( short for deep marble) through true triaxial dynamic tests and continuous‐discrete coupling simulations. First, the true triaxial split‐Hopkinson pressure bar (SHPB) tests were conducted to measure the dynamic mechanical properties of marble specimens. Then, a continuous‐discrete coupling model was established based on the triaxial simplified grain‐based model and the application of force–velocity transfer channel to the coupling interface. Finally, the established continuous‐discrete coupling model was calibrated against test data and used to further analyze the damage mechanical behaviors of the specimens. The results show that the peak stress, maximum strain, strain rate, damage of the specimens, and maximum electrical signals of the lateral pressure bars all increase as the impact velocity increases. The strain rate effect is noteworthy. The dynamic mechanical responses and damage characteristics of the specimens under different lateral stresses show a unique ratio of lateral stress to axial stress (RLAS) effect. With the increase of RLAS, the dynamic peak stress first increases and then decreases, while the maximum deformation capacity of the specimens changes inversely. The relatively high confining pressure can make the interior of the specimens denser, improve energy transfer efficiency, and reduce energy loss. With the increase of RLAS, the damage degree of the specimen first increases and then decreases. As the impact load increases, the dissipated energy increases and the damage degree of the specimens becomes more severe. These numerical simulation results can better explain the strain rate effect and the RLAS effect.