A coupled thermo-hydro-mechanical model for capturing frost heave under chilled gas pipelines

Authors: SeonHong Na, Mahyar Malekzade Kebria, Kshama Roy[NC]
Published/Presented: International Pipeline Conference IPC 2020, Calgary, Alberta

Abstract

This paper presents a thermo-hydro-mechanics theory and corresponding computational framework to capture the freeze thaw action of frozen porous media and associated frost action under chilled gas pipelines. Based on the mixture theory, frost-susceptible soils are formulated to capture the Darcy flux and thermal actions below the pipelines. Constitutive models that combine the cryo-suction are presented to reproduce the changes in volume, strength, and thermal characteristics of solid grain, pore water, and ice crystal. A generalized hardening rule is adopted to replicate the elasto-plastic responses which strengthens the frozen porous media due to ice crystallization. Changes in permeability and thermal diffusivity are also incorporated by considering the phase transitions of pore water and ice crystal. Numerical examples for pipeline applications are designed to analyze the influence of the freezing and melting process around the pipelines.

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