干旱区生态环境知识资源中心(Arid): 非饱和土水气迁移与相变:两类锅盖效应的发生机理及数值再现

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	非饱和土水气迁移与相变:两类锅盖效应的发生机理及数值再现
其他题名	Moisture transfer and phase change in unsaturated soils: physical mechanism and numerical model for two types of canopy effect
	滕继东 1; 贺佐跃 2; 张升 1; 盛岱超 1
来源期刊	岩土工程学报
ISSN	1000-4548
出版年	2016
卷号	38 期号:10 页码:1813-1821
中文摘要	结合非饱和土水气迁移的物理过程和内在机理,将锅盖效应分为两种情形。第一类锅盖效应定义为非饱和土水气的冷凝过程,而第二类锅盖效应定义为水气迁移成冰过程。相较于前者,第二类锅盖效应会造成覆盖层下土体含水率大幅度提高,且现有非饱和土水热气迁移理论无法给出合理解释。综合考虑水分的蒸发、冷凝和冻结3个相变过程,建立了非饱和冻土水热气耦合迁移的数学模型,并通过数值模拟求解,再现了第二类锅盖效应的形成过程。另外计算结果表明:温度梯度下的气态水迁移并成冰会造成覆盖层下土体接近饱和含水率;一定表层深度范围内,土体含水率增加存在两个陡升段。由于现行工程设计很少考虑防气隔气,在寒旱地区进行工程建设需对第二类锅盖效应引起足够重视。
英文摘要	Considering the physical process and mechanism of liquid water-vapor transfer in unsaturated soils, this study divides the canopy effect into two types. The first is the process of coupling movement of liquid water-vapor and vapor condensation, whereas the second is the vapor transfer facilitated by changing the phase into ice. Differing from the first type of canopy effect, the second one can lead to a large amount of water accumulated beneath the impermeable top cover, while the available theory cannot give reasonable predication. This paper attempts to reveal its mechanism by proposing a new theory for liquid water-vapor-heat coupling movement in unsaturated freezing soils, in which the phase changes of evaporation, condensation and de-sublimation of vapor flow are taken into account. On basis of numerical simulation, the proposed model can hence reproduce the unusual moisture accumulation observed in relatively dry soils. The results show that the vapor transfer-induced freezing can produce a water content close to full saturation for soil under the cover, and two remarkable rises can be observed for the water content of soil at certain depth. Since isolating vapor/air is rarely considered in the current engineering design in China, the second type of canopy effect needs more attention when performing engineering construction in cold and arid regions.
中文关键词	非饱和土 ; 锅盖效应 ; 水气迁移 ; 相变 ; 数值模拟
英文关键词	unsaturated soil canopy effect vapor transfer phase change numerical simulation
语种	中文
国家	中国
收录类别	CSCD
WOS类目	CONSTRUCTION BUILDING TECHNOLOGY
WOS研究方向	Construction & Building Technology
CSCD记录号	CSCD:5833407
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/235208
作者单位	1.中南大学土木工程学院, 高速铁路建造技术国家工程实验室, 长沙, 湖南 410075, 中国; 2.中南大学土木工程学院, 长沙, 湖南 410075, 中国
推荐引用方式 GB/T 7714	滕继东,贺佐跃,张升,等. 非饱和土水气迁移与相变:两类锅盖效应的发生机理及数值再现[J],2016,38(10):1813-1821.
APA	滕继东,贺佐跃,张升,&盛岱超.(2016).非饱和土水气迁移与相变:两类锅盖效应的发生机理及数值再现.岩土工程学报,38(10),1813-1821.
MLA	滕继东,et al."非饱和土水气迁移与相变:两类锅盖效应的发生机理及数值再现".岩土工程学报 38.10(2016):1813-1821.