Analysis of the tunnel immersion for the Busan-Geoje fixed link project through scale model tests and computer simulations

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Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering OMAE2009 May 31 - June 5, 2009, Honolulu, Hawaii, USA

Deift University of Technology

Ship Hydromechanics Laboratory

Library

Mekelweg 2

2628 CD Deift

Phone: +31 (0)15 2786873

E-mail: p.w.deheer©tudelft.nl

Hans Cozijn Offshore Department, MARIN Wageningen, the Netherlands

ABSTRACT

In Korea a four lane motorway is constructed between the

city of Busan and the island Geoje, reducing traveling times

from 1 hour by ferry to just 10 minutes by car. The so-called

Busan-Geoje Fixed Link consists of 2 cable-stayed girder

bridges and a tunnel,

crossing

the bay of Jinhae. The

submerged tunnel is

built by transporting each of its

18

elements below 2 pontoons from a construction dock to their

final positions and lowering them on the sea bed. The project is unique, because the tunnel elements are installed in a bay with

direct access towards open sea. For this reason, the effects of

incoming swells and wind seas were investigated in detail, so

that the operational limits of the tunnel element immersion

could be accurately determined. This was achieved by using an

approach of combined hydrodynamic scale model tests and

time-domain computer simulations.

First,

scale model tests were carried out in MARIN's

Shallow Water Basin. A detailed test set-up was constructed, including the trench in which the tunnel elements are placed, as

is shown in the photograph. Models of a tunnel element, two

pontoons, the moorirtg system, contraction lines and suspension wires were constructed at a scale of 1:50. The motions of the

pontoons and the submerged tunnel element, as well as the tensions in the lines, were measured in a range of different

wave conditions. Different stages of the tunnel immersion were investigated.

Second, a simulation model of the pontoons and tunnel

element was constructed in MARIN's time-domain simulation tool aNySIM. The large number of mooring lines, contraction

lines and suspension wires resulted in a relatively complex numerical model. The simulation model was calibrated such

OMAE2009-79385

ANALYSIS OF THE TUNNEL IMMERSION FOR THE BUSAN-GEOJE FIXED LINK

PROJECT THROUGH SCALE MODEL TESTS AND COMPUTER SIMULATIONS

Jin Wook Heo

Daewoo Engineering and Construction, Ltd. Busan, South Korea

that the results from the model tests could be accurately

reproduced. Subsequently, a sensitivity study was carried out, investigating the parameters most critical to the operation and the mooring system of the pontoons was further optimized.

Finally, the operational limits of the tunnel immersion were

evaluated by carrying out more than 6,500 time-domain

simulations, investigating a large number of different

combinations of wind sea and swell. The simulation results

included motions, velocities and accelerations, as well as line tensions. The extreme values were used to perform a combined evaluation of more than 10 structural and operational criteria.

The photograph below (copyright Peter de Haas, Royal Haskoning) shows the immersion of the first of 18 tunnel

elements in the bay of Jinhae, in February 2008.

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INTRODUCTION

The Maritime Research Institute Netherlands (MARIN)

was requested by Daewoo Engineering & Construction, Ltd. to

carty out hydrodynamic scale model tests and time-domain computer simulations to investigate the immersion of tunnel

elements for the Busan-Geoje Fixed Link. The model tests and

computer simulations were carried out in the fall of 2007.

Earlier research on the tunnel immersion for the Busan-Geoje Fixed Link project was presented in References [1] and [2]. In a way the present research is a continuation of these studies. In this publication, however, the present research project is

considered as a separate piece of work and the results of earlier studies are not further discussed.

The model tests were carried out in MARIN's Shallow

Water Basin at a scale of 1:50. The subsequent computer

simulations were carried out using MARlIN's multi-body time-domain simulation tool aNySIM. The model tests and computer

simulations are discussed in more detail in the remaining

sections of this paper. The objective of the combined model tests and computer simulations was to develop an accurate

time-domain simulation model of the tunnel element immersion

and to use this simulation model in an extensive down-time

analysis.

