Document Type : Research Article
Ph.D. Student, Department of Civil Engineering, Urmia University
Department of Civil Engineering, Urmia University
The effect of freeze-thaw cycles on the hydraulic conductivity (HC) of clayey barriers in water retaining structures and municipal solid waste landfills is a key issue in designing barrier systems in those structures. The effect of freeze-thaw cycles on the hydraulic conductivity of compacted clayey soil from Nazlou Region of Urmia City and a geosynthetic clay liner (GCL), and the effect of effective stress on the hydraulic conductivity change of clayey soil in freeze-thaw cycles were investigated for water and leachate. The flexible-wall triaxial hydraulic conductivity apparatus was used to measure the HC of specimens subjected to freeze-thaw. During the freezing process, ice lenses grow in the soil sample and when the ice lenses melt, a network of cracks is left and thus, the HC increases. Increasing the effective stress reduces the increased hydraulic conductivity due to freeze-thaw. The results show that on the contrary to compacted clayey soil, the application of freeze-thaw cycles do not significantly affect the HC of GCL. Interaction of clayey soil with leachate leads to a decrease in thickness of the diffuse double layer and thus, the hydraulic conductivity of clayey soil increases. Increase in hydraulic conductivity of clayey soil and GCL subjected to freeze-thaw and permeated with leachate is lower than that for water.