Research On Deformation Characteristics Of Ballastless Track And Vehicle Dynamic Response Under Frost Heaving Of Subgrade In Seasonally Frozen Area

With the large-scale construction of high-speed railways in seasonally frozen land areas in my country,the problem of subgrade frost heaving had become the biggest challenge affecting the normal operation of high-speed railways in these regions.The advantages of smoothness,high stability and less maintenance of ballastless track had become an important infrastructure to lead and support the operation of high-speed trains.And the high-speed railway lines with a design speed of more than 350 km per hour all use ballastless track.When the ballastless track passes through the severe cold area where the seasonally frozen soil is widely distributed,it is faced with the problem of subgrade frost heaving.The deformation of the subgrade frost heaving will cause the change of the geometric state of the ballastless track structure,which could result in interlayer displacement,separation,and upward mapping to cause the track surface deformation.Finally,they will affect the the safety and comfort of the vehicle and other indicators.At the same time,the unevenness of the ballastless track structure due to the subgrade frost heaving will increase the dynamic response of the wheels and the track structure,which will aggravate the deformation and separation of the track structure,and then affect the operation state of the entire system.In order to provide some theoretical reference for revealing the coordinated mapping mechanism between the subgrade frost heaving and the static and dynamic mechanical response of the ballastless track,and ensuring the safe operation of the high-speed railways in the seasonally frozen land areas.It is necessary to carry out research on the deformation law of ballastless track and vehicle dynamic response under the action of subgrade frost heaving.In this paper,taking the Beijing-Shenyang high-speed railway subgrade section which was in seasonally frozen areas as the research background,and obtained the measured subgrade frost heaving waveform by using the field frost heaving detection data of the Beijing-Shenyang.Based on the ABAQUS finite element software and the vehicle-track coupling dynamics theory,the influence of subgrade frost heaving waveform on ballastless track deformation,separation and vehicle dynamic response were analyzed.The main research contents of this paper are as follows:(1)Based on the least square method,the subgrade frost heaving data were curve-fitted,which could obtain two kinds of frost heaving waveforms as Gaussian and Fourier.The two subgrade frost heaving fitting waveforms were compared with the classical cosine frost heaving waveform.(2)The classical cosine frost heaving waveform was used as the most severe waveform,and the influence of different frost heaving positions,amplitudes and wavelengths on the deformation and separation of the track structure were analyzed by using classical cosine frost heaving waveform.(3)Using ABAQUS finite element software,a vehicle-track coupling dynamic model that cotains frozen subgrade was established,and the influence of different frost-heaving waveforms on the vehicle dynamic response was analyzed.(4)Using the classical cosine frost heaving waveform as the most severe waveform,the influence of different frost heaving amplitudes,wavelengths and operating speeds on the vehicle dynamic response were analyzed.