Abstract: This study focuses on the freeze-thaw deformation of sandy soil under different freezing temperatures, examining the impact of water content and Alhagi sparsifolia root content, using typical sandy soil and the desert vegetation Alhagi sparsifolia root system from the northern slope of the Tianshan Mountains in Xinjiang as the research subject. Indoor unidirectional freezing experiments are conducted to simulate natural freeze-thaw conditions, and orthogonal experiments are used to determine the correlation and significance of various factors with the freeze-thaw deformation of sandy soil. The study analyzes the freeze-thaw deformation mechanism of sandy soil under varying water contents, freezing temperatures, and root contents, and proposes a fitting formula for the freeze-thaw deformation of sandy soil. The results show that the order of influence on the maximum deformation of freeze-thaw sandy soil is water content > freezing temperature > root content. The maximum deformation of freeze-thaw sandy soil is positively linearly correlated with water content, negatively linearly correlated with freezing temperature, and exhibits a quadratic function relationship with root content. Low water content bare sandy soil and root-containing sandy soil exhibit freeze shrinkage during the initial freezing stage and thaw expansion in the melting stage, while high water content bare sandy soil and root-containing sandy soil exhibit slow freeze expansion during the initial freezing stage and thaw settlement during the melting stage. A multi-factor regression model is developed based on this pattern, enabling accurate prediction of the maximum deformation of freeze-thaw sandy soil and offering guidance for the safety assessment of vegetation ecological slope protection in cold and arid regions.

Key words: freeze-thaw deformation, root content, freezing temperature, water content, sandy soil