TO STUDY THE EFFECT OF SOIL NAILING FOR THE STABILITY OF SLOPES

Abstract

Slope instability poses significant challenges to infrastructure development and environmental safety, often resulting in catastrophic failures with severe social and economic consequences. Soil nailing has emerged as a useful and cost-effective solution for stabilizing slopes and retaining walls. This technique involves the insertion of reinforcement elements, such as steel bars, into the soil to enhance its shear strength and improve overall stability. Despite its widespread application, understanding the critical factors influencing the performance of soil nailing systems remains an area of ongoing research. This research investigates the effect of soil nailing on slope stability by examining key parameters such as soil properties, including cohesion, angle of internal friction, nail spacing, orientation, length, and material properties. The research employs a combination of analytical simulations using PLAXIS Software and experimental analyses to assess the act of soil-nailing systems under various conditions. The slope models were developed using the Mohr-Coulomb failure criterion, incorporating calculated soil characteristics. Slope angles of 30°, 45°, and 90° were analyzed with nail inclinations of 0°, 10°, 20°, and 30° with the horizontal plane and nail lengths of 6m, 8m, 10m and 12m to determine the optimum configuration. The Factor of Safety (FOS) was calculated for the slope under both unreinforced and reinforced conditions. Results indicated that FOS decreases with increasing slope and backslope angles but significantly improves with optimized nail orientation and length. A nail inclination of 10° with the horizontal, a nail length of 8 m and a nail diameter of 6mm were found to be the most effective, yielding a maximum FOS of 1.539. The optimum configuration identified through numerical modelling was validated experimentally using a scaled model at a 1:100 ratio. The physical model was made in a tank with dimensions of 40 cm × 15 cm × 20 cm. The backfill material was sourced from the DTU ground, and basic soil properties such as cohesion and angle of internal friction—were determined to ensure accurate input for slope stability analysis. Static loads were applied at the crest of the slope, and deformations were measured using a magnetic dial gauge.