Dynamic cumulative effect of ballast settlement considering sleeper void using 3D Train–ballasted track model

The uneven ballast settlement caused by the train cyclic load affects the dynamic response of the train-railway ballast system, and this further accelerate the development of ballast settlement. In order to precisely analyze the "dynamic cumulative effect" (DCE), this study introduced a three-dimensional model of train-ballasted track (TBT) and the University of Illinois at Urbana-Champaign (UIUC) empirical model. At the same time, an improved Newton iteration method was adopted to simulate the sleeper void. By comparing and analyzing the evolution of ballast settlement and dynamic performance of TBT system with different water contents and aging, the influence of ballast settlement on DCE and sleeper voiding was analyzed. The following important conclusions were drawn: 1) DCE will accelerate the ballast settlement and the deterioration of the TBT system. 2) When considering nonlinear DCE, the ballast settlement and the performance evolution of the TBT system exhibit sudden local characteristics. 3) For ballasts with a worse condition than AB L30, the dynamic response of the ballasted track will increase by 30%, and the reduction rate of wheel load will also double, it is necessary to pay attention to monitoring the areas with greater TBT system force. 4) For ballasts with a worse condition than AB L50, close monitoring or maintenance may need to be considered.