Effects of strain softening on the penetration resistance of offshore bucket foundation in nonhomogeneous clay

The concrete-made bucket foundations were employed as emerging solution to support the wind turbine or breakwater, where the relatively large thicknesses of skirts and the strain softening effect related to the soil sensitivity and ductility were necessary to be explicitly accounted for. However, few of current study concerned this topic. This paper therefore reported an extensive parametric investigation of penetrating behaviour for bucket foundation in nonhomogeneous clay to allow a better estimation of penetration resistance of bucket foundation. The three-dimensional (3D) large deformation finite element (LDFE) analysis model incorporating the effect of strain softening on soil strength was set up and validated by comparing to the published centrifuge data. Then the evolution of soil flow mechanism and the distribution of soil strength softening were examined with the soil plug generated inside skirt assessed. Based on the numerical results, a new analytical model was proposed to predict the penetration resistance of bucket foundation in clay accounting for a partially-remoulded condition. •The penetration of bucket foundation was investigated by CEL large deformation analyses with the strain softening soil model.•The soil flow mechanism and the strength softening during penetration were examined with the soil plug inside the skirt.•A new analytical model was provided to estimate the penetration of bucket foundation in the partially remoulded clay.