Wave Transformation and Soil Response Due to Submerged Permeable Breakwater

2006 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Hong-Bin Chen ◽  
Dong-Sheng Jeng ◽  
Kuan-Hong Chen
Keyword(s):  
Pore Pressure ◽  
Wave Spectrum ◽  
Experimental Results ◽  
Wave Transformation ◽  
Harmonic Mode ◽  
Submerged Breakwater ◽  
Soil Response ◽  
Higher Harmonic ◽  
Wave Induced ◽  
The Waves

This study reports the experimental results of the wave transformation and the wave-induced soil response when the waves pass through the submerged permeable breakwater. The model of the submerged breakwater was built on a horizontal sandy bottom. The experimental results of the spectrum of the wave transformation and the wave-induced pore-pressure are first analyzed in this paper. It is found that the wave spectrum is similar to the condition of the impermeable bottom that the higher harmonic mode appears when the waves pass over the submerged structure. However, the higher harmonic mode is not found in the spectrum of the wave-induced pore pressure, showing that the nonlinearity of the pore pressure is damped by the porous bed. The influences of the geometry of the submerged breakwater to the transformation of the wave height and the pore-pressure are also investigated. Based on the experimental results, the regression formulas for the coefficients of the wave reflection, the wave transmission and the wave energy dissipation are obtained in the paper.

Wave-Coherent Airflow and Critical Layers over Ocean Waves

2013 ◽  
Vol 43 (10) ◽  
pp. 2156-2172 ◽  
Author(s):  
Laurent Grare ◽  
Luc Lenain ◽  
W. Kendall Melville
Keyword(s):  
Momentum Flux ◽  
Wave Spectrum ◽  
Phase Speed ◽  
Ocean Waves ◽  
Naval Research ◽  
Critical Height ◽  
Office Of Naval Research ◽  
Mean Wind Speed ◽  
Wave Induced ◽  
The Waves

Abstract An analysis of coherent measurements of winds and waves from data collected during the Office of Naval Research (ONR) High-Resolution air–sea interaction (HiRes) program, from the Floating Instrument Platform (R/P FLIP), off the coast of northern California in June 2010 is presented. A suite of wind and wave measuring systems was deployed to resolve the modulation of the marine atmospheric boundary layer by waves. Spectral analysis of the data provided the wave-induced components of the wind velocity for various wind–wave conditions. The power spectral density, the amplitude, and the phase (relative to the waves) of these wave-induced components are computed and bin averaged over spectral wave age c/U(z) or c/u*, where c is the linear phase speed of the waves, U(z) is the mean wind speed measured at the height z of the anemometer, and u* is the friction velocity in the air. Results are qualitatively consistent with the critical layer theory of Miles. Across the critical height zc, defined such that U(zc) = c, the wave-induced vertical and horizontal velocities change significantly in both amplitude and phase. The measured wave-induced momentum flux shows that, for growing waves, less than 10% of the momentum flux at z ≈ 10 m is supported by waves longer than approximately 15 m. For older sea states, these waves are able to generate upward wave-induced momentum flux opposed to the overall downward momentum flux. The measured amplitude of this upward wave-induced momentum flux was up to 20% of the value of the total wind stress when Cp/u* > 60, where Cp is the phase speed at the peak of the wave spectrum.

scholarly journals Experimental Study on the Distribution of Wave-Induced Excess Pore Pressure in a Sandy Seabed around a Mat Foundation

2019 ◽  
Vol 7 (9) ◽  
pp. 304
Author(s):  
Yuan ◽  
Liao ◽  
Zhou
Keyword(s):  
Pore Pressure ◽  
Numerical Study ◽  
Experimental Results ◽  
Excess Pore Pressure ◽  
Offshore Platforms ◽  
Pressure Area ◽  
Mat Foundation ◽  
Mat Foundations ◽  
Wave Induced ◽  
Excess Pore

Mat foundations are widely used in jack-up offshore platforms to support and transfer loads. Regarding mat foundations working on the seabed, the excess wave-induced pore pressure is critical to seabed stability, which may finally cause structural failure. Therefore, it is important to investigate the distribution of the excess pore pressure in the seabed around the mat foundation. In this study, experiments were performed to study the excess pore pressure distribution around a mat foundation in scale considering the true load state by recording wave profiles and pore pressures inside a sandy seabed. To guarantee the reliability of experiments, a numerical study was conducted and compared with the experimental results. Experimental results indicate that with the existence of the mat foundation, the excess pore pressure is higher at the region, the range of which is the width of the model mat (Wm) before the structure. The maximum pore pressure appears at 0.55 Wm in front of the center of the mat foundation. In addition, the current significantly increases the range of high pore pressure area and the amplitude of the excess pore pressure. As the mat orientation changes, the position of the maximum pore pressure changes from the front to the edge of the mat.

