Gradu uation T Thesis

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Gradu
uation Thesis
T
M
M.Sc.
Offfshore & Dredg
ging Engineering
g
Subm
marine so
oil-struc
cture intteraction
n in offshore win
nd turbines
Introdu
uction
The fund
damental natural
n
fre
equency ass measured
d on installed
offshore wind turb
bines (OWT
Ts) is sign
nificantly higher than
n its
designed
d value, and
a
this is likely tto stem from a poor
p
description of sub
bmarine so
oil-foundattion interaction. In this
respect, while usual
u
OW
WT vibratio
ons do not mobilise
remarkab
ble soil no
on-linearity
y, the pressence of the
t
intersttitial
water iss believed
d to considerably aaffect the foundatio
onal
response
e.
Under fa
ast cyclic lo
oading, no
o soil volum
me variatio
ons take place
until watter is expe
elled from (or sucked
d into) the soil skeletton:
this gives rise to th
he so-called “undrain
ned” behav
viour, which is
globally stiffer tha
an its “fully drained
d” counterrpart. In this
perspecttive, the actual trransient rresponse of OWT
Figure
e: OWTs on monopiles
foundatio
ons will be
b close to either the undrained or
drained limit depen
nding on the
t interplaay of loading frequency and h
hydro-mech
hanical
soil prop
perties (stifffness and permeabil ity).
Aim
The pressent projecct aims at numerical ly explorin
ng the influ
uence of hhydro-mech
hanical
coupling on the vibrational properrties of monopile-b
m
based OW
WTs. A su
uitable
commerccial softwa
are will be employed to setup a two-phase finite ellement mo
odel of
the soil/O
OWT syste
em. The se
ensitivity o
of the OWT
T fundamental frequeency to diffferent
foundatio
onal factorrs will be parametrica
p
ally investig
gated for design
d
purpposes.
Require
ed Skills
The com
mputationall nature off this projeect require
es the stud
dent to posssess reaso
onable
backgrou
und/motiva
ation on nu
umerical m
modelling and computter program
mming.
Superviision
This projject will be
e entirely carried out at the TU Delft CiTG
G - Section of Offshorre
Engineerring. For more
m
inform
mation: Secction of Offfshore Eng
gineering
Committtee Chairm
man:
Andrei Me
etrikine
: +31 (0)15
(
27 84
4749
@: [email protected]
delft.nl
Superrvisor:
Federiico Pisanò
: +3
31 (0)15 227 82844
@: [email protected]
Sectiion Offshorre Engineering - Deparrtment Hyd
draulic Engineering - F
Faculty CEG
G
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