The investigation of the impact of geosynthetics reinforced unpaved roads using plate load tests and finite element method

This study investigates experimental and finite element (FE) analysis to examine the effect of geogrid reinforcement for unpaved sections with weak subgrade. The experimental results of 47 static plate load tests performed at the Louisiana Research Transportation Center indicated a permanent deformation reduction, from 8% to 50%, by inserting geogrid as a reinforcement layer. The finite element simulations confirmed these results by demonstrating improved stress distribution and reduction in vertical permanent deformation. Geogrid installed at the upper one-third of the base layer performed better than other configurations and provided maximum settlement reduction and better load-bearing capacity. The results indicated that optimal reinforcement arrangements could reduce settlement by as much as 50% and elevate the bearing capacity ratio (BCR) to a maximum of 2.2. The results illustrate the importance of reinforcing modulus, placement depth, and base course thickness in enhancing the performance of unpaved road systems. A parametric study for unpaved finite elements was performed, including geosynthetic tensile modulus, placement depth, subgrade strength, number of layers, and base course thickness. The highest performance was RS580i (2000 kN/m), which reduced settling by 50% and had a BCR in the range of 1.5–2.0. Geosynthetic in the base course's upper third maximizes single-layer reinforcement and reduces settlements by 50% and BCR to 1.4–1.8.