Optimisation of gravity retaining walls under bounded uncertainties

The article presents the optimisation of gravity retaining walls under bounded uncertainties using Differential Evolution method. This problem is a two-level optimisation, i.e. main loops for the objective function optimisation and inside loops for the most disadvantaged circumstances of constraints, which are the wall sliding, the wall overturning and the soil bearing capacity. The uncertainties are of the surcharge intensity, the backfill soil and the ground soil properties. Since the constraints are continuous and monotonic functions of uncertainties, the search of the worst condition of constraints in inside loops can limit at vertices of the feasible region defined by the lower and upper bounds of uncertainties instead of the whole region. Four cases of the wall heights are illustrated for this approach.