Análise experimental do comportamento hidráulico-mecânico de muros em solo residual reforçado com geogrelhas

Abstract

The behavior of geosynthetic-reinforced soil walls under wetting conditions induced by climatic events represents a significant challenge, especially when fine-grained soils are used as backfill. This study aimed to experimentally investigate the hydro-mechanical behavior of geogrid-reinforced soil walls constructed with low-permeability residual soil and subjected to different rainfall and inundation regimes in large-scale tests. In addition, the study sought to evaluate construction elements capable of mitigating the effects of wetting. A design methodology for walls under unsaturated conditions was also proposed, accounting for the influence of rainfall events. Four physical models were constructed and tested, varying the internal drainage conditions, facing type, vertical spacing between reinforcements, and geogrid stiffness. The results indicated that, although matric suction decreased after rainfall events, a residual suction was maintained at levels sufficient to limit deformation mobilization and reduce tensile forces in the reinforcements. Evaporation during dry periods played a fundamental role in the partial recovery of suction levels. It was found that the use of sand cushions as internal drainage systems favored the redistribution of loads from the connection to the soil mass, while gabion facings although highly permeable resulted in larger displacements due to their lower stiffness. Reducing the vertical spacing between reinforcements proved to be the most effective strategy for controlling excessive displacements and deformations, even when lower-stiffness geogrids were used. Comparisons among the models showed that the smallest reinforcement spacing provided the best overall performance under rainfall and inundation, whereas models incorporating drainage elements exhibited intermediate behavior. Finally, the applicability of different tensile load prediction methods was evaluated, and the Kru method, proposed in this research, demonstrated the best agreement with the experimental results, as it incorporates unsaturated conditions and their effects on reinforcement mobilization.