Study On The Mechanical Behavior Of The Interface In Arch Ring Concrete Cast In Layers Of Rigid Skeleton Concrete Arch Bridge

The interface formed by the external concrete casting layer by layer of the strong skeleton arch bridge may become the weak part of the arch structure,which affects the overall bearing of the arch.Therefore,it is necessary to conduct in-depth research on the stress mechanism of the concrete interface and its impact on the overall structure.This paper conducted a theoretical analysis of the stresses in the construction and bearing process of the external concrete section of the arch ring based on the construction method of the external concrete of the rigid skeleton arch bridge.Four groups of 20 specimens with two molding methods(casting in whole and casting in layers)and two sizes were designed in this paper.And a certain pre-stress was applied to the layer-casting specimens.The compressive failure test of the specimens was completed,and the deformation and ultimate bearing capacity of each specimen and the strain at the interface during the loading process were tested to analyze the bearing performance of the concrete interface.The analysis of force characteristics and influencing factors of the concrete interface was carried out using ABAQUS finite element software.The numerical simulation results were in good agreement with the test results.The effects of the influencing factors on the ultimate bearing capacity and the interface bearing characteristics of the specimens were analyzed.The main work and research results are as follows:(1)This paper analyzed the bearing model and section stress model of the outer concrete of the arch ring of the rigid skeleton arch bridge in the construction stage and bearing stage.It is known that there is a stress difference at the interface of the layer-casting outer concrete of the stiff skeleton arch bridge.And an analysis to obtain the possible failure mode of the arch ring concrete is the first ring of tensile failure,the third ring of compressive failure or interface reinforcement shear failure(2)Through the axial compression failure tests of four groups of reinforced concrete specimens,the results showed that cracks may first occur at the interface during the loading process of the layer-casting specimens,and there would be a certain slip between the concrete on both sides of the interface.The initial stress difference between the two rings would aggravate the slip degree,but the bearing capacity of it was not significantly reduced compared with that of the integral casting specimens.With the increase of the web thickness,the interface of the specimen could bear greater sliding deformation before failure.(3)The finite element analysis of the specimens was carried out by ABAQUS finite element software.The results show that stress concentration occurred at the interface of the layer-casting specimens and that the degree of the stress concentration increased with the magnitude of the initial stress difference.In addition,there was a discontinuity in the distribution of the stress nephogram at the interface.The increase in the initial stress of concrete would cause a linear decrease in the bearing capacity of each parameter specimen,while the larger the interfacial reinforcement rate,the less the specimen’s bearing capacity would decrease.The slip at the interface would increase according to the initial stress applied to the concrete.The stress concentration could be reduced by increasing the reinforcing rate at the concrete interface.