Assessing the effects of subgrade frost heave on vehicle dynamic behaviors on high-speed railway

The subgrade frost heave of high-speed railways has an inevitable effect on track irregularity in severely cold regions. To research the influence of the subgrade frost heave on the dynamic behavior of high-speed railway vehicles, a multi-body dynamics rigid vehicle model and the finite element method flexible track model are coupled using the rigid-flexible coupling dynamics method. The typical frost heave deformation is used as the excitation source, and the effects on dynamic behaviors of the wheel/rail system are analyzed considering various conditions of frost heave, slab track stochastic irregularity, and train speed. The calculation results show that subgrade frost heave has a significant influence on the safety index (the vertical wheel/rail force and the wheel load reduction rate) and the stability index (the vertical acceleration of the carbody and the vertical sperling index) of the vehicle. Both the safety index and the stability index increases linearly as the frost heave amplitude grows and decreases nonlinearly as the frost heave wavelength grows. The safety index is more sensitive to the wavelength, while the stability index is more sensitive to the amplitude. The frost heave region that has an amplitude greater than 15 mm and a wavelength of less than 15 m should be focused on more. Compared to the frost heave deformation, the growth of slab track stochastic irregularity has greater influence on the vertical wheel/rail force. The influence on the other vertical indexes are relatively insignificant. Higher train speeds lead to a worse safety and stability index, and slowing down the speed is an effective way to ensure the safe and stable operation of the high-speed vehicle.