Comparison of Geoacoustic Models for Unfrozen Water Content Estimation

This paper reviews eight geoacoustic models applied to frozen soils: crystal growth models(grain cementing, grain coating, matrix supporting, and porefilling), the weighted equation (WE) model,Zimmerman and King's model (KT), the Biot‐Gassmann theory modified by Lee (BGTL), and a two‐endmember model. We verify the capacity of these models to estimate unfrozen water content (UWC) basedon“reference”UWC results and jointPandSwave velocities for different soil types. Thesatisfactory UWC estimates of saline unconsolidated sand and overconsolidated clay based onVpdata provethat the KT, BGTL, and two‐end member models are capable of modeling“smooth”transitions in theice crystal growth mode, while they may provide less accurate UWC values when abrupt change ofcrystallization mode occurs. None of the tested soil types show a single crystallization mode throughout thefreezing process, as assumed by individual crystal growth models.Vs‐based UWC estimates are lessaccurate due to significant but difficult‐to‐estimate influence of effective stress and soil initial cementation.All models, except porefilling and matrix supporting, can matchVsversusVpmeasurement results forsands and silts but gradually provide inconsistent estimates with increasing clay content. We conclude thatmodel validation by independent UWC measurements is necessary and that consistency between UWCvalues estimated fromVsandVpis insufficient to ensure proper model validation.