An Analytical Solution for Wave-Induced Soil Response and Seabed Liquefaction

2010 ◽  
Author(s):  
Xiang-Lian Zhou ◽  
Jian-Hua Wang ◽  
Yun-Feng Xu
Keyword(s):  
Shear Modulus ◽  
Pore Pressure ◽  
Effective Stress ◽  
Fourier Transformation ◽  
Saturated Porous Medium ◽  
Helmholtz Equations ◽  
Soil Response ◽  
Depth Increase ◽  
Vertical Effective Stress ◽  
Wave Induced

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.

scholarly journals Long-term wave growth and its linear and nonlinear interactions with wind fluctuations

2008 ◽  
Vol 26 (4) ◽  
pp. 747-758 ◽  
Author(s):  
Z. Ge ◽  
P. C. Liu
Keyword(s):  
Wave Field ◽  
Wind Wave ◽  
Wave Spectrum ◽  
Wave Interactions ◽  
Wave Growth ◽  
Linear And Nonlinear ◽  
Equilibrium Range ◽  
Wave Induced ◽  
The Waves

Abstract. Following Ge and Liu (2007), the simultaneously recorded time series of wave elevation and wind velocity are examined for long-term (on Lavrenov's τ4-scale or 3 to 6 h) linear and nonlinear interactions between the wind fluctuations and the wave field. Over such long times the detected interaction patterns should reveal general characteristics for the wave growth process. The time series are divided into three episodes, each approximately 1.33 h long, to represent three sequential stages of wave growth. The classic Fourier-domain spectral and bispectral analyses are used to identify the linear and quadratic interactions between the waves and the wind fluctuations as well as between different components of the wave field. The results show clearly that as the wave field grows the linear interaction becomes enhanced and covers wider range of frequencies. Two different wave-induced components of the wind fluctuations are identified. These components, one at around 0.4 Hz and the other at around 0.15 to 0.2 Hz, are generated and supported by both linear and quadratic wind-wave interactions probably through the distortions of the waves to the wind field. The fact that the higher-frequency wave-induced component always stays with the equilibrium range of the wave spectrum around 0.4 Hz and the lower-frequency one tends to move with the downshifting of the primary peak of the wave spectrum defines the partition of the primary peak and the equilibrium range of the wave spectrum, a characteristic that could not be revealed by short-time wavelet-based analyses in Ge and Liu (2007). Furthermore, these two wave-induced peaks of the wind spectrum appear to have different patterns of feedback to the wave field. The quadratic wave-wave interactions also are assessed using the auto-bispectrum and are found to be especially active during the first and the third episodes. Such directly detected wind-wave interactions, both linear and nonlinear, may complement the existing theoretical and numerical models, and can be used for future model development and validation.

Wave-Induced Pore Pressure and Effective Stresses in a Porous Seabed With Variable Permeability

1997 ◽  
Vol 119 (4) ◽  
pp. 226-233 ◽  
Author(s):  
D. S. Jeng ◽  
B. R. Seymour
Keyword(s):  
Pore Pressure ◽  
Offshore Structures ◽  
Soil Permeability ◽  
Soil Response ◽  
Mathematical Procedure ◽  
Effective Stresses ◽  
Variable Permeability ◽  
Seabed Interaction ◽  
Wave Induced ◽  
Interaction Problem

An evaluation of wave-induced soil response is particularly important for marine geotechnical engineers involved in the design of foundations for offshore structures. To simplify the mathematical procedure, most theories describing the wave-seabed interaction problem have assumed a porous seabed with uniform permeability, despite strong evidence of variable permeability. This paper presents an analytical solution for the wave-induced soil response in a porous seabed with variable permeability. Verification is available through a reduction to the simple case of uniform permeability. The results indicate that the effect of variable soil permeability on pore pressure and effective stresses is significant.

scholarly journals Meshless Model for Wave-Induced Oscillatory Seabed Response around a Submerged Breakwater Due to Regular and Irregular Wave Loading

2020 ◽  
Vol 9 (1) ◽  
pp. 15
Author(s):  
Dong-Sheng Jeng ◽  
Xiaoxiao Wang ◽  
Chia-Cheng Tsai
Keyword(s):  
Theoretical Models ◽  
Irregular Waves ◽  
Degree Of Saturation ◽  
Submerged Breakwater ◽  
Soil Response ◽  
Irregular Wave ◽  
Mesh Free ◽  
Low Degree ◽  
Height Increase ◽  
Wave Induced

The evaluation of wave-induced seabed stability around a submerged breakwater is particularly important for coastal engineers involved in design of the foundation of breakwaters. Unlike previous studies, a mesh-free model is developed to investigate the dynamic soil response around a submerged breakwater in this study. Both regular and irregular wave loadings are considered. The present model was validated against the previous experimental data and theoretical models for both regular and irregular waves. Parametric study shows the regular wave-induced liquefaction depth increases as wave period and wave height increase. The seabed is more likely to be liquefied with a low degree of saturation and soil permeability. A similar trend of the effects of wave and seabed characteristics on the irregular wave-induced soil response is found in the numerical examples.

