Research On Key Construction Technology Of Double-wall Steel Boxed Cofferdam For Cross-sea Bridge

The construction of a cross-sea bridge will play an important role in promoting the country's strategy of strengthening the development of the ocean.In the process of building a cross-sea bridge,the construction of the cofferdam is particularly affected by the marine environment.Therefore,it is necessary to carry out research on key construction techniques for cofferdams of sea-crossing bridges under severe sea conditions.At present,there are mainly three kinds of cofferdams,such as steel sheet piles,steel sleeves and steel hanging boxes,for building deep water foundations of bridges.Among them,double-wall steel box cofferdam is widely used in the construction of deep-water foundation of sea-crossing bridges due to its advantages of high rigidity,good water-tightness,good applicability,safety and reusability.This paper takes the RC01 bridge pier cofferdam project in the deep water area of the Pingtan Strait Rail-Road Dual-purpose Cross-sea Bridge as the research object.This paper introduces the key technologies for the construction of steel hanging box cofferdams for sea-crossing bridges under complex sea conditions,including the following preparations for cofferdam construction;factory production and transportation technology for cofferdams;overall decentralization technology for cofferdams;closed-top concrete split-casting technology;pile cap and pier construction;cofferdam rapid dismantling technology,and so on,to provide reference for similar steel steel box cofferdam construction in the future.This paper use Midas-civil and Midas-fea two software to carried out the finite element calculation of the cofferdam construction process and select wind load,water flow force,wave force,hydrostatic pressure,floating force,etc.as the external load of the cofferdam.At the same time,according to the construction process,four working conditions of the cofferdam and two working conditions of the concrete for the bottom cover were selected.Then,according to different working conditions,the load combination is carried out,and the deformation and stress of each member of the cofferdam and the concrete at the bottom of the concrete under the corresponding load combination are analyzed,and the calculation is carried out according to the specifications,which proves the safety of the overall structure and construction process of the cofferdam..In summary,this paper proposes a targeted key construction technology for the construction difficulties of steel box cofferdams under complex sea conditions,ensuring the smooth construction of the cofferdam.At the same time,this paper simulates the overall force of the cofferdam under various working conditions,and carries out the check and check to ensure the safety of the whole construction process.