Research On Key Technique Of Rotation Construction Of Cast On-site Presstress Concrete T-shaped Rigid Frame Span Railway

Bridge rotation construction is a construction method to rotate part or whole bridge structure to the finished bridge position by turning around a fixed point such as pier column or arch after it is constructed at the non-finished bridge position,which is convenient for construction.At present,the common rotation methods include vertical rotation,horizontal rotation and the combination of the two.The technology of rotary body construction can effectively improve the construction efficiency and avoid the impact on the existing traffic lines or buildings under the bridge.However,in the process of rotary body construction,the technical requirements for auxiliary facilities and control of rotary body are relatively high.Based on the construction of the 64 m+64 m T-shaped frame bridge of Zhangtang Railway,this thesis carries out the analysis and research on the rotating body construction.The main work and conclusions are as follows:(1)The construction scheme of the 64m+64m T-shaped structure rotary bridge of Zhangtang Railway is studied.The key structure design and specific implementation scheme of ball hinge,slide and turntable in the rotary body construction process are completed.And the feasible rotary body construction technology suitable for the site is proposed.(2)Design and numerical simulation analysis were carried out for ball hinge in rotating construction,revealing the mechanical characteristics of ball hinge structure.The counterweight scheme and weighing principle in the rotating body were studied systematically.Aiming at insuring the wind-resistant stability of the rotating body,the good anti-overturning performance was studied and verified.(3)The closure construction scheme of 64m+64m T-shaped frame after its body turned was studied,and the results of pre-arch degree,alignment,internal force and stress of the bridge structure under different closure schemes were compared and analyzed.The results show that different closure schemes have a certain effect on the cumulative vertical displacement of the main girder during the bridge completion stage.The optimal scheme was determined to be closure scheme 2,namely,the bracket was cast in place A1,and finally the A2 closure section was poured.(4)The linear shape and stress monitoring and control of the 64m+64m T-shaped frame bridge during its rotating process were carried out.The stress of the turntable and sand box were monitored and analyzed.The measured results show that the stress and linear error of each control section of the T-shaped frame of 64 m +64m in Zhangtang Railway are all within the allowable range,and the linear control is good.The related research results provide reference for the construction of similar T-shaped frame.