Coupling Vibration And Running Safety Of Vehicle-Track-Transition Section System Under Seismic Excitations

At present,the total mileage of high-speed railroad operation in China has reached 42,000 km,and the mileage of operation and the scale of construction are the first in the world.With the increasing speed of high-speed trains,how to ensure the safety and passenger comfort of trains in the process of driving,the stability of high-speed railroad lines poses a serious challenge.Road and bridge transition section structure as a weak link affecting railroad operation is a key factor limiting the speed of high-speed rail.However,China has a wide distribution of seismic zones and is one of the countries in the world that suffer the most from seismic disasters,which makes the safety of train operations under the effect of earthquakes receive serious challenges.To study the safety of high-speed trains through the transition section of road and bridge under seismic effects,this paper selects the ARMA method to generate artificial seismic waves that satisfy the conditions and uses the multi-body dynamics software UM to investigate the effects of seismic effects on the dynamic response of train-track-transition section and the safety index of train travel and then constructs the GWO-BP prediction model to realize the high-speed trains under seismic effects The GWO-BP prediction model is used to predict the dynamic response of the coupled system under the transition of the bridge and the road,to establish the train quality evaluation model,and to investigate the evaluation method for the classification management of train safety under the earthquake.The main work is as follows.(1)The traditional method of simulating seismic waves is to multiply a smooth random signal corresponding to a specific response spectrum by a defined time-varying envelope curve,and the acceleration generated by this traditional method is somewhat artificially subjective.The use of real ground shaking as the target wave can make the simulated wave more consistent with the real characteristics of ground shaking,and the use of canonical correction of the target wave can make the generated simulated wave meet the design requirements.Ground shaking is a strongly non-stationary process,and the random ground shaking model based on the ARMA method proposed in this paper can consider both amplitude and frequency non-stationary,and by using the residual chi-square test of the generated simulated wave and the target wave,and by performing the power spectrum and the power spectrum test,we can simulate the wave with the random ground shaking model.The results demonstrate that the ARMA model can effectively simulate real ground shaking by comparing the generated simulated waves with the target waves through the residual chi-square test and the power spectrum and response spectrum.(2)Considering the nonlinearity of the model,various damping elements in the vehicle subsystem are characterized by force-displacement curves and damping force-velocity curves;the flexibility of key structures is fully considered,and key structures such as wheel pairs,frames,and tracks are modeled flexibly.The vehicle-track-transition section coupling system dynamics model will be established for relevant response calculations,and the correctness of the established model is verified by comparing it with the existing relevant information literature and standard documents.(3)The existing domestic evaluation indexes for high-speed trains are introduced.Because of the defects of the existing evaluation indexes,more suitable evaluation indexes for the safety of train operation under earthquake effects are selected,i.e.,derailment coefficient overrun time,wheel weight reduction rate overrun time,wheel lift,and contact point transverse displacement.The influence of the dynamic response of the vehicle,track,and under-rail structure at different speeds of the train under the change of ground vibration intensity was investigated,after which the safety of the high-speed train under the earthquake effect through the transition section of the road and bridge at different speeds was analyzed.(4)Based on the results of the previous analysis,the GWO-BP prediction model is constructed to achieve the accurate and efficient prediction of the coupled system dynamic response of high-speed trains passing through the transition section of the road and bridge under earthquake action.The DHNN model is used to construct a train running quality evaluation model based on the coupled system dynamic response,to explore the grading management evaluation method of running safety under earthquake action,and finally to give specific high-speed train running quality indexes under earthquake action.