Short-crested wave-induced soil response in a porous seabed of infinite thickness

Keyword(s):  
2019 ◽  
Vol 15 (8) ◽  
pp. 866-877
Author(s):  
Yuzhu Li ◽  
Muk Chen Ong ◽  
Ove Tobias Gudmestad ◽  
Bjørn Helge Hjertager

2011 ◽  
pp. 789-796
Author(s):  
D.-S. JENG ◽  
Y. ZHANG ◽  
J.-S. ZHANG ◽  
C. ZHANG ◽  
P. L.-F. LIU

Author(s):  
Titi Sui ◽  
Chi Zhang ◽  
Jinhai Zheng ◽  
Dong-Sheng Jeng

Wave-induced seabed soil response and its resultant liquefaction is common observed in a silt seabed with relative poor drainage condition, which poses a great threaten to the foundation safety of marine structures. Regarding the governing equations, three different approaches namely the Fully-dynamic (FD), Partialdynamic (PD) and Quasi-static (QS) model, have been used in the previous studies. Among these, both PD and FD approaches consider the effect of the inertial terms of soil skeleton/fluid. It has been reported in the literature that effects of the inertial terms on the seabed response could not be neglected, especially for the seabed around a movable structure (Ulker et al., 2010). However, these studies only focused on the oscillatory mechanism which are probably seen in a sandy seabed with high permeability. Recently, Zhao et al. (2017) investigated the residual soil response around a pile foundation by integrating a RANS wave model and a QS seabed model. In their study, the inertial terms of soil skeleton and pore water were neglected. To the authors’ best knowledge, up to now, effects of the inertial terms on the residual response of a silt seabed have not been investigated.


Géotechnique ◽  
1996 ◽  
Vol 46 (3) ◽  
pp. 427-440 ◽  
Author(s):  
D. S. Jeng ◽  
J. S. C. Hsu

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Jianfeng Zhu ◽  
Hongyi Zhao

Abstract In this paper, a three-dimensional integrated numerical model for a small-scale case of wave-induced oscillatory soil response around a semi-buried pipeline (PORO-WSSI-PIPE 3D) is proposed. In this model, we combine the Reynolds-averaged Navier–Stokes (RANS) equations for the 3D wave motions and the Biot’s consolidation equations for a porous elastic seabed foundation through pressure continuity at common boundaries, with pipeline being an elastic and impermeable medium. The computational results are validated through comparison with previous analytical solutions and laboratory wave flume tests, obtaining good agreement. Following validation, the numerical model is applied to simulate wave-seabed-pipeline interaction with different obliquities between pipeline and incident wave, varying from 30 deg to 90 deg. Snapshots of wave-seabed-pipeline interaction, as well as dynamic pore pressure distributions at typical locations in the vicinity of a semi-buried pipeline, are obtained and analyzed. The three-dimensional consolidation process of seabed under gravitational forces including the body forces of a pipeline is also discussed.


2001 ◽  
Vol 123 (4) ◽  
pp. 177-181 ◽  
Author(s):  
D. S. Jeng

The evaluation of wave characteristics has been widely studied by ocean engineers in the past. However, conventional investigations for determining wave characteristics have been focused on the nonlinear wave effects in a rigid seabed. On the other hand, most previous investigations for the wave-induced seabed response in a porous seabed have been only concerned with the soil response after wave pressure penetrate into seabed. In this paper, employing a complex wave number, the whole wave-seabed interaction problem will be re-examined. Based on the new closed-form analytical solution, a new wave dispersion equation is derived, including the seabed characteristics. The numerical results indicate that the wave characteristics (such as the wavelength, wave pressure and wave profile) are affected by the soil permeability and shear modulus in a shallow water.


Author(s):  
Xiang-Lian Zhou ◽  
Jian-Hua Wang ◽  
Yun-Feng Xu

In this study, an analytical method to solve the wave-induced pore pressure and effective stress in a saturated porous seabed is proposed. The seabed is considered as a saturated porous medium and characterized by Biot’s theory. The displacements of the solid skeleton and pore pressure are expressed in terms of two scalar potentials and one vector potential. Then, the Biot’s dynamic equations can be solved by using the Fourier transformation and reducing to Helmholtz equations that the potentials satisfy. The general solutions for the potentials are derived through the Fourier transformation with respect to the horizontal coordinate. Numerical results show that the permeability and shear modulus of the porous seabed has obvious influence on the response of the seabed. The vertical effective stress and attenuation velocity of pore pressure along seabed depth increase as permeability k increases. The liquefaction may be occur at the surface of seabed when shear modulus decreasing.


2018 ◽  
Vol 01 (03) ◽  
pp. 1850004 ◽  
Author(s):  
Zuodong Liang ◽  
Dong-Sheng Jeng

To better understand the physical processes involved in the wave–seabed–pipeline interactions (WSPI), a three-dimensional numerical model for the wave-induced soil response around an offshore pipeline is proposed in this paper. Seabed instability around an offshore pipeline is one of the key factors that need to be considered by coastal engineers in the design of offshore infrastructures. Most previous investigations into the problem of WSPI have only considered wave conditions and have not included currents, despite the co-existence of waves and currents in natural ocean environments. Unlike previous studies, currents are included in the present study for the numerical modeling of WSPI, using an integrated FVM model, in which the volume-averaged Reynolds-averaged Navier–Stokes (VARANS) equation is used to solve the mean fluid field, while Biot’s consolidation equation is used to describe the solid–pore fluid interaction in the porous medium. Numerical examples demonstrate a significant influence of ocean current direction and angle on the wave-induced pore pressures and the resultant seabed liquefaction around the pipeline, which cannot be observed in two-dimensional (2D) numerical simulation.


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