Akademik Veri Yönetim Sistemi
Transportation Geotechnics, cilt.37, 2022 (SCI-Expanded)
© 2022 Elsevier LtdIt is well known that the moment distribution on the sleepers is very sensitive to deformations of the ballast caused by cyclic axle load over time and other environmental factors. To limit the non-uniform deformations of the ballast, reinforcement of the ballast or sub-ballast with geosynthetics can be a cost-effective solution. In this study, B70 prestressed concrete sleepers were tested under static loading conditions in a special test box developed to simulate the in-situ condition of a railroad track in the laboratory. The main test parameters were the degree of settlement of the ballast and the type of geosynthetics used. Four different settlement levels and two reinforcement types (sub ballast with geonet and ballast with geocells) were considered. The deflections and surface strain maps of the concrete sleepers were measured using the two-dimensional digital image correlation (2D-DIC) method. Following the experimental part, an analytical study was also carried out to investigate the ballast pressure distribution and consequently the moment distribution on the concrete sleeper. Based on the vertical deflection shape of the sleeper, a new algorithm was developed to derive the ballast pressure distribution under the sleeper by back calculation. The experimental results showed that using geocells to reinforce the ballast layer increased the stiffness of the ballast against the vertical deflection of the sleeper. From the analytical results, the magnitude of the negative bending moment increased significantly with increasing settlement level.