Study On The Interface Contact Law Of Longitudinal Connecting Bridge System Under The Settlement Of Continuous Beam Side Pier

High-speed railway construction has been an important part of China’s modernization in recent years and is one of the important achievements in the economic,social,and technological development since the reform and opening-up policy.Against the background of economic globalization and rapid urbanization,high-speed railway construction can not only improve transportation efficiency but also promote regional economic development,improve people’s travel conditions,and enhance their quality of life.Within high-speed railway lines,simply supported beam bridges account for a large proportion.However,when the line needs to cross key areas such as existing railways,highways,and residential buildings,it is necessary to build continuous beam bridges with strong crossing capability.The area connected between the continuous and simply supported beam bridges is a special location where the hyperstatic and statically determinate structures transition.After the abutment settlement,the mechanical behavior of the two structural systems in this position is significantly different,which can have a certain impact on the train’s performance.Therefore,this article analyzes the static and dynamic contact characteristics of the longitudinal connection bridge system interface under abutment settlement,providing a reference for the design of the longitudinal connection bridge system.The main research content of this article is as follows:(1)Based on ABAQUS,a nonlinear spatial model of the longitudinal connection bridge system is established,which considers the initial boundary displacement and the discontinuous effect of interlayer contact.The parameter settings and principles of the nonlinear spatial model are described in detail,and the results are compared and verified with the existing theoretical model calculation results.Based on the nonlinear spatial model,the train is introduced into the model through the wheel-rail normal HERTZ contact and tangential sliding friction contact,and a nonlinear spatial model of the train longitudinal connection bridge system is established.The method of ABAQUS-MATLAB combined simulation is used to achieve rail unevenness,and the vertical force value of wheel-rail under no pier settlement is compared and verified with the calculation results of the existing multi-body dynamics model.(2)Based on the nonlinear spatial model of longitudinal continuous bridge system considering the effects of pier settlement and interlayer contact discontinuity,this study analyzes the typical deformation modes of longitudinal continuous bridge system under pier settlement,determines the process and development law of interlayer connection failure in longitudinal continuous bridge system,summarizes the typical positions of interlayer connection failure and the values of clearance length and height between bridge and rail,proposes the expression of clearance height relationship,and explores the influence of interlayer interaction force,stress development law and rail deformation under different pier settlement values.Under pier settlement,the continuous bridge system undergoes three types of deformation modes: follower deformation,self-weight deformation,and suspension separation.The failure of interlayer connection goes through three stages,and the interlayer interaction force and rail deformation are concentrated in the settlement area,with stress exhibiting uneven distribution.When the pier settlement value is 30 mm,the tensile strength of the base plate exceeds the specification limit.(3)Based on a nonlinear spatial model of the train longitudinal alignment bridge system considering the effects of the settlement of bridge piers and the discontinuity of interlayer contact,this text analyzes the distribution characteristics of the stress of the track structure under the vehicle load caused by the settlement of bridge piers.It clarifies the trends of the clearance length,clearance height,and vertical displacement of the track structure at the bridge-track contact interface before,during,and after the vehicle passes,as well as the dynamic distribution laws of the bridge-track contact force and clip force.Based on this,an evaluation value of the vehicle’s dynamic performance is obtained.The stress of the track structure does not change significantly before and after the vehicle passes,but when the pier settlement reaches 20 mm,the stress of the base plate exceeds the specification limit as the vehicle enters the settlement area.The dynamic contact force between the bridge and track is more affected by the static effect of the pier settlement than the dynamic effect of the vehicle load,while the clip force shows the opposite trend.When the pier settlement reaches 40 mm,the wheel load reduction rate exceeds the specification limit.