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

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1 Proceedings of he ASME 28h Inernaional Conference on Ocean, Offshore and Arcic Engineering OMAE29 May 31 - June 5, 29, Honolulu, Hawaii OMAE ANALYSIS OF THE TUNNEL IMMERSION FOR THE BUSAN-GEOJE FIXED LINK PROJECT THROUGH SCALE MODEL TESTS AND COMPUTER SIMULATIONS Hans Cozijn Offshore Deparmen, MARIN Wageningen, he Neherlands Jin Wook Heo Daewoo Engineering and Consrucion, Ld. Busan, Souh Korea ABSTRACT In Korea a four lane moorway is consruced beween he ciy of Busan and he island Geoje, reducing raveling imes from 1 hour by ferry o jus 1 minues by car. The so-called Busan-Geoje Fixed Link consiss of 2 cable-sayed girder bridges and a unnel, crossing he bay of Jinhae. The submerged unnel is buil by ransporing each of is 18 elemens below 2 ponoons from a consrucion dock o heir final posiions and lowering hem on he sea bed. The projec is unique, because he unnel elemens are insalled in a bay wih direc access owards open sea. For his reason, he effecs of incoming swells and wind seas were invesigaed in deail, so ha he operaional limis of he unnel elemen immersion could be accuraely deermined. This was achieved by using an approach of combined hydrodynamic scale model ess and ime-domain compuer simulaions. ha he resuls from he model ess could be accuraely reproduced. Subsequenly, a sensiiviy sudy was carried ou, invesigaing he parameers mos criical o he operaion and he mooring sysem of he ponoons was furher opimized. Finally, he operaional limis of he unnel immersion were evaluaed by carrying ou more han 6,5 ime-domain simulaions, invesigaing a large number of differen combinaions of wind sea and swell. The simulaion resuls included moions, velociies and acceleraions, as well as line ensions. The exreme values were used o perform a combined evaluaion of more han 1 srucural and operaional crieria. The phoograph below (copyrigh Peer de Haas, Royal Haskoning) shows he immersion of he firs of 18 unnel elemens in he bay of Jinhae, in February 28. Firs, scale model ess were carried ou in MARIN's Shallow Waer Basin. A deailed es se-up was consruced, including he rench in which he unnel elemens are placed, as is shown in he phoograph. Models of a unnel elemen, wo ponoons, he mooring sysem, conracion lines and suspension wires were consruced a a scale of 1:5. The moions of he ponoons and he submerged unnel elemen, as well as he ensions in he lines, were measured in a range of differen wave condiions. Differen sages of he unnel immersion were invesigaed. Second, a simulaion model of he ponoons and unnel elemen was consruced in MARIN's ime-domain simulaion ool anysim. The large number of mooring lines, conracion lines and suspension wires resuled in a relaively complex numerical model. The simulaion model was calibraed such 1 Copyrigh 29 by ASME

2 INTRODUCTION The Mariime Research Insiue Neherlands (MARIN) was requesed by Daewoo Engineering & Consrucion, Ld. o carry ou hydrodynamic scale model ess and ime-domain compuer simulaions o invesigae he immersion of unnel elemens for he Busan-Geoje Fixed Link. The model ess and compuer simulaions were carried ou in he fall of 27. Earlier research on he unnel immersion for he Busan-Geoje Fixed Link projec was presened in References [1] and [2]. In a way he presen research is a coninuaion of hese sudies. In his publicaion, however, he presen research projec is considered as a separae piece of work and he resuls of earlier sudies are no furher discussed. The model ess were carried ou in MARIN's Shallow Waer Basin a a scale of 1:5. The subsequen compuer simulaions were carried ou using MARIN's muli-body imedomain simulaion ool anysim. The model ess and compuer simulaions are discussed in more deail in he remaining secions of his paper. The objecive of he combined model ess and compuer simulaions was o develop an accurae ime-domain simulaion model of he