Response Of Saturated Sloping Seabed And Pipeline Under Solitary Wave

With the development of ocean engineering,the number of engineering structures in coastal waters is increasing day by day.The near-shore seabed is dominated by gentle slopes and is an important transitional zone for "landing" of oil and gas pipelines on the seabed.The stress conditions of the seabed and pipelines are susceptible to wave action in the coastal shallow water environment.Waves in shallow waters show special forms such as solitary waves.When isolated waves climb and fall on gentle seabed,changes in pore water pressure may cause liquefaction and landslides on the sea floor,thus endangering nearshore structures such as submarine pipelines.In this paper,the numerical simulation method is used to study the response of the submarine gentle seabed and submarine buried pipe under the action of solitary waves.(1)Numerical simulation and verification of wave,seabed and subsea pipelines.Through the establishment of reasonable turbulence model,boundary conditions and NS control equations,the numerical simulation of the rising and falling process of solitary wave on gentle slope is implemented in FLOW 3D software.The pressure distribution of the gentle slope surface wave is distributed in the development characteristics.Based on Biot consolidation theory and linear elasticity theory,a gentle slope sea bed and a buried submarine pipeline model under the action of wave pressure are established in multi-field analysis software COMSOL to calculate and analyze the pore water pressure of the seabed soil.By comparing with the experimental data and analytical solutions in the literature,the rationality and accuracy of the analytical method are verified.(2)A one-way coupled model of solitary wave-gentle slope seabed is established to study the pore water pressure response of the gently sloping soil body under solitary wave.The influence of solitary waves on the development and change of pressure on the gentle slope,the pore pressure response at different positions of the gentle slope and the influence of gentle slope soil parameters on the pore pressure were discussed.The results show that the wave pressure near the coastline suddenly drops to a negative value during the fall of solitary wave,resulting in a significant drop in pore pressure.Saturation,permeability coefficient and gentle slope gradient have an important influence on pore pressure with time and vertical distribution.(3)Considering the influence of submarine pipelines,a coupled model of isolated wave-gentle slope-pipe was established to calculate the porewater pressure response and vertical effective stress response of the soil around the embankment buried in gentle slope under the action of solitary waves,Deformation.The results show that the buried pipeline near the coastline is more unfavorable than the horizontal seabed and gentle slope.The wave climb and fall,pipeline depth,soil parameters and gentle slope slope have important influence on the calculation results.