Uneven frost heave is frequently encountered in the subgrade-bridge transition zones (SBTZ) in seasonally frozen soil regions, which could lead to the deformation of track and even jeopardize running safety of vehicles. To this end, this paper conducts dynamic analysis of a vehicle-track coupled system accounting for the effect of frost heave deformation. Initially, the finite element method is used to obtain the relationship between rail irregularity and frost heave deformation. Then, a vehicle-track vertically coupled dynamics model is established, and its accuracy is validated by the measured data, published results and existing model. The time-domain dynamic responses of a vehicle-track coupled system under typical frost heave are analyzed. Afterwards, parametric analysis of frost heave deformation is conducted. Finally, the control threshold of frost heave is proposed from aspects of vehicle running safety, comfort, and track deformation. Numerical results indicate that the allowable amplitude of frost heave should be respectively restricted to 5, 20, and 25 mm for frost heave wavelengths less than 10 m, between 10 and 15 m, and greater than 15 m. The research findings offer theoretical support for the maintenance and operation of track in the SBTZ in seasonally frozen soil regions.

To maximize the use of urban land, many cities have built buildings above metro depots. However, the low-frequency vibration caused by metro operation affects the lives of surrounding residents, which seriously restricts the further development of over-track buildings. To study this problem, Firstly, the vibration of the metro depot and surrounding sensitive areas are tested on a large actual metro depot in Southwest China, and the rail, sleeper/support column, bearing column, and cover plate are mainly tested. Then, considering nonlinear factors such as mechanical properties of building materials, soil layering characteristics, and artificial viscoelastic boundary, the numerical coupled model of the train-track-depot-building is established, and the simulation data are compared with the test data to verify the accuracy of the numerical model. Finally, the impact of metro operation on the over-track buildings is evaluated. Results show that for the over-track buildings concerned in this paper, the floor vibration near the rail is the strongest, the main vibration frequency of the office building is concentrated in 10-20 Hz, and the maximum Z vibration level (VLzmax) of the office building is 52.02 dB. The main vibration frequency of the residential building is similar to that of the office building, and the superposition of floor vibration energy causes the vibration of the mid-span point to be larger than the vibration of the corner point and the side wall point. The vibration wave of lower floors mainly propagates through the bearing column, and the vibration of the parking garage is larger than other buildings. The research results can provide a reference for the vibration control and design of over-track buildings above the metro depot.