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Frost heave is the expansion of soil upon freezing due to the formation and growth of segregated ice lenses. Because of the large stresses and displacements associated with frost heave, it is an import design consideration for geotechnical structures such as roads, foundations, and buried pipelines, particularly in cold regions. The objective of this research was to characterize frost heave expansion within the context of design and analysis applications. A series of laboratory-scale frost heave experiments were conducted to examine frost heave under one-dimensional freezing. The previously established segregation potential concept (SP) was utilized to characterize both the intrinsic frost heave behavior of two reference soils. A novel modification was proposed to account for the observed variation of SP with freezing rate; it was noted that ignoring this influence would lead under-predictions the heave expansion. The thermal properties of frozen soils were explored. A method for characterizing the anisotropic thermal conductivity was proposed utilizing existing composite models in a multi-level homogenization. Ultimately it was determined that for ice lens-rich soils, a simpler and isotropic expression may provide similar performance, namely the geometric mean approximation. Additionally, a method was proposed to characterize the thermal conductivity of composite materials containing discrete particle phases using numerical simulations of complex phase geometries. This method was used to develop a specified characterization of discrete particle composites. iv A two-dimensional, fully coupled thermal-mechanical and implicitly coupled hydraulic frost heave model was formulated from thermodynamic principles. The model included the proposed form of SP to characterize the mass transport process. The finite element method was used to implement the model and its performance was validated in one-dimension through comparative analysis with the laboratory frost heave tests. Finally, the model was applied to a two-dimensional, full-scale problem involving the frost heave- induced displacement of a chilled natural gas problem. / Thesis / Doctor of Philosophy (PhD) / An experimental investigation was conducted and a numerical model was developed to predict the effects of frost heave in freezing soils. Frost heave is the expansion of soils caused by the formation of a specific type of ice, called ice lenses. This expansion can cause damage and lead to failure in roads, foundations, buried pipelines and other infrastructure exposed to heaving soils. The research developed a model capable of providing engineers with the information necessary to account for, and possibly avoid, these effects when designing such infrastructure. A series of experiments were conducted to produce frost heave in soils in a laboratory. The information gained from these tests was used to both develop and confirm the performance of a frost heave model using established numerical techniques. Finally, the model was used to simulate the upward movement of a buried natural gas pipeline exposed to frost heave in a cold region.

<p> A stream function finite element model is developed to solve for particle paths within a large ice mass. A steady-state primitive variable finite element model, treating ice as an incompressible non-Newtonian fluid, is used to furnish the necessary input velocities and rotations for the stream function finite element model. Time-integration along the particle paths is used to determine the age of the ice within the ice mass.</p> <p> Two ice masses are studied: the Barnes Ice Cap, Baffin Island, N.W.T., and Mount Logan, Yukon Territory. It is shown that if a realistic approximation of the velocity field of an ice mass can be established, the age of ice determined by time-integration along particle paths corresponds to the age determined by standard methods. Results of simulations using a transient model suggest that the elastic response of large ice masses is negligible.</p> / Thesis / Master of Engineering (MEngr)

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