Abstract: In order to provide basic data for settlement analysis of compacted sandy soil foundation after freeze-thaw deformation stabilization, the compressibility of compacted sandy soil in Yinchuan Plain after 20 cycles of freeze-thaw was studied, with saturation of 30%, 50% and 70% and compactness of 0.88, 0.93 and 0.98 respectively. All results from our researches show that cyclic freeze-thaw increases the compressibility of compacted sand. The compressibility increment under the condition of supplementary freeze-thaw is obviously larger than that under the condition of non-supplementary freeze-thaw. Water supplementary condition is an important influencing factor. Water insulation is an effective measure to reduce the influence of freeze-thaw on compressibility. With the increase of compactness, the effect of freeze-thaw on compressibility decreases under no-water supplementary condition, but increases under water supplementary condition. Compactness and saturation have significant effects on the compressibility of compacted sand after freeze-thaw, both of which are the dominant factors. There is a good linear correlation between compressibility increment and freeze-thaw volumetric deformation rate. The compressibility increment can be estimated by freeze-thaw volumetric deformation rate to reduce test workload. All coming out of our research results have practical significance for evaluation and prevention of frost damage of compacted sand engineering in Yinchuan Plain.

Key words: compacted sand, water supplementary condition, freeze-thaw, compressibility