Dynamic Response And Liquefaction Of Seabed Around Piles Under Wave Loading

In a complex marine environment,wave loading is one of the main causes of damage to offshore structures.Wave load will cause huge deformation of offshore structures and seabed,resulting in excessive deformation stress of buildings and loss of bearing capacity due to liquefaction of the seabed.Based on the COMSOL multiphysics finite element simulation software,the wave-seabed-group pile model and the wave-single pile 3D model are established.Based on the wave-seabed-group pile model,the liquefaction of the soil around the pile is analyzed.The main work conclusions of the thesis are as follows:(1)2D model building:By introducing an artificially applied background sound field,considering the incidence and transmission of sound press.at the junction of the seabed and the water surface,a total sound field is solved,and the size and direction of waves are controlled by the total sound field;In porous media,Biot theory is used to describe the deformation of the solid matrix in saturated porous media.(2)The following conclusions are drawn by applying the two-dimensional model: When the wave frequency is low,the deformation of the seabed is large;The greater the wave incident angle,the greater the displacement of the pile;The stress in the lower part of the pile body is greater than the stress in the upper part,and the stress in the pile body gradually decreases from inside to outside;The pore water press.gradually increases with depth.(3)By using the model,the seabed liquefaction is analyzed.The results show that as the wave frequency increases,the liquefaction depth of the seabed gradually decreases.As the wave incident angle increases,the liquefaction depth on one side decreases and eventually disappears.The increase of porosity can increase the inhibition effect of wave incidence angle on seabed liquefaction.(4)2D model building:The fluid field solves the Naiver-Stokes equations,and the VOF method tracks the free surface;The generalized Hooke's law is used for the solid physics field;the two-phase flow physics field is studied by the "two-phase flow-level set" method.(5)By applying a three-dimensional model,it is concluded that: As the diameter increases,the velocity in the physics field gradually decreases,and the displacement of the pile top increases.The velocity of the pile surface is much larger than that of the seawater.The elastic modulus of concrete does not change the overall characteristics of the deformation of the sea pile.The reduction of elastic modulus will lead to the reduction of the pile's ability to recover deformation.