Settlement deformation behavior of geogrid-reinforced sandbag revetments under soft muddy geological conditions

Traditional sandbag embankments often fail to meet engineering durability and safety requirements when constructed on soft silty clay deposits. Geogrids, leveraging their exceptional tensile properties, offer significant advantages in soft soil stabilization and present a novel approach for reinforcing sandbag embankments. However, the settlement deformation mechanisms of geogrid-reinforced sandbag embankments under such weak soft geological conditions remain poorly understood. This study conducted a series of laboratory-scale model tests to investigate the settlement and deformation characteristics of geogrid-reinforced sandbag revetments. Subsequently, a numerical model was developed using PLAXIS software and validated against the experimental results to ensure its accuracy. A parametric analysis was then performed to examine the effects of geogrid stiffness, sandbag layer thickness, embankment slope ratio, and embankment base width. The results indicate that foundation settlement increases with embankment height, sandbag layer thickness, and slope steepness, but decreases with increasing geogrid stiffness, which is accompanied by a reduction in geogrid tensile force. Broadening the embankment base transforms the foundation surface settlement profile from a parabolic to a basin-shaped distribution, and correspondingly shifts the geogrid tensile stress distribution from a parabolic to a saddle-shaped pattern. It is recommended that for engineering applications, the geogrid stiffness should not be less than 600 kN/m, and the maximum embankment slope should not exceed 1 ∶2, to effectively control foundation settlement and enhance the long-term stability of the structure. These findings provide valuable theoretical guidance for the design and construction of geogrid-reinforced sandbag embankments in soft muddy geological conditions.