Numerical Study on Mechanical Properties of the Freezing-Thawing Cycle of Tailings Based on Particle Discrete Element Method

To study the effects of the number of freezing-thawing cycles (F-T cycles), the dry density, and the average particle diameter on the mechanical properties of tailings, the calibration laws of the fine-scale parameters in the discrete particle element numerical simulation software PFC2D(Particle Flow Code) were first tested, and then pre-experiments were conducted in the form of orthogonal tests. Finally, according to the results of the pre-experiments and the analysis of the pre-experimental results by SPSS (Statistical Product Service Solutions) software, uniaxial tests were carried out for different numbers of freeze-thaw cycles, different dry densities, and different average particle sizes. The tailings specimens were subjected to uniaxial compression simulations. The results showed that (1) the uniaxial compressive strength of the tailings specimens decreased with each freeze-thaw cycle, and stabilized after seven freeze-thaw cycles. (2) With a greater number of freeze-thaw actions, the porosity of the tailings increased after freeze-thawing. The peak of porosity was much higher than that of the models with fewer than seven freeze-thaw actions. (3) The contact number of tailings specimens showed a significant decrease after the number of freeze-thaw cycles reached seven. However, the amount of exposure was not the main factor affecting the strength of tailings (4). As the number of freeze-thaws increased, the tailings model was more prone to stress concentration. Previously, PFC software has been applied to tailings simulation studies, and this study verifies the feasibility of this method. This research is able to offer a reference for studying the mechanical property changes of tailings in the cold highland area.