EFFECT OF FREEZE-THAW ON THE HYDRAULIC CONDUCTIVITY AND MORPHOLOGY OF COMPACTED CLAY
EFFECT OF FREEZE-THAW ON THE HYDRAULIC CONDUCTIVITY AND MORPHOLOGY OF COMPACTED CLAY
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DOI：
10.1139/t93-020
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发表时间：
1993-04-01
影响因子：
3.6
通讯作者：
BENSON, CH
中科院分区：
文献类型：
--
作者：
OTHMAN, MA;BENSON, CH
几项研究表明，冻融会引起压实粘土的水力导电性的变化。由冰透镜和收缩形成的裂缝导致水力导率增加。在本文中，水导率的变化与形貌的变化有关。冰冻标本的薄片照片显示，在封闭系统中冻结时，在压实的粘土中形成冰透镜。照片还显示，在一维和三维冻结中获得了相似的冰结构，这解释了为什么在两种情况下获得了相似的水力导率。这些照片还显示，在一个单一的冻融循环中形成了一个重要的裂缝网络。随着额外的循环，新的冰透镜被创造出来，因此水力传导率继续增加。然而，在大约三个循环之后，新的冰透镜的数量变得可以忽略不计，因此水力传导率的进一步变化停止。温度梯度和应力状态影响冻融作用下压实粘土的形态和导流系数。在较大的温度梯度下，形成更多的冰透镜，因此水力导率增加。相反，覆盖层压力的施加抑制了冰透镜的形成，并减小了透镜融化时剩余裂缝的大小。因此，水力导电性降低。
Several studies have shown that freeze-thaw causes changes in the hydraulic conductivity of compacted clays. Cracks formed by ice lensing and shrinkage cause the hydraulic conductivity to increase. In this paper, changes in hydraulic conductivity are related to changes in morphology. Photographs of thin sections of frozen specimens show that ice lenses form in compacted clay during freezing in a closed system. Photographs also show that similar ice structures are obtained for one- and three-dimensional freezing, which explains why similar hydraulic conductivities are obtained for both conditions. The photographs also show that a significant network of cracks forms in a single cycle of freeze-thaw. With additional cycles, new ice lenses are created and thus the hydraulic conductivity continues to increase. However, after about three cycles the number of new ice lenses becomes negligible and hence further changes in hydraulic conductivity cease. The temperature gradient and state of stress affect morphology and hydraulic conductivity of compacted clays subjected to freeze-thaw. At larger temperature gradients, more ice lenses form and hence the hydraulic conductivity increases. In contrast, application of overburden pressure inhibits the formation of ice lenses and reduces the size of the cracks remaining when lenses thaw. As a result, the hydraulic conductivity is reduced.