Optimum Design for Soil Nailing to Stabilize Retaining Walls Using FLAC3D

Abstract

The behavior of a reinforced soil system depends on parameters such as the structural geometry, execution steps, density and mechanical properties of the soil, density of reinforcement materials, deformation, and flexural stiffness of reinforcement materials. A critical parameter in the design of a soil-nailed system is the optimal use of materials with respect to cost. It is necessary to find an optimal design that is cost-effective within the parameters affecting the behavior of the nailed system. A common problem in nailed excavations is an increase in the excavation depth beyond the initial design of the wall, which will require more reinforcements. In this research, we used one approach not used before the method is placing one and two rows of long nails placed at the appropriate depth. In this study, a comparison between safety factor, horizontal displacement, and lateral pressure behind the wall has been made at two nail placement depths using FLAC3D finite difference software that reveals the optimal depth for efficiency is approximately at the middle of the finished wall height. When the number of reinforcement nails with the same lengths was considered, the installation of two rows of nails in comparison with 5 or 3 rows of nails reduced the maximum wall displacement to a greater extent. A greater factor of safety was achieved.

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