The Impact Of Dredging Access Channel On Harbor Oscillation

Harbor oscillation has become a very important research direction in coastal engineering and has received wide attention from scholars.Harbor oscillation have occurred in many ports at home and abroad,which greatly affected the loading and unloading operations of the port and the safety of mooring vessels in the port.First of all,this paper briefly introduces the background and significance of harbor oscillations,and summarizes the research contents of harbor oscillations in terms of physical model experiments and numerical simulations.Then,the modified mild slope equation used in this paper is introduced and verified.This model adds the slope square term and curvature term of the terrain,which can effectively improve the applicability of it to the fast-changing water depth.This paper explores the influence of dredging access channel on harbor oscillation in the following aspects:Waves will occur refraction,reflection and diffraction and other phenomena when encounter sudden changes of water depth in the process of propagation.This paper explores the diffraction of low-frequency waves around harbor entrance with access channel.The numerical simulation results show that the channel has a significant influence on the wave propagation,channel will speed up the reduction of the wave height.When the wave incident perpendicularly to the breakwater at the gap,the relative wave height will decrease along the channel,but become stable at final.When there is no channel in the harbor,the relative wave height will rise behind the breakwater,the maximum relative wave height is greater than 1.2.When the channel exists,this phenomenon will significantly weaken,and the maximum relative wave height is less than 1.0.And,the channel have different influences on the waves with different periods.The larger the period,the smaller the wave is affected by the channel.The modified mild slope equation is used to investigate the influence of the channel and wave incident angle on harbor oscillation.The first four peaks of the amplification coefficient diagrams are analyzed in this paper.The numerical results show that under the influence of the channel,the natural frequencies of the harbor will become larger,and the numerical value of the amplification factor will decrease,and the high frequency zone will receive more influence than the low frequency zone,but when the channel exists,there will not be new natural frequencies.The width of the channel also has a certain impact on the natural frequencies and resonant mode of the harbor,the water surface of the whole harbor will become more complex.The change of the incident angle of the wave will not affect the natural frequencies of the harbor,but the numerical value of the amplification factor is decreased.The height of the peaks in the first four modes is decreased but the width is constant,that means,the probability of harbor oscillation does not change.Finally,the modified mild slope equation is used to establish the model of Tema Port.The actual data is used as a reference to explore the influence of the channel on the natural frequencies and resonant mode of the harbor with complex water depth.