Research On The Stress And Deformation Of Deep Water Pile Foundation Under Wave Force

As the most widely used foundation type for deep-water structures such as bridges,pile foundations often bear wave loads that change with time and space during structural construction and service,affecting project safety.Therefore,studying the stress and deformation characteristics of the pile foundation under the action of wave force and the changes of the two with the relevant parameters has important engineering reference value for the design,construction and operation management of deepwater projects.Based on the linear wave theory in this paper,relying on the pile foundation project of a bridge project,for the sloshing problem caused by the navigable vessel during the pile foundation construction process,using theoretical calculation,numerical simulation and combined field monitoring data on the wave force The stress and deformation of the pile foundation under deep water and its variation with several key parameters were systematically studied.In previous studies on the wave force of deep-water pile foundations,only the free section of the pile body in the water was considered,and the pile foundation was fixed at the bottom of the water,ignoring the influence of the rock and soil layer on the pile foundation stress and deformation In this paper,the problem of pile-soil contact is fully considered.The main research contents and conclusions are as follows:(1)According to the water depth of the bridge site area,the wavelength of the traveling wave and the characteristic scale of the pile foundation,the linear wave theory is selected,the wave force calculation program is compiled based on the Morison equation,and the resultant force and dynamic change of the linear wave force on each section of the cylindrical pile body are obtained law.(2)According to the actual situation of the deep-water pile foundation construction process,a three-dimensional finite element numerical model of the pile cap-group pile-rock layer is established,and the natural vibration frequency of the pile foundation is analyzed.The pile body wave force calculated by the Morison equation is limited.Loaded in the meta software,calculated the horizontal displacement generated by the platform under the action of wave force,and compared the numerical simulation results with the monitoring data on the construction site to verify the reliability of the numerical model and the numerical simulation method used to analyze the deep-water pile foundation Feasibility of force and deformation under the action of wave force.(3)Based on the finite element numerical simulation method,the force and deformation characteristics of the free pile in the water under the action of wave force are analyzed.The results show that: in the direction perpendicular to the wave propagation,the axial force and pile end of the same row of piles The shear force at the end and the bending moment of the pile body are the same;at the same time,the axial force of the pile end of the front and rear rows basically shows the law of equal magnitude and opposite direction,and the shear force of the top of the rear row pile is much larger than the value of the front row but usually the same The pile bottom shear force and pile body bending moment of the front and back rows of piles are basically kept the same.Under the action of wave force,the shear force distribution of the pile top of the pile group foundation is uneven,and the connection between the cap and the pile foundation should be paid attention to in the design and construction.The deformation of the pile body is shown as side bending and the foundation piles are kept in sync,shaking back and forth mainly along the wave propagation direction.(4)Carry out 4 sets of finite element numerical simulations under different parameter conditions,and analyze the influence of different parameters on the internal force of the deep-water pile foundation in the free section of the water and the horizontal displacement of the platform under the wave force.The results show that: with the upper layer of the foundation As the thickness of the weak soil increases,the internal force of the pile foundation and the horizontal displacement of the bearing cap generally increase,and the increase rate will increase significantly after exceeding a certain "critical thickness";as the depth of the rock-socket bottom increases,the internal force of the pile foundation And the horizontal displacement of the bearing cap is obviously reduced,and the reduction rate is obviously increased after exceeding a certain "critical depth";the increase in the pile diameter will cause the wave force of the pile body to increase,and the shear force and bending moment at the bottom of the pile will increase first.After the reduction,the axial force of the pile end,the shear force of the pile top and the horizontal displacement of the bearing cap gradually decrease;with the gradual increase of the concrete strength level,the internal force of the pile body increases significantly,and the horizontal displacement of the bearing cap decreases significantly,its peak value It shows a nearly linear decrease.(5)Based on the conclusions of the numerical simulation research,for the investigation,design,construction and reinforcement of the pile foundation engineering of the bridge and the pile foundation engineering around the deep water,several control suggestions and measures on wave damage are proposed.