Analytical Study on the Safety of High Speed Railway Vehicle on Excited Tracks

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 case of disasters caused by earthquakes. Recent reports imply that railway vehicles could derail solely by the ground motions of earthquakes without fatal damages of vehicles or tracks. Based on the reports and facts, we believe that we should further study the derailment mechanism of a high speed railway vehicle excited by great seismic motions, to pursue to minimize the risk of railway system safety against great earthquakes. At the start of the study, we developed our original vehicle dynamics simulation and then employed it for numerical analyses. At the present stage, through the analyses, we obtained the following major outcomes. (1) Most of derailments are brought as the result of the rocking motion of a vehicle by track excitations underneath. Interestingly, the derailing motions are observed similarly regardless of vehicle speed. (2) By contrast, the excitation amplitudes for derailment are influenced by vehicle speed particularly in lower input frequencies. This can be explained by the sensitivity of the relative wheel/rail slide due to creepage. (3) The excitation amplitudes for 30 mm of wheel lift are relatively independent of vehicle speed. (4) The wheel/rail slide strongly depends on the friction coefficient if a vehicle stationed, being relatively independent of the friction coefficient at higher speeds.