Numerical Simulation Of Extreme Irregular Waves And Study Of Dynamic Response To Pile Action

With the establishment of marine power planning,more and more marine projects are put into development.Waves as the main load of marine environment often bring adverse effects on structural stability.Therefore,in order to ensure the safety of marine engineering structures subjected to waves with large wave heights,large wave steepness and asymmetric waveforms,this paper carries out numerical simulations of extreme forms of irregular waves represented by deformed waves and typhoon waves,and numerical studies of the dynamic response of small-scale piles under their action.The main work and conclusions are as follows:The time course of seven groups of measured fluctuation free surface was inverted by spectral analysis method(frequency domain angle)and stream function method(time domain angle)respectively,and the similarities and differences of wave surface,water quality point velocity and acceleration under the two methods were discussed: the simulated wave surface can reproduce the real waveform better by power spectrum estimation judgment and wave height period control iteration;the horizontal velocity values and motion trend of water quality point of wave surface obtained by the two theoretical methods are more consistent,and the horizontal acceleration obtained by the two methods were verified by using central difference method,and it was found that the stream function method matches better and has better stability than the spectral analysis method.The dynamic response model of "wave-pile" is constructed by combining Morrison’s equation and dynamic finite element with the radial basis point interpolation function.The differences of pile top displacement,velocity,acceleration and pile bottom bending moment at the mud surface are compared and analyzed based on the flow function method and the spectral analysis method with and without considering the coupling case.The results show that the inertia force term multiplied by the conversion factor can be used instead of the drag force term in the actual engineering calculation to simplify the calculation purpose.The results of both methods also show that the dynamic response of the pile is greater when fluid-solid coupling is considered than when fluid-solid coupling is not considered.It is also found that the results obtained using spectral analysis method are overall conservative when calculating the dynamic response of piles by strong nonlinear waves.In conclusion,for the sake of structural safety,it is recommended to use the stream function method to solve the dynamic response of piles considering fluid-structure coupling under the action of extreme irregular waves.