Response of Track Vibration under the Coupling Effect of Wheel Flat Scar and Track Irregularities

In order to accurately express the train load, the quasi-static train moving load expression is derived considering the wheel flat scars and track irregularities. By performing Fourier transform on time and wavenumber transform along the track direction, the three-dimensional space problem can be simplified into a two-dimensional plane problem. Combining boundary conditions and Galerkin method, a 2.5-dimensional train track quasi saturated foundation finite element dynamic analysis model equation is obtained. The track structure is regarded as an Euler beam on an unsaturated foundation, and the modified train load is obtained in the time space domain through fast Fourier inverse transform. The influence of train speed, load conditions, and foundation saturation on track vibration is explored. Calculations show that when the wheel flat scars and track irregularities are coupled, the amplitude of track vibration is more than twice that of the ideal moving load, and much greater than the individual effect of the wheel flat scars or track irregularities. When the train speed is 120 km/h, the amplitude of track vibration caused by wheel flat scars is greater than that of track irregularities, while the opposite is true when the train speed approaches the shear wave velocity. The saturation of the foundation decreases from 100 to 95%, and the vertical displacement of the track increases significantly, while the vertical acceleration increases slightly, and the acceleration power spectrum will slightly decrease. During low and high-speed operation, the acceleration power spectrum experiences near missing phenomena at 20 and 50 Hz, respectively. The peak of acceleration power spectrum appears at 13.5 Hz during low-speed operation (for all four types of loads), and at 40 Hz and 30 Hz during high-speed operation.