unnel elemen immersion and o use his simulaion model in an exensive down-ime analysis. NOMENCLATURE α = "risk parameer"; allowed probabiliy of exceedence of exreme value X design - ρ = densiy of waer onnes/m 3 σ x = mean value of variable X A = added mass marix onnes, onnes.m 2 b (1) = linear damping coefficien kns/m, knms/rad b (2) = quadraic damping coefficien kns 2 /m 2, knms 2 /rad 2 C i = hydrosaic spring marix of body i kn/m, knm/rad EA = line axial siffness kn F i = exernal force vecor of body i kn, knm H s = significan wave heigh m M i,j = mass marix of body i, as a resul of moions of body j, onnes, onnes.m 2 N = number of oscillaions in duraion for which X design is deermined - R i,j = marix of reardaion funcions of body i, as a resul of moions of body j kns 2 /m, knms 2 /rad, τ = ime s T = naural period s T p = wave specrum peak period s x i = moion vecor of body i m, rad X = moion vecor m, rad x = velociy vecor m/s, rad/s x = acceleraion vecor m/s 2, rad/s 2 X design = design (exreme) value for variable X X mean = mean value of variable X APPLIED APPROACH The immersion of he unnel elemens was invesigaed using a combinaion of hydrodynamic scale model ess and compuer simulaions. The complee scope of work included he following seps. 1. Model ess were carried ou o invesigae he overall behavior of he unnel elemen and ponoons during he immersion process. The scope of work included a large number of differen irregular wave condiions and several sages of he unnel elemen immersion. 2. A ime-domain simulaion model was developed, including a unnel elemen, wo ponoons, mooring lines, conracion lines and suspension wires. Furhermore, he rench and already insalled unnel elemens were modeled. 3. The ime-domain simulaion model was calibraed using he resuls from he model ess. Where necessary, added mass and damping coefficiens were adjused such, ha he numerical model could reproduce he model es resuls as accuraely as possible. 4. The validaed simulaion model was used in a down-ime analysis sudy. The scope of work included more han 6,5 ime-domain simulaions and he combined evaluaion of more han 1 differen operaional crieria. The hydrodynamic scale model ess, he ime-domain compuer simulaions and he down-ime analysis are furher discussed in he following secions. SCALE MODEL TESTS Hydrodynamic scale model ess of he unnel elemen immersion were carried ou in MARIN's Shallow Waer Basin. The basin measures L x B = 22 x 16 m. The waer deph can be adjused, he maximum deph being 1.1 m. The basin has a pison-ype wave generaor, which is paricularly suiable o generae waves in shallow waer. In he basin a se-up was modeled including a rench, a unnel elemen and wo ponoons. Moions and loads were measured in differen environmens of irregular waves. Tes Objecives The model ess served wo differen purposes. The firs objecive was o confirm he overall feasibiliy of he unnel elemen immersion. For example, he model ess could possibly reveal any unexpeced dynamic behavior of he unnel elemen and ponoons. The Second objecive of he ess was o provide measuremen daa for he calibraion of numerical models. Descripion of he Scale Models The models used in he ess included a unnel elemen, wo ponoons, mooring lines, conracion lines and suspension wires, all buil a a model scale of 1:5. Furhermore, a rench 2 Copyrigh 29 by ASME

3 wih a gravel bed was modeled, including an already insalled unnel elemen. The unnel elemen model was consruced of wood and accuraely represened he geomery of he acual unnel elemen. Figure 1 shows a phoograph of he model. The weigh disribuion of he unnel elemen, including mass, CoG posiion and radii of ineria, was calibraed according o he specified values. The unnel elemen model was equipped wih wo owers, fairlead poins for he conracion lines and suspension wires and wo guiding beams a he primary end of he unnel elemen. The main pariculars of he unnel elemen can be found in Table 1. The wo ponoon models