Investigation of drainage function of geosynthetics for basal-reinforced embankments

Abstract

This study investigates the behaviour of basal-reinforced embankments under seepage flow. For this purpose, physical embankment models with dimensions of 195 cm long, 100 cm wide and 110 cm high were constructed in the laboratory. The seepage gradient within the embankment was generated by applying a constant water head of 100 cm at the water compartment located behind the models. The unreinforced embankment experienced seepage erosion at the toe section which triggered deep-seated global failure. Due to the limited transmissivity of the non-woven geotextile, the geotextile-reinforced embankment exhibited similar pore-water pressure distribution to that of the unreinforced embankment, which resulted in lateral spreading failure between the base of the embankment and the non-woven geotextile. In contrast, the geocomposite drain, which has a higher in-plane flow capacity compared to that of the geotextile, significantly alleviated the pore-water pressures within the embankment. The behaviour of the physical models was verified numerically by variably saturated flow modelling conducted for a wide range of in-plane permeabilities for the basal reinforcement. The effect of increasing in-plane permeability of the basal reinforcement layer on pore-water pressure reduction was quantified irrespective of the geosynthetic type.