NOMENCLATU RE

a "risk parameter'; allowed probability of exceedence of

extreme value Xdesig,i

p density of water tonnes/m3

mean value of variable X

A added mass matrix tonnes, tonnes.m2

b'

linear damping coefficient kNs/m, kNms!rad b2 quadratic damping coefficient kNs2/m2, kNms2/rad2

C =

hydrostatic spring matrix of body i kN/m, kNmlrad

EA = line axial stiffness kN

F' = external force vector of body i kN, kNm

H= significant wave height

m

M= mass matrix of body i, as a result of motions ofbodyj,

tonnes, tonnes.m2

N= number of oscillations in duration for which is

determined

-R= matrix of retardation functions of body i, as a result of

motions ofbodyj kNs2!m, kNms2/rad

t, t =

time 5

T0 = natural period S

T = wave spectrum peak period S

xl = motion vector of body i m. rad

x

motion vector m, rad

x= velocity vector

mis, radls

x= acceleration vector

n-/5 rad/s2

Xdesign = design (extreme) value for variable X Xmeafl = mean value of variable X

APPLIED APPROACH

The immersion of the tunnel elements was investigated using a combination of hydrodynamic scale model tests and computer simulations. The complete scope of work included

the following steps.

Model tests were carried out to investigate the overall behavior of the tunnel element and pontoons during the immersion process. The scope of work included a large

number of different irregular wave conditions and several stages of the tunnel element immersion.

A time-domain simulation model was developed, including a tunnel element, two pontoons, mooring lines, contraction

lines and suspension wires. Furthermore, the trench and

already installed tunnel elements were modeled.

The time-domain simulation model was calibrated using

the results from the model tests. Where necessary, added mass and damping coefficients were adjusted such, that the numerical model could reproduce the model test results as accurately as possible.

The validated simulation model was used in a down-time

analysis study. The scope of work included more than

6,500 time-domain simulations and the combined evaluation of more than 10 different operational criteria.

The hydrodynamic scale model tests, the time-domain computer simulations and the down-time analysis are further

discussed in the following sections. SCALE MODEL TESTS

Hydrodynamic scale model tests of the tunnel element

immersion were carried out in MARIN's Shallow Water Basin. The basin measures L x B = 220 x 16 m. The water depth can be adjusted, the maximum depth being 1.1 m. The basin has a

piston-type wave generator, which is particularly suitable to generate waves in shallow water. In the basin a set-up was modeled including a trench, a

tunnel element and two

pontoons. Motions and loads were measured in

different

environments of irregular waves. Test Objectives

The model tests served two different purposes. The first objective was to confirm the overall feasibility of the tunnel

element immersion. For example,

the model tests

could possibly reveal any unexpected dynamic behavior of the tunnel element and pontoons. The Second objective of the tests was to

provide measurement data for the calibration of numerical

models.

Description of the Scale Models

The models used in the tests included a tunnel element,

two pontoons, mooring lines, contraction lines and suspension wires, all built at a model scale of 1:50. Furthermore, a trench

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with a gravel bed was modeled, including an already installed tunnel element.

The tunnel element model was constructed of wood and

accurately represented the geometry of the actual tunnel

element. Figure 1

shows a photograph of the model. The

weight distribution of the tunnel element, including mass, CoG

position and radii of inertia, was calibrated according to the

specified values. The tunnel element model was equipped with

two towers,

fairlead points for the contraction

lines and

suspension wires and two guiding beams at the primary end of the tunnel element. The main particulars of the tunnel element can be found in Table I.

The two pontoon models were constructed of a light foam

material that was made water proof using an epoxy resin.

Figure 2 shows one of the models. Similar to the tunnel

element, the weight distribution and stability of the pontoons were calibrated according to their specified values. The main particulars of the pontoons can be found in Table 2.

The mooring lines, contraction lines and suspension wires

were made of thin steel wire. The correct axial stiffness was obtained by including a calibrated linear spring in each line.

The line properties can be found in Tables 4,5and 6.

Instrumentation

During the model tests wave heights, model motions and line tensions were measured. The wave heights were measured using resistance wire wave height probes. These were placed at

a number of locations in the test set-up. The motions of the tunnel element and both pontoons were measured using an

optical motion measurement system. The system measures the positions of three infrared LEDs, placed on each of the models,

and derives from these the motions in 6 degrees of freedom.

