Prototype Fatigue Test Of CRTS â…  Slab Track

With the wide application of ballastless track to the high-speed railway in China, during the long-term operation service period, the ballastless track has to burden the combined action of the train load of high density and the long-term temperature load, which tends to cause the fatigue damage for the ballastless track. Judging from current situation, the fatigue damage has occurred to a part of ballastless track, which is a hidden danger to the mechanical performance of the track structure and the train operation. Therefore, it is significance to study the fatigue characteristics of the ballastless track for track maintenance and management.In this paper, the CRTS â… -slab track was considered to be the research object. The development and current situation of application for the slab track at home and abroad were reviewed and summarized. Also the related theories on the model experiment were introduced. Through the combination of the prototype fatigue test and theoretical calculation, the fatigue characteristics of the ballastless track was studied. The main research contents were listed as follows.(1) The prototype model was used for the fatigue test, in which the design of the track structure was in accordance with the corresponding current standards. The temperature load was simulated by steam heating and air cooling, and the train load was loaded by cyclic loading machine. For data collecting, the temperature sensor, displacement meter and earth pressure cell were buried in the track slab, baseplate and subgrade in advance. In order to observe the mortar void height at different stages, the measure points were marked.(2) During the fatigue test, the real time monitoring and analyzing was conducted for the vertical displacement of the rail, track slab and baseplate, the reaction of sleeper supports, the surface stress of track slab, the soil pressure of the surface layer of subgrade bed, the mortar void height as well as the temperature data of the inner track structure and the outer circumstance temperature. The results show that the fluctuation of the displacement values of rail and slab is related to the changes in environment temperature. The void height at the side of mortar layer increases with the loading times, but the influence of fatigue loads on it is limited.(3) By establishing the beam-solid finite element model under different damage conditions, the stress data of the track structure were obtained. Based on the statistical data of temperature and load obtained from the test, using the fatigue equations and the linear accumulated fatigue damage theory, the experimental fatigue damage was simulated. According to the comparison between the experimental results and theoretical simulation conclusions, it shows that the damage development process for the mortar layer without initial damage approaches to the test reality. The simulation calculations show that the fatigue resistance of the mortar layer without initial damage is favorable. The damage develops from the bottom of the mortar layer. The slower development of the damage leads to the longer service life. The mortar layer with initial damage has a poor fatigue resistance. The damage develops from the top surface of the mortar layer, and it rapidly develops. The damage needs timely maintenance in a short time.