Relative Ice Saturation and Unified Elastoplastic Modeling of Frozen Soils

Modeling the mechanical behavior of frozen soils is crucial for geotechnical engineering, especially in cold regions. Despite advancements in constitutive modeling, a reliable and unified model applicable to various types of frozen soils remains unavailable. This study develops a unified constitutive model that extends the unified hardening framework to account for the unique characteristics of various types of frozen soils, particularly the effects of ice cementation. A novel state variable, relative ice saturation (Si), is proposed and incorporated into the model, which can be determined by measuring the unfrozen water content of frozen soils. By integrating Si into the yield function and hardening law, the model is formulated and used to predict the mechanical behavior of various frozen soils, including sand, silt, silty clay, clay, and saline sandy soils, under different temperatures and confining pressures. Results demonstrate that the proposed model can accurately reproduce key mechanical features such as the stress–strain relationship, dilatancy, and softening/hardening of various types of frozen soils. Additionally, the model holds potential for integration into thermo-hydro-mechanical simulators to analyze multiphysics coupling processes in frozen soil engineering.