Investigating the effect of different bonding areas on the lateral resistance of polyurethane-mixed ballast using the discrete element method

In order to investigate the characteristics of the lateral resistance of the polyurethane-mixed ballast with different bonding areas, a sleeper-ballast model was established using the discrete element method. The lateral resistance of the polyurethane-mixed ballast with single and combined bonding modes was analyzed. The results show that the lateral resistance increases with the increase of the bonding depth of the shoulder ballast. After the bonding depth of the crib ballast and the base ballast reaches 5 cm and 15 cm below the bottom of the sleeper, respectively, there is no significant development of the lateral resistance. The lateral resistance cannot be improved efficiently by bonding the slope ballast. The combined bonding of the crib ballast and the base ballast is an effective method to improve the lateral resistance. With the gradual failure of the bonding contact points between the sleeper and the ballast, the average value of the lateral resistance decreases linearly and the lateral resistance presents a greater randomness under the more complex bonding mode.