The freeze-thaw history of soil is important to assess and predict frost heave. Different freezing modes will lead to redistributions of water and salt and variety of dry density. Choosing three freezing modes of unidirectional freezing

circular freeze-thaw with sinusoidal wave and circular freezing with negative temperature

experiments of red silty clay along the Qinghai-Tibet Railway are carried out in order to analyze variation of frost heave amount

redistribution condition of water and salt and change law of dry density. The results show that salt transfer is kept out of the freezing soil for ice self-purification during the unidirectional freezing; deformation amount of the soil experienced freezing and thawing is uncumulative. Salt convection with water is accompanied with salt diffusion during freezing and thawing. The existent compression deformation shows the intensified effect of freeze-thaw on soil structure.