Interlocking Settlement Induced by Widening Subgrade of Railway Line

In areas where it is difficult to secure additional land for railways, a plan to increase rail transport capacity by widening existing embankments is required. When widening the embankment, additional stress is generated at the bottom of the existing embankment, resulting in an additional settlement (interlocking settlement) of the existing embankment. Reinforced subgrade for railways (RSR) is an efficient method for widening embankments without additional sites. In this study, an existing railway embankment in operation was widened using the RSR, with the interlocking settlement evaluated and analyzed during and after construction. Results show that a widened embankment using RSR can secure train operation stability on existing tracks, even in ground conditions including shallow soft layers. The interlocking settlement was mainly affected by the backfill load and hardly affected by the wall load of the RSR. In addition, it was confirmed that the interlocking settlement mainly occurred in the backfill construction and stabilization period of RSR construction and converged early.