Experimental study on wayside monitoring method of train dynamic load based on strain of ballastless track slab

Abstract

In the long-term service of ballastless track, which constantly bears the cyclic load from high-speed trains, it is important to obtain the long-term mechanical behavior of train dynamic load on the ballastless track. In this paper, a novel wayside monitoring method of train dynamic load is proposed, which takes CRTS III ballastless track as the research object and embeds Fiber Bragg grating (FBG) strain sensors into the track slab. The traditional wayside method installing strain gauges on the rail is used to compared with the sensors embedded in the track slab, which was tested in the field. Then, the time domain and frequency domain information of rail strain and slab strain are analyzed in detail, and the correlation analysis of signals is carried out. Finally, the calculation method of the running trains information and dynamic load is proposed. The results show that the vertical strain level of track slab is low under the action of high-speed train dynamic load. The time history curve shows that the adjacent wheel has obvious coupling effect on the slab strain signal, rather than rail strain. The frequency domain analysis of the signals indicates that the low-frequency components of the rail strain and slab strain have a strong correlation. However, the high-frequency components of train dynamic load are buffered out due to the effect of the fastener system. The mapping relationship between the track slab strain and the dynamic load can be found through calibration test, which provide a novel monitoring method of dynamic train load. The monitoring method can realize the real-time monitoring of train running information and record the long-term train dynamic load cycle law, and provide important parameters for the ballastless track boundary condition model.