Construction Technology And Application Of Full Support Cast-in-situ Box Girder Of Hefei Rail Viaduct

Under the engineering background of viaduct construction of Hefei rail transit line3 project,this paper first introduces the application of cast-in-situ support construction in rail transit viaduct,compares the specifications and materials,single pole bearing capacity,node characteristics and material cost of bowl buckle support and disc buckle support,and determines the construction scheme of cast-in-situ urban rail Transit Viaduct with disc buckle full support.Then,the construction technology,key points of construction management and quality and safety assurance measures of cast-in-situ bridge construction with full support are introduced in detail.Secondly,the stability theory of full support structure and the factors affecting the safety of support structure are briefly introduced.For engineering cases,the standard method is used to calculate the overall anti overturning of foundation and support,the finite element method is used to analyze the turnbuckle support system and square timber,and the control variable method is used to analyze the vertical and horizontal distance,step distance,diagonal brace,upper cantilever length The influence of joint stiffness and other factors on the bearing capacity of the support.Finally,select a span turnbuckle support for preloading test monitoring,load step by step,and collect stress and deformation data to verify whether the calculation model is consistent with the actual stress condition of the support under the corresponding load condition.Compared with the municipal viaduct,the track viaduct has the characteristics of high beam section and large self weight.When using the in-situ cast-in-situ method,the turnbuckle support should be preferred.The transverse distance,step distance,cross bracing arrangement and upper cantilever length of the turnbuckle support have a significant impact on its bearing capacity.The simulation of node stiffness has a significant impact on the accuracy of the calculation model.Both rigid nodes and hinged nodes can not well reflect the real node conditions of the turnbuckle support,and should be considered as semi-rigid nodes.The stress monitoring and deformation monitoring results of the buckle support system show that the change trend of the theoretical calculation value is basically consistent with the measured value,that is,the theoretical calculation is in good agreement with the actual stress,which verifies that the semi-rigid node calculation model can better reflect the actual stress of the buckle support system.