Effect of nail Arrengment on Stability and Performance of Soil Nailed Walls

Nowadays, soil nailing is a common method of excavation stabilization which its design is based on the arrangement of nails along the wall height. Nail arrangement is typically selected by a trial and error approach among different arrangements which satisfy allowable stability safety factor and allowable deformation. In This Study, by considering the decreasing trend of nail length along the wall height, an ordered arrangement is introduced by presenting “L” as base nail length and “” as inclination of stabilized zone border and the effect of nail arrangement on safety factor and deformation of nailed wall is investigated. Also, by introducing nail density per unit area of wall surface (Dn), its effects on soil nail wall behavior is studied in each arrangement. The results show that by increasing L and safety factor increases and wall top deformation decreases. It’s also recognized that safety factor and deformation values, apart from arrangement parameters, are Proportionate and corresponding to the nail density key parameter. It was also found that with an increase in nail density, safety factor increases and deformation decreases but these trends will decline in a specific nail density which is called the effective nail density. By investigating wall deformation mode in different arrangements, it was found that when  is small, maximum wall deformation occurs in its top and the deformation mode is overturning, while by increasing  and enhancing upper nail lengths, maximum deformation of wall transfers to mid depth of the wall and the deformation mode changes to bulging.