RUNNING SAFETY OF RAILWAY VEHICLE AS EARTHQUAKE OCCURS

The dynamic behavior of railway vehicles on track vibrated by an earthquake has been studied by using numerical simulations, through a simulation program adapted to a large displacement, such as a vehicle derailment or overturn. The dynamic behavior of the vehicle was analyzed as the track was vibrated in lateral and vertical directions by using the new simulation. The influence of vertical vibration added to lateral vibration on these running safety limits is investigated. It was found that the lateral vibration is dominant in the vehicle behavior near the running safety limit, although the vertical track vibration promotes jumping of wheels. In the low frequency area, the rolling motion of the car body is excited gradually, and the vehicle overturns when the amplitude of track vibration exceeds the running safety limits. In the high frequency area, the wheel flange comes into collision with the rail even in a small number of waves of vibration, and it causes jumping of wheels and derailment, and the acceleration of lateral track vibration at the running safety limit is comparatively large.