were consruced of a ligh foam maerial ha was made waer proof using an epoxy resin. Figure 2 shows one of he models. Similar o he unnel elemen, he weigh disribuion and sabiliy of he ponoons were calibraed according o heir specified values. The main pariculars of he ponoons can be found in Table 2. The es se-up included an already insalled unnel elemen, which was placed and fixaed in he rench. Some addiional gravel was added a he sides of his unnel elemen. Furhermore, he necessary anchor poins for he mooring and conracion lines were placed on he basin boom a he required locaions around he rench. Mooring lines were placed beween he wo ponoons and he basin boom, keeping he ponoons in posiion. The suspension wires were conneced beween he ponoons and he op of he unnel elemen, carrying he weigh of he unnel. The conracion wires were conneced o he ponoon, hen guided hrough pad eyes on he unnel elemen and fixed o he basin boom. The purpose of he conracion wires was o preven undesired ransverse moions of he unnel elemen during immersion. The mooring lines, conracion lines and suspension wires were made of hin seel wire. The correc axial siffness was obained by including a calibraed linear spring in each line. The line properies can be found in Tables 4, 5 and 6. Insrumenaion During he model ess wave heighs, model moions and line ensions were measured. The wave heighs were measured using resisance wire wave heigh probes. These were placed a a number of locaions in he es se-up. The moions of he unnel elemen and boh ponoons were measured using an opical moion measuremen sysem. The sysem measures he posiions of hree infrared LEDs, placed on each of he models, and derives from hese he moions in 6 degrees of freedom. The measuring accuracy is beer han.5 mm /.1 deg (model scale values). The line ensions were measured using ringshaped srain gauge ransducers. Descripion of he Tes Se-up Prior o he sar of he model ess wo renches were consruced in he Shallow Waer Basin. The firs rench was buil in a direcion ransverse o he basin, while he second rench was buil under an angle of 3 deg. In his manner wave direcions of 6 and 9 deg relaive o he unnel elemen could be modeled in he ess. This is shown in Figure 3. The renches were modeled in concree on he basin boom. On he boom of he rench is a gravel bed of 1.5 m hickness. This gravel bed was also included in he es se-up. A cross secion of he rench is shown in Figure 4. During he ess always one of he wo renches was in use, while he oher rench was covered by seel plaes. Thus, any possible unwaned influence of he second rench on he sysem behavior was avoided. In addiion o he phoograph above, Figure 5 shows he mooring lay-ou in op-view, including line numbering. Figure 6 shows a cross secion. Tes Programme An exensive es campaign was carried ou, in which he waer deph, wave condiions and wave direcions were varied. Also differen sages of he unnel elemen immersion were invesigaed. The es scope can be summarized as follows. Waer dephs of 12 m and 23 m. Wave direcions of 9 deg and 6 deg relaive o he lengh of he unnel elemen. Wind seas (shor wave periods), swell (long wave periods) and combined wave condiions (sea + swell). Tunnel elemen suspended.5 m above he gravel bed and 1. m below he waer surface. Tunnel elemen overweigh of 2%, 3% and 5%. In oal 5 model ess in irregular waves were carried ou. 3 Copyrigh 29 by ASME

