Research On Key Technologies Of Construction Control Of High- Speed Small Curve Long-span Overpass Bridge

Bridge rotation has become a common construction method for crossing existing lines and rivers at present because of its remarkable social and economic benefits such as short construction period,low cost and little impact on existing lines.The construction of bridges in high-speed railways must meet the strict requirements for the smoothness of lines.In the construction of bridges in high-speed railways,the elevation must be strictly controlled.In the process of bridge swing construction,not only the elevation and position of the beam should be monitored,but also the stress at the spherical hinge should be monitored in detail.The stress condition of small radius curved girder is special,which leads to the complex change of stress and deflection in the construction process.The larger the span of the bridge,the more obvious the present situation is.Therefore,in order to ensure that the internal force and elevation of the bridge in each construction stage meet the requirements,the stress and deflection of the bridge in each construction stage must be controlled to ensure that the overall alignment and stress state of the bridge structure after closure meet the design requirements.Firstly,this paper introduces the development of the theory of swivel bridge and curve bridge.Then,combined with the construction of the new Left-Line super-large bridge of Lianyungang-Zhenjiang Railway Huaiyang Liaison Line,the force analysis of curve bridge,the analysis of the alignment and stress monitoring in the cantilever casting process and the simulation analysis of the swivel accelerated rotation process are carried out.The main research work is as follows:1.Summarized the development of construction monitoring theory,summarized the theoretical study of curved girder,construction technology development and the process of swivel bridge,and analyzed the key factors of Swivel Construction Control of small radius curved continuous girder.2.The finite element model is established to analyze the stress and displacement of small radius curved continuous beams in the construction process and the maximum cantilever stage.The stress distribution and displacement variation characteristics of small radius curved continuous beams are summarized to provide theoretical support for stress monitoring.3.The key points of stress monitoring and alignment control point arrangement in cantilever construction monitoring of bridges are expounded,and the suggestions of stress monitoring at rotating spherical joints are put forward,and the layout mode of strain gauges is given.In addition,the stress at the spherical hinge during rotation was monitored.4.The maximum theoretical acceleration of the rotating body is obtained by theoretical calculation,and the finite element model is established by ABAQUS.The stress distribution of the beam under the maximum theoretical acceleration is analyzed,which provides data support for the control of acceleration in the rotating body.5.Unbalanced weighing experiments are carried out on curved beams with small radius,and the top force which makes the rotating structure fretting is calculated by drawing load-displacement curves.Based on these results,the friction coefficient and friction moment of the rotating structure are calculated and weighted.Through the analysis of spherical hinge stress in the process of rotation,the accuracy of unbalanced weighing test data of small radius curved beam is illustrated.The balance effect of small radius curved beam rotation is good through unbalanced weighing test.