Effective-stress analysis of berm-supported retaining walls

Earth berms left in place against a wall during bulk excavation can provide an effective means of enhancing the stability and reducing the displacement of an embedded wall. Stability calculations for an earth berm supported wall will often need to be carried out using effective stress ( rather than total stress) analysis representing long-term or drained ( rather than short-term or undrained) conditions. In this paper, a multiple Coulomb wedge analysis using effective stress soil parameters is used to estimate the pressure distribution on the wall as the result of the presence of the berm. Its use in limit equilibrium wall stability calculations is compared with two commonly used empirical methods of representing a berm in such an analysis. It is shown that the raised effective formation method of representing a berm-which gives good results in an undrained or total stress analysis-is unconservative for an analysis using effective stress soil parameters, and a modified raised effective formation method is proposed.