Mechanical characteristics of ballasted track under different tamping depths in railway maintenance

Abstract

Tamping is an effective maintenance measure for ballasted track, but it can also cause ballast breakage and sleeper abrasion. To balance the advantages and disadvantages of tamping operation, a ballasted track-tamping device model was constructed using discrete element method (DEM) and multibody dynamics (MBD) coupling method, and a function module to control tamping vibration was developed. Thus, the tamping operation can be accurately simulated in coupling model, verified by field test. On this basis, the model was utilized to study the mechanical characteristics of ballast and sleeper under different tamping depths, comprehensively considering the damage and maintenance effort caused by tamping operation. The results indicate that tamping depth has a negative correlation with sleeper stress but a positive correlation with ballast contact force. A tamping depth with limits of 20 mm and 50 mm for the lower and upper thresholds are determined to mitigate the damage to sleeper and ballast, respectively. The best maintenance effort is achieved when the depths are 20 mm or 30 mm, and the corresponding voidage of ballasts under the sleeper are 29.31% and 28.75%, respectively. Therefore, 20–30 mm is recommended as the optimal tamping depth. This research can provide insights for low-damage and high-quality tamping maintenance in railway lines.