ABSTRACT
Bucket foundations are a promising alternative for foundations of offshore wind energy converters. Jacket structures can be supported by three or four single buckets located in the edges of the foundation’s footprint. For such multipod structures, tensile loading under large wind or wave loads is often the design-driving load case. Under transient loads the soil behaves partially drained or even undrained. Depending on magnitude and duration of the load, negative pore water pressures (suction) occur and a water-filled gap can develop between bucket lid and soil. A numerical model is presented which enables the calculation of the behavior of a single bucket in sand under tensile loading, taking a possible occurrence of a gap between lid and soil into account. It is shown that the magnitude of cyclically accumulated heave strongly depends on the magnitude of the cyclic load and to a smaller extent also on the loading period.
