Wave (Current)-Induced Pore Pressure in Offshore Deposits: A Coupled Finite Element Model
Abstract
:1. Introduction
2. Theory and Methods
2.1. Wave Module
2.2. Seabed Module
2.2.1. Oscillatory Response of Soil
2.2.2. Residual Response of Soil
2.3. Coupling Method
2.3.1. Time Scheme
2.3.2. Mesh Scheme
2.3.3. Boundary Conditions
2.3.4. Coupled Process
3. Model Validation
3.1. Wave Verification: Comparison with an Analytical Solution
3.2. Seabed Verification: Comparison with Experimental Data
3.2.1. Validation of the Oscillatory Pore Pressure
3.2.2. Validation of the Residual Pore Pressure
3.3. Wave-Seabed Interaction Verification
4. Model Application
5. Conclusions
Author Contributions
Acknowledgments
Conflicts of Interest
Nomenclature
Symbol | Description | Units |
ui | Fluid velocity | [m/s] |
xi | Coordinate | [m] |
t | Time | [s] |
Fluid density | [kg/m3] | |
p | Fluid pressure | [N/m2] |
gi | Gravitational force | [m/s2] |
Viscous stress tensor | [N/m2] | |
Source Region | [-] | |
Si | Momentum source function | [m/s2] |
Angular frequency | [/s] | |
k | Wave number | [/m] |
Wave obliquity | [1] | |
Wave amplitude | [m] | |
L | Wavelength | [m] |
C | Wave velocity | [m/s] |
Free surface elevation | [m] | |
pe | Wave-induce pore pressure | [Pa] |
Oscillatory pore pressure | [Pa] | |
Residual pore pressure | [Pa] | |
Unite weight of water | [N/m3] | |
ns | Soil Porosity | [1] |
Volume strain | [1] | |
Compressibility of pore fluid | [/Pa] | |
us, ws | Soil displacements | [m] |
Kw | True elasticity modulus of pore water | [Pa] |
Pw0 | Absolute water pressure | [Pa] |
S | Seabed degree of saturation | [1] |
Total stress | [Pa] | |
Effective stress | [Pa] | |
Kronecker delta | [1] | |
G | Shear modulus | [Pa] |
Poisson’s ratio | [1] | |
Kv | Bulk modulus of soil | [Pa] |
Plastic volumetric strain | [1] | |
R | Material parameters | [1] |
Cyclic stress ratio | [1] | |
Maximum amplitude of shear stress | [Pa] | |
Initial effective stress in vertical direction | [Pa] | |
Wave pressure on seabed surface | [Pa] | |
Shear stress at the seabed surface | [Pa] | |
h | Seabed thickness | [m] |
Turbulent dissipation rate | [1] | |
Kinetic viscosity | [kg/m/s] | |
Eddy viscosity | [kg/m/s] |
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Wave Characteristics | Value | Soil characteristics | Value |
---|---|---|---|
Wave period (T) | 12.0 s | Permeability (K) | 1.0 × 10−4 m/s |
Porosity (ne) | 0.30 | ||
Wave length (H) | 170.0 m | Shear modulus (G) | 1.0 × 107 N/m2 |
Thickness (h) | ∞ m | ||
Water depth (d) | 30.0 m | Poisson’s ratio (μ) | 0.35 |
Degree of saturation (S) | 1 | ||
Wave amplitude (η) | 2.5 m |
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Liao, C.; Jeng, D.; Lin, Z.; Guo, Y.; Zhang, Q. Wave (Current)-Induced Pore Pressure in Offshore Deposits: A Coupled Finite Element Model. J. Mar. Sci. Eng. 2018, 6, 83. https://doi.org/10.3390/jmse6030083
Liao C, Jeng D, Lin Z, Guo Y, Zhang Q. Wave (Current)-Induced Pore Pressure in Offshore Deposits: A Coupled Finite Element Model. Journal of Marine Science and Engineering. 2018; 6(3):83. https://doi.org/10.3390/jmse6030083
Chicago/Turabian StyleLiao, Chencong, Dongsheng Jeng, Zaibin Lin, Yakun Guo, and Qi Zhang. 2018. "Wave (Current)-Induced Pore Pressure in Offshore Deposits: A Coupled Finite Element Model" Journal of Marine Science and Engineering 6, no. 3: 83. https://doi.org/10.3390/jmse6030083