Indoor simulation test research on cumulative longitudinal displacement of rail based on force and displacement...

The train sometimes needs to brake frequently on the turnout, although the braking force does not exceed the limit resistance of fastener, cumulative displacement of rail occurs because of the long-term effect of the train brakes, thus, the relationship between the cumulative displacement of rail and the number of train braking actions should be explored. Aiming at the spring bar type III fastener, a 1:1 physical indoor simulation test was carried out, and an electromagnetic relay device was used to simulate the train load, force, and displacement sensors for data collection. Then a single load no more than the maximum resistance of fastener was applied to the rail end to explore the relationship between the number of loads and the rail cumulative deformation. The rail longitudinal cumulative displacement changes linearly in positive correlation with the number of load actions, and increases faster when the number of load actions is small. As the number of repeated loads increases, the above-mentioned relationship approximately and credibly obeys the power function distribution. Repeatedly applying load no more than the maximum longitudinal resistance of fastener to the rail, the existence of the rail cumulative displacement caused by frequent train braking can be demonstrated, and the relationship curve between the rail displacement and the number of loads can be obtained. Applying the fitting formula, the rail displacement after a specific number of loading times can be attained, and then referring to specific codes, we can determine whether it will exceed the safety limit.