4 Resuls and Preliminary Conclusions The ess provided valuable insigh in he overall behavior of he ponoons and unnel elemen in waves. Based on he resuls of he model ess he following preliminary conclusions could be drawn. 1. The unnel elemen moions are sensiive o he wave period. Longer waves generally resul in larger moions. 2. The unnel elemen moions are generally larger in 12 m waer deph han in 23 m waer deph, while he differences in line loads are small. 3. The unnel elemen horizonal moions are generally larger a.5 m above he gravel bed, han a 1. m below he waer surface. The verical moions, on he oher hand, are larger when he unnel elemen is close o he waer surface. 4. The unnel elemen moions are generally smaller for 6 deg wave direcions han for 9 deg (beam on) waves. An excepion are he heave moions, which are similar in boh cases. Some effec of wave direcion on he line ensions can be observed. COMPUTER SIMULATIONS The compuer simulaions in his projec were carried ou using MARIN's ime-domain simulaion ool anysim. This program can model he behavior of any number of (floaing) rigid bodies, including all hydrodynamic and mechanical ineracions. Time-domain simulaions were performed, so ha non-linear effecs, such as he ponoons' mooring sysem loaddisplacemen characerisics, could be correcly modeled. The simulaion approach in he anysim program is similar o he approach used in he LIFSIM program, see for example References [3] and [4]. Diffracion Calculaions Prior o he ime-domain simulaions a linear diffracion analysis was carried ou for he unnel elemen and he wo ponoons. The effec of he presence of he rench and an already insalled unnel elemen was included by modeling hese as addiional bodies. An example of a panel disribuion used in he diffracion calculaions is shown in Figure 7. The resuls of he analysis included hydrodynamic reacion forces (added mass and damping coefficiens), as well as firs order (linear) wave forces and second order (quadraic) wave drif forces. The diffracion calculaions are carried ou in he frequency domain. All hydrodynamic ineracions beween he modeled bodies are aken ino accoun. Time-domain Simulaion Model The anysim ime-domain simulaion program ransforms he frequency domain resuls from he diffracion analysis ino ime domain daa ha are used in he acual simulaions. The frequency dependen added mass and damping coefficiens are ransformed ino a se of frequency independen added mass coefficiens and associaed reardaion funcions. The resul is a se of ime-domain coupled equaions of moion, see for insance Reference [5] and [6]. The equaions of moion are formulaed as follows. M 11 M 12 M 13 1 x M 21 M 22 M 23 x M 31 M 32 M 33 3 x 11 R ( τ) 21 R ( τ) 31 R ( τ) C 1 C 2 x 12 R ( τ) 22 R ( τ) 32 R ( τ) 1 x C 3 3 x 2 x + 2 x = 13 R ( τ) 1 x 23 R ( τ) x 33 R ( τ) 3 x 1 F 2 F 2 x (x,x,x,x,x,x,) The above se of coupled equaions of moion includes 18 degrees of freedom; 6 for each of he wo ponoons (body 1 and 2) and 6 for he suspended unnel elemen (body 3). I is noed ha he hydrodynamic ineracions beween hese 3 bodies are aken ino accoun, including cross coupling erms in added ineria and damping. Furhermore, linear and quadraic damping forces are included in he model as exernal forces in he righ hand side of he equaion. In his manner viscous roll and pich damping, as well as low frequency damping forces can be modeled. Tuning of he Simulaion Model The model es resuls were used o une he numerical model. The values of cerain parameers in he simulaion model (e.g. damping coefficiens) were seleced or adjused based on he model es resuls. The aim was o obain a simulaion model capable of accuraely reproducing he model es resuls. The following seps can be disinguished in he uning process: 1. Moion decay ess were analyzed and compared wih simulaions. The objecive was o find he appropriae damping coefficiens for he simulaion model and o adjus he calculaed added mass coefficiens, where 3 F 4 Copyrigh 29 by ASME

