The silty clay and silty loam are two typical soil types obtained from two test sites along the Qinghai-Tibet railway. The two types of soil have been designed various initial dry densities, water contents, temperature conditions in repeated freezing and thawing testswith free access to water at the bottom. After freeze-thaw cycles, the moisture content in the freeze-thaw zone increases more than that in the unfrozen zone to the peak approximately at the top of the samples. With comparison of the water contents in the frozen and thawed states, the moisture content in the upper freeze-thaw zone in the frozen state is greater than that in the thawed state, while that in unfrozen zone in the frozen state is smaller than that in the thawed state. Within the region of the frost front, the water content in frozen state is smaller than that in thawed state. These findings help to study the freeze-thaw mechanisms deeply and perfect the forecasting module of moisture transferring in freeze-thaw cycles.
