Safety Analysis Of High-speed Train Running On Bridge Under Tornado

Tornado is a kind of natural disaster with small spatial scale,strong sudden,short duration,large wind speed and dramatic changes.Although the probability of occurrence is very low,with the development of high-speed railway in China,the probability of railway train,bridge and other nodes suffering tornado attack is greatly increased,and once these nodes are damaged,it will seriously affect the normal operation of society and economy.Therefore,we neen to study the operation safety of the train under the action of tornado.In this paper,the safety of the train running on the bridge under the action of tornado is studied as follows: firstly,the structure of tornado field and the stress characteristics of the train running in the tornado field are studied by the method of CFD numerical simulation,and then the wind time history of the train is loaded into the matlab vehicle bridge program to study and analyze the safety of the train running.The details are as follows.(1)The research status of tornado field is summarized,and the reference for numerical simulation of tornado field is determined.Through the analysis of the structure of tornado wind field obtained by numerical simulation,the law of the change of wind speed and air pressure in the wind field is obtained.(2)The influences of grid type,grid size,inlet wind speed,inlet angle,the height and radius of inflow area,outflow area on wind field structure are analyzed and compared.By using the above rules,the tornado field structure which is consistent with the wind tunnel test,field measurement and theoretical model is established.(3)The dynamic train model is established by overlapping grid method,and its accuracy is verified.And it is combined with tornado wind field to calculate the train stress.The influence of train running position,wind speed and train speed on train stress is analyzed.(4)The wind time history of the train running in the wind farm is introduced into the program to calculate the operation safety index of the train,and the operation safety of the train is analyzed.The final analysis results show that the most important factor affecting the driving safety is the train position,the second is the wind speed,and the least is the train speed.The closer the train is to the center of vortex core,the higher the operational risk coefficient is.It is not safe to drive at 0.5 times of the vortex core radius from the center,but it is within the safe value at 2 times of the vortex core radius,and derailment may occur with the increase of wind speed and train speed when driving at 1 times of the vortex core radius.Therefore,the establishment of tornado early warning mechanism can effectively improve the safety of the train.When e ncountering tornado,reducing the train speed can reduce the risk factor of train to a certain extent.