5 necessary. This was done for all degrees of freedom of he ponoons and unnel elemen. 2. The wave elevaion ime records measured in he model basin were used o generae he 1s and 2nd order wave loads on he ponoons and he unnel elemen. In his manner, he wave frequency and low frequency moions of he 3 bodies in he simulaions will show he bes correspondence wih hose measured in he model ess. 3. Finally, ime domain simulaions in irregular waves were performed and he resuls from simulaions and model ess were compared. By performing he simulaions in order of increasing complexiy, he numerical model could be refined sep by sep. A comparison of he model es and simulaion resuls showed ha an accurae overall correspondence was achieved afer uning of he anysim model. The highes accuracy is achieved for he cases where he unnel elemen is suspended a.5 m above he gravel bed. The cases wih he unnel elemen a 1. m below he waer surface are more complex from a numerical poin of view, due o he relaively hin layer of waer on he large area of he upper side of he unnel elemen. Neverheless, also in hese cases a good agreemen beween model ess and simulaions was achieved. Simulaion Scope The scope of work of he simulaions wih he uned model consised of wo separae pars. Firs, a sensiiviy sudy was carried ou, in which a number of inpu parameers were varied and he effec on he moions and loads was invesigaed. Second, a down-ime analysis sudy was performed, which included a large number of simulaions (several housands) and he evaluaion of more han 1 operaional parameers. The sensiiviy sudy included 18 simulaions, varying he following parameers; specrum ype (PM, JONSWAP, Whie Noise), wave peak period, wave direcion, mooring sysem (long mooring lines, shor mooring lines) and curren velociy. The resuls of he sensiiviy sudy were used o make he final selecion of cases for he down-ime analysis. The resuls are furher discussed in he following secion. The down-ime analysis included over 6,5 simulaions. The scope of work included simulaions in 3 differen environmenal direcions (A, B and C), wih he unnel elemen suspended a 1. m below he waer surface (Series A1, B1, C1) and.5 m above he gravel bed (Series A2, B2, C2). The simulaion scope is summarized in Table 7 and Figures 8, 9 and 1. The down-ime analysis is described in more deail furher below. Resuls of he Sensiiviy Sudy The resuls of he sensiiviy sudy revealed he following rends in he behavior of he wo ponoons wih he suspended unnel elemen. 1. The simulaion resuls are more sensiive o he period of he incoming waves han o he specral shape. Longer period waves generally cause larger moions and loads. 2. Long-cresed waves wih a direcion exacly ransverse o he unnel elemen (27 deg) can be considered as conservaive. Oher (near) beam-on wave direcions and shor-cresed seas resul in smaller moions and loads. 3. The lay-ou wih long mooring lines showed lower exreme mooring loads han he lay-ou wih shor mooring lines. The long lines mooring lay-ou was herefore used in he down-ime analysis. 4. The presence of a curren ransverse o he unnel elemen resuls in increased mean and maximum mooring loads. The damping effec on he unnel elemen moions was found o be limied. I is noed ha, prior o he sar of he ime-domain simulaion sudy, he design of he ponoons was up-daed. For his reason, he ponoons modeled in he ime-domain simulaions are somewha differen (larger) han he ponoons in he model ess. To include he up-daed ponoon shape in he simulaion model, new diffracion calculaions were carried ou. The ponoon dimensions and main pariculars can be found in Tables 2 and 3. DOWN-TIME ANALYSIS The operaional limis of he unnel immersion were evaluaed by carrying ou more han 6,5 ime-domain simulaions, invesigaing a large number of differen combinaions of wind sea and swell. The simulaion resuls included moions, velociies and acceleraions, as well as line ensions. The exreme values were used o perform a combined evaluaion of more han 1 srucural and operaional crieria. CONDOR Grid Compuing The necessary compuaion ime on a single PC, for each of he 6,5 anysim simulaions, is approximaely 5 minues. The use of a single machine o carry ou all simulaions in his sudy would herefore be very impracical. Insead, he simulaions were disribued over a large number of PCs (approximaely 2) wihin MARIN's nework, using CONDOR sofware. CONDOR is an open source sofware package ha allows submiing simulaion jobs on oher compuers wihin a nework. Simulaions jobs can be submied from a limied number of dedicaed machines ("conrol nodes") in he nework and are carried ou by all oher machines in he nework. 5 Copyrigh 29 by ASME

