Study On The Line Dynamic Response Of Loaded And Unloaded Wagon Trucks And The Alignment Parameters Of Heavy Haul Railway

The dynamic responses of the loaded and unloaded wagon trucks are different when passing the curves. Loaded wagon truck can pass through safe and sound while the unloaded wagon truck is not that stable. In view of this, the paper was dedicated to study the differences between the dynamic responses to the curve parameters of the loaded and unloaded wagon trucks. If these differences are taken into consideration when determining the line parameters, a more comprehensive and rigorous analysis of the curve parameter of the heavy haul railway line can be got. The general terrain of China is high in the west and low in the east, because of which, the construction of heavy haul railway in the mountains is often limited by terrain condition. In order to reserve the alignment and control cost, the superimposition arrangement of vertical and horizontal curves is necessary to be studied. The main research works are as follows:(1) Based on the established research methods of railway parameters and according to the characteristics of heavy haul railway line, the paper simply introduces the main line parameter both of the horizontal curve and vertical profile.(2) Simulated model of loaded and unloaded wagon trucks were established based on Multi-body System Dynamics. The dynamic evaluation indexes were introduced. The models were used to obtain the nonlinear critical speeds both of the loaded and unloaded wagon trucks and verify the reliability of the models. The result could prove the credibility of simulation results and provide the basis for the subsequent dynamic analysis.(3) The 25t axle load C80 heavy haul wagon model which was widely applied was chosen to simulate the influences of different curve radius and transition curve length to the dynamic responses both of the loaded and unloaded trucks when passing through them. A comparative analysis of the dynamic response differences between the loaded and unloaded trucks under the simulation conditions in this paper indicated that the security and stability evaluation indicators of the loaded truck is superior to the unloaded truck under the same line conditions, while the unloaded truck is superior to the loaded truck in the vehicle-track dynamic action evaluation indexes. It will be obtained to offer a theoretical foundation to refer to the dynamic responses both of the loaded and unloaded trucks when determining the curve line parameters.(4) The 30t axle load heavy haul wagon model was chosen in view of the popularity of the heavy haul railway in our country and the major railway technology policies. Under the condition of different combination of circular curve parameters and passing speeds, the variation trends of dynamic responses of the loaded and unloaded trucks were explored when passing through different horizontal curve radius. Reasonable values of curve radius were obtained which met the safety requirements of the 30t axle loaded and unloaded heavy haul wagon trucks. Considering the dynamic responses both of the loaded and unloaded trucks under the simulation conditions in this paper, the minimum radius of horizontal curve is suggested to 1400m; when the passing speed of curve is 70km/h, the minimum radius of horizontal curve is suggested to 800m; when the passing speed of curve is 60km/h, the minimum radius of horizontal curve can be the 600m. The bigger curve radius is better to be chosen in the line design. Under the working condition of a certain part of the evaluation indexes, the larger curve radius with high passing speed is similar to the small curve radius with low passing speed or even smaller.At the same time, the accelerated speeds and the stability responses for different distances at the start and end points both of the vertical and the transition curve will be simulated respectively. It is suggested that the distance from the start to end between the vertical and the horizontal curve should not less than 20m under the condition of simulation in this paper. The research of this article will offer the theoretical basis and reference for the curve parameter setting of heavy haul railways.