The Study Of Motion Response In Waves For Shore Floating Pier Near A Reef Island

The floating pier is a hot issue in research of ocean engineering in China and abroad.At present,for the motion response of floating structures,many scholars have conducted research for many years.But research results about reef Marine and terrain environment,analysis of motion response of the floating structures near reefs is few in number.However,when the wave spread from deep sea near to the reef,due to the complicated topography,wave will occur a series of changes such as refraction,diffraction and reflection.The mutual interference between the floating bodies is more complicated.Therefore,it is very important to study the motion response on the shore floating piers in real bottom.This paper is research on the motion responses of floating piers in real bottom.Based on the three dimensional potential flow theories in AQWA numerical simulation software to simulate the floating piers,at the same time,do comparison and analysis with the results on model test.The major works and research achievements of this paper are as follows:(1)Focus on the influence of real bottom for single and multiple floating structures,and establish related calculation models.(2)Introduced the application of calculation principle in this paper.Including the three dimensional potential flow theory,potential water power calculation analysis theory,the motion response of structure under the regular wave,the frequency equation of motion and time domain equations of motion.The velocity potential of floating body in flow field can be obtained by using the Green function.Thereby,we can further calculate the wave force and the floating body suffered hydrodynamic coefficients,and get the equation of motion of structures by time domain analysis method.At the same time,diffraction,radiation and other related parameters between multiple floating structures can be deduced.(3)LINE module of AQWA software is used to calculate the hydrodynamic performance of the single floating pier.Get the change law of Hydrodynamic parameters in the frequency domain.NAUT module of AQWA software is used to calculate the motion responses of the single floating pier with mooring lines,numerical simulation and the result was compared with test results.The results show that hydrodynamic parameters are influenced by the reef,computer simulation and experimental results on the incident wave direction are well matched but there are some differences in vertical direction.Motion of floating pier in irregular waves is highly associated with its natural period.(4)The hydrodynamic performance of multiple floating piers is calculated to get the change law of Hydrodynamic parameters in the frequency domain.The motion responses of multiple floating piers with mooring lines and numerical simulation are calculated,the numerical simulation results were compared with test results.The results show that the reef results in sway among each pier,which cause the transfer of radiation waves unbalanced.The 1st order wave motion presents the famous theory of shallow water effect,but the 2st order wave motion is not significantly influenced.Meanwhile,attenuation and loss of energy are also reflected among floating piers on the direction of wave approach.Numerical simulation value is well matched with model test value of three-bodies and seven bodies floating piers with mooring lines.Under the influence of irregular waves,water depth of shallow to heave motion of floating piers is very obvious.(5)The hydrodynamic parameters in the frequency domain of single and multiple floating piers in deep and shallow water with the reef is calculated.This chapter further analyses the influence of water-depth to the hydrodynamic parameters of single and multiple floating piers.The results show that the influence on added mass of single floating pier is mainly in surge,sway,heave,roll and pitch,the influence on added mass in roll is small.However,the influence on added mass of multiple floating piers is mainly in sway,heave and pitch,the influence on added mass in surge,roll and yaw is small.Deep and shallow water depth on RAOs of single and multiple floating piers has significant effects.(6)In order to floating pier roll as the main target,this chapter puts forward the modification plans comprehensively considering sway and heave.By comparing with the prototype,we set on improved solution about floating piers,and get the excellent pier retrofit by calculating.