Spudcans as foundations for offshore jack-up rigs - Problems and calculation methods

Spudcans as foundations for offshore jack-up rigs - Problems and calculation methods For the installation of wind parks jack-up rigs can be used. Jack-up rigs are founded on the seabed before start of operation to receive sufficient stability and to reduce wave induced influences. One possible foundation for jack-up rigs on the seabed is the so-called spudcan. A spudcan is a circular foundation attached to the legs of the jack-up rig to transfer the vertical loads into the ground. The use of spudcan-foundations is state-of-the-art in the oil- and gas industry. Nevertheless, the design of this type of foundation is still challenging. For example, the correct determination of the load-settlement-response with respect to different soil conditions is complex and the definition of the safe side is not always clear. Another problem related to the spudcan depositioning onto layered soil is the so-called punch-through-failure. This means that during installation onto dense sand overlying weak clay the spudcan may suddenly punch through the sand layer into the weaker layer. This can even lead to a total loss of the jack-up rig. In this contribution, different methods for spudcan design recommended in literature and international guidelines are summarized. Furthermore, open questions and results of ongoing research are discussed to give the reader an impression of the capabilities and the difficulties regarding spudcan foundations.