Study On The Influence Of Subgrade Frost Heave To Structure Of Double-block Ballastless Track On High-speed Railway

With the rapid development of China’s high-speed railway,the frost heave of railway subgrade has become the first engineering problem to be solved in the construction and operation of high-speed railway in seasonal frozen soil area.The frost heave of subgrade will cause arch deformation of track structure,which will seriously affect the track smoothness,which poses a serious threat to the safety and stability of driving,and will also increase the maintenance workload of railway workers,resulting in waste of manpower,material and financial resources.Lanzhou-Xiinjiang high-speed railway passes through many geological areas in China at the same time,among which the line near Qilian Mountains is prone to frost heave deformation;the track structure adopts large unit double-block ballastless track structure,which is more sensitive to the influence of roadbed frost heave deformation.Based on the measured data of frost heave of roadbed of Lanxin High-speed Railway and related literature,this paper studies the influence of roadbed frost heave on the structure and dynamic performance of double-block ballastless track of high-speed railway,and preliminarily discusses the management limit of roadbed frost heave deformation.The main work is as follows:Firstly,based on the finite element method and vehicle-track coupling dynamics theory,a transfer model of frost heave deformation of double-block ballastless track-roadbed of high-speed railway is established.It is found that the frost heave of roadbed will cause similar deformation of track structure,and also will cause the separation between different layers of track structure.The larger the frost heave amplitude of roadbed,the more obvious the separation phenomenon and the longer the frost heave wavelength of roadbed.The phenomenon gradually weakens,and the track structure will show a certain degree of follow-up.Secondly,the influence of Subgrade Frost Heaving on the deformation and vibration characteristics of track structure and the dynamic performance of high-speed driving is studied.UM train dynamic simulation model is established.The track deformation caused by Subgrade Frost heave is taken as the input of irregularity excitation,and the influence of Subgrade Frost Heave on the dynamic characteristics of driving is studied.The finite element analysis model of rail-track-subgrade is established,and the train moving load is applied to study the influence of Subgrade Frost Heaving on the vibration characteristics of track structure.The calculation shows that the dynamic response indexes of track structure are greatly affected by the void of track structure,and will increase with the increase of frost heave amplitude of subgrade and decrease with the increase of frost heave wavelength of subgrade.Finally,the influence of Subgrade Frost Heaving on each response index is quantitatively analyzed by different frost heaving wavelength,different frost heaving amplitude and different driving speed.Based on the driving safety,stability and vibration characteristics of track structure,the recommended value of subgrade frost heaving deformation management limit is preliminarily discussed.The research shows that the frost heave of subgrade will affect the vibration characteristics of track structure,aggravate the dynamic interaction between wheel and rail,and affect the driving safety and stability.Shorter frost heave wavelengths can easily lead to the void of track structure,resulting in excessive dynamic displacement of track structure.Focus is placed on the frost heave deformation of subgrade with shorter frost heave wavelengths.Considering the driving safety,stability and dynamic displacement of track structure,the recommended value of frost heave management limit for roadbed with driving speed of 200 km/h to 300 km/h is put forward.