Thaw Consolidation Properties of Fine-Grained Permafrost Soils of the Mackenzie Valley, Canada

Abstract

In this study, the thaw consolidation properties of fine-grained permafrost soils are investigated in terms of the characteristics of the relationships between the effective stress (σv′), the void ratio (e), and the hydraulic conductivity (kv). A total of 182 individual soil samples are included in the analysis covering a wide range of hydromechanical properties. The data are obtained from geotechnical studies undertaken for the Canadian Arctic Gas Pipeline project in the 1970s in the Mackenzie River Valley, Canada. The investigated characteristics are defined in agreement with the definition formulated by previous thaw consolidation models for fine-grained soils. Based on the general interpretation of the behavior of thawing soils, relationships are developed for the compression index of the thawed soil, the residual stress, the hydraulic conductivity change index of the thawed soil, and the initial hydraulic conductivity of the thawed soil. All properties are influenced by the ice content, which is characterized by the initial thawed void ratio for ice-rich soils and by the thawed void ratio for ice-poor soils. The liquid limit, the clay content, and the median grain size of the fine fraction are used as predictive parameters in combination with the initial ice content. The median grain size of the fine fraction yields the lowest error for the prediction of the characteristics of the σv′−e−kv relationships.