Analysis of shallow instabilities in soil slopes reinforced with nailed steel wire meshes

A model based on the limit equilibrium method is developed for the analysis of shallow instabilities in soil slopes reinforced with nailed steel wire meshes. Shallow instabilities are associated to ground weathering or shallow water flow affecting a moderate depth, about 10–20% of the slope height. These effects are considered in the analysis as a reduction of the soil strength. The reinforcing mesh is assumed to act as a distributed pressure on the slope surface. The aim is to determine the value of the normal pressure needed to reach a given safety factor against shallow instability. The proposed method is presented first for an infinite slope, leading to a closed form solution. If the height of the slope has to be considered as finite, a second analysis is developed dividing the unstable layer of soil in finite blocks. The result is given as a correction factor to be applied to the infinite slope solution. An application example is used to illustrate the design of practical cases.The results of the limit analysis are compared with finite element calculations. The stabilization effect achieved by the wire mesh is evaluated as the increase of the possible reduction of the soil strength before the slope failure.