Effect of geogrid spacing on the global stability of reinforced slope: a finite element approach

Accurate estimating of a slope’s safety factor against failure is crucial when considering geotechnical concerns. Landslides, in general, incur significant financial costs, impede mobility, and can result in fatalities in the most severe instances. To design a properly reinforced slope, it is essential to focus on various slope parameters, which lead to failure. In the current investigation, The geogrid reinforced slopes based on various geogrid spacing (0.5 m, 1 m, 1.5 m, 2 m, 2.5 m, 3 m, and 3.5 m) are considered to stabilize the slope. The behavior of a geogrid reinforced slope in terms of factor of safety, deformation, development of internal forces, and shear strain was investigated using 3D numerical analyses by utilizing the finite element program MIDAS GTS NX (340) 2023 v1.1. The Factor of Safety (FoS) for geogrid-reinforced slopes is higher than for unreinforced slopes due to the geogrid providing enhanced tensile strength, which stabilizes the soil. The percentage increase in the Factor of Safety for reinforced slopes with geogrid spacings of 0.5 m, 1 m, 1.5 m, 2 m, 2.5 m, 3 m, and 3.5 m are 79.01%, 88.88%, 90.12%, 89.50%, 86.41%, 82.71%, and 58.64%, respectively, compared to the unreinforced slope (FoS 1.62). Among various configurations, the 1.5 m spaced geogrid (S-1.5) offers the best performance (FOS 3.08), indicating 1.5 m as the optimal spacing for FoS. Additionally, a 0.5 m geogrid spacing significantly reduces the failure region, achieving a 93.2% reduction in total deformation compared to unreinforced slopes due to the increased number of layers. Internal forces predominantly develop in the vertical direction, with higher forces in more widely spaced geogrid-reinforced slopes. Optimal membrane forces between geogrid layers are achieved with 1–1.5 m spacing. The outcomes of this study assist designers in applying the findings to real-world projects.