Existing electro-osmotic calculation models are mostly based on the assumption of a porous medium with uniform pores, whereas natural soil has pores of different sizes. This is especially significant in the case of low-permeability soil, whose pore size can vary over five or six orders of magnitude, from the nanometre to the millimetre scale. Experimental results have revealed significant differences in the electro-osmotic flow characteristics of soils with various pore sizes, indicating a strong dependence on pore size distribution (PSD). This dependence is termed the pore size effect (PSE) on electro-osmosis. In this paper, a series of one-dimensional electro-osmosis experiments on three types of low-permeability clay soil are conducted to quantify the PSE on electro-osmosis. Based on the experimental results and an analysis of electro-osmotic characteristics, a modified analytical approach considering the actual soil PSD and its effect on electro-osmosis is proposed and thereby two modified analytical models are established. Using the experimental results, the modified models are compared with the existing Helmholtz–Smoluchowski model and other models that assume uniform pores. The results show that the PSE increases with increasing thickness of the electric double layer and that the modified models can be used to reasonably calculate the electro-osmotic permeability of low-permeability soil.

中文翻译：

---

考虑孔径效应的低渗土壤电渗实验与分析研究

现有的电渗计算模型主要基于具有均匀孔隙的多孔介质的假设，而天然土壤具有不同大小的孔隙。对于低渗透性土壤而言，这尤其重要，因为土壤的孔径可以从纳米级到毫米级变化超过五个或六个数量级。实验结果表明，具有各种孔径的土壤的电渗流特征存在显着差异，这表明对孔径分布（PSD）的依赖性很大。这种依赖性被称为电渗透的孔径效应（PSE）。本文对三种类型的低渗透黏土进行了一系列的一维电渗实验，以量化电渗过程中的PSE。根据实验结果和对电渗特性的分析，提出了一种考虑实际土壤PSD及其对电渗影响的改进分析方法，从而建立了两种改进的分析模型。使用实验结果，将修改后的模型与现有的Helmholtz-Smoluchowski模型以及其他假定孔隙均匀的模型进行比较。结果表明，PSE随双电层厚度的增加而增加，改进模型可用于合理计算低渗透性土壤的电渗渗透率。修改后的模型与现有的Helmholtz-Smoluchowski模型以及其他假定孔隙均匀的模型进行了比较。结果表明，PSE随双电层厚度的增加而增加，改进模型可用于合理计算低渗透性土壤的电渗渗透率。修改后的模型与现有的Helmholtz-Smoluchowski模型以及其他假定孔隙均匀的模型进行了比较。结果表明，PSE随双电层厚度的增加而增加，改进模型可用于合理计算低渗透性土壤的电渗渗透率。