Stability numbers for an unsupported vertical circular excavation in c–ϕ soil

By using an axisymmetric lower bound finite element limit analysis formulation, the stability numbers (γH/c) for an unsupported vertical circular excavation in a cohesive–frictional soil have been generated. The numerical results are obtained for values of normalized excavation height (H/b) and friction angle (ϕ) greater than those considered previously in the literature. The results compare well with those available in literature. The stability numbers presented in this note would be beneficial from a design point of view.