冻融对银川平原压实砂土压缩性的影响

Effect of freeze-thaw on compressibility of compacted sand in Yinchuan Plain

为了给冻融变形稳定后的压实砂土地基提供沉降分析用基础数据,设饱和度依次为30%、50%和70%,压实度依次为0.88、0.93和0.98,考虑不同的补水条件,研究银川平原压实砂土经20次循环冻融后的压缩性.研究结果表明:循环冻融使压实砂土的压缩性增大,补水冻融条件下的压缩性增量明显大于非补水冻融条件下的压缩性增量,补水条件是重要的影响因素,隔水是减轻冻融对压缩性影响的有效措施.随压实度的增大,冻融对压缩性的影响在非补水条件下减小,在补水条件下则增大.压实度和饱和度对压实砂土冻融后的压缩性影响均为显著,二者都是主导因素.压缩性增量与冻融体积变形率间存在很好的线性相关性,可用冻融体积变形率估算压缩性增量,以减少试验工作量.研究结果对银川平原压实砂土工程的冻害评价与防治具有重要的现实意义.

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.