6 The approach is shown schemaically in he picure below (source: probabiliy of exceedance (similar o using 1/N o deermine he MPM-value). However, o carry ou his mehod auomaically for all simulaions is relaively complicaed and was herefore no considered in he presen sudy. Operaional Limis The unnel immersion operaion can be carried ou as long as he operaional limis are no exceeded. These operaional limis are relaed o allowable line ensions, capaciy of he applied winches and he allowed moion envelope of he unnel elemen. Two ypes of operaional limis were specified. Firs of all, he srucural limis, exceedance of which would resul in damage o one of he componens in he sysem. And second, he availabiliy limis, exceedance of which would require a emporary inerrupion of he immersion operaion, hus causing a delay. The applied srucural and availabiliy limis are summarized in Table 8. When a simulaion job is submied o he CONDOR sysem, i searches for available compuers on he nework. Any machine no in use for abou 5 minues is considered o be available. If he owner of his machine sars using he compuer, he CONDOR job is cancelled and removed. The sysem hen searches for a new available compuer unil all jobs are finished. Nowadays a MARIN he CONDOR sofware is commonly used in sudies were large numbers of simulaions are carried ou, see for example also Reference [7]. Daa Analysis Because of he large amoun of daa, only he saisical oupu of he 6,5 ime-domain simulaions was used for furher analysis and inerpreaion of he resuls, while he ime records hemselves were no sored. Based on he saisical oupu (mean value, sandard deviaion, minimum and maximum) he exreme values for he design were deermined. Insead of using he single exreme values from each simulaion, saisically more reliable exreme values were deermined. Mos probable maximum (MPM-) values were deermined for he unnel elemen moions, velociies and acceleraions, as well as for he mooring line, conracion line and suspension wire ensions. The following formulaion was used. N X design = X mean + σ x 2 ln α The above formulaion was proposed by Ochi, see Reference [8], and is based on he well known formulaion by Longue-Higgins, see Reference [9]. The formulaion by Ochi is valid for small values of α and large values of N. Alernaively, he design values could be deermined from (Weibull) disribuion plos, by aking he value of α/n as he Graphical Presenaion of he Resuls The large number of simulaions and he many operaional crieria o evaluae, required a graphical presenaion of he resuls. In his manner, an insan impression of he operabiliy can be obained, as well as an undersanding of he rends in he sysem behavior. Colors are used o indicae if he operaional limis are exceeded. Red indicaes exceedance of one or more of he srucural limis, while orange indicaes exceedance of one or more of he availabiliy limis. Green indicaes ha no operaional limis are exceeded. The simulaion resuls are presened in a graphical forma in scaer diagrams, wih he wave peak period on he horizonal axis and he significan wave heigh on he verical axis. An example is shown in Figure 11. The colors indicae if he operaional limis are exceeded for each combinaion of wave heigh H s and period T p of he incoming wind sea. To represen he resuls for combined wind sea and swell condiions, he scaer diagrams wih he resuls for he wind sea condiions are organized in a paern showing he swell period in he columns and swell heigh in he rows. In his manner nesed scaer diagrams are creaed. An example is shown in Figure 12. By presening he simulaion resuls in his manner, he relevan resuls can be found in he se of nesed scaer diagrams by selecing he relevan diagram based on he swell peak period and significan wave heigh. The resuls are presened in a graphical manner for each of he srucural and availabiliy limis separaely, as well as for all operaional limis combined. In his manner, he effec of changes in he design (and hus he operaional limis) on he workabiliy of he immersion operaion could be easily invesigaed. 6 Copyrigh 29 by ASME

