A Study On The Mooring System Of A Medium-sized Reef Floating Structure In The Complicated Environment Of The South China Sea

In the field of ocean engineering,the mooring system is related to the usability,safety and other major issues of various floating structures.Therefore,mooring technology is one of the key technologies in the design and practical application of floating structures.Its implementation difficulty is decided by floating structures,and the characteristics of the Marine environment.In this paper,the medium-sized reef floating body,faced with a more complex reef operatiom environment.For the engineering needs,it is necessary to study the floating structure mooring system under such specific environment.In this paper,the study on a medium-sized reef floating structure in the South China Sea with the complex operation environment,should consider reef asymmetric terrain,coral reef geomorphology,very shallow water conditions and other special marine geographical environment.Therefore,the mooring system of the medium-sized reef floating structure can't be simply solved by the existing typical mooring form;In addition,it also needs to consider anti-typhoon factors,life material transportation,and the berthing of ships on the offshore side of the platform under the operation condition.According to the geologic and topographical characteristics of the medium-sized reef floating structure operation position,the mooring layout of the platform is analyzed and designed in detail.Based on the theory of three-dimensional potential flow,numerical simulation in time-domain and frequency-domain of the mooring system is carried out by a variety of commercial software,and then the model test under corresponding operation conditions is carried out to verify the reliability of numerical calculation.The model test,considering the topography of the reef,the influence of the shallow water and so on,includes the decay test and the six-degree-of-freedom response test under different conditions.The first chapter introduces the background of the research,the development history of the medium-sized reef floating structure,the relevant summary of the mooring system and the development trend at home and abroad,as well as the research content and main innovation.The second chapter describes the research methods and research theories used in this paper,mainly related to: three-dimensional potential theory,including detailed discussion of the solution of speed potential;analysis of marine structures subjected to various external forces;how to establish mooring system calculation model;conversion frequency domain between time domain and so on.In the third chapter,the hydrodynamic parameters of the medium-sized reef floating structure are analyzed.From the overview of system model to the establishment of computational model,the use of Hydro D is intruduced.The hydrodynamic calculation is in 3m and 2m draft.In chapter 4,the design criteria of mooring system,mooring cable material selection,tension length determination and arrangement method are introduced.Secondly,the paper summarizes the design scheme and obtains two mooring schemes of tension mooring and catenary mooring.At last,the research and analysis methods of the mooring system are introduced,including numerical calculation and model test.In the fifth chapter,the numerical calculation process and method of mooring system of the medium-sized reef floating structure are discussed.Using Orcaflex analysis mooring system,the motion response data and mooring cable force information of the medium-sized reef floating structure are obtained under different environment conditions of different mooring schemes.In the sixth chapter,the concrete process of the model test is introduced.Starting from the adjustment of the weight center of the model,the marine environment simulation and the measurement method of the test data are expatiated.The main work of the seventh chapter is to compare and analyze the results of numerical calculation and model test,and then compare and analyze the mooring results of two sets of mooring schemes in five different marine engineering environment.The mooring results focus on the six-degree-of-freedom motion of the platform and the time history of the chain tension.By comparing different mooring schemes and different operation conditions,the characteristics of the mooring system of the medium-sized reef floating structure are studied.And finally determine the appropriate mooring scheme.Finally,the eighth chapter summarizes the work of the whole paper,and prospects the future research direction.