Multi-phase-field microporomechanics model for simulating ice-lens growth in frozen soil

This article presents a multi-phase-field poromechanics model that simulates the growth and thaw of ice lenses and the resultant frozen heave and thaw settlement in multi-constituent frozen soils. The growth of segregated ice inside the freezing-induced fracture is implicitly represented by the evolution of two-phase fields that indicate the locations of segregated ice and the damaged zone, respectively. The evolution of two-phase fields is induced by their own driving forces that capture the physical mechanisms of ice and crack growths, respectively, while the phase-field governing equations are coupled with the balance laws such that the coupling among heat transfer, solid deformation, fluid diffusion, crack growth, and phase transition can be replicated numerically. Unlike phenomenological approaches that indirectly capture the freezing influence on the shear strength, the multiphase-field model introduces an immersed approach where both the homogeneous freezing and the ice-lens growth are distinctively captured by the freezing characteristic function and the driving force accordingly. Verification and validation examples are provided to demonstrate the capacities of the proposed models