چكيده به لاتين
In the current study, the application of tire derived aggregate (TDA) mixed with ballast grains has been introduced as an approach for enhancing the ballasted track performance in the presence of sand fouling. In order to assess the TDA influence on sand-fouled ballast, a series of ballast box tests was carried out on the mixture of TDA and ballast with AREMA 4A gradation, containing the Tabas desert windy sand with particle size range of 0.075-0.84 mm. Considering four TDA weight percentages of 0, 5, 10 and 15% and three weight percentages of 0, 50 and 100% for windy sand as the contaminant material, totally 36 experiments have been conducted. In this matter, the gradation of TDAs was similar to that of ballast so as to prevent them from disrupting the ballast layer drainage. On the basis of the laboratory outputs, the settlement, ballast breakage and damping ratio of samples were discussed. The experimental results indicate that increasing the sand percentage results in the reduction of mixture damping ratio, as well as the rise in settlement and ballast breakage of samples. On the other hand, the growth in TDA percentage led to an increase in ballast sample settlement, damping ratio and breakage. On the whole, the 5%-TDA sample was determined as the suitable ballast/TDA mixture in terms of breakage and stiffness of ballast layer, while the more TDAs continuously raised the damping ratio of samples. Furthermore, three regression equations have been presented for evaluating the ballast settlement, breakage and damping ratio in terms of loading cycle, TDA and windy sand percentages within the samples.In addition, some samples were modelled with PFC 3D to validate experimental results. Therfore, modelling of clear ballast samples mixed with 0 and 5 percent of TDA have been conducted using discrete element method.
