Investigation Of The Differential Settlement And Reinforcement Of Ballasted Track And Transition Zone Under Train Loading

In recent years,the development of railway transportation in our country is speeding up.With the faster and heavier trends of trains,the deterioration of the existing ballast track bed is aggravating,and the subgrade disasters occur frequently.Moreover,the sudden change of settlement in the transition zone of road and bridge seriously affects the safety and comfort of railway transportation.In order to ensure the safety of railway transportation,it is necessary to maintain the railway subgrade in time.The aim of this study is to systematically analyzes the settlement law of Ballasted Track Subgrade and the reinforcement of geocell,and evaluates the feasibility of different reinforcement methods for the ballasted track transition through theoretical analysis and numerical simulation method.Based on the finite element method,the three-dimensional model of ballasted track subgrade is established by using ABAQUS finite element software,and the settlement rule of ballasted track is analyzed systematically,which reveals that most of the track settlement is mainly concentrated in the ballast layer.The load parameters of the train and the ballast properties have influence on the ballast settlement,among which the axle load of the train,the elastic modulus of the ballast and the friction angle have great influence.On the basis of three-dimensional ballast track subgrade model,the reinforcement effect of geocell on railway track bed was studied,and the influences of geocell rigidity and aperture shape on the reinforcement are also discussed.The results shown that the influence of geocell stiffness is significant.With the increase of the geocell stiffness,the reinforcement efficiency of subgrade increases at first and then tends to be stable gradually;different geocell shapes have shown varies reinforcement efficiency,and the reinforcement efficiency of hexagonal geocell seem to be the highest under the same material consumption.Considering the characteristics of the transition zone of ballasted track bridge and the common structural forms of the transition zone in domestic and foreign projects,the treatment measures of the transition zone,such as concrete slab transition wedge,asphalt concrete and short piles are selected as the research objects.Three different transition zone models were established by using ABAQUS finite element software.The simulation results show that due to the abrupt change of subgrade stiffness at the transition zone,the uneven settlement is the largest,which is in agreement with the conclusions of practical engineering.On this basis,this study has compared the reinforcement effect of three kinds of transition zone treatment measures,among which the best performance was wedge-shaped concrete reinforcement and then the short pile reinforcement effect,the asphalt concrete reinforcement effect is not particularly obvious in this study.The simulation results could provide engineering suggestions for the design and maintenance measures of the transition zone of the ballasted track.