Study on ice condensation characteristics and deformation laws of two-dimensional orthopermafrost

With the further development of the permafrost area in the country, the research on geotechnical engineering is becoming more and more in-depth at this stage. Aiming at the two-dimensional freezing problem of frozen soil subgrade on slopes in alpine mountainous areas of Xinjiang, this paper studies the frost-heave segregation characteristics and deformation laws of silt and silty clay under two-dimensional freezing conditions through laboratory experiments, theoretical analysis and model calculations. The temperature field, moisture field and displacement field distribution of two-dimensional slope frozen soil under different working conditions are obtained from the laboratory test. On the basis of experiments, a hydrothermal coupling numerical calculation model for the growth criterion of two-dimensional ice permeable crystals is established. The results show that the temperature gradient will occur at the same soil layer during the two-dimensional freezing process, namely the temperature gradient generated by the initial temperature difference between the upper and lower roofs and the temperature gradient between the soil layers caused by the tilt of the upper roof. And due to the difference in soil properties, the temperature of silty clay at the same position is slightly higher than that of silt soil at the same upper roof inclination. In the case of two-dimensional freezing, water migrates from the unfrozen area in the lower part of the soil layer to the frozen area, and the water in the unfrozen area and the frozen area will also migrate horizontally to the right. The evolution of frost heave displacement can be divided into three stages: frost heave stage, frost heave rapid development stage, and stability stage. The frost heave displacement of the upper surface of the two-dimensional frozen soil sample is non-uniform, and the displacement of the middle position of the middle of the soil at the same height is greater than that of the two sides. The displacement of silt soil is slightly larger than that of silty clay, and different working conditions have the greatest influence on displacement at x = 0 m, and the influence of working conditions at x = 0.1 m is the smallest. The numerical simulation results are in good agreement with the experimental data, with a temperature field simulation accuracy of 90%, a water content error of less than 5% for the freezing front of the moisture field, and a maximum displacement error of 4.5% for the displacement field. The established model successfully reproduced the lateral migration of moisture and uneven frost heave deformation caused by the asymmetric temperature field, revealing that the two-dimensional coupling of heat, water, and force is the core disaster mechanism of slope frozen soil roadbed diseases. This model provides a reliable theoretical tool for predicting and preventing frost heave in cold region slope roadbeds. Analysis of the two-dimensional deformation mechanism of frozen soil subgrade in high-altitude mountainous areas and the provision of improved preventive measures.