Influence of slope geometry and nail parameters on the stability of soil-nailed slopes

Abstract

Soil nailing is one of the in-situ soil reinforcement techniques that have been used for the past four decades. The stability of a soil-nailed slope is closely related to slope geometry and nail parameters. This paper presents a parametric study on various factors influencing the overall stability of soil-nailed slopes. Stability analysis was performed to study the effect of slope geometry, nail parameters and effect of rising water surface within the slope on the overall stability of soil-nailed slopes. The stability of soil-nailed slopes is considered in terms of a factor of safety. The slope geometry varied for the present study includes slope inclination and back slope inclination while the nail parameters include nail inclination, nail length, nail length pattern, and nail layout (horizontal spacing). The study shows that with horizontal back slopes, the optimal nail inclination (α_<i>opt</i>) increases with the decrease in slope inclination but it increases with an increase in back slope inclination. Two nail length patterns: Pattern 1, nail length decreasing with depth of the slope and Pattern 2, nail length increasing with depth of the slope have been studied. Pattern 1 is found to be effective for a 10.2 m high slope whereas Pattern 2 is found to be effective for 7.2 m high slope. Rising water surface within the slope, increase in horizontal spacing and decrease in length of the nail reduce the overall stability of a soil-nailed slope. Contribution of nails to the overall stability of soil-nailed slopes is different and found to be dependent on their location and inclination with respect to the slip surface.