Environmental Engineering Reference
In-Depth Information
measures can be found in, for example, [80]. The reader is referred to [81,82] for the
state of the art regarding scouring design.
Where preparation of the seabed and any potential anti-scouring measures are
undesirable or there is no subsoil with an adequate bearing capacity near the surface
of the seabed, then a deep foundation represents an alternative. Any scouring expected
is then taken into account directly in the design of foundation and piles as for steel
substructures. Extensive measures to prevent scouring are then unnecessary. On the
other hand, a deep foundation involves greater costs for the construction, transport and
erection. Therefore, which type of foundation is the best economic answer for a
particular offshore location must be determined after taking into account all the specific
boundary conditions.
5.4.2.5 Innovations
At the moment, new developments are mainly to be found in the areas of specialising
and optimising the offshore logistics, which is the responsibility of individual
companies. For example, one logistics concept being pursued by Ed. Zublin AG
involves transporting and erecting the concrete support structure, including shaft and
wind turbine, as one complete unit [83]. A “special carrier” is being developed for this
work, which uses semi-submersible technology and therefore overcomes the weather-
related limitations that apply to the heavy-lift crane vessels currently in use. Figure 5.21
shows computer images of the “special carrier” and also the individual steps in the
offshore logistics.
Ballast Nedam is currently developing the concept of a prestressed concrete monopile
[84]. The idea here is that a concrete monopile consisting of precast concrete rings is
assembled on land and prestressed in the longitudinal direction. The monopile is then
floated out to its offshore location (towed by tugs) and then installed with a heavy-lift
Fig. 5.21 Offshore logistics concept of Ed. Zublin AG. [83]
