A simple contact model for simulating hardening and softening behaviors of frozen soil under impact loading

Because frozen soil is widely distributed in cold regions, investigating the fracture of frozen soil under impact loading is significant for blasting projects. Previous contact models in the distinct element method studies cannot accurately and rapidly describe the hardening behavior of frozen soil under passive confining pressure and impact loading. This study simplified the ice cement in frozen soil to be the contact interface between the soil particles. Subsequently, the breakage and melting of the ice cement were considered as plastic deformation and damage to establish a contact plastic-damage-bonding model. The contact model was implemented in the particle flow code to simulate the frozen soil under impact loading. The model feasibility was verified using previous experimental and numerical results. The current results indicate that there were fewer mesocracks in frozen soil under passive confining pressure at compression stage than under no confining pressure; however, the average damage of the total contacts was larger. When frozen soil under passive confining pressure underwent axial impact loading, impact compression and stress release caused fracture and destruction of the frozen soil, and many mesocrack surfaces were perpendicular to the impact loading direction. When frozen soil under no confining pressure underwent axial impact loading, impact compression caused fracture of the frozen soil, and many mesocrack surfaces were parallel to the impact loading direction. This study addresses the limitations of previous contact models in investigating the mechanical behaviors of frozen soil and provides new insights into the fracture of frozen soil.