Hua Yan

Type Selection and Structural Characteristics of Ballastless Track in Seismic Region

The ballastless track has following advantages: good track regularity, favorable structural integrity and lesser maintenance. Because of the large rigidity, once damaged, the ballastless track is not easy to repair. Without considering the influence of earthquake on previous design of ballastless track, the track is laid on the substructures. According to the features of track foundation in seismic regions, aseismatic principles of ballastless track such as motionless in a small earthquake, repairable in moderate earthquake and changeable in strong earthquake are put forward. The calculating method of the influence of earthquake on ballastless track is determined. Based on adaptability analysis for earthquakes on several kinds of typical ballastless track, the resin mortar slab track for seismic region is presented. By means of theoretical calculation, the structure of resin slab track and the material parameters of resin mortar are further perfected. Through resin mortar material test and integral track fatigue test, the reliability of track is verified, which provides the theoretical and experimental basis for ballastless track laying in seismic regions.

Behavior and Performance of Ballastless Track with Damaged Cracks under Train Load

Recent development trend of high speed railway is more and more focused towards ballastless track due to its advantages of low maintenance, high availability, low structure height and low weight. However, damage cracks of ballastless track superstructure, which is built of reinforcement concrete, are not avoidable. Also, damage cracks may have effect on the behavior and performance of ballastless track. In this paper, in order to study the effect of concrete slab cracks on the mechanics of ballastless track, a spatial finite element model of ballastless track with damaged cracks was established , based on cracking characters of concrete slab, in which the singularity of crack tip was simulated by 20-node hexahedron isoparametric singular element using the theory of elastic fracture mechanics. The mechanics of ballastless track under train load was analyzed and the results show that the crack has little effect on the global stress and deformation of the track. Besides, bar stress at the crack has a sudden increase, and the crack width has little increase under train load. In addition, both bar stress at the crack and stress intensity factor (SIF) increase with the increase in the crack depth, and the crack is not likely to propagate only by general train load.

Long-Term Behavior and Performance of Ballastless Track Superstructure on China’s Suining-Chongqing Railway Line

This paper briefly shows the experimental ballastless track section of Suining-Chongqing railway line in southwest China, which was designed by China Railway Eryuan Engineering Group Co. Ltd (CREEC) and was put into operation in 2007. The design speed of the experimental section amounts to 200 km/h for passenger trains and 120 km/h for freight trains, which is the first railway line built with such speed in southwest of China. The long-term observations of the performance of the ballastless track superstructures were implemented in the past three years, which are introduced in details in this paper, such as the performance of reinforced concrete slab with lattice two-block sleepers, coupled or uncoupled prefabricated slab-superstructure etc. Ballastless track superstructures’ damages are summarized and classified. In addition, causes of damaged cracks on track superstructure are discussed.© 2010 ASME