Study On The Influence Of Uneven Frost Heave Of Subgrade On Ballastless Track Of High Speed Railway

With the rapid development of high-speed railway construction in China,the proportion of high-speed railways passing through severe cold regions is increasing,and the impact of roadbed frost heave on the operation of high-speed railways is becoming increasingly prominent.The deformation caused by subgrade frost heave will not only damage the overall smoothness of the rail,threaten the safety and comfort of driving,but also cause damage to the ballastless track structure and shorten the normal service life of the track structure.Therefore,it is of great significance to study the smoothness of ballastless track and the response of vehicle track dynamic system under uneven frost heaving deformation of subgrade.On the basis of summarizing the research on the influence of high-speed railway ballastless track types and uneven frost heaving on ballastless track at home and abroad,this paper studies the law of subgrade frost heaving deformation on track structure changes and the influence of vehicle rail system dynamic response,and analyzes the influence of different frost heaving deformation degrees on rail geometric deformation,interlayer contact and driving dynamic performance,A preliminary discussion was conducted on the management limits of roadbed frost heave deformation under different driving speeds.The main research content is as follows:Firstly,the CRTS Ⅲ slab ballastless track subgrade frost heave transfer model was established by using the finite element software,and the peak value of the subgrade frost heave at different positions of ballastless track was analyzed.With the maximum value of the gap as the unfavorable position,the deformation,stress and interlayer contact of ballastless track structure under subgrade frost heave were analyzed,and the influence of different wavelength and amplitude parameters on the static characteristics of ballastless track was compared,And change the parameters of self compacting concrete to study the characteristics of ballastless track.The results show that the deformation of ballastless track structure is similar to the frost heaving curve when uneven frost heaving occurs on the subgrade;Ballastless track will be comprehensively affected by the subgrade frost heaving wavelength and amplitude.The subgrade frost heaving wavelength is relatively short,and the rail geometric wavelength is larger than the subgrade frost heaving wavelength.With the increase of the frost heaving wavelength,the deformation of the two tends to be consistent,and the interlayer gap decreases and gradually disappears.Secondly,based on the theory of vehicle track spatial coupling dynamics,a vehicle track dynamics model was established to analyze the impact of roadbed frost heave deformation on the dynamic performance of the vehicle track system.The results show that the frost heaving deformation of subgrade will aggravate the interaction between wheel and rail,affect the safety and comfort of trains,and also cause the strengthening of the role of the ballastless track substructure.At the beginning of frost heaving,the vibration of the track substructure is most affected.Finally,the impact of roadbed frost heave on the dynamic indicators of the vehicle rail system at different speeds was analyzed,and the control limits for roadbed frost heave on high-speed railways were preliminarily explored.The results show that the subgrade frost heave will increase the interaction between the vehicle and the rail system,causing a large dynamic displacement of the ballastless track rail,which will seriously exceed the limit of the dynamic displacement of the rail.It is necessary to focus on the dynamic displacement of the rail within 20 m of the frost heave wavelength.Therefore,taking into account the safety and comfort of trains,this article preliminarily explores the management limits for roadbed frost heave in short waves at speeds of 200～350km/h.