Behavior of back-to-back mechanically stabilized earth walls as railway embankments

Twelve physical model tests were carried out to investigate the role of the type and arrangement of reinforcements on the behavior of back-to-back mechanically stabilized earth walls (BBMSEWs) supporting railway tracks. Six metal-strip reinforced BBMSEW models and six geogrid reinforced models were prepared with different reinforcement arrangements and then were vertically loaded to failure using wooden railway sleepers. The findings indicated that the reinforcement stiffness played a more prominent role in improving the bearing capacity than the pull-out capacity. The connection of two opposing walls with continuous reinforcements and the complete separation of them from each other were found to be the best and worst reinforcement arrangements, respectively, for improving the bearing capacity and reducing wall deformation in BBMSEWs. The respective use of these two arrangements mobilized the maximum and minimum forces in the reinforcements. Moreover, the creation of a proper connection between the opposing walls using continuous inextensible reinforcements or those with a sufficient overlap length were found to be efficient solutions to preventing the propagation of a failure plane across the back-to-back MSE walls.