ABSTRACT

The precipitation accelerates the migration of water and salt in the soil, and aggravates the deterioration of saline earthen sites. Based on the freeze-thaw tests of soil column, the water and salt migration process of earthen sites in northwest China after rainfall in early winter and snowfall in late winter was simulated. The results show that when providing the same quality of rain or snow, the water basically migrated to all parts of the soil column under the initial condition of rainfall infiltration, while the water redistribution range after snowmelt infiltration was just the upper part of the soil column. With the infiltration and evaporation of water, the salt in the surface layer of soil column leached downward and then migrated upward. After 20 freeze-thaw cycles, the contents of SO2–4 and Cl⁻ in the surface layer of soil column under rainfall condition were 89.13% and 99.27% of the initial value, respectively, while those under snowmelt condition were 61.58% and 60.65%, respectively. Snowmelt caused the soil surface to form rolled mud and salt efflorescence, while rainfall led to the formation of crust on the top surface of the soil column and saline zone at the bottom.

摘要

降水加速了土壤中水分和盐分的运移，加剧了盐渍土遗址的退化。基于土柱冻融试验，模拟了我国西北地区土遗址经过初冬降雨和晚冬降雪后的水盐运移过程。结果表明，当提供相同质量的雨雪时，降雨入渗初始条件下水分基本迁移到土柱各处，而融雪入渗后水分重新分布范围仅在土柱上部. 随着水分的入渗和蒸发，土柱表层的盐分向下淋溶，然后向上运移。经过 20 次冻融循环后，SO2-4 和 Cl ^-的含量降雨条件下土柱表层土柱表层水溶性分别为初值的89.13%和99.27%，融雪条件下分别为61.58%和60.65%。融雪导致土壤表面形成滚泥和盐分风化，而降雨导致土柱顶面结皮和底部盐碱带。