Design of Stable Concave Slopes for Reduced Sediment Delivery

Abstract

Constructed slopes are traditionally given a planar form. However, natural slopes are more likely to be concave in cross section. In addition, laboratory and computational studies have demonstrated that concave slopes yield less sediment than planar slopes. With current autoguided construction equipment, it is now possible to construct slopes with concave profiles and a more natural appearance, yet a simple method to describe such concave slopes for a given level of mechanical stability does not exist. This article begins with an examination of concave shapes satisfying a desired degree of stability and compares results with those from the FEM and limit-equilibrium method of analysis. An erosion model is used to demonstrate that the concave slopes proposed here yield 15–40% less sediment than planar slopes with the same factor of safety. Finally, a sensitivity analysis suggests that reasonable construction deviations do not compromise the stability of typical concave slopes.