Research On Horizontal Dynamic Response Of Offshore Pile Bearing Fan Under The Action Of Rayleigh Wave

In an earthquake,when a body wave reaches the surface or rock formation interface,a wave that propagates along the surface and has a large amplitude is called a surface wave.As the main surface wave generated in the earthquake,Rayleigh wave generally carries most of the seismic energy,and its particle moves along the elliptical trajectory,which often causes great damage to the foundation of the building structure.It is the main research object in seismology;The dispersion properties in layered soils are also widely used in geological exploration.In recent years,the contradiction between the booming economy and the current situation of energy shortage has become deeper and deeper.The abundant energy in the ocean has become an important way to resolve this contradiction.The offshore energy mining platforms such as offshore wind turbines have also been built on a large scale..Steel pipe piles have become the mainbasic form of offshore energy mining platform construction due to its advantages in bending performance,single pile bearing capacity,construction schedule,cost and ease of transportation.At present,the research results on the dispersion of Rayleigh wave at home and abroad are abundant,and the research on the dynamic response of the free-field caused by the free-field caused by the free-field,especially the simulated marine environment,is rarely heard.There is a certain gap in the dynamic response of the foundation;in addition,due to the hollow nature of the pipe pile and the complexity of the fan system,the difficulty of research on the dynamic response of the offshore pile wind turbine is deepened.In view of this,this paper studies the horizontal dynamic response of the offshore pile wind turbine in the marine foundation under the action of R wave.The main research contents are as follows:1.Based on the finite element-analytic method,the overlying soil layer and fluid layer are discretized into two-dimensional pedestal units.According to the four-node element stiffness matrix and the vertical displacement continuity condition of the seabed surface,the overall stiffness matrix and quality of the system are established.The matrix is then introduced into the potential function to obtain the relationship between the joint force and the joint displacement of the ground surface in the bottom half space,and iscoupled with the vibration equation of the beam unit,by transforming the Rayleigh wave dispersion characteristic equation in the wave-phase velocity(k-c)domain into The quadratic eigenvalue problem is used to obtain the dispersion characteristics and free-field dynamic response of Rayleigh wave multi-order modes in fluid-layered soils.2.Based on the saturated soil Biot dynamic equation and the ideal fluid dynamic equation,the horizontal dynamic response of the saturated soil foundation under the action of R wave is studied.In the calculation process,the potential function is introduced into the vector form of Biot wave equation,and the operator matrix is??used to calculate the wave velocity of the shear wave and the two compression waves in the saturated soil,and the saturated soil potential function for coupling the two compression waves is introduced.The expression form;combined with the continuity condition of the interface between the fluid layer and the saturated soil layer,the R-wave characteristic equation of the half-space saturated soil of the overlying fluid layer is obtained,and the horizontal dynamic response of the free field caused by the analysis is solved.3.Based on the dynamic characteristic equation of elastic medium and the Biot wave equation of saturated porous media incylindrical coordinate system,the Novak thin layer method is used to study the idea,ignoring the change of horizontal displacement of free field with the depth direction and the vertical displacement of free field caused by seismic wave.Combined with the continuity conditions between piles and soils and the constraints of free-field boundary,the dynamic impedance of piles and soils under the action of seismic waves in single-phase elastic medium and saturated medium is solved.4.Establish a calculation model for the offshore pile wind turbine,and calculate the pile bearing fan system in stages according to the medium in which the pile bearing fan is located.Solving the horizontal dynamic response equation of the variable section tower and the immersed fluid section pipe pile;combining the horizontal response of the free field caused by the R wave with the horizontal dynamic impedance of the pile surrounding soil and the pile core soil,respectively,the buried layered medium and saturated soil are established respectively.The differential vibration equation of the middle pipe pile is solved.The upper fan is simplified into a mass block,and combined with the continuity condition of the interface of the variable section tower,the immersed pile and the buried pile,the horizontal dynamic response of the embedded rock pile under the action of R wave is obtained.