Analysis and Research on Experimental Process of Water Thermal Migration of Freeze–Thaw Cracked Rock Based on Particle Tracking Method and Thermal Imaging Technology

In high-altitude and cold regions, external dynamic geological processes, such as glacial melting and other processes are intense, which frequently results in surface dynamic geological processes, such as slope collapse, landslides, debris flows, and ice avalanches along the route. For high and steep slopes in high-altitude regions containing controlled fractures, the key is to grasp the water-heat process and the evolution of the frost heaving force induced by it within the fractures. This can then lead to the exploration of the multi-phase and multi-field damage propagation, and a disaster mechanism within the fractures under repeated freezing and thawing. The visual tracking of the water-heat migration process within the fractured rock mass is helpful in observing the evolution process of frost-heaving force and providing a theoretical basis for the frost-heaving mechanism. First, research on particle tracking, thermal imaging tests, and image processing technology was conducted to demonstrate that particle tracking and thermal imaging techniques can track the freezing front within the rock fractures and the migration of liquid water inside the rock. Then, by selecting fluorescent particles and improving the observation window and using a waterproof insulation cardboard, the development of a visualization device system for the water-heat migration process was achieved, allowing the tracking of the water-heat migration process. The results of the verification test showed that under freezing and thawing conditions, the experimental device could effectively track the temporal and spatial changes of water-heat migration inside and outside the rock fractures and monitor the real-time changes of the freezing front. Reliable experimental results were obtained, which provided a visual record of the water-heat migration and water-ice phase transition within the fractured rock mass during the freezing and thawing process. Combining thermal imaging technology with the real-time recording of the motion rate of fluorescent particles, this experiment described the movement speed of the freezing front and the convection of free water within the fractures in rock water-heat migration, which is of significant importance for the study of the frost-heaving force under the influence of water-heat migration.