Centrifuge and Numerical Model Studies on the Behaviour of Soil-Nailed Slopes with and without Slope Facing

Abstract

This paper evaluates the significance of slope facing on the stability and deformation behaviour of soil-nailed slopes subjected to seepage. A short series of centrifuge tests was performed to study the behaviour of 5V:1H soil-nailed slopes with and without slope facing by maintaining the model slope height (240 mm) with horizontal back slope, nail inclination of 10º with horizontal and model nail spacing of 60 mm x 60 mm constant at 30 gravities. Effect of flexible as well as stiff facing on the performance of soil-nailed slopes was also studied. All models were instrumented with displacement and pore water pressure transducers and markers were digitized to arrive at displacement vectors with rising ground water table during centrifuge tests. It was observed that the slope facing prevents the local failure of the soil between the nails. Soil-nailed slope without facing was found to experience face failure due to bearing failure at slope surface and nail head surface as well as due to built up of excess pore water pressure at the toe region after 8.5 days of the seepage. Soil-nailed slope with woven geotextile (flexible) facing experienced 0.18 m of crest settlement and bulging of facing was observed in between nail heads. However, a soil-nailed slope with an aluminium facing was found to sustain large settlements and showed improved deformation behaviour at the onset of seepage. Further, finite element analyses of the slope models with and without slope facing were found to be in good agreement with those of physically observed centrifuge test results.