CALCULATION ON THE UPRIGHTING PROCESS OF A CAPSIZED SHIP

Transcription

1 rodogradnja/shpbuldng/open access Volume 67 Number 3, 17 De-we Pan Cheng-xn Ln h-je Lu De-png Sun ISSN 7-15 eissn CALCULATION ON THE UPRIHTIN PROCESS O A CAPSIED SHIP Summary UDC : :519.6 Orgnal scentfc paper The processes of marne salvage requre frstly the uprghtng of the capszed shp, essentally brngng the deck to pont up. Analyss and computaton are the keys for the success n the applcaton of the desgn schemes. Up to date, there are few researches on calculaton methods for uprghtng process of capszed shps at Chna and abroad. Researches about the effect of floodng quantty and the varaton of the longtudnal strength durng the uprghtng process of capszed and damaged shps are even rarer. In ths paper, hydromechancal equatons to descrbe the effect of floodng are establshed and a calculaton method for the longtudnal strength s ntroduced wth reference to the hydrostatc theory for shps. Three typcal uprghtng processes are summarzed accordng to the methods of treatment of damaged compartment. The stablty of the nverted shp s calculated and analyzed usng the eneral Hydrostatcs software(hs). Reserve buoyancy, shear forces, bendng moments and torques are calculated n nne postons along the shp. Key words: hydrostatc; capsze; damaged shp; uprghtng 115

2 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp 1. Introducton In tradtonal marne salvage, emprcal methods are appled to defne an uprghtng program, analyzng only some of the typcal condtons of the capszed shp. The calculaton process s complex and tme consumng, whle ncorrect calculatons and large errors can cause the occurrence of serous accdents [1]. Shp stablty and floataton must be determned before uprghtng. The poston of a floatng shp s determned by heelng angle, trm, and draft. hao [] proposed a soluton of equlbrum equatons of damaged shp usng an optmstc algorthm based on Vlasov parameters. Ln et al. [3] used a damaged shp s nsubmersblty and the reen formula to determne ts floatng condton. L [4] studed the floatng condton, stablty, and nsubmersblty of a lumber carrer, and completed a smulaton. Another factor affectng the stablty of the shp and the dffculty of salvage s the presence of free lquds. Couser [5] obtaned the statc effect of flud on a half-flled, prsmatc tank wth rectangular cross-secton, whch used to valdate the software program called Hydromax. The rato between the tank breadth and ts heght (b/h) was also studed, provdng the free surface effect. uo et al. [6] proposed an easy optmum method to determne the free surface effect, provdng three examples for a sphercal tank and showng the effcacy of the method and ts possble applcaton. The floodng of a damaged compartment ncreases the weght of the shp and affects ts floataton and stablty. Ruponen [7] dvded the floodng process nto three man phases, and consequently studed the effects of ventlaton ducts and the strength of the non-watertght subdvson. Vermee et al. [8] studed the sudden ngress of water n the transent stages by theoretcal calculaton and experments, applyng a longtudnal subdvson to avod the rapd capszng phenomenon. Mronuk [9] studed the accdents of Polsh warshps n , calculatng the quantty of water flooded to the nteror compartment and applyng the estmatng floodng tme method. Longtudnal strength, transverse strength and local strength are commonly used to assess the strength of a shp. Longtudnal strength, n partcular, s the most mportant parameter to ensure the safety of a shp structure [1]. Ivanov [11] proposed an analytcal approxmate method to calculate shear forces and bendng moments of stll water, whch are analytcally presented n dmensonless format, n order to compare results obtaned for shps of dfferent szes. Dubravka et al. [1] establshed a mathematcal model to determne transversal forces and bendng moments, and the errors between calculated results and the results from the book were analyzed. Khan and Das [13] derved the bendng moments based on a stress stran relatonshp, and the resdual strength of one tanker and two bulk carrers were determned usng Smth s method. Pak et al. [14] studed the ultmate strength characterstcs of shp hulls under torson wth large hatch openngs. Wang et al. [15] derved the method for the calculaton of the resdual strength of a hull grder for a broad spectrum of accdents, ndependently from the prncpal dmensons of a shp, wth a great advantage n cases of emergency or salvage operaton. Accordng to statstcs, calculaton wth smulaton software s more than twce as faster as tradtonal calculatons, and s also much more accurate [16]. Lu et al. [17] developed a software program va Mcrosoft Vsual asc 6., Mcrosoft Excel, and Mcrosoft Access, whch can calculate the weght of a shp n water and help desgn the confguraton scheme of pontoons. Lu et al. [18] devsed software that can help desgn the layout scheme of a workste for salvage engneerng. Lu et al. [19] dscussed the feasblty of a PDA (personal dgtal assstant) applcaton n rescue salvage and dvng. Huang et al. [] desgned a computer program to speed up salvage computaton. These programs have sgnfcant theoretcal and functonal value for salvage projects. 116

