不同地下水补给条件下非饱和砂壤土冻结试验及模拟

为研究土壤冻融过程中不同地下水位对土壤的补给规律，在室内进行了两组不同地下水边界条件下的土柱冻结试验: A组无地下水补给，土柱高度60cm；B组地下水维持在距土柱表层60cm深度处。土壤在冻结过程中水分及盐分均呈向上运移趋势，稳定浅地下水补给会加剧水分及盐分向上运移，造成上层土壤盐分的聚积，影响土壤剖面的热量平衡，引起剖面温度的重新分布，从而减缓冻结锋的推进速度。运用HYDRUS-1D冻融模块对不同地下水埋深（0.5m，1.0m，1.5m，2.0m，2.5m）情况下冻结过程中水分运移规律进行了模拟。模拟结果表明:累积补给量在埋深小于1.5 m时随埋深增加而有所增加，而当地下水埋深大于1.5 m时，累积补给量随着埋深增加而有所减小，甚至保持不变。

A study of freezing process in variably-saturated sandy-loam soil under different water table depths:Experiment and simulation

Two soil column freezing experiments were conducted to understand the effect of water table depths on the transport of water, heat, and salt in soil columns. Column A was 60 cm soil in height but without water recharge, while column B involved a stable water table at 60 cm depth from the soil surface. While the soil was freezing, water content and temperature were measured. Results show that water and salt move upwards during the freezing process, and accumulate at the freezing front when there is a shallow water table. The movement of water and salt brings heat to the frozen soil. Such a redistribution of heat in the soil column can slow the progress of a freezing front. The HYDRUS-1D freezing and thawing module was used to simulate water movement and heat transfer during freezing at different water table depths (0.5 m, 1.0 m, 1.5 m, 2.0 m, and 2.5 m). Results show that the shallower the water table, the smaller the cumulative recharge, that is, a shallow water table supplies water more intensely and seems to stop the progress of the freezing front; a deeper water table has difficulty in recharging the upper layers.