非饱和土水汽迁移与相变：两类“锅盖效应”的试验研究

张升; 贺佐跃; 滕继东; 刘岩; 盛岱超

doi:10.11779/CJGE201705022

非饱和土水汽迁移与相变：两类“锅盖效应”的试验研究 English Version

张升^{1, 2},
贺佐跃^{1, 2},
滕继东^1,2, ,,
刘岩^{1, 2},
盛岱超^{1, 2}

1. 中南大学土木工程学院,湖南长沙 410075;
2. 中南大学高速铁路建造技术国家工程实验室,湖南长沙 410075

基金项目: 国家重点基础研究发展计划（“973”计划）项目（2014CB047001）; 国家自然科学基金项目（51508578）

详细信息

作者简介:
张升(1979- ),男,教授,主要从事计算岩土力学等方面的教学和科研。E-mail: zhang-sheng@csu.edu.cn。

通讯作者:
滕继东，E-mail：tengjidong@163.com

中图分类号: TU431
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- 文章访问数: 537
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出版历程
- 收稿日期: 2016-01-21
- 发布日期: 2017-05-24

Water vapor transfer and phase change in unsaturated soils: experimental study on two types of canopy effect

ZHANG Sheng^{1, 2},
HE Zuo-yue^{1, 2},
TENG Ji-dong^1,2, ,,
LIU Yan^{1, 2},
SHENG Dai-chao^{1, 2}

1. Department of Geotechnical Engineering, Central South University, Changsha 410075, China;
2. National Engineering Laboratory for High-Speed-Railway Construction, Changsha 410075, China

摘要

摘要: “锅盖效应”定义为：不透水覆盖层下土体含水率大幅提高甚至饱和。最新的理论研究将“锅盖效应”分为两类,第一类由非饱和土内水气冷凝引起,第二类是冻结条件下由气态水迁移引起。为试验验证两类“锅盖效应”,研究其内在机理,利用新研制的非饱和冻土水汽迁移试验仪,对不同初始含水率的试样开展不同温度条件的水汽迁移试验。试验结果表明：冻结和未冻结两种状态均能使钙质砂试样顶部含水率增加,但冻结状态下的增加幅度显著。冻结状态下,含水率峰值位置与冻结锋面大致相同,且初始含水率越大,试样顶部和冻结锋面处的含水率增加越显著,降温速率越小,气态水迁移越显著;初始含水率增加也能使未冻结状态下的钙质砂试样顶部含水率增加,并且温度梯度对气态水迁移有一定的抑制作用,温度梯度越小,抑制作用越明显。试验结果很好地验证了两类“锅盖效应”的理论。
- 非饱和土 /
- 水汽迁移 /
- 冻结试验 /
- 锅盖效应
Abstract: The canopy effect refers to the phenomenon where moisture accumulates underneath an impervious cover. It can lead to full saturation of the soil immediately underneath the impervious cover. A recent theoretical study separates the canopy effect into two types, the first one is caused by the evaporation-condensation in unsaturated soils, while the second one is induced by the freezing-enhanced vapor transfer in unsaturated soils. In order to experimentally validate these two types of canopy effect and to reveal their mechanisms, water vapor migration experiments are carried out through a newly developed laboratory apparatus for unsaturated frozen soils. Six conditions are performed on a calcareous sand with different initial water contents and boundary temperatures. The results show that the water content in the upper position of the sample increases under an upward temperature gradient, and the increment of water content is greater if the soil is subjected to freezing. For the freezing cases, the depth of a peak water content is in line with the freezing front, and the greater the initial water content, the more the water content accumulated at the freezing front. A smaller cooling rate seems to facilitate the vapor migration. For the unfreezing cases, the water content in the upper position of the sample also increases and the increment becomes more apparent with a higher initial water content. The temperature gradient can inhibit the vapor migration. A smaller temperature gradient always results in a more notable inhibition effect. The test results verify the theory of the canopy effect.
- unsaturated soil /
- water vapor migration /
- freezing test /
- canopy effect

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参考文献(23)

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非饱和土水汽迁移与相变：两类“锅盖效应”的试验研究 English Version

作者简介: 张 升(1979- ),男,教授,主要从事计算岩土力学等方面的教学和科研。E-mail: zhang-sheng@csu.edu.cn。

通讯作者: 滕继东，E-mail：tengjidong@163.com

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出版历程

Water vapor transfer and phase change in unsaturated soils: experimental study on two types of canopy effect

计量

出版历程

目录

作者简介:
张升(1979- ),男,教授,主要从事计算岩土力学等方面的教学和科研。E-mail: zhang-sheng@csu.edu.cn。

通讯作者:
滕继东，E-mail：tengjidong@163.com