Research on spatial variation of soil particles in railway saline soil subgrade under freeze-thaw cycles

In order to study the relative displacement and spatial position variation characteristics of soil particles inside railway saline soil subgrade, as well as the relationship between the number of freeze-thaw cycles and soil particle displacement, four monitoring points were set in samples with different moisture contents. After undergoing 0, 10, 20, and 30 freeze-thaw cycles, the position of monitoring points was determined through CT scanning to study the spatial variation characteristics of soil particles. Through research, it was found that: (1) After 10, 20, and 30 freeze-thaw cycles, the spatial position of the monitoring points in the sample showed significant changes. And with the increase of water content, the spatial changes of monitoring points become more and more obvious. (2) After 30 freeze-thaw cycles, the horizontal and vertical displacement of monitoring point 4 in the sample with a moisture content of 4% were the smallest, with values of 4.827 um and 40.39 um, respectively; The maximum horizontal and vertical displacement at monitoring point 4 in the sample with a moisture content of 10% were 113.34um and 28.239 um, respectively. (3) As the water content increases, the relative spatial displacement between monitoring points continues to increase. (4) Comparing the theoretical calculated displacement with the experimental displacement, the two show a consistent trend of change, and the highest similarity between the two is 0.91, with an average similarity of 0.67. The research results reveal the spatial variation pattern of soil particles inside railway saline soil subgrade.