Study on pore size effect of low permeability clay seepage

Effect of Sodium Chloride Concentration on Saturated Permeability of Remolded Loess

“…Exchange and adsorption, which are reversible, refer to the process of the conversion between the adsorbed ions on a particle's surface and the ions in a solution [54]. This action controls other physical-chemical properties of soil, such as hydraulic conductivity, by changing the thickness of the diffuse double layer (DDL) on the surface of soil particles [14,19,39,40,55]. A DDL structure diagram is shown in Figure 9.…”

“…With increasing the concentration of a pore solution, the double electric layer is compressed, and the trellis pores that are formed between the particles increase the soil's porosity, thus resulting in an increase of soil permeability [13]. Furthermore, Chen et al found that the thickness of the DDL that was obtained by quantitative calculation decreased with increasing NaCl concentration, while the permeability of the clay increased [19]. The saturated hydraulic conductivity of the remolded loess samples increased with the increasing concentration of the NaCl solution.…”

“…In addition, in-depth studies have been conducted that have shown that changes of hydraulic conductivity are related to the type and concentration of inorganic solutions [12][13][14][15]. The chemical composition during the leaching process has been studied to reverse the changing mechanism that underlies permeability [16][17][18][19]. During the process of seepage, water and soil interactions like dissolution and precipitation, exchange and adsorption, hydration and hydrolysis, as well as redox reactions, take place.…”

“…A number of studies have deeply discussed the changes of the diffuse double layer on the surface of clay particles that are caused by the type and concentration of the solution. These studies have suggested that hydraulic conductivity is closely related to the thickness of the diffuse double layer [19,21,25]. Increasing salt concentration can enhance permeability by decreasing the thickness of the diffuse double layer, which also leads to the flocculation of clay particles and the change of their microstructure [14,24,26,27].…”

Fractal Analysis in Pore Size Distributions of Different Bituminous Coals

“…Asit Kumar Gain 6 found that the pore morphology, compressive strength and elastic modulus could be changed dramatically by increasing the pore forming agent. Combining the microscale seepage of the circular tube model and the seepage theory of the pore size effect, Jian Chen 7 demonstrated that the seepage behavior of low-permeability clays is influenced by the pore size distribution effect. For rock materials, A. Fakhimi’s 8 research results show that in addition to porosity, the pore size can have drastic effects on the elastic modulus, crack initiation stress and rock strength.…”