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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. [ABSTRACT FROM AUTHOR]

The paper aims to evaluate the pseudostatic seismic bearing capacity of shallow foundations on geosynthetic-reinforced granular soil subjected to inclined/eccentric combined loading. This is achieved through a comprehensive set of lower-bound finite-element limit analysis (LB FELA) simulations adopting the second-order cone programming. The pseudostatic seismic loading is incorporated into the element equilibrium equations as body forces. Both sliding and structural modes of geosynthetic failure are simulated within the FELA framework. The influences of pseudostatic acceleration, embedment depth (u), and the ultimate tensile strength (Tu) of the reinforcement layer on the failure mechanism, bearing capacity ratio, and failure envelope of the overlying obliquely/eccentrically loaded shallow foundation are thoroughly investigated and discussed. It is generally concluded that at a given reinforcement embedment depth, failure envelopes shrink substantially with the increase of the seismic horizontal acceleration and the reduction of the geosynthetic ultimate tensile strength. [ABSTRACT FROM AUTHOR]

In this research, a numerical investigation was conducted to study the effects of backfill constitutive behavior on the vertical and horizontal deformations of geosynthetic-reinforced soil (GRS) piers under static axial loads. A finite-difference program was used to model full-scale GRS piers. The backfill soil was simulated using three constitutive models: the elastic-perfectly-plastic Mohr-Coulomb model, the plastic-hardening model, and the plastic-hardening model combined with strain-softening behavior. The results showed that the deformation response of GRS piers under service loads is satisfactorily predicted by the plastic-hardening model. At ultimate failure loads, however, only the model accounting for the plastic-hardening and the strain-softening behaviors was judged to reasonably capture the behavior of GRS piers. The relative displacement of soil and geotextile at the soil–geotextile interface was also investigated. The results showed that under working conditions with small applied load, there is no sliding between the soil and geotextile; however, as the load increases, sliding is first initiated at the corners of the pier and progressively mobilized toward the center of the pier. A parametric study on the effects of soil–geotextile interface properties on the deformation behavior of GRS piers under axial loading was also conducted using the validated plastic-hardening model combined with strain-softening behavior. It was found that increasing the interface friction angle decreases the settlement of GRS piers when the axial strain is greater than 2% for piers with a concrete masonry unit (CMU) facing and 4% for piers without CMU facing. The results suggest that when calibrating the interface friction angle (or cohesion), the postyielding response of GRS pier should be used. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of the performance of geosynthetic-reinforced soil (GRS) bridge abutments under static loading conditions. Simulations were conducted using a finite-difference program to model the Founders/Meadows GRS bridge abutment during construction and service. Simulated results are in good agreement with field measurements, including displacements, lateral and vertical earth pressures, and tensile strains and forces in reinforcement. The simulations also indicate that horizontal restraint from the bridge structure has a significant influence on abutment deflections. A parametric study was then conducted to investigate the performance of a single-span full bridge system with two GRS abutments, including effects of bridge contact friction coefficient, backfill soil relative compaction, backfill soil cohesion, reinforcement spacing, reinforcement length, reinforcement stiffness, and bridge load. Results indicate that backfill soil relative compaction, reinforcement spacing, and bridge load have the most significant influence on lateral facing displacements and bridge footing settlements for GRS abutments. Differential settlements between the bridge footing and approach roadway were small for all simulated conditions. [ABSTRACT FROM AUTHOR]