Research On Mechanical Characteristics Of Ballastless Track In High-Speed Railway

With excellent stability, low maintenance workload and ability of preserving the geometrical features, great attention has been paid to ballastless track by Japan, Germany and many other countries where high-speed railway is developed rapidly. At present, ballastless track is widely applied in passenger dedicated line under construction in our country, and it has broad prospect. The research on mechanical characteristics of ballastless track is of great significance for the world-class construction of railway in our country. Meanwhile, the research is important for the large scale improvement of technical equipment of railway line for passenger traffic. Based on comprehensive investigation of documents, and by taking Type II slab track as the main research object, systematic and deep research on ballastless track from static and dynamic aspect (including ballastless track system on bridge and subgrade) has been done within this paper. The main research contents are as follows:1.The development, application and research status of ballastless track are summarized.On the basis of extensive investigation on the development and application of ballastless track at home and abroad, a systematic summarization has been made with focus on the designing model, development course, the characteristics and advantages as well as disadvantages of the typical ballastless track in Germany and Japan. Moreover, a description of ballastless track development process in our country is given. With the summarization of static and dynamic research status, analysis of the deficiency of present ballastless track research is put forward. Thus the research contents and innovation points can be drawn up.2.Static and dynamic finite element analysis model of ballastless track are established.With the finite element platform of ANSYS, three static models are established for the calculation of ballastless track: composite beam model, beam slab model and beam body model. Comparison and selection is made among the three models, and the difference as well as application of each model have been analyzed.The modeling method with the use of ABAQUS and the relevant problems are discussed. The dynamic finite element models on bridge and subgrade are established, and the simulation results are compared with the dynamic test results of ballastless track in Sui-Yu Railway Line, thus the reliability of the modeling method can be verified. 3.Research is done on the influence of static characteristics of ballastless track caused by structure parameters and foundation deformation (bridge deflection and uneven settlement of subgrade).With the static finite element model, the main design parameters, including dimension of track plate, elastic modulus of mortar, parameters of HGT Layers, fastening stiffness, subgrade coefficient and the depth of pre-splitting crack are taken as the static parameters of ballastless track.Research is done on the difference of calculation methods under the condition of uneven settlement of subgrade. Analysis is made on stress influence caused by longitudinal reinforcement and uneven settlement of subgrade influence. Study is done on stress influence on ballastless track caused by longitudinal reinforcement, recurvation effect on the fixed bearings of the continuous beam, beam end rotation and differential settlement of bridge piers. Then a proposal is offered with respect to the design of ballastless track under the condition of foundation deformation.4. Research is done on the influence on dynamic characteristics of ballastless track caused by structure parameters. Dynamic simulation is carried out on ballastless track on subgrade and bridge under medium and high speed.Based on the finite element model, taking fastening stiffness, mortar elastic modulus,HGT Layers elastic modulus and subgrade coefficient as study parameters, analysis is done on dynamic characteristics of ballastless track. Suggestions are put forward for the design of ballastless track.Research is done on dynamic response of vehicle, ballastless track, subgrade and bridge system under medium and high speed. Combined with dynamic evaluation indexes and relevant regulations at home and abroad, an overall evaluation of dynamic response for the ballastless track on subgrade is given.5. Comparative study is done on mechanical characteristics of ballastless track with different longitudinal connection forms.From static aspect, using the method of continuously welded rail track on bridge, comparison of ballastless track on bridge with different connection forms is studied. From dynamic aspect, comparison is made on ballastless track on subgrad, bridge and the transitional section between road and bridge with different connection forms. Based on the above work, evaluation of the ballastless track with different connection forms is given.