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Chen, L.; Zhai, H.; Wang, P.; Zhang, Q.; Wang, S.; Duan, L., and Jeng, D.-S., 2022. Experimental study on irregular wave (current)-induced pore-water pressures around a monopile. Journal of Coastal Research, 38(1), 114–132. Coconut Creek (Florida), ISSN 0749-0208. In this study, a series of flume tests was systematically conducted to study the pore-water pressures around a monopile under wave and current loading, as well as the hydrodynamic response. Unlike in previous studies, the combined irregular wave and current action were studied, and a partially embedded monopile was considered. Moreover, the influence of wave spectra on the pore-water pressures was studied. The following results were obtained. (1) The irregular wave (current)-induced hydrodynamic response and seabed response around the monopile are stronger than those induced by the representative regular wave (current) loading. (2) A larger irregular wave energy can more often cause a larger pore-water pressure. The influence of irregular wave parameters on the pore-water pressures is mainly concentrated in the upper seabed, and the influence range is enhanced for the existence of current. (3) The current greatly influences the pore-water pressures in the upper and middle layers of the seabed; however, in the lower seabed below the monopile, it has a weaker but more complicated effect on the pore-water pressures. (4) Wave spectra have remarkable effects on the pore-water pressures, and the influence range deepens for the action of current on the wave field. [ABSTRACT FROM AUTHOR]

Duan, L.; Xing, L.; Wang, D.; Fan, M., and Wang, P., 2021. Numerical investigation of wave-induced uplift force exerted onto a shallowly buried pipeline using a two-dimensional fully coupled model for wave-seabed-structure interaction. Journal of Coastal Research, 37(4), 800–812. Coconut Creek (Florida), ISSN 0749-0208. In this paper, a novel two-dimensional numerical model for wave-seabed-pipeline interaction is proposed to investigate the wave-induced uplift force exerted onto a shallowly buried pipeline. Unlike previous models, the present model is fully coupled, and the effects of fluid shear stress at the seabed surface on the soil dynamic response are considered. In this study, the Reynolds-averaged Navier-Stokes equation was applied to simulate flow motions, and the level set method was used to track the free water surface. Meanwhile, Biot's poroelastic equation (u-p mode) was taken to govern the wave-induced oscillatory response of the seabed, and the pipeline was treated as elastic. After validation using data from laboratory experiments in the literature, the novel model was first employed to investigate the distribution of the wave-induced transient seabed response around the shallowly buried pipeline. Then, the effects of the wave parameters, the soil properties, and the pipeline diameter and burial depth on the wave-induced maximum uplift force exerted onto the structure were systematically examined in detail. Finally, wave-induced maximum uplift of the shallowly buried pipeline was predicted based on the numerical results, which may provide some references for engineering practice. Numerical results confirmed that both the nonlinear pipeline-seabed contacts and the fluid shear stress at the seabed surface can greatly affect the soil dynamic response, which should be considered in determining the wave-induced uplift force exerted onto a shallowly buried pipeline. [ABSTRACT FROM AUTHOR]

Duan, L.; Jeng, D.-S.; Wang, S., and Zhu, B., 2019. Numerical investigation of the wave/current–induced responses of transient soil around a square mono-pile foundation. Journal of Coastal Research, 35(3), 625–636. Coconut Creek (Florida), ISSN 0749-0208. A mono-pile foundation is a commonly used supporting base for marine infrastructure in shallow water, such as offshore wind turbine foundations and cross-sea bridges and platforms. Sea floor instability around a pile foundation has attracted much attention among offshore geotechnical engineers. In this paper, a three-dimensional numerical model for wave–seabed–structure interactions is proposed using open field operation and manipulation (OpenFOAM). Unlike previous studies, currents are included in the proposed model and applied to a square cross-section mono-pile foundation. In the model, the flow motion is described by the Reynolds-averaged Navier–Stokes (RANS) equation and k–ϵ turbulence model, and the water free surface is tracked using the volume of fluid (VOF) method. Meanwhile, the soil response is determined by the Biot's poro-elastic equation (u–p approximation), in which the accelerations of the soil displacements are included. After the model is validated with the previous laboratory experiments, it is further used to investigate the transient soil response around the square mono-pile foundation. Numerical results demonstrate that the cross-section shape has significant influence on the distribution of wave/current–induced transient pore pressure but little influence on the maximum soil liquefaction depth. On the other hand, both the current velocity and the seabed permeability can greatly affect the maximum soil liquefaction depth and slightly affect the distribution of pore pressure. Furthermore, the cross-section dimension significantly affects both the maximum soil liquefaction depth and the distribution of the pore pressure around a mono-pile foundation. [ABSTRACT FROM AUTHOR]

Wang, C.; Jiang, Z.; Wang, D.; Feng, D., and Duan, L., 2020. Effects of the porous medium seabed on the wave load acting on the single pile. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 192–197. Coconut Creek (Florida), ISSN 0749-0208. The characteristics of the seabed greatly affect the interaction between waves and the single-pile foundation structure. It is normal to simplify the porous medium seabed into a rigid, impermeable solid seabed, which ignores the effect of the porous medium seabed on wave energy. This study investigated the effects of the seabed characteristics of porous media on the wave load of the single pile based on the wave-flume test and the three-dimensional numerical model. Five seabed wave-flume tests and the common ocean conditions wave-soil-structure interaction numerical analysis model were designed to verify the accuracy of the numerical model and to analyze the effect of porous media seabed characteristics on wave loads. Results show that the wave load on the single pile depends on the seabed porosity, the average seabed-particle diameter, and the seabed thickness. The seabed-particle diameter has the most significant influence on the wave load of the single pile. The formula for the relationship between the wave load of the single pile and the seabed-particle diameter is derived under different wave conditions. [ABSTRACT FROM AUTHOR]