Finite Element Analysis of Geogrid Behavior Under a Strip Footing

Purpose. This paper presents a two-dimensional finite element analysis (FEA) aimed at evaluating the effectiveness of multi-layer geogrid reinforcement under a strip footing on clayey and sandy soils. The research quantifies the impact of vertical spacing (h) on bearing capacity, settlement reduction, and stress distribution. Design / Method / Approach. The FEA methodology utilized the Mohr-Coulomb model and interface elements to simulate soil-geogrid interaction. Simulations were performed using Plaxis 2D, with the depth of the first geogrid layer fixed at u = 0.33B, while the vertical spacing ratio (h/B) ranged from 0.1 to 0.5, keeping other geometric parameters constant. Findings. The results confirmed the overall effectiveness of the reinforcement, leading to a significant increase in ultimate bearing capacity and a substantial reduction in settlement compared to unreinforced soil. The analysis identified distinct optimal spacings of h/B = 0.3 for clayey soil and h/B = 0.2 for sandy soil. Theoretical Implications. This research validates the role of geogrids as rigid barriers that modify failure surface trajectories. It provides a detailed understanding of load transfer mechanisms by identifying unique tensile signatures: a “bell-shaped” distribution for clay and an "M-shaped" distribution for sand. Practical Implications. These findings provide concrete design charts, allowing practitioners to optimize the vertical layout of reinforcement layers to ensure maximum efficiency without material waste. Originality. The originality and value of this work lie in the direct and simultaneous comparison of two contrasting soil types under identical geometric configurations, offering a comprehensive perspective on the influence of lithology on geogrid reinforcement. Research Limitations. However, the study has limitations, notably its purely numerical and two-dimensional nature, which restricts direct extrapolation to square or circular footing configurations. Future Research. Future studies would benefit from incorporating laboratory experimental tests to calibrate the numerical models. Article type. Applied Research.