3 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, Table 1 Table of symbols Characterstc Abbrevaton Unt Characterstc Abbrevaton Unt Waterlne WL ravty of shp W N Reserve buoyancy N Rghtng force N Total buoyancy force of all compartments both above and below the waterplane that are watertght or can be made watertght to wthstand the external hydrostatc pressure Dsplacement of ntact shp Mass densty(water) Dsplacement volume of flooded water uoyancy force of salvage pontoons Rghtng arm Heelng angle Trm Coordnates of center of gravty of ntact shp Coordnates of buoyancy center of ntact shp xed coordnate system Shp fxed coordnate system Unt vector of the fxed coordnate system Rghtng moment C C R SP, C, C C C O 1 Oxyz, j, k M S,, N Moment of nerta of the lqud surface wth respect to the barycentrc axs (of the free surface) parallel to the axs of heelng N Area of the damage openng m g/m 3 Poston of breach Area A m 3 Three components of the M, M, M N.m rghtng force moment N Three components of the M, M, M moment of buoyancy force m low coeffcent Center of gravty of ntact shp uoyancy center of ntact shp Coordnates of the rghtng force functonal pont Inflow quantty of the damaged compartment of the -th value Rghtng force per unt length at secton x Intal floodng quantty Three components of the moment of shp weght N.m Shear force at secton x Waterlne of shp n neutral W L Total volume of damaged poston compartment of the -th value New waterlne of shp n the W 1L 1 Center of gravty of damaged neutral poston compartments Waterlne of compartment of W cl c Longtudnal load per unt shp n neutral poston length at secton x New waterlne of compartment W c1l c1 Total floodng quantty Orgnal centre of gravty of the lqud New center of gravty of the lqud Heelng moment produced by the nclnaton of the lqud surface Mass densty (Lqud) Volume occuped by the lqud Longtudnal dstance between g and g Transverse dstance between and g g Lqud mass g g M l l l Dstance between W 1 L 1 W c 1Lc1 and Dstance between the breach of the damaged compartment and the surface of the damaged compartment Dstance between the damaged.m compartment s breach and the sea surface Kg/m 3 ravty forces per unt length at secton x m 3 endng moment at secton x l m Center of gravty of damaged 1 compartment l m Center of gravty of damaged shp l Poston vector r Load on the certan shp cross I A,, q f (x) I M, M, M x C x C,, N(x) y C, q(x) W h 1 h g(x) M(x) y C, z C z C CD, CD, CD m ton Torque at secton x T (y, z) N.m secton of secton x orce(k) vector K Three components of force(k) Three components of the moment of K Coordnates of the force(k) functonal pont Transverse dstance between the load actng pont and the balance poston M K MK, M K, uoyancy center of damaged shp,, uoyancy forces per unt length at secton x l (y, z) m m 4 m 3 N m 3 N m 3 N N m m m N N.m q (y, z) N K, K, K CD, CD, CD b (x) N 117

4 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp However, at present, the calculaton used for uprghtng process manly consders the varaton of the heelng angle and the draft, neglectng the effects due to the trm of the shp. Consequently, the results of the calculaton may be wrong for salvagng shps wth complex shp lnes, damaged shps and large shps. The force module of a wrecked shp s establshed consderng ts buoyancy and stablty. The floodng quantty of damaged compartments and the calculaton method of the longtudnal strength of the shp are consequently derved. Three dfferent typologes of uprghtng processes were smulated by HS and the varaton of reserve buoyancy, stablty, shear forces, bendng moments and torques durng uprghtng were obtaned.. Typcal types of damaged shp The uprghtng process of a damaged, capszed shp s nfluenced by buoyancy, stablty, and slack tank. Accordng to the methods for treatment of damaged compartments, the followng three condtons can be suggested as typcal, n reference to the stuaton shown n gure 1. g. 1 The dagram of hull and compartments Case 1: Durng the uprghtng process, damaged compartments underwater cannot be repared (gure ). The damaged compartments regard as ntact compartments wth 1% load. loodng water s consdered as part of the dead weght of the vessel. WL s the waterlne. g. Dagram of the frst case Case : Durng the uprghtng process, the damaged compartments can be repared, but they cannot be fully draned (gure 3). ree water n the slack tank adversely affects engneerng, however the capszed shp of Case has hgher reserve buoyancy than Case 1. A greater uprghtng force s requred for better uprghtng control. 118

