Multi-Scale Process of Soil Freezing, Thawing, and Thaw-Settlement

摘要

Freezing and thawing of soils are processes that span multiple spatial scales and involve multi-physics phenomena such as phase change and multiphase flow. Of particular importance is freezing and thawing in soils susceptible to heaving. Frost heave and thawing of ice-rich soils directly affect Army operations in cold regions and the state of infrastructure. This research was focused on the study of the fundamental processes and causes of frost heaving and thaw-weakening in soils. A model describing frost heaving in soils has been developed that well captures the heaving process as function of the initial and boundary conditions. The model has been extended to include the entire freeze-thaw cycle, and to predict the consequences of phase change on thaw-weakening of soils. The effects in soils with non-segregation freezing have been included in the model. Frost heaving is described by introducing an ice growth tensor, which captures the anisotropic growth of ice lenses. The evolution of the soil strength during both freezing and thawing is described through a hardening/softening plasticity model including the effects associated with freeze-thaw cycles. The model has been calibrated, it was implemented in the finite element method, and it was used to simulate boundary value problems.