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本文讨论的粗粒土,包括碎石土及除粉砂以外的砂类土。粗粒土冻结时水分迁移的特点与细粒土有质的差异。砂土颗粒可以有吸着水但无薄膜水,当粉粘粒含量小于某数值时,砂土中不存在连续结合水膜,因此就不像细粒土那样产生薄膜水正向迁移(水分向冻结面迁移)。相反,由于上部土层孔隙中自由水冻结后体积膨胀,对下层土体内孔隙水产生超静水压力,在有水分排出条件时,使水分反向迁移,即水分离开冻结面。根据博任诺娃所进行的土冻胀试验发现:在冻结粘土中,愈接近冷锋面水分含量愈增加,冻结后试样上部含水量达80.9％,下部含水量只有36.8％,平均含水量为63.9％;相
The coarse-grained soils discussed in this paper include crushed-stone soils and sand-like soils other than silt. Moisture migration characteristics of coarse-grained soils and fine-grained soils are qualitatively different. The sand particles may have absorbed water but no film water. When the content of the clay particles is less than a certain value, there is no continuous water film in the sand, and thus there is no positive migration of film water like the fine-grained soil (the moisture is frozen Surface transfer). On the contrary, due to the volume expansion of the free water in the pores of the upper soil, the pore water in the underlying soil will have an excess hydrostatic pressure. When there is a water discharge condition, the water will migrate backward, that is, the water will leave the frozen surface. According to the soil frost heaving test conducted by Boyenova, it is found that in the frozen clay, the closer to the cold front the moisture content increases. After freezing, the upper moisture content of the sample reaches 80.9%, the lower moisture content is only 36.8%, and the average water content is 63.9%; phase