Abstract

Frost heave is a common phenomenon in the Arctic, where soil absorbs moisture and expands in the direction of heat loss due to ice lens growth upon freezing. It also occurs if a refrigerated structure is buried in unfrozen frost heave-susceptible soil, and thus, special considerations are required when designing chilled or LNG pipelines.

The current study focuses on the numerical modeling of frost heave of a chilled gas pipeline based on the framework of the porosity rate function. New developments to the porosity rate function are proposed to extend its application to simulate transient temperature boundary conditions under thawing scenarios. The extended functionality allows the model to simulate soil freezing and corresponding heave, as well as soil thawing and corresponding settlement for multi-year temperature cycles.

This paper first presents a cyclic frost heave numerical model validated by long-term full scale field measurement available in the literature. Then, correction factors of key parameters involved in the frost heave process, such as temperature gradient, in-situ stress, and soil porosity are introduced. Finally, recommendations to mitigate the potential hazard of cyclic frost heave and corresponding pipeline strains are presented, providing guidelines for new pipeline developments in the Arctic region.

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