The long-term settlement of subsea pipelines on a clayey seabed is crucial for the on-bottom stability of the pipelines, especially in deep waters. In this study, a poro-elasto-viscoplastic finite element analysis is performed for predicting long-term settlement of subsea pipelines by incorporating a rheological constitutive model. A method for identifying the creep-settlement (Sc) from the total-embedment (Sk) is proposed on the basis of the obtained linear relationship between the secondary consolidation coefficient (C alpha e) of the clayey soil and the total-embedment (Sk) of the pipe. The identifying method is validated with the existing theoretical solutions and experimental data. Parametric study is then performed to investigate the key influential parameters for long-term settlement of subsea pipeline. A non-dimensional parameter Gc is introduced to quantitatively characterize the soil rheology effect on pipeline settlement. The relationship between the proportion of creep-settlement in the total-embedment (Sc/Sk) and Gc is eventually established for identifying whether the proportion of creep-settlement in the total-embedment is remarkable.
