Research On Key Technology Of Construction Control Of High-pier And Long-span Railway Rigid Frame-Continuous Composite Girder Bridge

Many researches on the construction control of double-width separated rigid framecontinuous composite girder bridges has presented in China,while the construction control of the new type double-width connected rigid frame-continuous composite girder bridges is insufficient.This thesis is based on the engineering background of the Nanxi River Four Lines Extra-Bridge of Yunnan Yumo Railway,which is a double-width connected high-pier long-span rigid frame-continuous composite girder bridges.Its structure is different from ordinary rigid frame-continuous composite girder bridges.The main girder of the double-width bridge is consolidated the middle high piers with 0# blocks,and the main pier structure adopts herringbone sloped double-column rectangular rigid frame pier.In order to ensure the safety of the main bridge structure and the smooth realization of the design linear shape of the new structure,this thesis conducts research on the key technical issues such as closing sequence,jacking construction and asynchronous construction in the construction control process.The main research contents are as follows:（1）The large-scale bridge calculation softwares Midas Civil and Bridge Doctor V4.3 are used to establish a full bridge finite element model.Aiming at the closing problem of rigid frame-continuous composite girder bridges,the influence of different closing sequences on the internal force and line shape of the full bridge structure is analyzed;and the closure pushing conditions is analyzed and the pushing force is calculated;after the right-width mid-span closure pushing,the erecting elevation of the main girder on the left-width bridge is modified.（2）The torsion effect of the pier structure during the construction of the single-width closure pushing is analyzed,combined with the calculation formula of the torsion components bearing capacity and the torsion analysis calculation theory of the rectangular section components;and effective simulation calculations on the mechanical behavior of the rectangular rigid frame pier in the process of closure pushing is carried out,and the torsion resistance mechanism of rectangular rigid frame piers under complex stress conditions is presented.（3）Aimed at the safety problem of pier structure in the construction stage of single pier,the influences of asynchronous construction of tie girder between piers on pier structure force,pier top displacement and pier section stress is analyzed,and its influence law is summarized.The temporary support position between the piers is analyzed,calculate the jacking force and check the stability of the temporary support.（4）The linear shape,stress,etc.of Nanxi River Four Lines Extra-Large Bridge were monitored,and the measured data and theoretical data were compared and analyzed to modify the finite element analysis model in real time.The measured data of the whole construction process show that the construction control of the bridge has achieved the expected goal and the control method has achieved good application effect.