Study On The Influence Of Subgrade Uneven Settlement On The Mechanical Characteristics Of Railway Track

As the foundation of high-speed railways,the roadbed is also a weak link in railway line engineering.In recent years,with the rapid development of high-speed railways,increasing the running speed has become the mainstream development direction of railway transportation.The excessive uneven settlement has become one of the diseases of high-speed railways,which not only restricts the increase of train running speed,but also seriously affects the safety and stability of trains,and at the same time,it will aggravate the destruction of the track structure.Therefore,it is of great significance to study the influence of uneven roadbed settlement on the mechanical properties of railway vehicles and track structures.Firstly,based on the relevant knowledge of track calculation theory and subgrade uneven settlement control standards,the two-piece ballastless track and the coupled static model of ballasted track and ballastless track transition section on the roadbed were established by finite element analysis software ABAQUS.Using the double-block ballastless track model,the deformation and stress characteristics of the track structure under the cosine-type subsidence of the roadbed are analyzed,and the static settlement characteristics of the double-block ballastless track with different settlement amplitudes and wavelengths and track parameter changes are compared.Law of influence.Using the model of ballasted track and ballastless track transition section,the deformation and stress of the track structure under the action of subgrade corner settlement are analyzed,and the different settlement amplitude and the length of the corner area are compared to the static of ballasted track and ballastless track transition section.Law of influence of mechanical properties.The results show that the track structure will produce a follow-up deformation similar to the settlement curve when the roadbed is unevenly settled.However,under different settlement conditions and track parameters,the deformation and stress of the railway track structure are greatly affected.Secondly,combining vehicle-track coupled dynamics system theory and vehicle-track-subgrade system dynamics related knowledge,vehicle-dual block ballastless track-subgrade coupling dynamic model and vehicle-ballasted track and ballastless track are established respectively The transition-subgrade coupling dynamics model investigates the effect of uneven subgrade settlement on the dynamic response of the train-track system.The influence of different settlement conditions on the vibration characteristics of railway track is analyzed and compared.The results show that: when the cosine-type settlement of double-block ballastless track subgrade occurs,the vibration effect at the maximum settlement position is the largest;when the angle-type settlement occurs at the transition between the ballast track and the ballastless track,the vibration effect at the starting point of settlement maximum.At the same time,the uneven subgrade settlement amplitude,settlementwavelength and driving speed all have significant effects on the dynamic response of the railway track.Finally,according to the evaluation indicators,the characteristics of the influence of uneven roadbed settlement on driving safety and stability are revealed.Under the conditions of different settlement conditions,according to the changes of wheel-rail force,derailment coefficient,wheel load reduction rate and vehicle body vibration acceleration,combined with the study of the static and dynamic characteristics of railway tracks,a double-block ballastless track and Subgrade settlement control limits for the transition between ballasted and ballastless tracks.