Experiment and FDM-DEM Simulation of Impact Dynamic Mechanical Behavior of Frozen Soil after Freeze-Thaw Cycles

The stability and durability of frozen soil in cold regions are significantly affected by freeze-thaw cycles (FTCs) and impact loads. In this study, dynamic impact compression experiments were performed on frozen soil under different numbers of FTCs (0, 1, 3, and 5) and different strain rates (350, 450, and 600 s(-1)) to explore the influence of FTCs on the impact dynamic mechanical properties of frozen soil. The experimental results revealed that the frozen soil exhibited significant strain rate and FTC effects. The strength of frozen soil decreased with an increase in the number of FTCs and a decrease in the strain rate, and there was a critical threshold for FTCs. A three-dimensional split Hopkinson pressure bar (SHPB) numerical model was constructed by coupling finite difference method (FDM) and discrete element methods (DEM). The SHPB and frozen soil were modeled using FLAC(3D) and PFC3D software, respectively. The impact dynamic mechanical behavior of frozen soil after FTCs was simulated using a parallel bond model as the contact model between the particles. The stress-strain and crack evolution behaviors in frozen soil after FTCs were discussed. A comparison of the simulation results and experimental data confirmed the validity and reliability of the coupled FDM-DEM simulation.