Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites
Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites
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DOI：
10.1016/j.clay.2008.04.001
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发表时间：
2009-01-01
影响因子：
5.6
通讯作者：
Ledesma, Alberto
中科院分区：
文献类型：
--
作者：
Jacinto, Abel Carlos;Villar, Maria Victoria;Ledesma, Alberto
为分析热-水-力耦合过程(THM问题)，重点研究了温度、孔隙率(干密度)等变量对膨胀土持水曲线的影响。干密度对吸水能力的影响取决于吸力范围，其极限值在30 Mpa左右。对于超过这一阈值的吸力，含水率方面的保留能力随着干密度的增加而增加，而对于较低的吸力，干密度越低，特定吸力的含水率越高。截留能力随温度的升高而减小，比空气-水界面张力的变化预测的要大，特别是在高温和低吸力的情况下。预测非饱和土导水系数的封闭方程。土壤科学。SoC。上午好。J.，44,892-898。]已经提出了符合实验值的定律。温度和孔隙率对水保持能力的影响(而不是传统上包括在进气值系数中的影响)通过与实验证据相似的经验定律被纳入。通过一个拟合过程，确定了这项工作中使用的材料在这些定律中的系数的值。最后，为了分析考虑或不考虑温度和密度对水保持曲线的影响的后果，使用计算机代码“CODE-BLART”进行了几次I D THM模拟。(C)2008 Elsevier B.V.版权所有。
The main objective of this work is to highlight the influence of variables like temperature and porosity (dry density) on the water retention curve of expansive clays for the analysis of thermo-hydro-mechanical coupled processes (THM problem).The paper presents retention curves of MX-80 bentonite measured under isochoric conditions for different dry densities and temperatures. The influence of dry density on the water retention capacity depends on the suction range, the limiting value being around 30 MPa. For suctions above this threshold value, the retention capacity in terms of water content is higher as the dry density increases, whereas for lower suctions, the lower the dry density the higher the water content for a particular suction. The retention capacity decreases with temperature, more than predicted by the change in interfacial tension of air-water, especially for high temperatures and low suctions.Accordingly, some modifications of the van Genuchten [van Genuchten, M.Th., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J., 44, 892-898.] law have been proposed to fit the experimental values. Effects of temperature and porosity on the water retention capacity (other than the traditionally included in the air entry value coefficient) were incorporated through empirical laws that resemble the experimental evidences. By a fitting process, values of the coefficients in those laws were determined for the material used in this work. Finally, several I D THM simulations using the computer code "CODE-BRIGHT' have been performed in order to analyse the consequences of considering or not temperature and density influences on the water retention curve. (C) 2008 Elsevier B.V. All rights reserved.