Influence of wicking geotextile installation on moisture migration in silt under rainfall infiltration

Silt is widely used in subgrade construction in the middle and lower reaches of the Yellow River in China due to limited availability of high-quality fill. However, its high moisture sensitivity and low strength often lead to pumping, settlement, and deformation. This study investigates the hydraulic performance of a wicking geotextile in silt under simulated rainfall infiltration using one-dimensional soil column experiments. Three installation configurations were evaluated: (i) a control sample (CS) without geotextile, (ii) an embedded sample (ES) with the geotextile fully installed as a capillary barrier, and (iii) a surface-exposed sample (SES) with the geotextile extended to the atmosphere to improve drainage. Suction-volumetric moisture content relationships were monitored at multiple depths, and both water storage capacity and drainage mechanisms were assessed. Results indicate that ES and SES reached stabilization at similar suction thresholds, however, the SES more effectively delayed saturation and facilitated moisture migration by evaporation. Surface exposure induced a relative humidity gradient, generating suction and improving drainage, while a siphon effect redistributed water approximately 25 cm below and 15 cm above the geotextile. These findings confirm that the wicking geotextile can act as a capillary barrier and drainage medium, and provide guidance for silty subgrade design. • Hydraulic behavior of wicking geotextile was investigated in silt under simulated rainfall. • Prior research mainly focused on coarse soils, data for silts remain limited. • Surface-exposed wicking geotextile delayed silt saturation and improved drainage. • Installation configuration influenced suction distribution and water redistribution. • Wicking geotextile exhibited dual barrier and drainage functionality in silt.