5 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, g. 3 Dagram of the second case Case 3: Durng the uprghtng process, the damaged compartments are not repared. The breach s not sealed, and water contnues flowng nsde out the compartments (gure 4). As a result, the total amount of water changes durng the course of uprghtng. In ths case, the nsubmersblty of the shp must be consdered. g. 4 Dagram of the thrd case The success of the uprghtng process depends on the accurate calculaton of buoyancy, stablty, floodng quantty, uprghtng moment and longtudnal strength of shp. 3. Theoretcal calculaton 3.1 Reserve buoyancy Calculaton of reserve buoyancy contrbutes to makng uprghtng plan. The method of sealng compartments or salvage pontoons can be used to ncrease reserve buoyancy. Reserve buoyancy of damaged shp s composed of four parts: R g (1) SP Where s the total buoyancy force of all compartments both above and below the waterplane that are watertght or can be made watertght to wthstand the external hydrostatc pressure, s the dsplacement of ntact shp, s the dsplacement volume of flooded water, s the buoyancy force of salvage pontoons. SP 3. Lqud heelng moment When a vessel wth a partally-flled tank s heeled, the lqud wll seek to reman parallel wth the waterlne. The centre of gravty of the lqud, beng the centre of ts volume, wll move wth the lqud and can have a consderable effect upon the vessel s stablty. gure 5 shows a tank contanng a lqud whose surface s free to move wthn a small angle wthout touchng the tank top or bottom. 119

6 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp g. 5 The shp tlted at a small angle : The heelng moment produced by the nclnaton of the lqud surface s represented by M I ll g tan l gi tan () l l Where s the lqud densty, s the moment of nerta of the lqud surface wth respect to the barycentrc axs (of the free surface) parallel to the axs of heelng. l I g. 6 The shp tlted at a bg angle Often the lqud surface s not free to behave as n gure 6 and ts shape changes when t reaches the tank top or bottom. Then, we cannot use the equatons shown above. The same happens when the heelng angle s large and the forms of the tank such that the shape of the free surface changes n a way that cannot be neglected. In such cases the exact trajectory of the centre of gravty must be calculated. As shown n gure 6, the resultng heelng moment s represented by: Where M m g l sn l cos ) (3) l1 l ( 1 m l s the lqud mass. 3.3 loatng parameters enerally, the man methods of uprghtng nclude floatng pontoon method, hydraulc jack method and floatng crane method. These methods are able to rotate the capszed shp by applyng external vertcal forces through dfferent ways. 1

7 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, The uprghtng process can be dvded nto numerous statc states, wth ther relatve mechancal equlbrum. The poston of a floatng shp s determned by the relaton between a fxed coordnate system and the shp fxed coordnate system. gure 7 shows the orgn of the fxed coordnate system, whch exsts n the cross area of water plane area of shp under the uprght floatng condton, the mdshp secton, and the longtudnal md-secton. The orgn O of the shp fxed coordnate system exsts n the cross area of the base plane, the mdshp secton, and the longtudnal mdsecton. The axes drectons are as follows: Ox s the ntersecton of the base plane and the longtudnal md-secton; the stern represents the postve drecton. Oy s the ntersecton of the base plane and the mdshp secton; the starboard represents the postve drecton. Oz s the ntersecton of the longtudnal md-secton and the mdshp secton; the postve drecton s over the base plane. Oxyz O 1 O 1 g. 7 The fxed coordnate system and the shp fxed coordnate system enerally, Euler angle parameters, Vlasov angle parameters and olegman angle parameters can be used to determne floataton. Vlasov angle parameters are wdely used n Chna, especally for damaged shps, but the parameters lead to values of draft approachng to nfnty for heelng angle or trm up to 9. Applyng olegman angle parameters, the value of draft approach nfnty for trm s 9. Therefore, n uprghtng calculaton, Vlasov angle parameters and olegman angle parameters may brng obvous error. To study the uprghtng process of capszed shp suffcently, theoretcal calculaton are made applyng Euler angle parameters. or the convenence of engneerng analyss, headng s to avod any angular dsplacements. In addton, the orgn of the fxed coordnate system s concdent to the orgn of the shp fxed coordnate system, and the relaton between the two systems s descrbed by the followng equaton: cos sn sn cos sn x cos sn y z sn sn cos cos cos (4) 11

