EFFECT OF STRUCTURAL PROTECTION AGAINST WATER SATURATION OF FOUNDATION SOILS ON RAILWAY EMBANKMENT STABILITY

Abstract

Ensuring the stability of railway embankments under high groundwater conditions is an important geotechnical challenge, as the saturation of weak foundation soils may alter their strength and deformation characteristics and lead to additional displacements of the earthwork. This study aims to numerically assess the stability and deformation behaviour of a railway embankment incorporating an integrated structural solution in which a gravel layer is positioned 0.5 m above the design high-water level and the foundation is reinforced with geosynthetic materials. Numerical modelling was performed using the finite element method in PLAXIS 2D, employing the elastoplastic Mohr–Coulomb model. Stability was evaluated using the Strength Reduction Method under both basic and special load combinations. In addition, the deformation behaviour of the embankment was analysed after 300 days of consolidation. Under the basic load combination, the calculated factor of safety was 1.47, compared with the minimum permissible value of 1.20. Under the special load combination incorporating seismic action, the factor of safety decreased to 1.10, compared with the prescribed value of 1.08. The maximum calculated foundation settlement was 0.151 m, while the maximum horizontal and vertical displacements were 0.280 m and −0.450 m, respectively. The results demonstrate that the proposed structural configuration satisfies the adopted stability criterion under both load combinations, although the special load combination governs the available stability margin. The findings characterise the combined response of the drainage gravel layer, geosynthetic reinforcement, and foundation soils and may support the design of railway embankments under challenging hydrogeological conditions.