Stability of slopes with berms on rigid foundations

The finite element method was used to assess the influence of berms on the stability of slopes resting on rigid foundations for three different slope angles. Both purely cohesive soils and soils exhibiting cohesive and frictional strength properties were considered. The results of the analyses are presented in non-dimensional graphical and tabular form for design purposes and show that, for each case considered, there is a unique (berm width):(slope height) ratio after which further increases in the berm width produce no further increases in stability. Example design calculations are presented and validated using Bishop's simplified method.