Influences of plasticity on a sheet pile phased stochastic FE analysis

The paper deals with the stochastic analysis of the stability of a sheet pile soil structure. Most areas in the Netherlands have layered soil conditions. The decisive parameter in the nonlinear FE analysis is the behaviour of the soil. For layered soil conditions, the correct modelling of the non-linear behaviour of the soil is decisive for the result. Laboratory or in situ tests on the soil give a wide distribution of the material parameters. As a result, a deterministic input for soil material behaviour in an FE analysis is not straightforward. The normal solution is to use partial safety factors. A stochastic analysis is however more in place to analyse soil structures. Recently plane strain 2D FE models are becoming common practice to describe the behaviour of the soil, especially for layered soil conditions. The behaviour of the soil is described with a Mohr-Coulomb model; the interaction of the soil with the sheet pile is modelled with interface elements which behaviour is described with the Coulomb friction model. The full paper describes the FE analysis of the excavation of soil during construction, inclusive the installation of a sheet pile and an anchor. The model includes 3 layers of soil including different water levels and an anchor, which is grouted on the end of the anchor. The analysis is carried out using a 2D plane-strain-model and a full-3D model. A stochastic module is added to a common FE code [1] in order to analyse stochastic structural behaviour. Consequently the excavation is analysed including the stochastic behaviour of the soil. The stochastic analysis results in a probability of failure and in safety factors. The full paper shows the effect of the plasticity regarding to the 2D plane strain and full 3D model.