Systematic review of gabion-faced geogrid and pile systems for slope and embankment stability

Slope instability is a major geotechnical hazard intensified by rainfall infiltration, seismic loading, groundwater fluctuations, and human disturbances. Composite reinforcement systems-such as gabion-faced geogrid walls combined with piles or geosynthetic-encased columns (GECs)-are increasingly implemented to address multi-hazard conditions. This study presents a PRISMA-guided systematic review of empirical, numerical, centrifuge, and field investigations on hybrid slope-stabilization systems. The review advances prior work by explicitly incorporating multi-field coupling and soil-structure interaction (SSI) terms into the search strategy, applying transparent screening and data-extraction procedures supported by a reusable metadata codebook, and conducting cross-study triangulation across field evidence, centrifuge modelling, and 2D/3D numerical analyses. The synthesized evidence shows that hybrid systems can significantly enhance slope performance, with reported improvements of up to ∼45 % in factor of safety and >30 % reduction in settlement, depending on reinforcement configuration, soil conditions, and coupled rainfall-seismic effects. The study further highlights current limitations in optimisation practice, long-term monitoring, and design standardisation, and outlines directions for uncertainty-aware and performance-based slope design.