Damage mitigation and maintenance enhancement of rock ballast: A novel tamping method

Tamping is the foremost technique used in rock ballast maintenance. With the goal of minimizing tamping-induced degradation of rock ballast and enhancing maintenance effects, a novel tamping method with a smart tamping tine was developed. First, the new tamping machine was designed, allowing automatic toggling between retracted and extended states of the tine structure during tamping. Subsequently, a model of ballasted track subjected to tamping was established and validated against field-measured ballast acceleration data. Using this model, the dynamic responses and mechanical states of rock ballast were analyzed, and the optimal size of the tamping tine was determined. The results showed that the new tamping method could significantly mitigate damage to rock ballast and improve maintenance effects. The maximum improvement in the uniformity index of the rock ballast using the new tamping method reached 182.96% compared with that using the old tamping machine. The optimal width and height of the tine structure for the new tamping method were 60–70 and 75–80 mm, respectively.