Effects of Multitiered Configuration on the Internal Stability of GRS Walls

Design guidelines for geosynthetic-reinforced soil (GRS) walls in a tiered configuration are often limited to two tiers with zero batter. To facilitate rational expansion of current design, this paper extends the current top-down procedure, based on limit equilibrium analysis, from single GRS walls to multitiered walls. For a given factor of safety, the required reinforcement tension distribution and connection load are determined for each reinforcement layer. The approach considers the impact of potential compound failures. Parametric studies are conducted to investigate the influences of backfill soil, wall geometry (i.e., wall batter, number of tiers, and offset distance), and reinforcement layout. The results demonstrate quantitively that increasing the internal friction angle of backfill soil, wall batter, number of tiers, and offset distance reduce the required maximum tension. The tiered configuration in GRS walls leads to localized increase in connection load at the toe elevation of each tier. Using close reinforcement spacing could significantly reduce the connection load. The critical offset distance is realized when the reinforcement in each tier acts internally independent of others. Its value decreases with increasing the internal friction angle of backfill soil, wall batter, and number of tiers. The observations in this study are significant in the context of optimal design of multitiered GRS walls.