Train Live Load Effects on the Subsidence of the Backfill Behind the Sheet Retaining Wall

Live loads generated by trains are a significant load in lateral pressure and settlement calculations. Studies emphasize the meaning of “accurately calculating live loads” to ensure the initial straightness of retaining walls. So, overestimating the effect of live loads generated by trains will lead to an overdesign of retaining walls and the surrounding soil and increase the cost of shoring. However, calculating these loads accurately will result in sufficient reinforcement without the need for excessive design of the retaining walls, leading to a durable design of the train system at a lower cost. In the present work, a laboratory model of a 1/7 scaled railway track was manufactured and employed. The influence of the live load induced by the trains passing on the cumulative settlement of backfill soil behind the sheet retaining walls was studied. Many parameters were studied, consisting of different burden amplitudes (0.22, 0.44, and 0.66 tons), vibration frequencies (2, 4, and 6 Hz), relative density (30% loose, 55% medium, and 75% dense sand), and different distances between the railway and retaining wall (0.5H, 1H, and 1.5H). The results showed that under the same cyclic burden amplitude, increases in the backfill relative density significantly impacted the dynamic settlement of the railway. The cumulative dynamic settlement ratio decreased as the horizontal distance between the railway and the retaining wall increased. The cumulative dynamic settlement ratio decreased by about 27.8% and 18.3%, as the railway location relative to the retaining wall changed from 0.5H to 1H and 1H to 1.5H, respectively. Dynamic settlement decreased as frequency increased when the conditions were kept constant. The settlement ratio increased with the live loading amplitude. Finally, dense backfill soil acted more efficiently than the medium soil, reducing the railway settlement and improving the overall behavior of the railway track adjacent to retaining walls.