A DEM-based approach for modeling the thermal-mechanical behavior of frozen soil

The mechanical characteristics of frozen soil under various temperatures have theoretical and engineering significance for improving the efficiency of permafrost excavation and ensuring the stability of permafrost area engineering. A novel approach based on Discrete Element Method (DEM) is proposed to simulate the temperature effect of frozen soil. An existing 3D contact model for cemented granular material is extended to include the effects of temperature on bond strength and modulus of ice cementation, which are verified by existing analytical solutions and experimental data, and a simplified method is employed to simulate the influence of ice crystal expansion on the void ratio of frozen soil, whereafter, the modified contact model is calibrated by the results of the temperature-controlled triaxial test. This approach was proven to be effective by comparing the simulation results with the experimental results. The micro mechanical behavior of frozen soil samples was studied. The results showed that different types of bond contact had different effects in the shearing stage. The structural 'weakening' and 'strengthening' of the frozen soil occur simultaneously during the loading process, and the structural damage is mainly caused by the plastic damage induced by the relative slip between soil and ice particles.