| ABSTRACT:The proposal of"eight vertical and eight horizontal"passenger transport network marks that China's high-speed railway development has entered a new'stage.With the extension of high-speed railway,more lines pass through coastal windy areas and windy areas in valleys,etc.There took place many train stoppage and overturning accidents caused by strong crosswind.Wind load is one of the key factors affecting the high-speed operation of trains.Therefore,it is of great significance to study the safety of high-speed trains under wind loads.High-speed trains running on bridges in the windy area are prone to derailment or overturning under the influence of strong cross wind.At present,wind barriers are commonly used to create a safer driving environment for high-speed trains.In addition,with the increase of train speed,the influence of train-induced wind on train vibration cannot be ignored.Therefore,it is of great practical significance to study wind-proof measures of the train in wind areas and train-induced wind effects.Taking the second double line of Lanzhou-Xinjiang Railway as the engineering background,this paper adopts the method of wind tunnel test,numerical simulation and theoretical analysis method to obtain the wind barrier parameters that are conducive to the safe operation of the train,and to provide the basis for the actual project.Then the influence of train-induced wind effect to vehicle vibration characteristics can be legitimately estimated in order to evaluate the safety performance of the train and provide reasonable advice for train operation management.At the same time,the influences of wind barrier effect and train-induced wind effect on vehicle safety are considered.The main contents and results of the full text are as follows:(1)By introducing the development history of high-speed railways at home and abroad,the high-speed train overturning accidents in strong wind environments and the current research status of high-speed train aerodynamics,the significance of this topic and the basis for its project are explained.This paper expounds the research progress of wind barrier,train wind effect and wind-train-bridge theory,explains the significance of researching the dynamic response of train-bridge system caused by train-induced wind and the operation safety of train on bridge,and summarizes the measures that can be used to improve the safety of train operation in strong wind field.And then,the problems faced by wind-proof measures high-speed trains and train-induced wind effects in wind districts are put forward.Finally,the main contents and research ideas of the paper are clarified on the basis of existing research.(2)Taking the train on the second double line of Lanzhou-Xinjiang Railway and bridge as the research background,the model test for the influence of wind barrier on the vibration of train-bridge system is introduced in detail,and the adopted wind tunnel test method including force test method and pressure test method is described,as well as the processing method of different data.This paper studies the aerodynamic characteristics of train-bridge system of wind barriers under such circumstances as with or without wind barriers and with different wind barriers parameters,obtains the variation law of the three-component coefficients of train and bridge on the height and porosity of the wind barrier,and gives the optimal parameters of the wind barrier from the perspective of ensuring vehicle safety.The three-component force coeff-icient of train-bridge system under different wind barrier layout positions and driving positions is compared,and the aerodynamic interference effects between single-line vehicles and bridges or double-line vehicles and bridges are analyzed.Based on the three-component coefficients of vehicles under different wind velocities,the anti-overturning performance of the following vehicles in different line structures is analyzed.The wind tunnel test data will provide validation for subsequent numerical models.(3)The commonly used turbulence models,numerical methods of flow field calculation and train motion methods are briefly introduced.Based on the theory of computational fluid dynamics,a three-dimensional geometric model of CRH2 high-speed train-bridge system considering the high-speed movement of trains is established.The computational:fluid dynamics software Star-CCM+ is used to calculate the presence or absence of cross-wind conditions.The wind field is verified by wind tunnel test data.Star-CCM+,a computational fluid dynamics software,is used to calculate the wind field around the high-speed train running on the bridge with or without transverse wind,which is verified by the wind tunnel test data.By comparing the train-induced wind velocity when using the moving car model and static car model,the variation law of wind pressure of the monitoring point versus the lateral distance and the vertical height when the train passes by is illustrated.The wind field around the train-bridge system under the combination of train-induced wind and crosswind,and the variation law of combined wind field with wind velocity and train speed under different operating conditions are expounded.Finally,the influence of wind velocity on the surface pressure of the train is analyzed.(4)Based on the wind field analysis of the rain-bridge system,the wind load of train and bridge are calculated.The variation law of wind loads with the train speed and wind velocity is analyzed.The wind load of train--bridge system is fitted with the variation law of train speed and wind velocity to obtain the suggested formula for calculating the wind load of vehicle-bridge system.According to the contact relationship between wheel and rail,the wind load in the train-induced wind field and the combined wind field are used as the excitation input of the train-bridge system.The dynamic interaction analysis model of wind-train-bridge system considering the longitudinal freedom of the train is established,and the method of inter-system interaction for solving the system equation is introduced.A MATLAB program for solving the dynamic response of the wind-train-bridge system is developed.(5)The evaluation indexes of running safety and stability of high-speed train are briefly introduced,and the evaluation index limits of CRH2 type train are given.For the Lanzhou-Xinjiang second double-track high-speed railway line,a finite element model of the bridge is established by the finite element software ANSYS,and the mass matrix and stiffness matrix are extracted to establish the wind-train-bridge coupled vibration analysis model.Based on the self-written MATLAB program for calculation and analysis,the dynamic responses of the train and bridge in the train-induced wind field and the combined wind field are calculated,and the train operation safety is analyzed.The vehicle safety and comfort indexes using the static car model and the moving car model are compared.The effects of train speed and crosswind velocity on the vehicle's dynamic response considering the train-induced wind effect are analyzed and the maximum safe running speed of the train at the wind velocity of 20 m/s and the maximum wind velocity of the safe operation of the train at the train speed of 200 km/h are calculated.The wind barrier-train-bridge numerical model is established to synthetically analyze the effects of wind barrier and train-induced wind on the dynamic response of the train-bridge system. |
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