Testing and Modelling of Screw Nailed Soil Slopes

Abstract

This paper aims at testing and numerical modelling of soil slopes reinforced by using screw nails. Two model soil slopes at 45 and 90 with the horizontal are stabilized by inclusion of six screw nails at 0 inclination with horizontal. The screw nailed soil slopes are subjected to an increasing surcharge load at slope crest and their failure mechanism is studied. The present investigation also examines the failure load and displacement, failure surface and volumetric deformation of screw nailed slopes. Numerical modelling of the two screw nailed slopes using limit equilibrium method and generalized finite element analysis method has also been carried out. Factor of safety along with failure slip surfaces has been analysed by limit equilibrium method. Generalized finite element analysis is used with strength reduction method to determine factor of safety and slip surfaces. The slope displacement, failure load and volumetric deformation of these two screw nailed slopes are also studied by generalized finite element analysis method. The model testing results are validated by its numerical modelling. It is found that factor of safety, slip surfaces, load–displacements from testing and modelling are in accordance with slight variations. A comparative study between factor of safety and load–displacement of slopes with smooth nails and screw nails under study is also done. A higher factor of safety and a decrease in slope displacement is observed for screw nailed slopes. With the advantage of ease of installation, the screw nails are found to provide sufficient slope stability for the two modelled slopes. Keywords Testing Modelling Screw nail Slope stability