2007, SEtech (Geotechnical Engineers) Limited, SHeringham Shoal Offshore Wind Farm, Geotechnical Integration Study
series
https://portal.medin.org.uk/portal/start.php?tpc=015_99f337dda68055299e532e4d6eb95575
Scira Offshore Energy Ltd (Scira) propose to construct and operate an offshore wind farm
at the Sheringham Shoal Wind Farm location. The site is located approximately 17km to
23km offshore from the Norfolk coastal town of Sheringham and approximately 5km north
of the offshore sand bank known as Sheringham Shoal. The development will comprise
offshore wind turbines, meteorological mast and transformer platforms in water depths
between 15m and 22m.
A series of investigations have been performed including geophysical and geotechnical
investigations. The geotechnical investigations have comprised shallow seabed
vibrocores and cone penetration tests and composite boreholes to a maximum depth of
70m below seabed. It should however be noted the database of testing is sparse, with
some inappropriate coverage of both seismic and boreholes. There is also limited quality
seismic data at depth.
This report has reviewed the available information and the data has been used to develop
a ground model for the site. This work finds that the geology at the site comprises the
following sequence of soils:
1. Holocene (recent) deposits – generally comprising a thin veneer of gravelly sand;
2. Bolders Bank Formation –predominately firm to stiff clay, typically 10 m thick;
3. Egmond Ground Formation – predominantly dense sand, approximately 5m thick;
4. Swarte Bank Formation – predominantly very stiff clay, variable thickness;
5. Chalk – unstructured occasionally structured chalk present at a variable depth
across the site.
The geotechnical data for the site has been reviewed and collated into the specific soil
units. Based on this work, the variability in each soil unit has been assessed and
geotechnical profiles are presented. The limited database has lead to coarse and
uncertain interpretation and wide ranges for parameter values.
To assist pile design, geotechnical design parameters have been presented for both best
estimate conditions for geotechnical design and upper bound associated with assessment
of pile driving for a series of representative design profiles.
Specific pile sizes are not known at this stage, hence the output of this study is presented
as a series of graphs to enable pile vertical capacity to be calculated and static resistance
to driving (SRD) to be used to assist selection of appropriate pile hammers. p-y curves
have been developed for input into appropriate pile analysis programmes to assist
prediction of the response of the monopole foundation.
20060101 20070328