Lateral Displacements of Geosynthetic-Reinforced Soil Walls in a Tiered Configuration

Current design methods for geosynthetic-reinforced soil (GRS) walls in a tiered configuration mostly focus on wall stability by determining required tensile strength and layout of reinforcement. A finite difference numerical model was firstly verified with the available field measured results of a single GRS wall and model test results of a two-tiered GRS wall in the literature, and then used to analyze lateral displacements of multitiered GRS walls with modular concrete block facing. A parametric study was conducted to evaluate the effect of backfill properties (friction angle and cohesion), elastic modulus of foundation soil, reinforcement parameters (stiffness, spacing, and length), and tiered wall geometry (offset distance, number of tiers, and height ratio of adjacent tiers), on facing lateral displacements of multitiered GRS walls. The numerical results showed that an increase of the shear strength of the backfill by its friction angle or cohesion reduced the wall lateral displacement. An increase in the reinforcement length of the upper tier in the two-tiered wall from 0.35 times to 0.60 times the total wall height resulted in approximately 21.3% and 34.7% reduction in the maximum lateral displacements for lower and upper tiers, respectively. The reinforcement stiffness and spacing had a significant impact on facing lateral displacements whereas the ratio of reinforcement stiffness to spacing had a negligible influence. An increase of the offset distance or a reduction of the number of tiers remarkably reduced wall facing lateral displacements. An analytical solution was developed for estimating the lateral displacement of a two-tiered GRS wall and compared well with the numerical results.