AN APPROACH TO LIMIT ANALYSIS WITH CONE-SHAPED YIELD SURFACES

The paper presents an algorithm for limit analysis with mixed approach by finite elements with application to geotechnical problems. The emp hasis is on a special technique to deal with the singularity at the ap ex of a cone-shaped yield surface. The approach is based on the direct application of the sub-differential concept to the flow law and is es sentially different from the Lagrange multipliers technique. The propo sed algorithm does not require the regularization usually adopted for the singularities at the boundary of the plastic admissible stress reg ion that occur in soil models. The case of a Drucker-Prager model is p articularly considered, as well as the Mohr-Coulomb model in plane str ain conditions. The algorithm is applied to a footing and a shallow tu nnel. (C) 1997 John Wiley & Sons, Ltd.