Soil nailing is an in-situ reinforcement technique that has been widely used in the stabilisation of slopes and excavations by retaining in-situ soils with metallic bars or relatively small fully bonded inclusions. Soil nails are normally subjected to tension, shear forces and bending moments across the potential soil slip planes, between the active and stable zones. Field measurements were made on the lateral deflection of the wall supported by driven steel tubes and soil deformation parameters were back analysed. This paper is an attempt to investigate the possible working mechanism using finite element analyses and the significance of bending stiffness of soil nails in an excavation in soft residual soils. Finite element analysis and measured field data indicated that bending moment has a significant role in restraining the lateral displacement of the wall during the excavation process and possibly at its ultimate limit state as well. The outcome of this investigation is that lateral bending has significant effects as the reinforced soil approaches failure and analytical procedures developed should accurately mimic the progressive change in the working mechanisms.
The use of soil nailing in excavations and slope stabilisation has gained wide acceptance in Southeast Asia, specifically in Malaysia and Singapore due to its effectiveness and huge economic savings. With various development schemes on-going in this region, this method has been extensively used in areas where the soil type is compatible with soil nailing such as residual soils and stiff cohesive soils of low plasticity. Recommendations Clouterre (1993) cautioned the use of soil nailing in soils containing high quantities of clay where moisture content might increase after construction. These restraints is based on the thinking that soft soils will creep significantly over long term and decreased in pullout resistance.