Research On Construction Control Of Beam-arch Association Bridges By Walking-type Incremental Launching Method

The beam-arch association bridge combines the advantages of beam and arch,overcomes the disadvantages of both,and is a kind of bridge structure with reasonable stress,beautiful shape and good prospects for the application.The incremental launching method has the characteristics of less influence on the environment under the bridge,less land occupation and quick construction,which has developed rapidly in recent years,but the cases of applying it to beam-arch association bridge are relatively few,and has certain construction control difficulty.In this paper,based on the research background of the beam-arch association bridge adopting walking-type incremental launching method,and relying on the actual project of the Nu River Lianxin bridge,through the means of simulation analysis and actual monitoring,the main force characteristics,force control of the main components and deviation control during construction are studied.It mainly includes the following contents:(1)the principle of the walking-type incremental launching is expounded at different levels,and the incremental launching system and technology are introduced from the composition,working mechanism,function and design of temporary facilities,etc.This paper introduces the core work of incremental launching construction control from the aspects of the whole and local simulation technology,monitoring emphasis and means,and finally sums up the common problems and strategies in the construction,reflecting the important difficulties and necessity of the construction control research.(2)the construction model of the bridge is built by Midas Civil,and the unfavorable working conditions of the main components are obtained.The influence factors and laws of the important control variables are obtained by studying the relationship between the boundary change and the supporting reaction force,the force of the arch beam bracing rod and the force of the main beam,it provides a theoretical basis for qualitative analysis and construction control of important structures in the process of incremental launching.(3)Aiming at the incremental launching of beam-arch composite bridge,the strategy of stress measuring point arrangement is summarized,and the stress monitoring scheme of the project is proposed.In combination with the actual working condition,the measured value and the theoretical value are analyzed from the stress curve and stress amplitude.The relevant conclusions verify the accuracy of the model and ensure the construction safety,and confirm and supplement the rule of the important control quantity of the structural force.In view of the difference between theoretical and measured values,based on the construction practice,a more comprehensive analysis and summary of the relevant factors.(4)this paper introduces the construction deviation and its disadvantageous influence of the walking-type incremental launching.Based on the first wheel incremental launching process of Nu River ferry bridge,the monitoring scheme of construction deviation is designed,and the related physical quantities are put forward from the measured data.From the point of view of force,this paper discusses the cause of the deviation of push-off according to the situation,lists real cases for concrete analysis,and finally puts forward practical control measures.