7 Resuls and Conclusions Based on he resuls of he more han 6,5 ime-domain simulaions, he following conclusions could be drawn. 1. For cases wih he unnel elemen a 1. m below he waer surface he conracion line ensions and he suspension angle are he mos limiing. Curren causes he line ensions o increases significanly, bu he effec on he suspension angle is relaively small. 2. For cases wih he unnel elemen a.5 m above he gravel bed he unnel elemen moions and velociies are he mos limiing. The effec of curren is small. 3. In general, collinear environmens from Souh (Series B) are more limiing han environmens wih curren and swell from Souh and wind sea from Norh Wes (Series A). The cases wihou wind sea (Series C) were he leas limiing. 4. The cases wih he unnel elemen a.5 m above he gravel bed are more limiing han he cases wih he unnel elemen a 1. m below he waer surface. Apparenly, he design limis are more sric when he unnel elemen is close o he boom and he already insalled unnel secions. CONCLUSIONS Based on he resuls of he model ess and he imedomain compuer simulaions, he following conclusions may be drawn. 1. The model es resuls showed ha he wo ponoons wih he unnel elemen are he mos sensiive o longer period waves. The simulaion resuls showed he same rend. 2. The resuls of he model ess showed ha he unnel elemen moions were larger in 12 m han in 23 m waer deph. 3. The horizonal unnel elemen moions are larges when he unnel elemen is suspended a.5 m above he gravel bed, while he verical moions are larger when he unnel elemen is a 1. m below he waer surface. This was observed in he model ess and he compuer simulaions. 4. In he model ess i was found ha smaller moions could be observed for he 6 deg wave direcion, compared o he 9 deg (beam on) wave direcion. 5. The sensiiviy sudy, included in he compuer simulaions, showed ha he modeling of long-cresed waves exacly perpendicular o he unnel elemen can be considered conservaive. Shor-cresed waves are expeced o resul in smaller moions and loads han long-cresed waves. 6. The resuls of he sensiiviy sudy showed ha long mooring lines generally give lower maximum line loads han shor mooring lines. 7. The presence of curren ransverse o he unnel elemen resuls in an increase of he mean and maximum line ensions, bu hardly gives and addiional damping for he unnel elemen moions. 8. The resuls of he down-ime sudy showed ha when he unnel elemen is suspended a 1. m below he waer line, he line ensions and suspension angle are he mos limiing operaional crieria. 9. The resuls of he down-ime sudy showed ha when he unnel elemen is suspended a.5 m above he gravel bed, he moions and velociies are he mos limiing operaional crieria. In general, he cases wih he unnel elemen a.5 m above he gravel bed are more limiing han he cases wih he unnel elemen a 1. m below he waer surface. 1. The environmenal condiions considered in Series B are more limiing han he environmenal condiions in Series A and C. In Series B collinear curren, swell and wind seas were considered. TABLES AND FIGURES Table 1 - Main pariculars of he unnel elemen Paricular Uni Value Lengh m 18 Widh m 26.5 Heigh m 1. Mass (a 2% overweigh) ons 49, Table 2 - Main pariculars of he ponoons (model ess) Paricular Uni Value Lengh m 24. Widh m 42.5 Heigh m 8.5 Mass ons 63 Table 3 - Increased ponoon size (down-ime analysis) Paricular Uni Value Lengh m 36. Widh m 42.5 Heigh m 8.5 Mass ons 1,4 Table 4 - Mooring line properies (model ess) Paricular Uni Value Number of Lines Lengh m Diameer mm 4 Axial Siffness kn 1, 7 Copyrigh 29 by ASME

