Study of the lateral resistance characteristics of ballast bed considering the sleeper group effect

By establishing the ballast track full scale model, this paper tested and compared the difference between the resistance of the sleeper group and the resistance of a single sleeper, and studied the effect of sleeper group on lateral resistance. The model of the ballast bed was established based on the discrete element method. We compared the lateral resistance of ballast bed composed of different number of sleepers and analyzed the particle movement and the contact characteristic. According to case calculations, we analyzed the lateral stability of continuous welded rail (CWR) considering the effect of sleeper group. The results show that the average resistance of five sleepers decreased by about 28% compared with that of a single sleeper. With the increase of sleeper's number, the average resistance gradually becomes stable. The reduction of lateral resistance under the effect of sleeper group mainly occurs in the ballast side and sleeper end area and there is a common area of resistance at the side and end of sleepers. When the sleeper displacement reaches 2 mm, the contribution rate of crib resistance in the independent area and the common area is about 4.3:1:1, and the contribution rate of shoulder resistance is about 3.2:1:1. To ensure the safety of the CWR operation, it is suggested that at least three sleepers should be pushed at the same time when testing the lateral resistance and use the average lateral resistance as a reference value.