The problem of the wave-seabed interactions around a pipeline has become an important issue in the field of coastal geotechnical engineering, due to the exploitation of oil and gas industry. To date, most existing studies adopted one-way coupling algorithm to integrate wave and seabed sub-model, which violated the physical phenomena. In the study, a new two-way coupling algorithm for the wave–seabed interactions around a pipeline is proposed. The numerical results indicate that the water surface elevation, pore-pressures, soil displacements and effective normal stresses obtained by two-way coupling model are smaller than that of the conventional one-way coupling model generally. However, the Shields number by two-way coupling model is extremely larger than that of one-way coupling model, which implies that two-way coupling is required for the prediction of the scour. Meanwhile, the existence of pipeline would increase the influences of two coupling models on wave and seabed characteristics.
Pipelines has been one of the key offshore installations for the exploitation and transportation of offshore oil and gas industry with the growth demand for marine energy resources. Therefore, the problem of fluid-seabed interactions around the pipeline has become an important issue in the offshore project regarding the seabed stability around the pipeline (Sumer, 2014; Jeng, 2018).
To date, most existing investigations for the wave–seabed interactions have adopted one-way coupling process, as shown in Fig. 1. In these approaches, the dynamic water pressures were treated as the only external loading for the seabed model, but ignored the feedback of seabed response to the flow field. At the early stage of the theoretical development of the wave-induced soil response, Yamamoto et al. (1978) and Hsu and Jeng (1994) obtained 2-D and 3-D analytical solutions, based on Biot's poro-elastic theory (Biot, 1941) with linear wave theory. Later, numerous numerical studies for the wave-seabed interaction have been available in the literature. Among these, Liu and Garcia (2007) established a fluid-seabed interaction numerical model to investigate the seabed response and the coupling between fluid and seabed was through stress and continuity condition on common boundaries. Later, Jeng et al. (2013) proposed an integrated model for the wave-seabed-structure interactions to investigate the seabed liquefaction around a composite beakwater. Recently, Liang et al. (2020) implemented an open-source numerical toolbox for modeling the seabed response with waves and structures based OpenFOAM framework and performed 2-D wave (current)-seabed interaction around a pipeline. This model was further extend to the case with irregular wave loading (Liang and Jeng, 2021).
