Discrete element method analysis of lateral resistance of different sleepers under different support conditions

Abstract

With the increasing speed of trains and the axle load of railways, the need to provide lateral stability of railways becomes more important. Small-radius curves on conventional tracks and temperature fluctuations pose a significant threat to the lateral stability of railway tracks as they increase lateral and longitudinal forces, leading to track buckling. Therefore, the lateral resistance of ballasted railway tracks must be improved in every way possible. To this aim, many approaches have been proposed, including modifying ballast and sleeper materials, changing the ballast layer geometry, and replacing conventional sleepers with specialized ones. Compared to conventional B70 sleepers, applying HA110, winged and middle-winged sleepers improved the lateral resistance by 31%, 50% and 17%, respectively, according to the findings of a Single Tie Push Test (STPT). Ballast supports often fail to ideally cover the sleeper bed. Thus, the lateral resistance of four different types of sleepers (i.e., HA110, winged, middle-winged, and B70) under four different support conditions (i.e., lack of rail seat support, full support, lack of center support, high center binding) with/without shoulder and crib ballasts was investigated by discrete element method (DEM). The results revealed that winged and HA110 sleepers showed similar behavior in providing the lateral track resistance without considering crib and shoulder ballasts in the absence of center and high center binding support conditions, while winged sleepers exhibited the highest lateral resistance in the presence of crib and shoulder ballasts in full support, lack of rail seat support, and lack of center support.