Simulation of Train Dynamic Load and Investigation of its Effects on Ground Surface Vibration

The purpose of this paper is to simulate train movement and investigate its effect on ground vibration. For this purpose, effective factors on dynamic load magnitude and frequency have been studied and variation of wagon force in a longitudinal model is considered. Fourier Amplitude Spectrum was then computed by means of Fast Fourier Transformation (FFT) of the dynamic train load and the frequency range of train load was determined. In the next step, low energy frequencies were filtered and the dynamic load as a point load was implied on a numerical model of Tehran Subway Tunnel Line 4, as a case study. History of velocity and acceleration in the model surface was then recorded and used as a descriptor to appraise the vibration level. Based on the FTA standard, the induced vibration level leads to residential annoyance in the ground surface. This occurs when two trains with 80 Km/s speed and 100 ton wagon weight pass from the tunnel cross section.