Numerical modeling of combined wave and current-induced residual liquefaction around twin pipelines

Abstract

With the operation of offshore oil & gas fields, offshore pipeline has been widely used in offshore engineering. So far, most studies have focused on exploring the seabed responses around a single pipeline, and ignored the effect of multiple pipelines on the physical process of the surrounding seabed. In this study, to investigate the residual seabed dynamic response around twin pipelines, a two-dimensional numerical model, combining the Shear-Stress Transport (SST) turbulence model with the porous seabed model, is developed. Unlike previous studies, this study focuses on three aspects: (1) the physical process of seabed around twin pipelines; (2) the wave and current-induced residual soil response; and (3) the effect of upstream pipeline on the liquefaction of downstream pipeline. Numerical results demonstrate the significant effect of current and twin pipelines’ arrangement on the residual pore pressure and liquefaction zone around the twin pipelines. Results show that the pressure fluctuation caused by the vortex between the twin pipelines deepens the residual liquefaction depth of the seabed.