黏性土的低渗透性使其在工程中常用来阻滞污染物的迁移,但有机溶剂会显著增加黏性土的渗透性,从而使屏障作用失效。为了研究有机溶液的介电常数和黏度对渗透性的影响,以粉质黏土为对象,开展不同质量分数丙三醇水溶液的界限含水率和渗透试验。试验结果表明,随着丙三醇水溶液质量分数增加,液限和塑限增大,而渗透系数先增加后减小;土体的渗透性与微观孔隙结构分布和流体特性有关,当丙三醇水溶液质量分数<40%时渗透性受土体组构控制,质量分数超过40%后渗透性受黏度控制;此外,土体的固有渗透率随着质量分数的增加先升高后降低,黏度增加导致了固有渗透率的降低。研究成果表明对于水溶性有机溶剂,需要考虑黏度变化对渗透性的影响。
Abstract
Clay is often used to block the migration of pollutants on account of its low permeability. However, the organic solvents can significantly increase the permeability of clay which will result in the failure of barrier. In order to study the effects of dielectric constant and viscosity of organic solution on the permeability of clay, we carried out tests on the consistency limits and permeability of silty clay with different mass fractions of glycerol-water solutions. Results unveil that with the increase of mass fraction of glycerol-water solutions, the liquid limit and plastic limit of silty clay both increase while the hydraulic conductivity increases first and then decreases. Soil permeability is related to microstructure distribution and fluid properties. If the mass fraction is smaller than 40%, permeability is controlled by fabric; when mass fraction is over 40%, the increase of viscosity leads to the decrease of permeability. In addition, the intrinsic permeability increases in the beginning and then declines with the growth of mass fraction owing to the increment of viscosity. For water-soluble organic solvents, the impacts of viscosity on permeability should be considered.
关键词
粉质黏土 /
丙三醇水溶液 /
界限含水率 /
渗透系数 /
介电常数 /
黏度
Key words
silty clay /
glycerol-water solution /
limit moisture content /
hydraulic conductivity /
dielectric constant /
viscosity
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基金
国家自然科学基金项目(11372078,11562007,41572293);广西建筑新能源与节能重点实验室资助项目(桂科能16-J-21-11)
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