Freeze-thaw characteristics of soils on the Tibetan Plateau

The Tibetan Plateau features a unique natural environment and geographic location that promote the widespread presence of permafrost and desertification. Currently, there is a notable lack of research offering a comprehensive understanding of freeze-thaw soil properties, which adds considerable uncertainty to the assessment of desertification risks in this region. Here, we optimise the freeze-thaw cycling equipment to simulate a more realistic freeze-thaw environment, with careful consideration of the freeze-thaw characteristics of soils in the Tibetan Plateau region, including measurement of soil physical properties, observation of the surface microstructure, and monitoring of axial deformation with or without loading. Our findings indicate a gradual decrease in surface soil water content with increased freeze-thaw cycles. We observed an initial increase followed by a gradual shift in total soil porosity and an inverse pattern in bulk density. The distribution of soil aggregate particle sizes also changed during the freeze-thaw processes, leading to reduced resistance to erosion. These changes were attributed not only to modifications in soil surface porosity but also to the axial soil deformations induced by freeze-thaw cycles. Notably, under loading conditions, the development of frost heave was limited, resulting in decreased frost heave. This research not only advances our understanding of the mechanisms of soil erosion due to freeze-thaw processes but also provides essential insights for managing desertification on the plateau.