Research On Gerenation And Deterioration Mechanism Of Separation Of CRTS ? Slab Track Based On Viscoelastic Theory

As the main track structure form of high-speed railway,slab track meets the demand of high-speed railway with better continuity,smoothness and stability.Because track structure is subjected to temperature load and train load,when the stress caused by the load exceeds the interlayer bond strength,there will be interlayer separation.These separations can not only destroy the integrity of the track structure,but also cause the mechanical properties change,seriously affecting train operation.In order to delay or even avoid the occurrence of the separation,improve the safety of the structure and reduce the cost of maintenance,researchers have done a lot of research on the generation and deterioration mechanism of separation by FEM.However,the CA mortar layer has been simplified as elastic material in the existing simulation model and its viscoelasticity has been ignored.These over-idealized models are impossible to accurately reflect the actual situation of track structure,and the simulation results may be greatly deviant from the actual situation.This paper takes Burgers model as the constitutive model of viscoelastic theory,and introduces viscoelastic parameters.The main research object is CRTS II slab track,taking advantage of bonding model,cohesive zone model and contact model with separation.Based on the above model,this paper will study mechanical properties of track structure,interlayer separation generation and growth law and influence of the position and size of the separation on the mechanical properties of the track structure under temperature gradient and train load.The reasonablity and accuracy of the introduction of viscoelastic parameters are verified by the compound block tests and finite element analysis.The result shows that:the stress,displacement and height of the separation are higher,and the cracking temperature gradient and the penetration temperature gradient are smaller based on viscoelastic theory.The position and size of separations will affect the mechanical properties of the track structure.Under the coupling of temperature gradient and train load,the stress and displacement of the track structure are greater than the separate load alone,and the cracking temperature gradient and the penetration temperature gradient decrease.In particular,the separation will become perforation when the temperature gradient is large.The height of the separation repeatedly changes under the dynamic load of train,causing flapping to substructure.It is very easy to produce cracks and other problems,which affect the durability of structure.Therefore,when analyzing the mechanical properties of track structure and the generation and deterioration law of separation,it is possible to get safer calculation results to establish models with viscoelastic theory.