Research On The Mechanical Characteristics Of Pile-column Fence Under The Action Of Wave And Current

Net Enclosure Aquaculture(NEA)is a recently developed ecological marine aquaculture model.The development of the cultivation model in China is still at an early stage,there are still many flaws in both structure design and process of implementation,for example,hampered by bad weather such as typhoon,the accidents often occur including the overturn of the main structure,the breakage of the pile,the failure of the net system,which usually lead to the escape of the cultured fish and result in serious economic loss to fishermen.In order to deal with these problems and improve the stability and safety of the pile structure of Net Enclosure Engineering,a series of analytical works have been conducted in this thesis to figure out the mechanical characteristics of the pile structure under the action of waves and current.This study opens out emphasis from the following,Firstly,the research method of the mechanical characteristics of the pile structure NEA under the action of horizontal load is briefly introduced,including adopting the constant method of the linear elastic foundation reaction technique,then combining with the foundation beam theory to establish the pilesoil interaction model;calculating the mechanical properties of the prestressed pile column;also,the determination of the horizontal resistance coefficient of the foundation and the calculation of water resistance.Secondly,the displacement and moment changes of pile structure under different dynamic conditions and different structural parameters are analyzed and discussed.Following main conclusions are obtained:(1)the displacement of the pile structure decreases gradually along the depth direction,and the bending moment value could be divided into positive and negative parts by the zero point of the first bending moment.The bending moment firstly increases and then decreases from the top of the pile to the bottom.The maximum displacement occurs at the top of the structure,and the maximum bending moment is within 5 m below the seabed.(2)When the structural parameters are constant,the displacement and the bending moment of the pile increase with the velocity and wave height,and there is a quadratic function between the velocity and the maximum displacement as well as bending moment;(3)Under the same dynamic condition,the displacement and bending moment of the structure increase with the water depth,meanwhile,the increase of the transverse spacing is conducive to the reduction of the horizontal displacement as well as the bending moment of the pile;(4)when the pile diameter or the depth of the mud increases,the maximum displacement of the structure gradually decreases but the maximum bending moment increases.Meanwhile,at the same point of the pile structure,the larger displacement,the smaller bending moment;(5)both the maximum displacement and bending moment of pile structure decrease with the increasing of soil parameters or pile rows.At the same time,The research achievement can be used as the basis for the design,construction and comprehensive performance evaluation of the pile type net enclosure aquaculture.Also,this study provides important reference data for the research and development of the wind wave resistance technology of the pile type net enclosure aquaculture engineering structure.