Dynamic effects of vehicles on tracks in the case of raising train speeds

Abstract

In order to enhance the efficiency of railway transportation, Chinese Railways has decided to raise the speed of trains on the existing railway main lines. A theoretical model and the corresponding simulation software, VICT, based on the vehicle-track coupling dynamics are employed to analyse dynamic effects of trains on track structures caused by raising train speeds. Chinese passenger cars and freight cars running on the lines where speed has been raised were chosen for investigation. It is shown that raising train speeds on the existing railway lines obviously intensifies the dynamic effects of vehicles on tracks, especially in the turnouts, in the welded rail joints, and in the sections of bridge-subgrade connections. The occurrence of wheel flats becomes more general after raising train speeds. An unfavourable peak of dynamic effects of wheel flats on tracks is observed in the speed range from 140 to 160 km/h, which is just the region of running speeds for passenger trains after the increase in the speed. Some basic countermeasures, including stricter maintenance standards for the speed-raised railways, are proposed to solve these problems, on the basis of dynamic analysis.

Track dynamic behavior at rail welds at high speed

“…However, so far few studies were focused on the vehicle-track coupling dynamics at rail welds. Zhai et al [15] used a vehicle-track coupling dynamic model to study the dynamical effect of welds irregularities on train and track interaction caused by raising train speed. In the model, the rail was modeled as an Euler beam, which is not suitable for simulating high frequency impact between the wheel and rail weld irregularities.…”

Dynamic Response of Wheel-Rail Interaction at Rail Weld in High-Speed Railway

“…Method Selection. In the past, the calculation of dynamic wheel-rail interaction was widely used in the multibody dynamic model [1,2,[7][8][9][10]. The wheelset in these models was generally considered as a rigid body, so that the response of axle-box acceleration, which oscillates as local vibration, cannot be obtained.…”

“…Moreover, as vehicle speed increases, wheel-rail high-frequency vibration inspired by short wavelength irregularity cannot be ignored [20]. To represent this characteristic, wheel and rail should be modelled as solid element but not beam as in traditional vehicle-track coupling dynamics model [1,[7][8][9][10]. Considering the above three factors, a 3D high-speed wheel-rail rolling contact FE model (hereinafter referred to as rolling model) is established in this section to accurately solve the dynamic contact behavior at the rail welds.…”

“…Obviously, this standard ignores the influence of geometrical wavelengths on wheel-rail force. Zhai et al [7] developed a vehicle-track coupling dynamic model to investigate dynamic behavior induced by rail weld and suggest some maintenance standard for speed-raised lines. Xiao et al [8] found that the wheel-rail force at the rail weld increases with the decrease of the wavelength and propose safety limits under different speed against the irregularity of rail welds based on dynamics index or dynamic factors.…”

“…Xiao et al [8] found that the wheel-rail force at the rail weld increases with the decrease of the wavelength and propose safety limits under different speed against the irregularity of rail welds based on dynamics index or dynamic factors. However, weld irregularities in [7,8] were modelled as ideal cosine waveform and different from the actual weld geometry. Thus, conclusions of the above researches are difficult to be applied in the maintenance of actual lines.…”