Train-induced environmental vibration analysis of large-chassis and multi-tower metro depots

To investigate the vibration response patterns at large-chassis and multiple-tower metro depots under the influence of train-induced vibration load, a refined numerical analysis model and efficient analysis techniques were employed. Based on the substructure method, the generation and propagation of vibrations were decomposed into two substructures. The analytical expression for wheel-rail forces in a half-train model was derived based on the simplified calculation method of half-bogie train load. A refined finite element model for the track-soil-building system was established. By applying the wheel-rail force load to the finite element model, the dynamic response of the system was solved, and the high-efficiency analysis was achieved through the multi-graphics processing unit (GPU)-heterogeneous parallel explicit algorithm. By taking a specific metro depot as the research subject, the accuracy of numerical simulation was validated with the on-site measurement data. The efficiency of multi-GPU heterogeneous parallel explicit algorithm was confirmed by comparing the solution times of different algorithms applied to the same model. On this basis, the propagation patterns of vibrations within the operation depot and over-track buildings were highlighted. Analysis results indicate that within the operation depot, the vibrations generated by train operation are predominantly characterized by medium to low frequencies. The dominant frequency band of the source strength concentrates on 10-50 Hz, with a peak frequency near 30 Hz. The vibration level at the column base of the operation depot decreases linearly with the increase in the horizontal distance from the vibration source. However, due to the slight constraint exerted by the structure on perimeter columns compared with others, the vibration response amplifies on the outmost perimeter columns of the operation depot. Given that trains pass directly between the supporting columns at the lowest structural level, the vibration propagation path is short with weak attenuation, leading to a richer vibration spectrum in over-track buildings, where the floor vibration advantageously concentrates on the frequency band of 20.0-31.5 Hz. A coherent vibration pattern of the over-track building floor is observed at low frequencies, with the maximum Z-vibration level at mid-span near the top floor. The floor vibration intensity is influenced by both its natural frequency and the spectral characteristics of source strength. Resonance is more likely to occur when the natural frequency of floor falls within the predominant vibration frequency band of source strength.