Assessment of the maintenance effect for rock ballast bed during tamping operation

Abstract

Tamping operation can damage rock ballast beds in railway; therefore, the assessment of maintenance effect is crucial for the safe running of a train. First, a ballasted track-tamping machine model was established using DEM-MFBD. Subsequently, a test method for the squeezing distance of tamping machine was developed and the model was verified. Using this model, the effects of tamping operation on mechanical states of rock ballast and sleeper were analyzed and the corresponding sensitive indicators were determined. Finally, the relationship between comprehensive mechanical state of ballast bed and squeezing distance was analyzed, and the assessment of maintenance effect was achieved. The results indicated that the coordination number and the compactness of ballast were sensitive to tamping, decreasing by 52.78% and 6.64% for 160 kN/mm stiffness, respectively. Additionally, the bottom contact density and pressure on sleeper were also sensitive to tamping, decreasing by 70.66% and 60.06%, respectively. The maintenance effect for rock ballast bed can be assessed according to the maximum squeezing distance of tamping machine.