CPT 1 2 3

1

2

3

DNV

CPT

qc

Robertson(2012) Kexian Li(2015)

Iwasaki(1982) ArcGIS

The Application of the Seabed Cone Penetration Test for Geologic

Hazard Assessment of Offshore Wind Farm

H.-T.Tsai L.-K. Chien C.-Y. Fang

ABSTRACT

There is great windpower potential on the western offshore of Taiwan. But Taiwan is suffered

from earthquakes and typhoons frequently, and the planned area of the wind farm is covered by

soft seabed. Various marine geological hazards bring a lot of risks and uncertainties to the plan and

design of wind turbine foundations, cables and construction. Taking DNV standards of marine

operations and cases of marine geological hazards as reference, this study considered soft soil and

soil liquefaction into marine geological hazards analysis. This study analyzed the potential of two

kind geological hazards, as soft soil and soil liquefaction, with recent seabed CPT data. Soft soil

was distinguished with qc value at each depth, and summed up the length of soft soil to be graded,

the result was compared with the former research which was analyzed with SPT data

simultaneously. Soil liquefaction analyzed with assessment methods by Robertson (2012) and

Kexian Li(2015) which calculated the cyclic resistance under the cyclic loading of earthquake and

typhoon-induced wave. The above-mentioned analysis results were demonstrated the results of

hazard potential with ArcGIS. Based on the concept of risk assessment, this study defined hazard

factor as the potential of soft soil and soil liquefaction, and vulnerability factor as the construction

cost of wind turbine foundations and cables in the whole offshore wind farm developments, then

combined both factors into risk matrix for the assessment, it indicated the expected influence level

of geologic hazards which affected the cost of offshore wind farm development. This study could

provide the recommended procedure of risk assessment of wind turbine foundations and cables

under geologic hazards during planning of offshore wind farm.

639

39 2017 11 Proceedings of the 39th Ocean Engineering Conference in Taiwan Hungkuang University, November 2017

Keywords: offshore wind farm, marine geological hazards, wind turbine foundations, submarine

cables, seabed CPT, disaster risk assessment

1.

2.

2.1

1

8-15 40

24 CPT

2.2

CPT

qc fs

Ic 2.6

Mayerhof(1956)

(1994)

3

qc

2 CPT

3

2.3

1

g

50

30 0.067g 80%

I 50 0.086g 63%

II 475 0.28g 10%

921 M=7.3 PGA I II (Peak Ground Acceleration, PGA)

1

640

CPT-qc

N

Robertson(1985-2012)

2 (2009)

50

NNW 7.55 12.40

2

Robertson

-CPT CRR

Kexian Li 2013

Robertson-CPT

CRRW

= 1.1 CRRe (1)

Ishihara & Yamazaki 1984

CSRW

3.3.2

FS CRRw CSRW

FS=CRRW / CSRW (2)

Iwasaki1982

PL

PL= F (z)W (z) dz20

0(3)

2.4

3

1 2 3 4 5

(m)

8

%

40

(PL)

0 0-5 5-10 10-15 >15

0 0-5 5-10 10-15 >15

ISDR(2002)

:=

ISO31000 =

GDG(2012)

3

4

51% 1 5

27% 2 4

13% 3 3

7% 4 2

2% 5 1

5

(Hazard)

(Vu

lnerab

ility)

1 2 3 4 5

2 4 6 8 10

3 6 9 12 15

4 8 12 16 20

5 10 15 20 25

4

()

641

3.1

CPT

qc 0.35MPa

5m

2m RA03 RA06RB11

qc

qc

3.2

ArcGIS 50 A PL 8.0-10.3 B PL 15.9-19.3

BH01()BH02(

)BH03()

CPT

CPT

FS PL 50 PL 50

4

6 50

7 50

642

PL

NNW 50 7.55m

12.40

A

B PL 3.38-3.93

PL 3.93-4.86

CPT

ArcGIS

ArcToolBox Geostatistical Analyst

6 8

6

4

2

ArcGIS ArcToolBox Times

8

643

50

AB

50 CPT

ArcGIS

9 50

10 50

9 50

10 50

644

CPT

CPT

GIS

1. (2009)

2. (2011)

3. (2013)

- 35

4. (2013)

5. (2015)

6. (2015)

7. P.K. Robertson and K.L. Cabal(2015), Guide

To Cone Penetration Testing 6th Edition,

pp.25-33, 96-120.

645

646