Abstract
A railway is organized by a variety of individual technologies, and functions safely and properly as a system, therefore it is necessary for the system safety to study each potential unsafe case caused due to large earthquakes. Recent reports indicate that railway vehicles could be derailed by earthquake ground motions with no fatal damages of vehicles or tracks. Thus, we should further study the derailment mechanism to pursue to minimize the risk of railway system safety against large earthquakes. Particularly, for more comprehensive understanding on the derailment mechanism of high speed railway vehicle, the derailment process of the case should be directly verified. Therefore, in this study, we arrange an experimental setup with 1/10 scale vehicle and roller rig providing both conditions of high speed wheel/rail rolling contact and large amplitude excitations. Through the experiment, we obtained the outcomes. (1) Two types of vehicle derailment motions are observed; one is rocking derailment and the other is sliding derailment. Derailment motions are similar regardless of vehicle speed. (2) By contrast, the excitation amplitudes for derailment decrease according to the increase of vehicle speed particularly by low frequency excitations. (3) The excitation amplitudes for wheel lift of flange height are relatively independent of vehicle speed. (4) Based on the similarity of fundamental vehicle dynamics between the 1/10 and full scale vehicles, those observed mechanisms in the scaled test should be applicable to that of full scale vehicle.
