Research On Upheaval Buckling Model Of Longitudinally Connected Slab Ballastless Track Under Temperature Load

The rapid development of high-speed railways in our country has brought significant changes to people’s lives and economic growth.However,the upheaval buckling of ballastless tracks often occurs under high temperature loads,which poses a serious threat to the safe operation and service life of high-speed trains.Therefore,it is necessary to explore the upper arch stability mechanism of longitudinally connected slab ballastless track under temperature load.In this paper,the CRTS II type longitudinally connected slab ballastless track is used as the research object,and the buckling analysis models of the ballastless track under the influence of the uniform temperature,the temperature gradient and the damage of the wide and narrow joints are established respectively.The energy variational method combined with the differential equation method is the main method to establish the total potential energy equation of the thermally induced upheaval buckling of the longitudinally connected slab ballastless track.The nonlinear equilibrium path of the model built in the three states and the stress and deformation characteristics of the critical state of the upper arch are analyzed.Finally,the simplified and feasible ballastless track structure analysis model is of great significance to the mechanical analysis and safety and stability of high-speed railway ballastless track.This paper mainly carries out the following research:Firstly,based on the fact that the upper arch of the track structure is a combined structure composed of rail and track plate,the equivalent bending stiffness and equivalent compressive stiffness of the track structure are proposed according to the reduced section method.The ballastless track is regarded as an infinite beam on the rigid basis,and the longitudinal compression instability model of ballastless track under the uniform temperature load is established.The accuracy of the analytical model was verified by finite element analysis software ABAQUS.On this basis,since the track structure is prone to further buckling and arched deformation in the initial arch deformation section,the instability model of ballastless track with initial arch deformation is established.The results show that when the initial arch deformation increases from 0 to 5 mm,it has the greatest influence on the stability of track under temperature load.Secondly,under the influence of temperature load,the influence of positive and negative temperature gradient on the stability of slab track thermal expansion upper arch is investigated.Using the energy variational principle is established there without a frantic jumble track buckling under the condition of temperature gradient model,further analyzes the model of nonlinear mechanical behavior and deformation characteristics,the results show that the existence of the positive temperature gradient is good for control structure on the arch instability,positive temperature gradient in the process of increased from 0 to30℃,safe temperature increased by 16.7%,Critical axial force increased by about 10%.Finally,through field observation,it is known that the damage of wide and narrow joints will affect the stress deformation and stability of the plate body,so the buckling model with wide and narrow joint damage is established.The stress change of the model is calculated and the influence of the cross-section center of gravity shift caused by the decrease of elastic modulus of narrow joints on the stability of the upper arch is studied.It is found that the damage of narrow joints has no obvious effect on the stability of the whole structure of infinite track.But local effect on board guide arch type,therefore,on this basis,through the finite element analysis software ABAQUS to local scope narrow seam breakage caused by without a frantic jumble arch on track thermal stability has carried on the exploration,the final research shows that cannot be ignored in the local scope width of joint damage on the effects of frantic jumble track instability.In addition,in order to explore the reasons that affect the stability of the track,this paper uses MATLAB scores to analyze the influence law of the elastic modulus of the track,the density software,the initial scale deformation and other factors on the stability of the longitudinally connected slab track,and proposes effective measures for the track to the sky.The theoretical design of ballastless track has guiding significance.