Abstract

The study of frozen soil failure behavior has been a major issue to focus on over the past decades since the changing climate was known to be the main reason for the gradual degradation of permafrost (or frozen soil) in cold regions. The assessment of the variation of strength and deformation properties of frozen soils with temperature is very critical in geotechnical applications such as foundation design, slope stability analysis, etc. Over the years, many numerical, laboratory, and field studies have focused on characterizing the behavior of frozen soils at various negative temperatures. In this research, available studies in the literature are reviewed for characterizing appropriate temperature dependent strength and deformation parameters for the stability analysis of frozen soil slopes. Parameters including cohesion c, friction angle φ, Young’s modulus E, and Poisson’s ratio υ are determined as functions of negative temperature for three different frozen soils, i.e. clay, silt, and sand. These parameters are used as the input data for the 2D plane strain finite element (FE) modeling on the slope stability analysis at different temperatures and the Drucker-Prager (DP) model is applied as the yield criterion. The stability analysis is based on investigating the shear band development, considering strain localization at different temperatures. The results indicate that as the temperature decreases, the strength of slope against shearing and collapse increases. In cases where slope failure occurs, the plastic strain in the close vicinity of slope is significant, leading to developing a curved thin shear zone extending from the top to the toe of slope. This critical zone acts as the slip surface for the slope. At lower temperatures, in general, plastic straining throughout the domain decreases, and the critical shear zone would not develop completely, therefore lowering the possibility of slope collapse (=higher factor of safety). The numerical approach is capable of depicting the deformation and failure characteristics of frozen soil slopes sensitive to temperature changes.
Keywords: Frozen soil failure behavior, permafrost, uniaxial compression test, triaxial compression test, finite element (FE) MATLAB code, frozen slope stability, Drucker-Prager criterion