The measuring accuracy is better than0.5 mm / 0.1 deg (model

scale values). The line tensions were measured using

ring-shaped strain gauge transducers. Description of the Test Set-up

Prior to the start of the model tests two trenches were

constructed in the Shallow Water Basin. The first trench was

built in a direction transverse to the basin, while the second

trench was built under an angle of 30 deg. In this manner wave directions of 60 and 90 deg relative to the tunnel element could be modeled in the tests. This is shown in Figure 3. The trenches were modeled in concrete on the basin bottom. On the bottom of the trench is a gravel bed of1.5 m thickness. This gravel bed

was also included in the test set-up. A cross section of the

trench is shown in Figure 4. During the tests always one of the two trenches was in use, while the other trench was covered by

steel plates. Thus, any possible unwanted influence of the

second trench on the system behavior was avoided.

The test set-up

included an already installed tunnel

element, which was placed and fixated in the trench. Some

additional gravel was added at the sides of this tunnel element. Furthermore, the necessary anchor points for the mooring and

contraction lines were placed on the basin bottom at the

required locations around the trench.

Mooring lines were placed between the two pontoons and

the basin bottom, keeping the pontoons in

position. The

suspension wires were connected between the pontoons and the

top of the tunnel element, carrying the weight of the tunnel. The contraction wires were connected to the pontoon, then

guided through pad eyes on the tunnel element and fixed to the

basin bottom. The purpose of the contraction wires was to prevent undesired transverse motions of the tunnel element

during immersion.

In addition to the photograph above, Figure 5 shows the

mooring lay-out in top-view, including line numbering. Figure 6 shows a cross section.

Test Programme

An extensive test campaign was carried out, in which the water depth, wave conditions and wave directions were varied.

Also different stages of the tunnel element immersion were

investigated. The test scope can be summarized as follows. Water depths of 12 in and 23 m.

Wave directions of 90 deg and 60 deg relative to the length of the tunnel element.

- Wind seas (short wave periods), swell (long wave periods) and combined wave conditions (sea + swell).

Tunnel element suspended 0.5 m above the gravel bed and 1.0 m below the water surface.

Tunnel element overweight of 2%, 3% and 5%.

In total 50 model tests in irregular waves were carried out.

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Results and Preliminaiy Conclusions

The tests provided valuable insight in the overall behavior

of the pontoons and tunnel element in waves. Based on the

results of the model tests the following preliminary conclusions

could be dra.

The tunnel element motions are sensitive to the wave

period. Longer waves generally result in larger motions.

The tunnel element motions are generally larger in 12 m water depth than

in 23 m water depth,

while the differences in line loads are small.

The tunnel element horizontal motions are generally larger

at 0.5 m above the gravel bed, than at 1.0 m below the

water surface. The vertical motions, on the other hand, are

larger when the tunnel element is close to the water

surface.

The tunnel element motions are generally smaller for 60

deg wave directions than for 90 deg (beam on) waves. An exception are the heave motions, which are similar in both cases. Some effect of wave direction on the line tensions can be observed.

COMPUTER SIMULATIONS

The computer simulations in this project were carried out

using MARlIN's time-domain simulation tool aNySIM. This program can model the behavior of any number of (floating) rigid bodies, including all hydrodynamic and mechanical

interactions. Time-domain simulations were performed, so that non-linear effects, such as the pontoons mooring system load-displacement characteristics, could be correctly modeled. The simulation approach in the aNySIM program is similar to the

approach used

in the LIFSIM program, see for example

References [3] and [4]. Djffraction Calculations

Prior to the time-domain simulations a linear diffraction analysis was carried out for the tunnel element and the two

pontoons. The effect of the presence of the trench and an

already installed tunnel element was included by modeling

these as additional bodies. An example of a panel distribution used in the diffraction calculations is shown in Figure 7. The results of the analysis included hydrodynamic reaction forces

(added mass and damping coefficients), as well as first order (linear) wave forces and second order (quadratic) wave drift forces. The diffraction calculations are carried Out in the frequency domain. All hydrodynamic interactions between the modeled bodies are taken into account.