Response of Pore Pressure and Effective Stress in Seabed to Waves Around a Permeable Submerged Breakwater

2015 ◽  
Author(s):  
Hao Chen ◽  
Jinhai Zheng ◽  
Qianzhen Li ◽  
Naiyu Zhang ◽  
Hanyi Chen ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Fluid Pressure ◽  
Wave Model ◽  
Pore Fluid Pressure ◽  
Submerged Breakwater ◽  
Great Ability ◽  
Wave Induced ◽  
Foundation Failure ◽  
Dynamic Wave

As the unexpected wave-induced seabed instability may cause foundation failure, the evaluation of wave-induced pore pressure and effective stress in seabed plays an important role in the design of the foundation of marine structures. In this study, a two-dimensional integrated mathematical model, based on COBRAS wave model and SWANDYNE seabed model is developed to numerically investigate the mechanism of wave-induced seabed response in the vicinity of a permeable submerged breakwaters. Numerical results indicate that this model has a great ability in predicting the dynamic response of the pore pressure and effective stress around the breakwater. Both the pore fluid pressure and effective stress in seabed largely changes with an increasing water depth. It is also found that the responses of the pore pressure and effective stress of different locations to the dynamic wave loading are significantly different in the cases with variable top width of the breakwater.

scholarly journals Numerical Simulation of Solitary Wave Induced Flow Motion around a Permeable Submerged Breakwater

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Jisheng Zhang ◽  
Jinhai Zheng ◽  
Dong-Sheng Jeng ◽  
Gang Wang
Keyword(s):  
Solitary Wave ◽  
Wave Structure ◽  
Wave Transformation ◽  
Navier Stokes ◽  
Submerged Breakwater ◽  
Mean Diameter ◽  
Flow Motion ◽  
Energy Dissipated ◽  
Structure Height ◽  
Wave Induced

This paper presents a numerical model for the simulation of solitary wave transformation around a permeable submerged breakwater. The wave-structure interaction is obtained by solving the Volume-Averaged Reynolds-Averaged Navier-Stokes governing equations (VARANS) and volume of fluid (VOF) theory. This model is applied to understand the effects of porosity, equivalent mean diameter of porous media, structure height, and structure width on the propagation of a solitary wave in the vicinity of a permeable submerged structure. The results show that solitary wave propagation around a permeable breakwater is essentially different from that around impermeable one. It is also found that the structure porosity has more impact than equivalent mean diameter on the wave transformation and flow structure. After interacting with the higher structure, the wave has smaller wave height behind the structure with a lower travelling speed. When the wave propagates over the breakwater with longer width, the wave travelling speed is obviously reduced with more wave energy dissipated inside porous structure.

scholarly journals Experimental Study for Wave-Induced Pore-Water Pressures in a Porous Seabed around a Mono-Pile

2019 ◽  
Vol 7 (7) ◽  
pp. 237 ◽  
Author(s):  
Shaohua Wang ◽  
Pandi Wang ◽  
Hualing Zhai ◽  
Qibo Zhang ◽  
Linya Chen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Spatial Distribution ◽  
Pore Pressure ◽  
Pore Water ◽  
Wave Height ◽  
Experimental Results ◽  
Period Increase ◽  
Pore Water Pressures ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, the results of a series of experiments on wave-induced pore-water pressures around a mono-pile are presented. Unlike the previous study, in which the mono-pile was fully buried, the mono-pile in this study was installed at 0.6 m below the seabed surface. In this study, we focus on the pore-water pressures around the mono-pile and beneath the pile. The experimental results lead to the following conclusions: (1) the seabed response is more pronounced near the surface (in the region above 30 cm deep), and the rate of pore pressure attenuation gradually slows down. For the region below 0.3 m, the response is much smaller; (2) in general, along the surface of the pile, pore pressures increase as the wave height and wave period increase; (3) the spatial distribution of pore pressure near the pile will vary with different wave periods, while the wave height only has a significant effect on the amplitude; and (4) At z = −0.15 m, the pore pressure in front of the pile is the largest, while at the point 0.1 m below the bottom of the pile, the largest pore pressure occurs behind the pile.

Wave-Induced Oscillatory Soil Response Around Circular Rubble-Mound Breakwater Head

2017 ◽  
Author(s):  
Dagui Tong ◽  
Chencong Liao ◽  
Jianhua Wang ◽  
Dongsheng Jeng
Keyword(s):  
Pore Pressure ◽  
Numerical Scheme ◽  
Wave Motion ◽  
Three Dimensional ◽  
Wave Structure ◽  
Soil Response ◽  
Seabed Interaction ◽  
Rubble Mound ◽  
Wave Induced

The wave-structure-seabed interaction (WSSI) around circular rubble-mound breakwater head is investigated using a three-dimensional (3D) numerical scheme. The result reveals that the presence of breakwater has strong effect on wave motion and seabed response. The turbulence induced by the breakwater head gives rise to extensive pore pressure around the breakwater head, which could further lead to liquefaction or scour and might eventually result in breakwater failure.

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