A Multi-Phase Field Model for Simulating Ice Lens Growth and Thawing in Frozen Porous Media

In this study, we present a multi-phase field thermo-hydro-mechanics model that simulates the growth and thawing of ice lenses and the resulting frost heave and thawing settlement in multiphase porous media. Based the Miller's theory, we assume that the ice lens can be viewed as a segregated ice inside the freezing induced fracture. In this model, the ice lens growth is implicitly captured via combination of two phase field variables that represent the state of the fluid and the fracture, respectively. Compared to phenomenological approaches that indirectly capture the freezing effects on the shear strength and stiffness, this approach distinctively captures the homogeneous freezing and ice lens growth by freezing characteristic function and the driving force, respectively. Evolution of two phase field variables are induced by their own driving forces that capture the physical mechanisms of ice-water phase transition and the crack growth, respectively, while their governing field equations are bundled with balance laws such that the coupling among solid deformation, fluid diffusion, heat transfer, phase change, and damage evolution can be observed numerically.