Key Construction Techniques of Danjiangkou Reservoir Bridge
The Danjiangkou Reservoir Bridge is a hybrid girder cable-stayed bridge with a main span of 760 m,The stay cables are arranged in double cable planes,with pairs of back stays anchored to the ground to form a partially earth-anchored cable-stayed system.The two pylons are H-shaped concrete structures supported by octagonal pile caps and bored piles.The anchorage-type abutments are prestressed concrete box structures.The superstructure in the main span consists of steel box girders that act compositely with the UHPC panels,featuring the axial-force-free connectors and expansion joints at the midspan,while the superstructures in the side spans are composed of double edge PC π-girders,diaphragm beams and concrete panels.During the construction of pile foundations and pile caps of main piers,gravity retaining walls and single-wall steel cofferdams were employed in accordance with the structural characteristics of the bridge and the hydrological condition at the bridge site,to create a dry construction environment,and in turn to cut down the construction schedule and costs.The tower columns were cast in segments using climbing formwork,two horizontal bracings were installed between the inwardly-inclined central pylon columns to ensure the load bearing performance and geometrical shape of the pylon columns during construction.The anchorage-type abutment was cast in situ zone by zone and layer by layer,and stitched to be an integral whole,to improve the cracking resistance of the mass concrete structure.The concrete girders in the side spans were cast in situ on steel tubular scaffolds.The steel girders in the main span were prefabricated to be individual components in the factory,and assembled to take shape in the storage area,and subsequently overlaid with UHPC course to be composite girders.The composite girder segments were then shipped to the bridge site for cantilever installation with deck cranes,and finally stitched together.This prefabrication process did not challenge the transportation capacity of the upper reaches of the Hanjiang River,and a five-step-installation of the steel-UHPC composite girders has been used for the first time,greatly improving the installation quality of the girders.The joints of the axial-force-free connectors at the midspan of main span were closed one by one with high precision,effectively ensuring the functions of the bridge structure.
partially-earth-anchored cable-stayed bridgesteel-UHPC composite girdercombined utilization of gravity retaining wall and single-wall steel cofferdamaxial-force-free connector at midspanconstruction technique
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维普
