Study On Vehicle Derailment Safety Under Seismic Action

Study on the safety of high-speed railway operation has always been the focus of the researches concerned. Inspired by the studies conducted by the scholars both home and abroad, this thesis, adopting the method of simulation calculation, thereby attempts to explore the vehicle derailment safety caused by earthquake through the way of establishing vehicle system dynamics equations and models under seismic action.Since the derailment problem of high-speed vehicles caused by seismic action is a dynamic behavior with which the traditional static derailment evaluation index is not compatible, the thesis establishes a derailment safety criterion that can take effect in terms of the analysis of derailment caused by seismic action, namely, the derailment evaluation criterion for the wheel/rail lateral relative displacement.The thesis establishes a calculation model of bridge subsystem and vehicle-railway subsystem under seismic action via MIDAS and ADAMS based on the vehicle dynamics theory model. The response of vehicle system to the seismic action can be calculated after inputting the result of normalization processed seismic waves into bridge subsystem model. The simulation result of typical working condition indicates that evaluation criterion for the wheel/rail lateral relative displacement is more reliable than the traditional derailment safety evaluation criterion, so that it can be used as a reference criterion for derailment safety evaluation under extreme working condition.The analysis of the influence exerted by the vehicle speed and the peak acceleration of seismic wave on the vehicle safety respectively shows that the traditional derailment safety index aggravates as these two parameters go up; wheel/rail lateral relative displacement index increases with the case of peak acceleration of seismic wave while has no obvious relationship with the vehicle speed. It should be noticed that wheel/rail lateral relative displacement index soars when the lateral peak acceleration of seismic wave is beyond2m/s2.Finally, a relatively comprehensive safety domain is established in this thesis based on the vehicle safety evaluation index from which it can be concluded that with the influence of different vehicle speed and peak acceleration of seismic wave, lateral wheelset force and wheel unloading rate are the most likely parameters that exceed the standard, then the derailment coefficient, and wheel-rail vertical force are relatively small.