Research On Structural Design And Optimization Of Pile Frame Of Large Pile Driving Ship

The maritime power strategy and the "Made in China 2025" program of action clearly stipulate that it is necessary to vigorously develop equipment and key systems for offshore resource development and utilization,operation support,etc.In recent years,as the country has promoted the strategic layout of the ring-to-sea economic circle,offshore engineering projects have been increasing day by day and continuously extended to the sea.Piling ships used in the construction of offshore wind power high pile cap piles,jacket piles and large bridge piles,especially large pile driving ships,have become more and more prominent in the construction of offshore pile foundations,and the application prospects are also becoming broader.Therefore,in this paper,researches are carries out on the design and optimization of the pile frame structure of large-scale piling ships,which has important theoretical significance and application value for meeting the requirements of large-diameter super-long pile foundation piling operations in the deep sea.The main research work and results are as follows:(1)The main working conditions of the deep-sea piling ship and the type of the pile frame of the existing piling ship are analyzed.In order to meet the needs of piling operation of large diameter and super long pile foundation in deep sea,three different types of pile frame,namely K type,gem type and Z type,are designed.(2)The basic theory and method of finite element analysis are studied,and three finite element models of pile frame structures are established with Hyper Mesh.In order to improve the efficiency and accuracy of finite element calculation,the members in each pile frame structure use beam elements,the large plane,the rear legs and the two front legs of each pile frame adopt shell elements,and the connection between the two is constrained by Kinematic coupling.(3)Abaqus is used to simulate and analyze the three different types of pile frames.The results show that the maximum stress on the gem-type,K-type and Z-type pile frames is 350.1 MPa,342.3 MPa,and 332.7 MPa,respectively,and the maximum node displacement is 145.3mm,142.2mm,and 131.5mm,respectively.Therefore,the Z-type pile frame structure is selected and used for further researches.(4)The stress and strain cloud diagrams of the Z-type pile frame under 8 typical working conditions are analyzed.The results show that under the condition that the strength and stability of pile frame conform to the specification requirements,the maximum stress of the pile frame structure is 343.5Mpa and the maximum node displacement is 326.6mm under all working conditions.(5)The method of optimizing the size of the pile frame is studied.An optimized model is built by using the variable cross-sections of the members and the thickness of the platform sheet as design variables,the maximum stress of the structure as the constraint condition,and the overall volume of the pile frame structure as the objective function.Then,the optimal Latin cube test design algorithm is used for optimizing calculation.Finally,the results show that the volume of the pile frame is reduced by 25.44%,and the weight of the pile frame is reduced by 379.08 t.The optimized pile frame becomes more reasonable in terms of the quality,volume and overall force.