The accurate characterization of permeability evolution in frozen soils is essential for the predictive modeling of hydro-thermal coupled processes in cold regions. As permeability is governed by the architecture of pore-scale transport pathways, its evolution reflects the dynamic restructuring of the pore network during freezing. However, traditional porosity-based theories often fail to capture the impact of microscopic ice morphology on pore topology, leading to a breakdown in permeability predictions during critical freezing stages. Using phase-field simulations of ice growth combined with sequential Stokes-flow calculations, this study reveals that this predictive failure stems from a regime transition in fluid connectivity. Our results identify two distinct evolutionary stages governed by different geometric principles: (1) the pore body filling regime, where ice grows within large pore spaces, resulting in a smooth permeability decay that follows a predictable geometric scaling law; and (2) the pore throat clogging regime, where ice encroachment into narrow constrictions triggers a topological mutation. We demonstrate that once critical pore throats are obstructed, the fluid network undergoes a connectivity loss rather than gradual constriction. This transition causes a precipitous drop in permeability that renders the classical Kozeny–Carman equation invalid. By comparing diverse media geometries, we clarify how ice crystal evolution characteristics dictate the medium-specific applicability of permeability correlations. We show that while geometric scaling holds for unconfined growth, the premature onset of topological severance of the connected liquid network in constricted structures explains the early breakdown of classical scaling laws.
Yu et al. (Fri,) studied this question.