Time-domain Simulation Model

The aNySIM time-domain simulation program transforms the frequency domain results from the diffraction analysis into

time domain data that are used in the actual simulations. The

frequency dependent added mass and damping coefficients are

transformed into a set of frequency independent added mass

coefficients and associated retardation functions. The result is a

set of time-domain coupled equations of motion, see for

instance Reference [51 and [6]. The equations of motion are

formulated as follows. x F' F2 F3 x x.2 .3 x

-I-(x',

,x2, 2, 3, , t)

The above set of coupled equations of motion includes 18 degrees of freedom; 6 for each of the two pontoons (body I and 2) and 6 for the suspended tunnel element (body 3). It is noted that the hydrodynamic interactions between these 3 bodies are

taken into account, including cross coupling terms in added

inertia and damping.

Furthermore, linear and quadratic damping forces are

included in the model as external forces in the right hand side of the equation. In this manner viscous roll and pitch damping, as well as low frequency damping forces can be modeled. Tuning of the Simulation Model

The model test results were used to tune the numerical model. The values of certain parameters in the simulation model (e.g. damping coefficients) were selected or adjusted

based on the model test results. The aim was to obtain a

simulation model capable of accurately reproducing the model

test results. The following steps can be distinguished in the

tuning process:

Motion decay tests were analyzed and compared with simulations. The objective was to find the appropriate damping coefficients for the simulation model and to

adjust the calculated added mass coefficients, where

M'2 M'3 M2' M22 M23 M3' M32 M'3

fR"(tt)

JR'2(t_t)

JR'3(tt)

JR21(t_t)

JR22(tT)

fR23(t_t)

5R3'(tt)

5R32(tt)

JR33(tr)

CI 0 0 0 0 x x 0 0 Cl x

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necessary. This was done for all degrees of freedom of the pontoons and tunnel element.

The wave elevation time records measured in the model basin were used to generate the 1st and 2nd order wave

loads on the pontoons and the tunnel element. In this

manner, the wave frequency and low frequency motions of

the 3

bodies in

the simulations will show the best

correspondence with those measured in the model tests. Finally, time domain simulations in irregular waves were performed and the results from simulations and model tests were compared. By performing the simulations in order of

increasing complexity, the numerical model could be

refined step by step.

A comparison of the model test and simulation results

showed that an accurate overall correspondence was achieved

after tuning of the aNySIM model. The highest accuracy is

achieved for the cases where the tunnel element is suspended at 0.5 m above the gravel bed. The cases with the tunnel element at 1 .0 m below the water surface are more complex from a numerical point of view, due to the relatively thin layer of

water on the large area of the upper side of the tunnel element.

Nevertheless, also in these cases a good agreement between

model tests and simulations was achieved. Simulation Scope

The scope of work of the simulations with the tuned model

consisted of two separate parts. First, a sensitivity study was

carried out, in which a number of input parameters were varied

and the effect on the motions and loads was investigated. Second, a down-time analysis study was performed, which

included a large number of simulations (several thousands) and the evaluation of more than 10 operational parameters.

The sensitivity study included 18 simulations, varying the following parameters; spectrum type (PM, JONSWAP, White

Noise), wave peak period, wave direction, mooring system

(long mooring lines, short mooring lines) and current velocity. The results of the sensitivity study were used to make the final

selection of cases for the down-time analysis. The results are

further discussed in the following Section.

The down-time analysis included over 6,500 simulations.

The scope of work included

simulations in 3 different

environmental directions (A, B and C), with the tunnel element suspended at 1.0 m below the water surface (Series Al, B I. Cl)

and 0.5 m above the gravel bed (Series A2, B2, C2). The

simulation scope is summarized in Table 7 and Figures 8, 9 and 10. The down-time analysis is described in more detail further below.

Results of the Sensitivity Study

The results of the sensitivity study revealed the following trends in the behavior of the two pontoons with the suspended tunnel element.

