Research on Key Technologies for Design and Construction of Steel Trestle Bridges in Deep Foundation Pit with Cover and Cut-Top Down Method
The steel trestle has become an important technical means to solve the construction difficulties such as the limited working space of the deep foundation pit with cover and cut-top down method,the excavation of the foundation pit and the difficulty of transportation of construction materials because of its convenient installation and disassembly and easy recycling.In this paper,the design and construction of steel trestle for deep foundation pit in water-rich sand layer are studied.The connection form between steel pipe column top and Bailey beam is discussed,and the'slope type'connection end is developed accordingly.The connection end is welded after the steel pipe column is excavated,which ensures the installation accuracy of the steel trestle and improves the construction efficiency.In order to optimize the construction method of pile column support,the steel pipe column and the anti-pulling pile reinforcement cage are reliably connected by the pre-insertion method,and then hoisted to the design elevation on the construction work surface,which ensures the verticality of the anti-pulling pile and the steel pipe column.The Bailey beam of the steel trestle and the support between the steel pipe columns are excavated with the earthwork and installed in sections and layers,which ensures the overall safety and stability of the steel trestle.With the help of Midas finite element analysis software,the main components of the steel trestle and the stability of the steel pipe column are numerically simulated.The results show that the steel trestle is safe and reliable and can meet the construction requirements.
cover and cut-top downdeep foundation pitsteel trestle bridgeconnection endBailey beamnumerical analy-sis
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