## 5 Conclusions  
Soil nailing system is a ground improvement method used to stabilize the soil slopes. The study presents the laboratory investigation of earth nailing system models of non-cohesive soil having various soil and building foundation parameters. The laboratory models are prepared to have three soil types with different relative densities, i.e., 35%, 48%, 69%, two angles of slope, i.e., 40\({}^{\circ}\), 45\({}^{\circ}\), two footing widths, i.e., 150 mm and 200 mm and four positions of building foundation from the upper slope corner, i.e., 75 mm (0.5 B), 150 mm (B), 225 mm (1.5 B), 300 mm (2 B). The displacement of the slope, force in the nail, settlement of the footing and the earth pressure in back-fill soil due to different soil and footing parameters (relative density, slope angle, footing width, footing position) are measured. The following conclusions may be drawn from the present study:  
* The maximum lateral displacement and slope face horizontal pressures occur in the middle third and minimum lateral displacement, and slope face horizontal pressures occur in the lower third of slope with different soil and footing parameters under various footing pressures. Figure 35: Effect of soil density on the vertical stresses under the nailed soil mass at mid-point; (**a**) numerical model; (**b**) laboratory model. * The lateral movement of slope and footing settlements reduces with an increase of soil density and decreases with an inclination of soil slope. The increase in footing width increases the slope face displacement and footing settlement. The increase in strip footing distance from slope crest reduces the slope face displacement and footing settlement. * The vertical and horizontal pressures behind the soil mass are unaffected during the construction process but begin to increase with the increase in the footing pressure. The distribution of vertical stress under the soil mass away from the slope part remains constant during various construction stages, and under different loading stages, the vertical stress under the soil mass is increased with an increase in foundation pressure. * A decrease in soil density leads to an increase in maximum tensile force mobilized in the nails. Increasing the soil slope results in increasing the maximum tensile force of nails at the middle third of the soil slope, while soil slope increase results in a decrease in the maximum tensile force of nails at the lower and upper third of the soil slope. The mobilized tensile forces in nails are increased due to an increase in soil density and a decrease in footing distance from the slope face. * The horizontal stresses at the slope face decrease with the decrease of relative density of soil while they are increased due to an increase in soil slope angle. The horizontal stresses at the slope face increase with the increase of footing width and decrease of footing distance from the slope crest. * The vertical stress under the soil mass is more in high slope soil, denser soil, larger footing and greater distance from slop. The increase in soil density and slope angle results in an increase in vertical stress behind the soil mass and a decrease in the horizontal stress behind the soil mass with the increase of soil density and slope angle. * Increasing the footing width leads to an increase in the vertical and horizontal stress behind the soil mass. The vertical and horizontal stresses behind the soil mass decrease with the decrease of footing distance from the slope crest. Conceptualization, M.H.M. and M.A. ; methodology, M.H.M. and M.A. ; resources, J.M. ; writing--original draft preparation, M.H.M. and M.A. ; writing--review and editing, J.M. ; project administration, M.A. and J.M. ; funding acquisition, M.A. All authors have read and agreed to the published version of the manuscript. Funding Funding for this research was given under award numbers R.G.P2/73/41 by the Deanship of Scientific Research; King Khalid University, Ministry of Education, Kingdom of Saudi Arabia.