Under the influence of large temperature differences in an impermeable pavement layer of wide embankment in permafrost regions, liquid water accumulates at the bottom of the impermeable cover. The phenomenon is known as the pot‐cover effect and leads to an increase in soil water content and a reduction in bearing capacity of wide embankments. At present, water vapor and liquid water migrations and their effect on embankment thermal‐moisture stability have not been fully confirmed. To better understand the moisture transport and accumulation process within embankments, hydrothermal field monitoring was conducted from 2009 to 2011 on an asphalt concrete layer highway in Beiluhe, central Tibet Plateau. The field monitoring results show that soil moisture content between 50 and 250 cm below the pavement continuously increases with the number of freeze‐thaw cycles, with the largest increase during the 2 years being 6.4%. Then, a coupled hydro‐vapor‐thermal transport model was established and verified. Furthermore, the model was used to analyze the numerical recurrence of the pot‐cover effect. The simulation indicates that the upward migration of liquid water during the freezing period is less than the downward migration during the thawing period, while vapor migrates downward during the thawing period but upward during the freezing period. The migration of water vapor within the embankment during the freezing period is the main cause of the pot‐cover effect in permafrost regions. In addition, the research results can provide new ideas for understanding the internal mechanism of thermal‐moisture dynamics of the embankment and the stability prediction of permafrost engineering.

中文翻译：

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多年冻土路堤中的盆盖效应：原位实验证据和机理模拟


在多年冻土区宽路堤的不透水路面层中，在大温差的影响下，液态水积聚在不透水覆盖层的底部。这种现象被称为盆盖效应，导致土壤含水量增加和宽堤的承载能力降低。目前，水蒸气和液态水的迁移及其对路堤热湿稳定性的影响尚未得到完全证实。为了更好地了解路堤内的水分输送和积累过程，2009 年至 2011 年在青藏高原中部北陆河的一条沥青混凝土层公路上进行了热液田监测。现场监测结果表明，随着冻融循环次数的增加，路面以下 50 至 250 cm 的土壤含水量持续增加，其中 2 年的最大增幅为 6.4%。然后，建立并验证了水-气-热耦合输运模型。此外，该模型用于分析罐盖效应的数值递归。模拟结果表明，冻结期液态水的向上迁移小于解冻期的向下迁移，而蒸汽在解冻期向下迁移，而在冻结期向上迁移。冰冻期间水蒸气在路堤内的迁移是永久冻土区盆盖效应的主要原因。此外，研究结果可为理解路堤热湿动力学的内部机制和多年冻土工程的稳定性预测提供新的思路。