Application of Discontinuity Layout Optimization to geotechnical limit analysis problems

Abstract

However, whereas finite element limit analysis involves the formulation and solution of a variational continuum mechanics problem, it is possible to alternatively formulate and solve a simpler discontinuum problem. For example, Alwis (2000) has proposed a model which uses rigid triangular elements separated by potential discontinuities. Unfortunately the restriction that discontinuities can lie only at the edges of elements positioned in a fixed mesh leads to a very restricted search space, and hence often to poor computed collapse load predictions. To overcome this a new computational limit analysis procedure has recently been proposed by Smith & Gilbert (2007). With this new procedure, termed ‘discontinuity layout optimisation’ (DLO), the problem is formulatedentirely in terms of lines of discontinuity (e.g. slip or yield-lines), rather than in terms of elements, and the procedure directly generates upper bound mechanisms without the need for operator input. Brief details of the DLO procedure will now be outlined.