Assessment of seismic deformations of geosynthetic reinforced soil (GRS) walls in literature has dealt with unsolved challenges, encompassing time-consuming analyses, lack of probabilistic-based analyses, ignored inherent uncertainties of seismic loadings and limited investigated scenarios of these structures, especially for tall walls. Hence, a novel multiple analysis method has been proposed, founded on over 257,400 machine learning simulations (trained with 1582 finite element method analyses) and numerous performance-based fragility curves, to promptly evaluate the seismic vulnerability. The conducted probabilistic parametric study revealed that simultaneously considering several intensity measures for fragility curves is inevitable, preventing engineering judgement bias (up to 52% discrepancies in damage possibilities). Up to 75% contrasts between failure possibilities of 8 and 20 m walls, especially under earthquakes with common intensities (e.g. PGA <= 0.3g), raised serious concerns in the application of height-independent designing methods of GRS walls (e.g. AASHTO Simplified Method). Decreases in deformation possibilities were nearly the same due to increasing reinforcement stiffness (J) (1000 to 2000 kN/m) and reinforcement length to wall height ratio (L/H) (0.8 to 1.5); a decisive superiority of J variations over increasing L/H, as a remedial plan. The proposed methodology privileges engineers to swiftly assess the seismic deformations of multiple GRS walls at the design stage.

This study conducted five centrifuge model tests to investigate the deformation characteristics of the Geosynthetics Reinforced Soil (GRS) abutments under vertical loads, considering the setback distance ab and beam seat width B as two major influencing factors. Test results show that a linear correlation existed between the maximum lateral facing displacements DL and the maximum settlements at the top of the GRS abutments Dv. The ab and the B had different effects on the deformation characteristics of the GRS abutments as well as the relationship between the DL and the Dv. The total volumetric strains of the GRS abutments were smaller than 0.3% for all the cases investigated in this study, indicating that it was reasonable to use the assumption of zero-volume change for the deformation calculation of the GRS abutments. This study proposed an improved semiempirical method to describe the relationship between the DL and the Dv. Centrifuge test results and data collected from the literature were used to validate the improved method. It was concluded that the improved method had the advantage of considering the effects of the ab and the B separately and therefore significantly improved the prediction accuracy of the deformations of the GRS abutments.

Traffic-induced cyclic loading generates repetitive stresses and cumulative deformations on the GRS abutments, which affect the serviceability of GRS abutments. To evaluate the stress distribution of GRS abutments under cyclic traffic loading, this paper presents reduced-scale GRS abutment models constructed with sand backfill and geogrid reinforcements. The GRS abutment models were subjected to staged cyclic loading with different cyclic loading amplitudes to investigate the influences of cyclic loading amplitude, bridge superstructure load, and reinforcement vertical spacing on the dynamic soil stress distributions. The results indicate that the increase in residual stresses due to stress redistribution induced by cyclic loading is most pronounced at the top of the abutment, while there is little stress redistribution down to the foundation level. Increasing the static load of bridge superstructure or the amplitude of cyclic loading results in an increase in the incremental dynamic vertical soil stresses. Reinforcement vertical spacing does not significantly impact the incremental dynamic vertical soil stresses under cyclic loading, while the cyclic load has the most significant influence. Closer reinforcement vertical spacing could provide stronger lateral confinement, resulting in larger dynamic lateral soil stresses behind wall facing.

This paper presents an experimental study on reduced scale geosynthetic reinforced soil (GRS) abutment models subjected to cyclic traffic loading, aimed at investigating the influences of cyclic load amplitude, self-weight of bridge superstructure, and reinforcement vertical spacing on the cumulative deformations. The GRS abutment models were constructed using sand backfill and geogrid reinforcement. A static load was first applied to account for the self-weight of bridge superstructure, and then the cyclic loads were applied in several phases with increasing amplitude. The results indicate that significant cumulative footing settlement under cyclic loading mainly occurs within the first few hundred loading cycles, and the settlement increases with increasing cyclic load amplitude. The cyclic load amplitude and reinforcement vertical spacing have significant impacts on the cumulative deformations of GRS abutments under cyclic loading. The maximum facing displacement under cyclic loading occurs near the top of the wall. The cyclic load has a greater impact on the reinforcement strains near the upper middle reinforcement layers, while it has a smaller impact on the lower reinforcement layers.