The mechanics of frost heaving
The mechanics of frost heaving
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DOI：
10.1086/623720
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发表时间：
1930-01-01
影响因子：
1.8
通讯作者：
Taber, S
中科院分区：
文献类型：
--
作者：
Taber, S
旧的理论认为，冻胀是由于冻结的水体积的变化是基于封闭系统的实验。野外观测和最近的实验表明，土壤在正常条件下冻结时，通常表现为开放系统。当饱和土壤的冻结导致很少或没有隆起时，部分水被迫通过冻结区以下的土壤空隙，压缩或排出空气。当水被拉过土壤，形成分离的冰层时，就会产生过度的隆起。这些冰层的厚度增加是因为水分子被拉入薄膜中，薄膜将生长的冰晶与下面的土壤颗粒分开。由于沉重的表面负荷可能会升高，需要很大的力量来拉水通过不透水的粘土，水被置于高张力下。隆起受到水中可能产生的张应力和土隙中冰晶向下生长的限制。这两个因素也可能解释了冰和粘土层交替形成的韵律条带。在固结良好的粘土中，表面隆起等于冰层的总厚度，冰层之间粘土的含水量保持近似恒定;但隆起是连续和规则的，而不是间歇的。在最低的冰层附近，粘土是软的，因为大部分的水是未冻结的，温度越低，冻结时间越长，硬度越高。通过在开放系统中冻结而不是在水中冻结，已经获得了额外的证据。
The old theory that frost heaving is due to change in volume of water frozen was based on experiments with closed systems. Field observations and recent experiments indicate that soils, when subjected to freezing under normal conditions, usually behave as open systems. When the freezing of saturated soils results in little or no heaving, part of the water is forced through the soil voids below the zone of freezing, compressing or expelling air. Excessive heaving results when water is pulled through the soil to build up layers of segregated ice. These ice layers grow in thickness because water molecules are pulled into the thin film that separates the growing ice crystals from underlying soil particles. Since heavy surface loads may be heaved and much force is required to pull water through impervious clay, the water is put under high tension. Heaving is limited by the tensile stress that may be developed in the water and by downward growth of ice crystals in soil voids. These two factors also probably explain the rhythmic banding due to alternating layers of ice and clay. In well-consolidated clays the surface uplift equals the total thickness of the ice layers, the water content of the clay between the ice layers remaining approximately constant; but heaving is continuous and regular instead of intermittent. Clay is soft near the lowest ice layer because much of the water is unfrozen, the hardness increasing higher up where the temperature is lower and freezing has gone on for a longer time. Additional evidence has been obtained by freezing in open systems other liquids than water.