Yes / An integrated Finite Element Method (FEM) model is proposed to investigate the dynamic seabed response for several specific pipeline layouts and to simulate the pipeline stability under waves loading. In the present model, the Reynolds-Averaged Navier-Stokes (RANS) equations are used to describe the wave motion in a fluid domain, while the seabed domain is described using the Biot’s poro-elastic theory. The interface between water and air is tracked by conservative Level Set method (LSM). The FEM and backward differentiation formula (BDF) are applied for spatial and temporal discretization respectively in the present model. One-way coupling is used to integrate flow and seabed models. The present model is firstly validated using several available laboratory experiments. It is then further extended to practical engineering applications, including the dynamic seabed response for the pipeline mounted on a flat seabed or inside a trench. The results show that the pipeline buried to a certain depth is better protected than that under partially buried in terms of transient liquefaction. / Energy Technology Partnership (ETP), Wood Group Kenny

Yes / In this study, a new three-dimensional (3-D) model was developed to provide better understanding of the mechanism for wave-induced seabed response around mono-pile. Based on poro-elastic theory, the fully dynamic (FD) formulations were adopted in the present model to simulate pore water pressure, soil stresses, displacements of both soil and mono-pile. Good agreement between numerical simulation and experimental results was obtained. Based on parametric study, numerical results indicated: (1) wave diffraction and reflection have significant effects on pore water pressure and soil displacements around mono-pile; (2) the most sensitive position for seabed parameter to pore water pressure around mono-pile locates in front of mono-pile while the least sensitive position is at the position of angle 3π/4 with respect to the incident wave direction; and (3) the increase of mono-pile horizontal displacement corresponds to the increase of wave height and the decrease of seabed Young's modulus. / National Science Fund for Distinguished Young Scholars (51425901), the National Natural Science Foundation of China (51209082, 51379071, 41176073), the Specialized Research Fund for the Doctoral Program of Higher Education of China (20120094120006, 20130094110014), the 111 project (B12032), the 333 project of Jiangsu Province (2013Ⅲ-1882)

Yes / The near-trapping effects on wave-induced dynamic seabed response and liquefaction close to a multi-cylinder foundation in storm wave conditions are examined. Momentary liquefaction near multi-cylinder structures is simulated using an integrated wave-structure-seabed interaction model. The proposed model is firstly validated for the case of interaction of wave and a four-cylinder structure, with a good agreement with available experimental measurements. The validated model is then applied to investigate the seabed response around a four-cylinder structure at 0° and 45° incident angles. The comparison of liquefaction potential around individual cylinders in an array shows that downstream cylinder is well protected from liquefaction by upstream cylinders. For a range of incident wave parameters, the comparison with the results for a single pile shows the amplification of pressure within the seabed induced by progressive wave. This phenomenon is similar to the near-trapping phenomenon of free surface elevation within a cylinder array. / Energy Technology Partnership (ETP), Wood Group

Yes / The wave–seabed interaction issue is of great importance for the design of foundation around marine infrastructures. Most previous investigations for such a problem have been limited to uncoupled or one-way coupled methods connecting two separated wave and seabed sub models with the continuity of pressures at the seabed surface. In this study, a strongly coupled model was proposed to realize both wave and seabed processes in a same program and to calculate the wave fields and seabed response simultaneously. The information between wave fields and seabed fields were strongly shared and thus results in a more profound investigation of the mechanism of the wave–seabed interaction. In this letter, the wave and seabed models were validated with previous experimental tests. Then, a set of application of present model were discussed in prediction of the wave-induced seabed response. Numerical results show the wave-induced liquefaction area of coupled model is smaller than that of uncoupled model. / Yes

Yes / Stability and safety of offshore wind turbines with mono-pile foundations, affected by nonlinear wave effect and dynamic seabed response, are the primary concerns in offshore foundation design. In order to address these problems, the nonlinear wave effect on dynamic seabed response in the vicinity of mono-pile foundation is investigated using an integrated model, developed using OpenFOAM, which incorporates both wave model (waves2Foam) and Biot’s poro-elastic model. The present model was validated against several laboratory experiments and promising agreements were obtained. Special attention was paid to the systematic analysis of pore water pressure as well as the momentary liquefaction in the proximity of mono-pile induced by nonlinear wave effects. Various embedment depths of mono-pile relevant for practical engineering design were studied in order to attain the insights into nonlinear wave effect around and underneath the mono-pile foundation. By comparing time-series of water surface elevation, inline force, and wave-induced pore water pressure at the front, lateral, and lee side of mono-pile, the distinct nonlinear wave effect on pore water pressure was shown. Simulated results confirmed that the presence of mono-pile foundation in a porous seabed had evident blocking effect on the vertical and horizontal development of pore water pressure. Increasing embedment depth enhances the blockage of vertical pore pressure development and hence results in somewhat reduced momentary liquefaction depth of the soil around the mono-pile foundation. / Energy Technology Partnership (ETP), Wood Group Kenny, and University of Aberdeen; the National Science Fund for Distinguished Young Scholars (51425901) and the 111 project (B12032).