I. The simulation results are more sensitive to the period of

the incoming waves than to the spectral shape. Longer

period waves generally cause larger motions and loads. Long-crested waves with a direction exactly transverse to

the

tunnel element (270 deg) can be considered as

conservative. Other (near) beam-on wave directions and

short-crested seas result in smaller motions and loads. The lay-out with long mooring lines showed lower extreme mooring loads than the lay-out with short mooring lines. The long lines mooring lay-out was therefore used in the down-time analysis.

The presence of a current transverse to the tunnel element

results in increased mean and maximum mooring loads. The damping effect on the tunnel element motions was

found to be limited.

It

is noted that, prior to the start of the time-domain

simulation study, the design of the pontoons was up-dated. For this reason, the pontoons modeled in the time-domain simulations are somewhat different (larger) than the pontoons in the model tests. To include the up-dated pontoon shape in the

simulation model, new diffraction calculations were carried

out. The pontoon dimensions and main particulars can be found in Tables 2 and 3.

DOWN-TIME ANALYSIS

The operational

limits of the tunnel immersion were

evaluated by carrying out more than 6,500 time-domain

simulations, investigating a large number of different

combinations of wind sea and swell. The simulation results

included motions, velocities and accelerations, as well as line tensions. The extreme values were used to perform a combined evaluation of more than 10 structural and operational criteria. CONDOR Grid Computing

The necessary computation time on a single PC, for each of the 6,500 aNySIM simulations, is approximately 5 minutes. The use of a single machine to carry out all simulations in this

study would therefore be very

impractical. Instead, the

simulations were distributed over a large number of PCs

(approximately 200) within MARIN's network, using CONDOR software.

CONDOR is an open source software package that allows submitting

simulation jobs on other computers within a

network. Simulations jobs can be submitted from a limited

number of dedicated machines ("control nodes") in the network and are carried out by all other machines in the network.

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The approach is shown schematically in the picture below (source: www.howstuffiworks.com).

When a simulation job is submitted to the CONDOR

system, it searches for available computers on the network. Any

machine not in use for about 5 minutes is considered to be

available.

If the owner of this machine starts

using the computer, the CONDOR job is cancelled and removed. The

system then searches for a new available computer until all jobs are finished. Nowadays at MARIN the CONDOR software is commonly used in studies were large numbers of simulations are carried out, see for example also Reference [7].

Data Analysis

Because of the large amount of data, only the statistical output of the 6,500 time-domain simulations was used for

further analysis and interpretation of the results, while the time

records themselves were not stored. Based on the statistical

output (mean value, standard deviation, minimum and maximum) the extreme values for the design were determined. Instead

of using

the single extreme values from each simulation, statistically more reliable extreme values were determined. Most probable maximum (MPM-) values were determined for the tunnel element motions, velocities and

accelerations, as well as for the mooring line, contraction line and suspension wire tensions. The following formulation was used.

Xdesign = Xmean + G

The above formulation was proposed by Ochi,

see

Reference [8], and is based on the well known formulation by Longuet-Higgins, see Reference [9]. The formulation by Ochi

is valid

for small values of a and large values of N.

Alternatively, the design values could be determined from

(Weibull) distribution plots, by taking the value of a/N as the

probability of exceedance (similar to using I/N to determine

the MPM-value). However, to carly out this method automatically for all simulations is relatively complicated and was therefore not considered in the present study.

Operational Limits

The tunnel immersion operation can be carried out as long

as the operational limits are not exceeded. These operational limits are related to allowable line tensions, capacity of the

applied winches and the allowed motion envelope of the tunnel element. Two types of operational limits were specified. First of all, the structural limits, exceedance of which would result in damage to one of the components in the system. And second,

the availability limits, exceedance of which would require a

temporaiy interruption

of the immersion

operation, thus causing a delay. The applied structural and availability limits are summarized in Table 8.

Graphical Presentation of the Results

The large number of simulations and the many operational

criteria to evaluate, required a graphical presentation of the

results. In this manner, an instant impression of the operability can be obtained, as well as an understanding of the trends in the system behavior. Colors are used to indicate if the operational limits are exceeded. Red indicates exceedance of one or more

of the structural limits, while orange indicates exceedance of

one or more of the availability limits. Green indicates that no operational limits are exceeded.

