On use of train-track-subgrade dynamic model for investigating the train-induced cumulative deformation of subgrade and its dynamic effects

This work focuses on two research projects. The first project deals with the prediction of the traininduced cumulative deformation of the high-speed railway subgrade based on the train-tracksubgrade dynamic model, and the second project deals with the long-term performance of the train-track-subgrade interaction system subject to the permanent deformation of the subgrade. The train-track-subgrade interaction is established as the model fundament, and the empirical model of soil cumulative deformation prediction is introduced to realize the joint analysis of the train-induced cumulative deformation of the subgrade and its effect on the performance of the time-varying dynamic system. From the numerical results, the train-induced cumulative deformation of subgrade shows a fast and then slow trend, and the deformation has periodic distribution in the longitudinal direction. Although the cumulative deformation of the subgrade for the ballastless track is small compared with that of ballasted track, its effect on the vertical response of the train-track-subgrade interaction system is obvious. With the development of cumulative deformation of subgrade, the vibrations of the car body are excited in the frequency band of 0-100 Hz. Furthermore, the maximum car body vertical accelerations, the wheel-rail vertical forces, and the vertical accelerations of track and subgrade increase by about 34-48.4%, 125 %, 400 %, and 66.7 %, respectively.