Influence of rainfall and drying periods on the performance of a large-scale segmental GRS wall model built with poorly draining local soil

Abstract

The use of poorly draining local soils as backfill material in geosynthetic reinforced soil walls has become a common practice despite the known risks. With climate change effects, it is crucial to understand how these structures will perform under such extreme conditions. In this study, the performance of a large-scale model of a modular block geogrid-reinforced soil wall, using fine-grained backfill material, is evaluated under varying simulated rainfall intensities and drying periods. The model was constructed in a laboratory environment, enabling the implementation of an extensive instrumentation program designed to monitor soil suction, volumetric water content, and the resulting deformation and reinforcement strains. Tensile loads mobilized by the geogrid within the backfill soil and at the connection with block wall facing are discussed in the paper. The study demonstrates the satisfactory performance of a poorly draining reinforced soil wall even after prolonged and intense simulated rainfall. The low hydraulic conductivity of the well-compacted backfill soil, combined with significant surface runoff, helped maintain low levels of soil suction which reflects in apparent cohesion. Drying periods led to varying but significant rates of suction recovery influenced by rainfall-drying patterns. The findings indicate that rainfall intensities of 10 mm/h (240 mm/day) for over 7 days were insufficient to fully eliminate suction in a poorly draining geogrid-reinforced wall.