Soil nailing optimisation: lost opportunities in current practice

This paper analyses 127 cases histories in the US and Europe to evaluate the current state of soil nailing practice with respect to soil nail lengths and density, wall heights, wall inclination, and shotcrete thickness, as well as applications. When the cases are considered by project size and soil type, certain inefficiencies appear. Namely, smaller projects exhibit conservatism in nail density and shotcrete thickness, and use only a fully vertical wall. In contrast on larger projects, there appears to be an optimization of these factors. What appears to occurring is that for smaller projects and/or shorter walls, contractors are adopting conservative rules of practice instead of actually designing the projects in accordance with published design manuals. A single, small case is reconsidered using the Geotechnical Engineering Circular No.7, GEC7 design guide resulting in an estimated 7.2% savings.