FSI analysis of small scale pile and solution of wave force using CFD method

DOI：10.7511/dllgxb201706010

 作者 单位 张力伟,李昕,赵颖华

基于Workbench平台建立了软土地基圆柱桩波浪作用分析的三维数值波浪水池，实现了线性波的数值模拟及波浪与桩柱的双向流固耦合分析，并得到波浪力数值解．对于小尺度桩柱，桩柱为刚性时其所受波浪力与《港口与航道水文规范》中规范解一致．考虑桩柱的柔性及流固耦合时，在达到峰值的位置波浪力与规范解相比既有增大也有减小，桩柱总波浪力最大增大5.7%，桩底弯矩最大增大54%．而采用直接加载法即不考虑流固耦合时桩柱的振动幅值大于耦合时桩柱振动，桩底弯矩最大，大于规范解84.6%．因此，在进行小尺度柔性桩柱设计时应采用流固耦合方法．

Three dimension numerical wave tank is established on Workbench platform for analysis of cylinder pile in soft soil foundation under wave actions. Simulation of linear wave and two-way fluid-structure interaction(FSI) analysis are realized, and numerical results of wave force on cylinder are obtained. For small scale pile, the wave forces obtained using CFD method are consistent with the results using standard method given in Code of Hydrology for Harbor and Waterway when the pile is treated as rigid, but when the pile is treated as flexible and considering the coupling action between the pile and water, the peaks of wave force increase or decrease indefinitely, the maximum total wave force increases by 5.7% and the bending moment at pile bottom increases by 54%. The pile vibrations when neglecting the fluid coupling are greater than that considering the coupling, and the bending moment at pile bottom using direct loading method which doesn′t consider the fluid coupling increases by 84.6% than that using standard method. Therefore, FSI method should be applied in design of small scale flexible piles.