Thermo-Hydro-Mechanical Interface Degradation of Offshore Monopiles in Seasonally Frozen Seabeds

Abstract

The structural integrity and long-term performance of offshore wind turbine foundations in cold regions are significantly challenged by complex environmental loading, particularly the cyclical freezing and thawing of the seabed. This paper investigates the thermo-hydro-mechanical interface degradation of offshore monopiles situated in seasonally frozen seabeds. By integrating principles from soil mechanics, thermodynamics, and hydrodynamics, the research delineates the mechanisms through which cyclic temperature variations induce moisture migration, phase changes, and subsequent volume expansions or contractions in the soil matrix surrounding the monopile. These physical alterations severely compromise the interface shear strength and adfreeze bond between the steel foundation and the marine sediments. Through an exhaustive review of existing theoretical frameworks and the development of a comprehensive experimental methodology, this study evaluates the degradation of skin friction under coupled thermo-hydro-mechanical loading conditions. The findings reveal that the formation of ice lenses and the subsequent thaw-induced excess pore water pressures critically diminish the effective stress at the soil-structure interface, leading to accelerated cyclic softening and potential foundational failure. This research provides critical insights for the robust design and maintenance of offshore structures in high-latitude marine environments, emphasizing the necessity of incorporating multi-physics coupling into geotechnical fatigue assessments.