Abstract: With the developments of geotechniques such as underground energy engineering, thermal foundation treatment, and nuclear waste treatment, the influence of thermo-mechanical coupling on soil has become one of the hot research topics in the field of geotechnical engineering. Based on the particle volume expansion method, the cyclic thermal consolidation experiment on loose particles (relative density D_r = 0.2) at different temperature changes (20 ℃, 40 ℃, and 60 ℃) is simulated by the PFC2D. From a macroscale point of view, it is found that the particles produce thermal consolidation during the temperature cycle, i.e. the process in which the void ratio of the sample cumulatively reduces as the number of temperature cycles increases. The studies have shown that the larger the amplitude of the temperature changes, the denser the granular material will be during the long-term temperature cycle, and the uneven distributions of void ratio, lateral stress, and vertical stress will appear. At the same time, the influences of temperature cycle and variable temperature amplitude on the number of contacts between particles, normal contact force, and tangential contact force are summarized by microscopic analysis. It is concluded that the amplitude of the temperature cycle in the thermal consolidation test has a greater impact on the anisotropy of the sample.

Key words: temperature cycle, thermal consolidation, discrete element method (DEM), variable temperature amplitude