This study employs 2D finite element modeling using Plaxis to investigate the behavior of the railway embankment constructed on the active Ganges-Bramhaputra floodplain. The parametric study considers three different train speeds, 100, 120, and 170 km/hr, and two different soil profiles along different chainages, chainage 82 km+183 m (Ch1) and 84 km+102 m (Ch2) of Padma Bridge Rail Link. Pseudo-static trainloads have been applied and the settlement of the ballast bottom (BB) and embankment bottom (EB) have been determined and compared along with the factor of safety (FS). From the obtained results, the maximum settlement of EB in Ch1 ranged between 27.45 cm to 29.2 cm which is lower by 9.2 cm from Ch2 on average. For BB, greater settlements have been observed as they varied between 33.25 cm to 36.20 cm for Ch1 and 42.80 cm to 45.31 cm for Ch2. Thus in both cases, Ch2 shows greater settlements. Also in both chainages, the settlements exceed the allowable range. As the train speed increases from 100 to 170 km/hr, the increase in the settlement is noticeable for the ballast bottom but not for the embankment bottom. Considering the FS, the embankments are assessed to be safe in all considered cases with an FS> 1.2, without any significant effect of train speeds.

The displacement, stress, and strain distributions of railway embankments on the soft deltaic deposit of the Ganges–Brahmaputra floodplain are investigated. A numerical model developed in general-purpose finite element software is used to simulate the design train load on a deltaic deposit for a 100 km/hr rail speed. The numerical analysis analogy is grounded in the spring model, where a beam under the unit load is modeled based on the Winkler foundation model concept. In the moving load simulation on soil, the static point load relating to the axle load is assigned in the form of a dynamic multiplier, determined using auxiliary software. The calculated shear force in terms of the influence line is applied as a dynamic multiplier. The numerical results demonstrate that under a dynamic train load, the loose ballast undergoes larger and more erratic displacement than the subballast. Comparative analysis between varying subballast stiffnesses shows that stiffer subballast yields smaller displacements. Moreover, a high subballast stiffness can counterbalance the potential of forming permanent deformation by generating lower strains. However, a stiffer subballast does not play a prominent role in reducing the displacement of ballast or vertical stresses. The subgrade is found to carry the maximum load, withstanding the maximum vertical stress; thus, the importance of using an improved subgrade with higher stiffness is also observed. A greater subgrade stiffness improves its load-carrying capacity but fails to reduce the tension responsible for the lateral spreading of the soft subsoil. To reduce the high radial strain, the effects of improving the stiffness properties of two immediately adjacent soft soil layers are numerically investigated. The improvement of subsoil alone is effective in reducing the radial strain, whereas the improvement of both subgrade and subsoil produces further reductions. The critical train speed generating the maximum displacement is identified as 120 km/hr, and the dynamic velocity amplitude decreases with depth. Finally, an allowable limit of rail embankment settlement on a soft deltaic deposit is observed.