8 Table 5 - Conracion line properies (model ess) Paricular Uni Value Number of Lines Lengh m Diameer mm 54 Axial Siffness kn 17, Figure 1 - Phoograph of he unnel elemen model (1:5) Table 6 - Suspension wire properies (model ess) Paricular Uni Value Number of Lines Lengh m 32 Diameer mm 58 Axial Siffness kn 2, Table 7 - Environmenal condiions down-ime analysis Environmen Direcion Number Series A1 and A2 Curren from S 2 velociies Wind Sea from NW 42 specra Swell from S 19 specra Series B1 and B2 Curren from S 2 velociies Wind Sea from S 42 specra Swell from S 19 specra Series C1 and C2 Curren from S 3 velociies Wind Sea Swell from S 22 specra Figure 2 - One of he ponoon models wih he unnel elemen Figure 3 - Modeled 9 deg and 6 deg renches in he basin Table 8 - Operaional limis down-ime analysis Sysem Elemen Limiing Componen Srucural Limis Value Mooring Sysem Winch 7 kn Conracion Sysem Deck lay-ou 9 kn Longiudinal Sysem Deck lay-ou 72 kn Suspension Sysem Forces Lugs 8,5 kn Suspension Angle 15% Guide Beam / Cach Tunnel Velociies.17 m/s Availabiliy Limis Mooring Sysem Winch Capaciy 35 kn Conracion Sysem Winch Capaciy 6 kn Longiudinal Sysem Winch Capaciy 6 kn Suspension Sysem Winch Capaciy 5, kn Guide Beam / Cach Tunnel Velociies.185 m Tunnel Moions.5 m/s Tunnel Angular Vel deg/s Tunnel Roaions deg 8 Copyrigh 29 by ASME

9 Figure 4 - Deail phoograph of he model rench in he basin Figure 9 - Environmens down-ime analysis "Series B" Curren (from S) Wind Sea (from S) Swell (From S) Figure 5 - Top view of he es se-up including mooring lines Figure 1 - Environmens down-ime analysis "Series C" Curren (from S) Swell (From S) Figure 6 - Cross secion of ponoon and unnel elemen Figure 11 - Example scaer diagram wih simulaion resuls Hs / Tp Figure 12 - Example nesed scaer diagram for sea+swell cases Figure 7 - Panel disribuion of rench, unnel and ponoons H s 3 H s H s T p 1 T p 2 T p 3 Figure 8 - Environmens down-ime analysis "Series A" Wind Sea (from NW) ACKNOWLEDGMENTS The informaion in his paper is based on he resuls of he model ess carried ou a MARIN's Shallow Waer Basin on behalf of Daewoo Engineering and Consrucion, Ld. and he subsequen anysim compuer simulaion sudy. The auhors would like o hank Daewoo Engineering and Consrucion, Ld. for heir kind permission o publish his paper. Curren (from S) Swell (From S) 9 Copyrigh 29 by ASME

10 REFERENCES [1] Parha Chakrabari (Zenech, Inc.), Subraa K. Chakrabari (Offshore Srucures Analysis, Inc.), Tommy Olsen (COWI A/S), Koo Im Sig, Kim Chang Whan and Huh Jin Wook (Daewoo), "Dynamic Simulaion of Immersion of Tunnel Elemens for Busan- Geoje Fixed Link Projec", OMAE , OMAE Conference 28, Esoril, Porugal. [2] I. H. Cho and D. J. Kwag (AdvaCT, Anyang, KOREA), S. Bang (Souh Dakoa School of Mines and Technology, Rapid Ciy, Souh Dakoa, USA) and Y. Cho (Daewoo Engineering & Consrucion, Seoul, KOREA), "Use of Sucion Piles for Temporary Mooring of Immersed Tunnel Elemens", ISOPE Conference 28, Vancouver, Canada. [3] Buchner, B., Wilde, J.J. de and Dijk, A.W. van (MARIN), "Numerical Muliple-body Simulaions of Side-by-side Mooring o an FPSO", ISOPE21-JSC- 285, ISOPE Conference, Savanger, 21. [5] Cummins, W.E., "The Impulse Response Funcion and Ship Moions", DTMB Repor 1661, 1962, Washingon D.C. [6] Ogilvie, T.F.: "Recen Progress owards he undersanding and predicion of ship moions". Proceedings of he 5h Symposium on Naval Hydrodynamics, [7] Wilde, J.J. de, Berg, J. van den and Dijk, A.W. van (MARIN), "Downime Assessmen of Side-By-Side LNG Operaions Using Time Domain Simulaions", 29-ISOPE-TPC168, ISOPE Conference, Osaka, 29. [8] Ochi, M.K.: "Principles of Exreme Value Saisics and heir Applicaion", Exreme Load Response Symposium, Arlingon, VA, Ocober 19-2, [9] Longue-Higgins, M.S., 1952, "On Saisical Disribuion of he Heighs of Sea Waves", Journal of Marine Research, No. 3, [4] Cozijn, J.L., Wal, R.J. van der (MARIN) and Dunlop, C. (Saipem UK), "Model Tesing and Complex Numerical Simulaions for Offshore Insallaion", 28-ISOPE-PT- 2, ISOPE Conference, Vancouver, Copyrigh 29 by ASME