Study on the strength and microstructure of loess under freeze-thaw based on temperature path

In seasonal frozen soil regions, the essence of loess landslides induced by freeze-thaw cycles is the deterioration of the physical and mechanical properties of loess. It is necessary to find out the influence of temperature and water migration on the strength of loess under freeze-thaw cycles and its mechanism. Therefore, a new freeze-thaw cycle method is adopted, which is carried out based on the temperature path that the soil goes through each year, to study the law of the shear strength of the soil under the action of the freeze-thaw cycle with dynamic temperature changes and the influence of repeated freeze-thaw cycles on soil cohesion, internal friction angle and microstructure. The test results show that during a freeze-thaw cycle, the soil strength is negatively correlated with temperature, and low temperature has a greater impact on the soil strength. As the freeze-thaw cycles increase, the cohesion of the soil decreases exponentially, and the internal friction angle has little change. The microscopic test shows that with the increase of freeze-thaw cycles, the large particles in the soil are broken and the pores increase, indicating that the particles tend to be uniform, and the medium-sized(5-10 mm) pores account for the largest proportion. This study simulates the temperature change process of soil, providing a reference for the prevention and control of seasonal freeze-thaw loess landslides in this area.