| Based on the thick-walled cylinder foundation,this paper puts forward the idea of prefabricating the foundation of offshore wind power on the water.Using the methods of numerical simulation,model test and prototype observation,the structure and floating stability on offshore prefabricated platform are studied.The main research contents and conclusions are as follows:(1)In view of the structural characteristics of the large weight,high center of gravity,and wide size of the bucket foundation,it is determined that the lower tube skirt of the foundation adopts floating prefabrication,and the upper concrete bottom plate and transition section adopt the sublevel prefabricated construction method.Combined with the force characteristics of the platform,the steel shell concrete structure is used as the main force component.Through the design of the platform slab-beam-column structure,the platform can reach the capacity of bearing the upper bucket foundation.The stability of the platform is enhanced by setting the four-corner stabilizing floating box,so that the platform maintains a relatively stable posture during the sinking and floating operations.(2)Considering the influence of the free liquid surface of the platform’s ballast tanks on the overall stability,the platform’s ballast tanks are divided so that the total ballast water meets the conditions for the platform to continue to sit on the bottom after the upper cylindrical foundation floats.In order to meet the requirements of the platform for the ballast water system during the sinking and floating operations,a set of mixed ballast discharge system with ballast pump as the main water injection,gravity flow as the auxiliary,and compressed air discharge was developed.(3)During the prefabrication of the cylindrical foundation,its own weight is relatively large.As the site foundation treatment is simple rip-off and leveling,there are local unevennesses.Through numerical simulation analysis,it is recommended that the gravity of the upper cylindrical foundation on the lower platform during prefabrication be controlled within 4000 t.Because the precast platform has a depth of 1.2m and a small section modulus,the overall bending rigidity is not strong,and relatively large vertical deformation will occur under the concentrated load of the upper tube skirt.In order to solve this problem,inertia release is adopted.The principle simulates various working conditions during the floating prefabrication process of the platform.By ballasting the side tanks and the stabilized pontoons,the overall deformation of the platform is effectively reduced.(4)The hydrodynamic software Moses was used to check the overall stability,floating stability of the platform,and through model tests and prototype tests,it proved the rationality and feasibility of the prefabricated platform structure and ballast system design,and finally formed a manual for the sinking and floating of the precast platform. |
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