Slope Stabilization by Soil Nailing

Abstract

The basic concept of soil nailing is to reinforce and strengthen the existing ground by installing closely spaced steel bars, called “Nails”, into a slope as construction proceeds from top to down. Soil nailing is an in-situ reinforcement technique by steel bars which can withstand tensile forces, shearing forces and bending moments. This process creates a reinforced section that is in itself stable and able to retain the ground behind it. Soil nailing technique is used to support very steep cuts with advantage of strengthening the slope with excessive earth works to provide construction access and working associated with commonly used retaining systems. This technique is commonly used for slope stabilization and retaining walls. Its behaviour is typical and involves essentially two interaction mechanisms: The soil-reinforcement friction and the normal earth pressure on the reinforcement. The mobilization of the lateral (soil-reinforcement) friction requires frictional properties for the soil, while the mobilization of the normal earth pressure requires a relative rigidity of the inclusions. This report presents comprehensive guidelines for evaluating and using soil reinforcement techniques in natural or cut slopes. In the present research work, nails have been inserted at an angle of 20° from the horizontal. The nails were tested on different slopes angles i.e. 45°, 60° and 90°. Two types of nails of length 15 cm have been used i.e. Screwed Nails and Helical Nails. The tests were performed with and without nails and the results reveal that the strength of the soil is increased in all the cases after the insertion of nails but the screwed nails were more effective than helical nails.