Influence Of Wind And Rain Environment On Operational Safety Of Intercity Train On Bridge

With the rapid development of high-speed railways,bridges occupy a significant part of railway lines.The strong wind drives the rainfall to worsen the turbulence effect of the pulsating wind in the wind and rain environment,intensifying its impact on the structure and making the train’s dynamics problem on the bridge under the combined effect of wind and rain more prominent.Therefore,analyzing the effects of wind and rain on the safety of intercity trains running on elevated bridges has become one of the important research topics in the current rail transit aerodynamic operational environment and safety technology research.This paper uses numerical simulation to analyze the impact of wind and rain on the aerodynamic characteristics of the trains on the bridge,study the changes in the aerodynamic load of the train with environmental factors parameters and discusses the safety control method of intercity train operation on the bridge based on operational safety analysis.The main content includes the following parts:(1)The influence of different characteristic parameters of the wind and rain environment on the raindrop density distribution and movement characteristics around the train is studied.The results show that the raindrop density near the windward side surface of the train and the bridge increases during the crosswind wind speed and wind direction angle increase.Some raindrops show a parabolic-like ejection characteristic due to the driving of the airflow.With the rise of crosswind wind speed and wind direction angle,the ejection distance also shows an increasing trend.In addition,with the increase of rainfall intensity,the density of raindrops near the surface of the windward side of the train and bridge showed an apparent increasing trend,but the ejection characteristics of raindrops did not show a noticeable change.Besides,the airflow structure changes significantly on the leeward side of the train on the bridge increased with the increase of wind speed and wind direction angle,but its sensitivity to rainfall intensity is relatively weak.The movement speed and vortex characteristics of the smaller raindrop particles are similar to the airflow characteristics,while the movement speed of the larger raindrop particles shows a decreasing trend.(2)The influence of different characteristic parameters of wind and rain environments on the surface pressure coefficient and aerodynamic coefficient of the train is analyzed.The results show that in the wind and rain environment,the influence of crosswind on the aerodynamic characteristics of the train is the dominant factor,and the additional effect of rainfall is relatively weak.Compared with non-rain conditions,the surface pressure,lateral force and overturning moment coefficients of the train under rain conditions tend to increase,but it shows a bit effect on the lift coefficient.In the rain conditions,the lateral force and overturning moment coefficients of the train show an increasing trend with the crosswind wind speed,wind direction angle and rainfall intensity increasing,but the lift coefficients are relatively less sensitive to changes in rainfall intensity.While the operational speed decreases,the aerodynamics load coefficients of the train have a downward trend.(3)Based on the simulation results of aerodynamic load and the safety index of intercity train operation,the influence of different characteristic parameters of wind and rain environment on the safety of intercity train operation on the bridge is studied.Based on the principle of the least-squares method,the train’s operational safety zone with different rainfall intensities and crosswind wind speed-rainfall intensity-critical operational speed coupling relationship based on the wheel load reduction rate are obtained.The results show that compared with non-rain condition(0 mm/h),in the rainfall of 20 mm/h,40 mm/h,60 mm/h,80 mm/h and 100 mm/h,the operating safety zone of the train is reduced by 0.56%,1.56%,4.80%,5.92% and 7.03%,respectively.