Drainage performance of wicking geotextiles under rainfall and capillary rise conditions

Wicking geotextiles have been developed to overcome the limitations of conventional geotextiles in unsaturated soil conditions. Over the past decade, research has demonstrated the effectiveness of woven wicking geotextiles in draining capillary water and improving lateral drainage. However, the performance of nonwoven wicking geotextiles under different drainage conditions remains largely unexplored. This study assesses the effectiveness of nonwoven wicking geotextiles in various unsaturated soils using soil column and soil box tests to simulate capillary rise and rainfall, respectively. In the column test, clayey sand was used to evaluate capillary rise, while the box test examined two subgrade materials: Ottawa sand (well-draining) and clayey sand (poorly draining). Volumetric water content was monitored under three conditions: wicking geotextile, non-wicking geotextile, and a control with no geotextile. Results indicate that the wicking geotextile significantly restricts capillary rise, reducing it by around 100 mm in clayey sand columns. After rainfall, wicking geotextile prevents water accumulation above the geotextile and enhances drainage efficiency in both sand types, with superior performance in Ottawa sand. By limiting upward water movement and promoting effective drainage, the wicking geotextile mitigates moisture-induced instability risks in embankments, offering substantial advantages over conventional geotextiles for geotechnical drainage applications.