Study On The High Speed Railway’s Running Safety Of Long-span Concrete-filled Steel Tubu Arch Bridge Under Temperature Deformation

With the improvement of high-speed railway construction technology in China,high-speed railway network is leading to more complex terrain and worse climate conditions.Chenggui railway is known as "the first mountain high-speed railway in the world".The construction difficulty of this project lies in the complex and dangerous mountainous area,which is affected by the complex environment such as near fault earthquake,deep canyon,strong ultraviolet,huge temperature difference and so on.The bridge structure will produce deformation under the temperature load,which will lead to the followed deformation of the track.And the followed deformation will caused the additional irregularity of the track,then,the driving safety and comfort will be affect.Taking Xixi River Bridge in Chenggui railway as the research object,this thesis studied the deformation law of bridge-track structure under the influence of temperature,the studied the dynamic response of train-track-bridge vibration system.This thesis also analyzed the dynamic response indexes of driving on bridge from two aspects,driving comfort and safety respectively.The main research contents and conclusions are as follows(1)This thesis expounds the current situation of Chenggui railway affected by climate.Based on summarizing the research status of the influence of the additional deformation of high-speed railway bridge on the train safety and comfort,this thesis points out track additional irregularity is deeply influenced by the additional deformation of long-span concrete-filled steel tubular arch bridge caused by temperature.This leads to the significance of studying the safety and comfort of driving on the bridge under the action of temperature.(2)This thesis introduced the simulation method of vehicle-track-bridge dynamic system based on multi-body dynamics.On this basis,the refined finite element model of Xixihe bridge and rail is established by ANSYS.According to the climate characteristics of Chenggui railway,the bridge structure deformation under temperature load is simulated by ANSYS APDL.The bridge structure deformation law under different temperature loads is analyzed.The result shows that the overall temperature rise(drop)has great influence on the deformation of bridge structure;The deformation under temperature gradient of CFST arch section is more obvious than that of main girder.Adding webs can effectively increase the stiffness of arch ribs.(3)This thesis used the minimum vertical curve radius and chord measurement to evaluates the additional track irregularities caused by the deformation of the bridge structure under different temperature loads.The result shows that under the highest temperature working conditions in history,the additional unevenness of the track meets the chord measurement value measured with a 10 m chord length,but does not meet the chord measurement value measured with the minimum vertical curve radius and 30 m chord length.(4)The vehicle model is established in SIMPACK,and the coupled vibration analysis model of vehicle-track-bridge is established by CO simulation which based on the bridge and rail model established by ANSYS.The random track irregularity is simulated by using the spectral density of German low-interference track.In order to study the dynamic response of the bridge structure and the comfort(safety)of train vehicles under different temperature loads(and different speed),the additional track irregularity and random track irregularity under the action of temperature are taken as the excitation of the system.The result shows that under the historical extreme temperature conditions,the bridge structure performs well in the dynamic response when the train passes the bridge,and the maximum vibration acceleration and deflection are within the safe range.(5)According to the calculation results of train-track-bridge coupling vibration,the dynamic response index of the train is analyzed comprehensively.The evaluation of comfort mainly uses the stability index and vehicle vibration acceleration.The result shows that the vertical Sperling index is more sensitive than the horizontal sperling index,and it is also greatly affected by the overall temperature rise(drop).The vibration acceleration of the vehicle body is evaluated as excellent under different temperature loads.Safety evaluation is mainly based on derailment coefficient,wheel load reduction rate and lateral force of wheelset.The result shows that the track height irregularity caused by bridge arch under temperature load is more likely to lead to the increase of train derailment coefficient than that caused by deflection.The wheel load reduction rate is the most sensitive index,which can be used as the main evaluation index of dynamic response control limit of high-speed railway arch bridge.The effect of temperature gradient will aggravate the vibration of the train when it is running,which will increase the dynamic response index of the train.