Theoretical Analysis And Finite Element Simulation On The Monolithic Track Bed Diseases Of MTR Ballastless Track

The Ballastless track is a new form of rail infrastructure, with the advantages ofhigher stability,higher uniform stiffness,less maintenance and so on. With the rapiddevelopment of China's railway infrastructure and urban rail transit construction, theBallastless track technology is extensive used. But, impactde by the vibration oftrain, structural performance, hydrogeological, construction quality such factors, theMonolithic track bed arised subsidence damage and other diseases, leading to greaterdifficulties and higher maintenance costs for Track maintenance. In this thesis, basedon the achievements of the previous literature,the study of the diseases inballastless track is investigatedwith the methods of theoretical study, numericalsimulation and experimental research. The main research work of this dissertation areconcluded as follows:(1) A mechanical analysis model are developed for the MTR ballastless tracksubsidence damaged disease. This model incorporates the necessary components ofthe railway system such as the train load, track and subgrade. The vehicles aredescribed as some concentrated load. The track is modeled as multiple beamssupported by vertical springs with consistent mass. The disease is modeled as theresistance coefficient of back-filling layer reducing or removing some flexibilityfoundation of the disease part. Through a certain assumptions and analysis, establish adouble beam ballastless track subsidence damaged disease mechanical analysismodel.(2) Derived and solved the four-order differential equations of the ballastless trackin good condition and Disease status. Using computational programs written inMatlab language, make mechanical analysis on ballastless track bed in different conditions. The results are as follows: When the resistance coefficient ofback-filling layer less 500 MPa/m, the subgrade must be strengthening andreinforcing treatment; Diseases in the most disadvantageous position is under themiddle span of ballast within the range of about 0.5m; The diseases radius nearly0.5m, deformation and settlement of ballast up to 20 mm, if the diseases rangecontinuously expanding, the track will be in state of insecurity. The agreementbetween the numerical results and experimental data and published literature showsthe validity of this created model.(3) Based on ABAQUS Platform, a three-dimensional finite element model ofrailway vehicle/track/subgrade system is developed to study the impact of differentdiseases factors and status to the track structure. According to the results obtained:With the resistance coefficient of back-filling layer decreased gradually, the stress atthe bottom of the track plate is gradually increasing; When diseases region in the 0.3m~0.5m, track plate is in a state of dangerous diseases, must be trained andmonitored.The simulation results and theoretical results show that two models havinganastomosis to some extent. But the solid model of Finite Element Simulation can bebetter simulating the actual stress state of Monolithic track bed, So , the stress, stressdistribution and settlement deformation calculated by using this model are closer to theactual situation.