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Effect of different contact surfaces between concrete sleeper and ballast on mobilized lateral resistance against impact loads

The amount of ballast particles surrounding a railway track significantly influences its resistance in all directions. As time goes by, with the development of high-speed trains, more attention has been paid to this issue owing to the increase in dynamic effects of rolling stock on track loading. The focus of the present study is on the investigation of the interaction between different surfaces (base, crib, and shoulder) of concrete sleeper and their adjacent ballast layer along with the related parameters under lateral impact loading condition. In this regard, by utilizing a pendulum loading test device, a number of lateral impact tests were conducted on an instrumented concrete sleeper in laboratory. On the basis of experimental results, the average contribution of base, crib, and shoulder zones in the total dynamic lateral resistance of sleeper was calculated as 48%, 23%, and 29%, respectively. Furthermore, in the lateral impact force domain of 13–28 kN, the sleeper–ballast dynamic friction coefficient at base and crib zones varied in the ranges 0.8–1.5 and 0.5–0.6. Moreover, a maximum impact factor of 2.5 was obtained for analysis and design purposes. It should be stated that the trend of laboratory results confirmed the common static friction coefficient of 0.8.