Abstract: Saline soil contains a large amount of soluble salts, and the change of water content and suction has an important effect on its engineering properties. At present, few studies focus on the water retention characteristics of saline soil, and there is no uniform and clear soil water characteristic curve of saline soil in the full suction range. In this paper, the pressure plate method, vapor equilibrium method, and chilled-mirror dew-point technique were used to measure the matric suction and total suction of saline soils. The influences of compaction degree and salt contents on the water retention characteristics of saline soils were studied by experiments. The experimental results showed that in the low suction range, with the increasing of compaction degree, the saturated volumetric water content of the soil sample decreases and the value of air-entry suction increases. The water retention capacity increases with the increase of compaction degree and pore solution concentration, and the pore solution concentration has an obvious influence on the matric suction especially for the soil with low compaction degree. In the high suction range, for the soil with high salt content, the compaction degree has a significant influence on the soil-water characteristic curve, and the water retention capacity of soil increases with the increasing of salt content.

Key words: saline soil, soil-water characteristic curve, pressure plate method, vapor equilibrium method, compaction degree, salt content