Indirect Assessment of Mechanical Behaviour of Varved Clays under Freezing-Thawing Cycle Using Soil-Water and Soil-Freezing Characteristic Curves of Constituent Laminae

Due to the increase in global average temperatures, seasonal ground deformation has become a crucial engineering aspect for the safe design of structures built on permafrost regions. The present study investigates frost heave and thaw settlement in a cold region through finite element modelling (FEM). The study focuses on the effect of sequential placement of laminae on reconstituted varved clay profiles under free convective flow due to temperature gradients followed by freezing and thawing processes. Two representative soils were chosen to simulate the two laminae of actual varved clays. To perform numerical modelling, the input for van Genuchten parameters, water contents, saturated permeability, index parameters, stiffness parameters, and shear strength parameters were determined through laboratory tests, and thermal properties were adopted from the literature. The soil freezing characteristic curves (SFCCs) were obtained using the corresponding soil water characteristic curves (SWCCs). The study shows that the two selected soils exhibit varying levels of deformation under similar temperature conditions. Furthermore, the sequential placement of the two soils to create a reconstituted varved clay profile also impacted the deformation.