ABSTRACT
Suction installation topics resemble those for shallow foundations, whereas those for intermediate offshore wind turbine monopile foundations are essentially the same as piles. Intermediate suction foundations are installed by a combination of self-weight and suction/pumping, and the top plate vent is open. During installation, tilt is small, generally less than 5° at final penetration. In addition, twist is essentially zero. Hence, a simple resistance model is used for penetration, namely an axially coring (unplugged pipe pile) model. Installation assessments assume that both load and resistance act centrally and that the foundation “cores” through the various soil layers during installation, i.e. it remains vertical. However, foundations may possibly tilt (become non-vertical) and/or twist (misalign in plan). Platform-type support foundations, especially if superstructure is braced, are normally not problematic regarding tilt and twist. Vibratory installation can provide an alternative to reduce the noise emission during monopile installation as vibro hammers are much less noisy, such that costly noise-mitigation measures are not necessary.
