A Novel Two-Dimensional Axisymmetric Thermo-Hydro-Mechanical Coupled Model for Subsea Pipeline-Soil System Considering Imperfect Interfacial Thermal Contact

Abstract

Subsea oil pipelines typically operate under high-temperature and high-pressure conditions, where imperfect contact at the pipeline-soil interface hinders heat transfer. However, existing calculation models neglect the effect of interfacial thermal resistance, leading to inaccurate predictions of pipeline-soil interactions. This article establishes a two-dimensional (2D) axisymmetric thermo-hydro-mechanical (THM) coupling model for deeply buried subsea pipeline and saturated soil based on single-phase thermoelastic theory and saturated porous thermoelastic theory, respectively. The general thermal contact model is introduced to characterize the interfacial thermal resistance effects. A semi-analytical solution for pipeline-soil interaction is obtained through Laplace transforms and separation of variables. The differences in THM coupled response between pipeline-soil system under various thermal contact models are examined, and the influence of thermal expansion coefficients on pipeline-soil interaction is parametrically investigated under the general thermal contact model. The results indicate that the general thermal contact model can describes the THM coupling characteristics of the pipeline-soil interaction more realistically; the interfacial thermal resistance effect causes a significant radial temperature gradient at the interface within the pipeline-soil system, slightly increases the axial temperature difference inside the pipeline, affects the influence of thermal expansion coefficient on the pipeline-soil interaction, and reduces the deformation compatibility; the influence of the interfacial thermal resistance effect becomes more pronounced as thermal expansion coefficient increases. The deformation compatibility of the pipeline-soil system decreases as the thermal resistance coefficient and partition thermal contact coefficient increase.