Earthquake response of the train–slab ballastless track–subgrade system: A shaking table test study

Abstract

Earthquake is one of the major factors that provoke train derailment. To investigate dynamic responses of the train–slab ballastless track–subgrade system and derailment features of the train subjected to earthquake, a first large-scale shaking table test on this system was carried out in China. The loaded seismic wave is an earthquake wave of Zhengzhou Yellow River Bridge Site provided by the China Earthquake Administration. It was observed that the elevation of subgrade and embankment could magnify acceleration responses, and the transverse amplification effect of the elevation in soil was more pronounced than the vertical amplification effect. The acceleration response of a track slab was weaker than that of the top subgrade because of integrality and rigidity of the track slab. The bogie shows a shock-absorbing effect in the transverse direction. When the input amplitude was not larger than 0.14 g, the transverse and the vertical acceleration of the rail increased with rising earthquake amplitudes and fluctuated later. Meanwhile, the current stopping threshold for trains is conservative because the derailment factor was less than 0.8 and the peak lateral displacement of wheels was much smaller than the cross-sectional size of the rail model under a 0.12 g earthquake excitation. The current stopping threshold in codes could be reasonable in view of limited quantity and limited types of loaded earthquake in the test. The critical derailment condition of trains was 0.23 g when the Zhengzhou Yellow River Bridge Site earthquake was loaded, and the displacement analysis showed that it would be a great danger for train safety.

Experimental Study of the Dynamic Characteristics of a New Antidrainage Subgrade Structure for High-Speed Railways in Diatomaceous Earth Areas

“…Figure 16 shows the distribution law for the vibrational acceleration along the subgrade in a waterlogged environment. The vibration acceleration at the same depth of the roadbed structure is the largest at the location of the track centerline, and the farther away from the track centerline, the smaller the acceleration is, which is due to the upper load acting directly here, resulting in the largest influence of the upper load at the location of the track centerline; thus, this is where the vibration energy is the largest [44]. In each depth direction below the bed surface, the attenuation amplitude is larger in the transverse range of 2 m from the track centerline, and the attenuation amplitude is, relatively, much smaller, in the range of 2~4 m. The attenuation rate is not consistent in each depth direction, and the deeper the depth, the slower the attenuation rate is within the vibration influence range.…”

Dynamic Response Characteristics of Railway Subgrade Using a Newly-Developed Prestressed Reinforcement Structure: Case Study of a Model Test

“…Dynamic responses generated in a reduced-scale system should be consistent with an actual prototype, but complete similarity between a prototype and a model that can make an exact prediction of the prototype behavior is difficult to satisfy in reality [ 35 , 36 ]. The Buckingham π theorem [ 37 ] serves as an important tool for dimensional analysis, and it can simplify the physical issue by considering the dimensional homogeneity, thus contributing to the reduction of the related variable numbers.…”