Investigation on the performance of walls reinforced by helical nails under strip footing loading using physical model test

In the current study, the performance of helical soil-nailed walls (HSNWs) was evaluated under footing loading using reduced-scale model tests. For this purpose, sixteen soil-nailed wall models were constructed with different lengths, patterns and inclinations of the helical nails and then were loaded to failure using the strip footing. The quantitative and qualitative responses of the models to footing loading were identified in terms of the wall displacements, the deformation modes and the bearing capacity of footing. Particle Image Velocimetry (PIV) technique was also used to trace shear bands and identify the failure mechanism. PIV results showed that increasing the nail length, as well as using a square pattern and a 15° angle to install the nails, could be three effective solutions to reduce the penetration depth of the slip surface and, consequently, to limit wedge failure dimensions. Findings also indicated that 15° can be introduced as the optimal inclination for installing helical nails in walls under strip footings to achieve the maximum bearing capacity and minimum lateral wall displacements.