| The safety and comfort of the Scheduled passenger train propose higher demands for the smoothness and stability of the track. Ballastless track circuit has the outstanding advantages of high stability, uniformity of rigidity, constancy of structure, easy maintain, etc. To develop the ballastless track is our country's great action to achieve great progress in rail transportation.The electromagnetic induction of the steel bar net and track in the ballastless track circuit change the primary parameter of the track circuit, and change the transmission performance of the non-insulated track circuit. This difference greatly changes the operational characteristic of the track circuit. The interference of the traction current is one of the important subject in the major of railway signal. The use of ballastless track will influence it's condition. Therefore the research on the transmission mode of the ballastless track and the interference of traction current has significant value in both theory and practice.Firstly, the types of ballastless track circuit, it's application in different countries, and the theory of non-insulated track circuit are introduced in this dissertation. The property, parameters and transmission equation of the non-insulated track circuit are analyzed. On the above basis, the main effect to non-insulated track circuit in ballastless track circuit is studied.Secondly, based the study of the effect which is the electromagnetic induction of the steel bar net and track change the primary parameter of the track circuit, the equivalent rail resistance mode and the transmission mode of ballastless track circuit are studied. The relations among the equivalent rail resistance of the ballastless track circuit, the transmission distance of the track circuit and the parameters of the steel bar net are analyzed and calculated. According to the comparison of the results from theory calculation and spot test, the proposals to optimize the physical parameters of the steel bar net in ballastless track circuit are put forward. The calculation results show that to raise the ballastless track rail 300mm properly will do effort to reduce the effect that the steel bar net to the transmission of the track circuit, to minish the steel resistance and to lengthen the transmission distance of the circuit.Finally, the interference of the traction current in the ballastless track is analyzed. To take the mode of ballastless track traction current as an example, the distributions of the traction current in the ballastless track and the steel potential along the rail are analyzed and calculated, and lines of the distribution are shown by MATLAB. Then the operation expression of the interferential voltage of the traction current is derived, and the interferential voltage of the track circuit receiving equipment from the traction current in ballastless track is quantitatively calculated.The comparison to the interferential voltage in ballast track shows that the steel bar net of ballastless track enlarges the rail current proportion in traction current in certain degree, which raise the rail interferential voltage from the traction current slightly. Compared with the minimal operational voltage of the track circuit sink, the existence of interferential voltage will not influence the normal operation of the track circuit. |