The simulation results are presented in a graphical format

in

scatter diagrams, with the wave peak period on the

horizontal axis and the significant wave height on the vertical axis. An example is shown in Figure 11. The colors indicate if

the operational limits are exceeded for each combination of

wave height H and period T of the incoming wind sea. To represent the results for combined wind sea and swell

conditions, the scatter diagrams with the results for the wind sea conditions are organized in a pattern showing the swell period in the columns and swell height in the rows. In this manner nested scatter diagrams are created. An example is

shown in Figure 12. By presenting the simulation results in this

manner, the relevant results can be found in the set of nested

scatter diagrams by selecting the relevant diagram based on the swell peak period and significant wave height.

The results are presented in a graphical manner for each of the structural and availability limits separately, as well as for all

operational limits combined. In this manner, the effect of

changes in the design (and thus the operational limits) on the

workability of the immersion operation could be

easily

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Results and Conclusions

Based on the results of the more than 6,500 time-domain simulations, the following conclusions could be drawn.

For cases with the tunnel element at 1.0 m below the water

surface the contraction line tensions and the suspension

angle are the most limiting.

Current causes the line

tensions to increases significantly, but the effect on the

suspension angle is relatively small.

For cases with the tunnel element at 0.5 m above the gravel bed the tunnel element motions and velocities are the most limiting. The effect of current is small.

In general, collinear environments from South (Series B) are more limiting than environments with current and swell from South and wind sea from North West (Series A). The cases without wind sea (Series C) were the least limiting.

The cases with the tunnel element at 0.5 m above the

gravel bed are more limiting than the cases with the tunnel element at 1.0 m below the water surface. Apparently, the

design limits are more strict when the tunnel element is

close to

the bottom and the already installed tunnel

sections. CONCLUSIONS

Based on the results of the model tests and the

time-domain computer simulations, the following conclusions may be drawn.

1. The model test results showed that the two pontoons with the tunnel element are the most sensitive to longer period waves. The simulation results showed the same trend.

The results of the model tests showed that the tunnel

element motions were larger in 1 2 m than in 23 m water depth.

The horizontal tunnel element motions are largest when the tunnel element is suspended at 0.5 in above the gravel bed,

while the vertical motions are larger when the tunnel

element is at 1.0 m below the water surface. This was

observed in the model tests and the computer simulations. In the model tests it was found that smaller motions could be observed for the 60 deg wave direction, compared to the 90 deg (beam on) wave direction.

The sensitivity study, included in the computer

simulations, showed that the modeling of long-crested

waves exactly perpendicular to the tunnel element can be considered conservative. Short-crested waves are expected

to result in smaller motions and loads than long-crested

waves.

The results of the sensitivity study showed that long

mooring lines generally give lower maximum line loads

than short mooring lines.

The presence of current transverse to the tunnel element

results in an increase of the mean and maximum line

tensions, but hardly gives and additional damping for the tunnel element motions.

The results of the down-time study showed that when the tunnel element is suspended at 1 .0 m below the water line, the line

tensions and suspension angle are the most

limiting operational criteria.

9 The results of the down-time study showed that when the

tunnel element is suspended at 0.5 m above the gravel bed, the motions and velocities are the most limiting operational criteria. In general, the cases with the tunnel element at 0.5

m above the gravel bed are more limiting than the cases

with the tunnel element at 1.0 in below the water surface. 10. The environmental conditions considered in Series B are

more limiting than the environmental conditions in Series A and C. In Series B collinear current, swell and wind seas were considered.

