Research On Threshold Value Of Seismic Urgent Handling System Of High-speed Railway

Earthquake can bring great threat to the safety of high-speed train. If theearthquake warning system is established in railway systems, the seismicemergency handling ability can guard the safety and stability of high-speed trainsmore effectively. Earthquake alarm threshold is an important component ofearthquake early warning system which is determined reasonably or not is closelyrelated to the effectiveness of the system. Some researches on the seismicemergency handling threshold value of the high-speed railway system have beendone in the thesis as follows：(1)The current situation and research significance as well as the problems ofseismic urgent handling threshold of the high-speed railway system that exit sofar are systematically illustrated.(2)Based on the design parameters of high-speed train, the vehicle-trackcoupling model is established, and then the vehicle-track coupling vibrationequations are set up. Focuses on the analysis of track irregularity, the trackirregularity spectrum suitable for calculation is selected, which is generated bynumerical simulation on the power spectrum density function with trigonometricseries method. Six typical seismic records which are used as the externalexcitations of the train are selected.(3)The normal forces are calculated based on Hertz nonlinear contact theoryand the creep forces are calculated based on Kalker linear creep theory. Theequations of motion are solved by Newmark-β numerical integration. Acalculation program is written using MATLAB software, and the reliability of theprogram is verified by calculation example.(4)Three evaluating parameters of security including derailment coefficient,wheel load rate and lateral wheel-rail force are selected. Based on the selectedcalculation parameters, the dynamic response of the running train underearthquakes is analyzed, and the response results of train under different vehiclespeed and different seismic strength are calculated. By comparative analyzingand processing the calculated results with the three security parameters, theinfluence of the vehicle speed and seismic strength on the train safety issummarized, and the earthquake alarm thresholds under different vehicle speed are presented as follows: considering the comfort of running train and extra risk,the value of EAT can be set as61Gal when the vehicle speed is below200km/h;When the vehicle speed exceeds200km/h, the threshold value has a lineardecrease as the increase of train speed. When the vehicle speed reaches350km/h,the value of EAT can be set as46Gal.