双电层对非饱和粘土渗透率的影响  

Effect of Electric Double Layer on Permeability of Unsaturated Clay

作　　者：何伟[1] 赵明华[1] 刘小平[1] 

机构地区：[1]湖南大学岩土工程研究所,湖南长沙410082

出　　处：《公路交通科技》2008年第9期47-51,共5页Journal of Highway and Transportation Research and Development

摘　　要：为研究非饱和粘土中电荷对其渗透率的影响,首先阐述粘土双电层产生的机理,分析了双电层对粘土中极性液体流动产生电滞阻力的原因;然后利用物理化学中关于胶体动电性质的有关公式和达西定律,导出了受到电效应影响的水相渗透率公式,并结合已有的非饱和土渗透率公式,得到了考虑电效应影响的非饱和土的综合渗透率公式;最后以钠高岭土为例,分别计算出在温度为15℃、4种不同浓度的NaCl溶液考虑电效应影响的渗透率ke和不同饱和度下不考虑电效应的渗透率k*。计算结果表明:(1)在温度恒定的情况下,渗透液的浓度对ke影响很大,随着浓度的增大,ke近似线性减小;(2)渗透液的饱和度对k*影响显著,随着饱和度的减小,k*显著减小。因而,在溶液浓度较低和饱和度较低的情况下,非饱和土水的渗透应考虑电效应的影响;在饱和土中,电效应的影响很小,可以不予考虑。In order to study the effect on the permeability by the charge of the unsaturated clay, at first the mechanism of the electric double layer of clay was expounded and the cause of the electric double layer＇ s resistance to the flow of polar liquid was analyzed. Secondly the formula of permeability with consideration of the effect of the electric double layer was produced by use of Darcy＇ s law and the relevant formula concerning the electrokinetic character of colloid in the subject of physical chemistry. In succession, by incorporating the established permeability formula of unsaturated soil, the synthetic formula of permeability was deduced. In the end, the example of Nakaolinite was given to calculate the permeability ke considering the electric effect with the NaCl solution of four diverse thicknesses at 15℃ and the permeability k^＊ without regard to electric effect with NaCI solution of different saturations. The result shows that （1） in the conditions of constant temperature the thickness has great effect on the permeability ke and the value of k^＊ has approximatively inverse relation with the thickness of solution; （2） the permeability k^＊ can keep remarkably consistent change with the saturation. Accordingly the effect of electric double layer on the percolating of water phase in the unsaturated soil can not be neglected when the thickness of solution is small and the saturation is very low and the electric effect on the permeability of saturated soil is so small that the effect can be passed.

关 键 词：道路工程 非饱和粘土 理论计算 渗透率 双电层 

分 类 号：U416.16[交通运输工程—道路与铁道工程]