TABLES AND FIGURES

Table I - Main particulars of the tunnel element

Table 2 - Main particulars of the pontoons (model tests

Table 3 - Increased pontoon size (down-time analysis

Table 4 - Mooring line properties (model tests

Particular Unit Value

Length m 180

Width in 26.5

Height in 10.0

Mass (at 2% overweight) tons 49.000

Length in 24.0

Width m 42.5

Fleight in 8.5

Mass tons 630

Length in 36.0

Width m 42.5

height m 8.5

Mass tons 1.400

Number of Lines ---- 8

Length m 62 - 66

Diameter mm 40

Axial Stiffness kN 100,000

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Table 5 - Contraction line properties (model tes s)

Table 6 - Suspension wire properties (model tests)

Table 7 - Environmental conditions down-time analysis

Table 8 - Operational limits down-time analysis

Figure 2 - One of the pontoon models with the tunnel element

Figure i- ivioueiea u oe

Length m

96-256

Diameter mm 54

Length m 32

Diameter mm 58

Environment Direction Number

Series Al and A2

Current from S 2 velocities

Wind Sea from NW 42 spectra

Swell from S 19 spectra

Series B! and B2

Current from 5 2 velocities

Wind Sea from 5 42 spectra

Swell from 5 19 spectra

Series Cl and C2

Current from S 3 velocities

Wind Sea

Swell from 5 22 spectra

System Element Limiting Coinpo nent

Value

Structural Limits

Mooring System Winch 700 kN

Contraction System Deck lay-out 900 kN Longitudinal System Deck lay-out 720 kN Suspension System Forces Lugs 8,500 kN

Suspension Angle 15%

Guide Beam/Catch Tunnel Velocities 0.17 mIs

Availability Limits

Mooring System \Vinch Capacity 350 kN Contraction System Winch Capacity 600 kN Longitudinal System Winch Capacity 600 kN Suspension System Winch Capacity 5.000 kN Guide Beam / Catch Tunnel Velocities 0.185 in

Tunnel Motions 0.5 rn/s Tunnel Angular Vel. 1.0-1.5 deg/s

Tunnel Rotations 1.5-2.0 deg

Figure 1 - Photograph o1 the tunnel element model (1:50)

I

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Figure 4 - Detail photograph of the model trench in the basin

Figure 5 - lop view of the test set-up including mooring lines

Current Swell

(fromS) _I(F.0mS)

Figure 6 - Cross section of pontoon and tunnel element

Figure 7 - Panel distribution of trench, tunnel and pontoons

Figure 8 - Environments down-time analysis "Series A"

\Wind

om NW)Sea

Figure 9 - Environments down-time analysis "Series B'

H, 3

H, 2

H, I

Current Swell (from S) (From S)

Figure 1] - Example scatter diagram with simulation results

Figure 12 - Example nested scatter diagram for sea+swell cases

Hii

I

ACKNOWLEDGMENTS

The information in this paper is based on the results of the

model tests carried out at MARIN's Shallow Water Basin on

behalf of Daewoo Engineering and Construction, Ltd. and the subsequent aNySIM computer simulation study. The authors

would like to thank Daewoo Engineering and Construction,

Ltd. for their kind permission to publish this paper.

Current Wind Sea Swell (from S) (from S) (From S)

Figure 10 - Environments down-time analysis "Series C"

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Ogilvie, T.F.: "Recent Progress towards the understanding and prediction of ship motions". Proceedings of the 5th Symposium on Naval Hydrodynamics, 1964.

Wilde, J.J. de, Berg, J. van den and Dijk, A.W. van (MARIN), "Downtime Assessment of Side-By-Side LNG Operations Using Time Domain Simulations",

2009-ISOPE-TPCI68, ISOPE Conference, Osaka, 2009. Ochi, M.K.: "Principles of Extreme Value Statistics and their Application", Extreme Load Response Symposium, Arlington, VA, October 19-20, 1981.

Longuet-Higgins, M.S., 1952, "On Statistical

Distribution of the Heights of Sea Waves", Journal of

Marine Research, No. 3, 1952.

[11 Partha Chakrabarti (Zentech, Inc.), Subrata K. Chakrabarti (Offshore Structures Analysis, Inc.), Tommy Olsen (COWl A!S), Koo Tm Sig, Kim Chang

Whan and Huh un Wook (Daewoo),

"Dynamic Simulation of Immersion of Tunnel Elements for Busan-Geoje Fixed Link Project", OMAE2008-57881, OMAE Conference 2008, Estoril, Portugal.

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