This paper presents coupled thermo-hydro-mechanical finite element analyses (FEAs) of undrained uplift capacity for buried offshore pipelines operating at elevated temperature. An anisotropic thermoplastic soil constitutive model was employed to simulate mechanical behaviour of seabed soil under the combined actions of thermal and mechanical loading. FEAs investigated the influences of different parameters, e.g., pipeline embedment depth, pipe-soil interface roughness, duration of pipeline operation, and operating temperature, on pipeline uplift capacity. Time-dependent evolutions of temperature and excess pore water pressure were also tracked in soil surrounding the pipeline. For different durations of pipeline operation, FEA results revealed an improvement in normalized uplift capacity Nu of pipelines operating under elevated temperature. However, such an increase in Nu was diminished by a maximum of 7 % with increase in the ratio RTH of thermal diffusivity to coefficient of consolidation of surrounding soil. For different normalized pipeline embedment, 20-30 % enhancement of Nu was observed after six months of pipeline operation at 60 degrees C. However, after six months of operation, further improvement in Nu was negligible. Based on FEA results, this paper proposes an equation to estimate pipeline uplift capacity as a function of operating temperature, depth of embedment, and duration of pipeline operation.
