Three-dimensional be-fe model of bucket foundations in poroelastic soils

Abstract

A three-dimensional BE-FE model for the time harmonic analysis of bucket foundations in poroelastic soils is presented. The soil follows the Biot's poroelasticity and is discretized using the BEM. The skirt of the bucket is modeled as a degenerated shell finite element. The soil-structure interaction is taken into account assuming a crack-like boundary from the soil point of view, where the Dual BEM is applied. It is shown that this simple representation is accurate and efficient. This model is applied to an analysis of the impedances of bucket foundations, where the influences of the foundation geometry and soil properties are studied. The study shows that, when considering realistic seabed soils, a poroelastic model should be used for the low-frequency range (< 1-6 Hz depending on the seabed soil). It is shown that this is particularly true for bucket foundations with small length to diameter ratios.