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为研究盐渍化冻土水分、盐分迁移规律以及变形特性,探索寒区旱区土壤盐渍化机制,配制了不同含盐量的粉质黏土进行模型试验。试验结果表明,温度、水分、盐分和土体变形之间相互耦合。温度降低有利于盐晶体析出和未冻水结冰;反之,温度升高易于晶体溶解和冰融化。水盐相变过程中伴随能量的释放或吸收,影响土体温度。盐分改变了流体的动力黏度和土体冻结温度,并且盐分结晶使土体产生较大的吸力,加剧了未冻水含量的变化。水分是盐分迁移的介质,盐分以离子形式随未冻水迁移。降温期水分盐分向上迁移,升温期迁移方向相反。迁移速率与吸力有关,冻结缘附近吸力最大,速率最快。盐渍化冻土的变形是盐分和水分共同作用的结果,含盐量较低时冻胀和融沉是土体变形的主要因素;当含盐量较高时盐胀和溶陷占主导作用。
In order to study the water and salt migration and salinity characteristics of salinized permafrost, the mechanism of soil salinization in cold and arid regions was explored, and silty clay with different salt contents was prepared for model test. The test results show that the temperature, moisture, salt and soil deformation between the coupling. Lower temperature is conducive to the precipitation of salt crystals and unfrozen water ice; the other hand, the temperature is easy to dissolve crystals and ice melting. Water and salt phase transition accompanied by energy release or absorption, affecting soil temperature. Salt changes the dynamic viscosity of the fluid and the soil freezing temperature, and the crystallization of salt makes the soil produce greater suction, exacerbating the change of unfrozen water content. Moisture is the medium of salt migration, and the salt migrates in the form of ions with unfrozen water. During the cooling period, the salinity of water will migrate upwards and the migration will take the opposite direction during the warming phase. The migration rate is related to suction, with the highest suction and fastest rate near the frozen edge. The deformation of salinized permafrost is the result of the interaction of salt and water. Frost heave and thaw settlement are the main factors of soil deformation when the salt content is low. Salt swell and dissolution dominate when the salinity is high .