Effect of internal drainage on deformation behavior of GRS wall during rainfall

Global warming-induced changes in the pattern and amount of precipitation are important from the viewpoint of long-term stability of geo-structures. In this paper, the effectiveness of in-plane drainage provided by permeable geosynthetic reinforcement was evaluated as a means to relieve the rainfall infiltration effect on GRS walls backfilled with marginal soil. A series of laboratory tests were performed using a reduced-scale model geosynthetic reinforced soil (GRS) wall (constructed with due consideration of the similitude law) with different rainfall characteristics and backfill soils. Layers of nonwoven geotextiles were used as reinforcement as well as in-plane drainage media. The results showed that the inclusion of internal drainage facilitated the dissipation of pore water pressure, thereby reducing the wall facing displacement. The discharge water volume and volumetric water content data measured in the reinforced soil zone supported the observation. The degree to which the internal drainage improves the deformation behavior of the GRS wall during rainfall was found to depend on the rainfall characteristics and the backfill soil type. Practical implications of the findings are discussed in detail.