Study On Environmental Vibration Induced By Elevated Unballast Tack

With the rapid development of our country’s economy, accelerating the pace of life,whichenhances passenger and freight requirement, that passenger demand rapid comfortable andfreight requirements overloaded. Over loading and high speed transport will inevitably resultin reducing passengers riding comfort, causing the environment along the railway noise andvibration. Because most of China high－speed rail is the elevated rail, so this article is basedon the problem to study about environmental vibration caused by elevated no－ballasted tack.According to the characters of coupledhigh sepped train－no－ballasted track－bridge－subgrade models, putting forward for the analysis of the problems of new vehicles unit andrail unit, using the finite element method and Lagrange equation, Setting up coupled highsepped train－no－ballasted track－bridge vertical dynamic analysis models and coupledbridge－soil dynamic analysis models, theirs damping matrix, rigidity matrix and qualitymatrix are given. The coupled high speed train－no－ballasted track－bridge verticalsystems only discretes into vehicle unit and rail unit, and no－ballasted track－bridge systemis divided into rail unit, a quarter vehicle discrete into f our independent driven wheel unit,So only when calculated form of one track－bridge system the stiffness matrix of the massmatrix and damping matrix, later in every step of the calculation, Only assembling thestiffness of the unit vehicle quality and damping matrix,forming total stiffness matrix, qualitymatrix and damping matrix. This unit has the characteristics of the programming of easy tocalculate and high computing efficiency.To the coupled high speed train－no－ballasted track－bridge vertical systems, usingNewmark solution to assembled dynamics model,then getting solution through Matlabprogramming. Because of the characteristics of the high speed no－ballasted track, at homeand abroad havn’t no－ballasted track irregularity spectrum,so this paper chooses Germanylow interference spectrum which the most close to the no－ballasted track spectrum tosimulation irregularity spectrum of our country’s high－speed railway. First, vibrationanalysis of high－speed trains through the bridge at speed of350Km/h, and work out the topof the bridge pier force; Then, the article analyzes the influence of vibration responsewhichthe track irregularity and speed the two factors on high－speed trains passing throughbridge. The conclusion is: along with the increase of speed and rail irregularities situationworse, the partial track response intensified, and have the cushion that layer derailed effect ofvibration reduction is superior to CA mortar layer; Finally, based on the bridge parameters on the effect of vibration response analysis which is blank. After study the bridge stiffness anddamping to no－ballasted track vibration response of the influence of the high speed trainthrough the bridge. We can know that, we can obviously affect the vibration response for thechange of the stiffness, the increase of the bridge stiffness, reducing vibration response. Forthe influence of damp relatives to the stiffness is much smaller, With the increase of the bridgedamping, the displacement response increase, and the speed response and accelerationresponse is reduced, and the trend in sometimes are not so obvious.High－speed trains through the bridge no－ballasted track caused environment vibrationthat will seriously influence on the near sensitive line and sensitive buildings.this paper onlyanalyzed the vibration response of sensitive area based on the test. So building coupled bridge－soil dynamic analysis models, considering the influence of the rubber pad under box girder.This model is called coupled rubber pad－bridge－soil space analysis models,which isestablished Through large－scale finite element analysis software－Ansys. The space modelof incentive source is bridge pier force that through coupled high speed train－no－ballastedtrack－bridge vertical systems, calculating the soil vibration response is away from pier indifferent distance(0m,10m,20m,30m,40m,50m and60m), The main response is accelerationresponse. The main conclusion that the decline of vibration is very big in the top10meters, inthe top20meters the response has completed, the response rebounded between30m and40m,reaction is not obvious outstrip the distance. So High－speed trains through the bridge no－ballasted track caused environment vibration that will seriously influence on the near sensitiveline and sensitive buildings, vibration damping measure is very important to the near sensitiveline and sensitive buildings.Participating in our country high speed railway tests during study,and a series of relateddata are acquired and analysised, founding that the acceleration of rail and numericalsimulation are very different, others is consistent, the big difference between rail is mainlydue to, this paper study the influence of vibration, don’t consider high frequency vibration.The test results show that the method is correct and feasible. The measured data also show thehigh frequency vibration decays down soon, the low frequency vibration quite a much slowerdecay.