8 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp 3.4 Shp stablty Due to the nfluence of underwater shp lnes, freeboard and superstructure, the computaton of ntal stablty s not applcable for a bg-angle tlted shp [1]. The rghtng arm of damaged shp at any spatal poston s represented by: Where ( ) ( ) ( ) ( ) 1 cos (, j) ; cos (, j) ( ) ( ) ( x x )cos ( z z )cos sn ( y y )cos ( z z )sn ( y y )sn sn ( z z )cos sn ( x x )cos ( y y )sn sn ( x x ) cos ( y y ) sn sn ( z z ) cos sn The essence of the uprghtng process s the rotaton process, whch starts when the rghtng force moment s greater than the rghtng moment. The rghtng moment s represented by: M ( g (6) S ) 3.5 The mathematcal model In the Cartesan coordnates, the moment of the force vector K actng on the orgn s defned as the cross product of the poston vector and K. M r K K The moment of K M M M K K K K K K j K k K ( K ( K K K ) ( K ) k K ) j s resolved nto three components along the coordnate axs: K K K Where,, are the coordnates of the force functonal pont. Accordng to equaton (7) and (8), the shp s weght s resolved nto three components along the coordnate axes where W s the gravty of the shp: W W W W sn W sn cos W cos cos 1 (5) (7) (8) (9)

9 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, The moment of shp's weght s resolved nto three components along the coordnate axes: M M M W cos cos W sn W sn cos W sn cos W cos cos W sn (1) In the same way, the shp's buoyancy force moment s resolved nto three components along the coordnate axes: M M M cos cos sn sn cos sn cos cos cos sn (11) Where s the buoyancy force of the shp. In the same way, rghtng force moment s resolved nto three components along the coordnate axes: M M M cos cos sn sn cos sn cos cos cos sn (1) Where,, are the coordnates of the rghtng force functonal pont. Accordng to equaton (1), (11) and (1), equaton (13) s obtaned: M M M M ( M ( M ( M M M M M M )cos cos ( )sn ( )sn cos ( )cos cos )sn cos )sn (13) The relatonshp between M, M and M s represented by: M sn M sn cos M cos cos (14) The statc equlbrum equaton of gravty, buoyancy force and rghtng force can be obtaned. W (15) Then, the mechancal model of uprghtng s establshed. 13

10 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp W M M MD M ( W M M M M ( W )sn ( W )sn cos ( W )cos cos )sn (16) g. 8 The dagram of damaged compartment gure 8 shows a flooded damaged compartment, whch s not flled wth water because of ar. ernoull equaton can be used to obtan the nflow quantty of the damaged compartment of the -th value []: q A g( h ) A g( h ) 1 1 1,,3,..., n (17) Here, A s the area of the damage openng; μ s the flow coeffcent. The total water quantty of damaged compartment of the -th value can be obtaned: I 1 q Where I s the ntal floodng quantty. Thus, the total floodng quantty can be solved durng uprghtng: W g (19) The center of gravty of a damaged compartment ( x C, y C, z C) can be obtaned based on shp lnes, nclnaton angle and the total floodng quantty. Then, the center of gravty of damaged compartments ( x C y z ) s solved., C, C The center of gravty of the damaged shp s determned accordng to the ntact shp and the total floodng quantty [3]. (18) 14

11 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, CD CD CD C C W x W W y C W W z C C C W g g g g g g () The buoyancy center of damaged shp can be obtaned based on buoyancy center of ntact shp and the center of gravty of damaged shp [4]. CD CD CD g y g C g g C C g g z x C C (1) Where v s the volume of watertght compartments below ntal water lne. Durng uprghtng, the shp s consdered to be n equlbrum under the acton of weght, buoyancy forces and rghtng force. The sum of buoyancy forces and rghtng force actng on a shp must be equal to the weght of the shp tself. However, the dstrbuton of those forces along the shp length s not unform. The dfference between those values on a certan cross secton of the shp gves the longtudnal load as follows: q( x) g( x) b( x) f ( x) () Where expresses the gravty forces per unt length at secton x, expresses the buoyancy forces per unt length at secton x, and f (x) s the rghtng force per unt length at secton x. Then the shear force and the bendng moment at secton x can be expressed as follows: g(x) x b(x) N( x) q( x) dx (3) x x M ( x) q( x) dxdx (4) In addton, the torque at secton x s as follows: T (y, z) y z q(y, z) l(y, z)dydz (5) Where q (y, z) s the load on the certan shp cross secton of secton x, l (y, z) s the dstance between the load actng pont and balance poston. Uprghtng calculaton s a multfarous course. Correlatve software can mprove desgn effcency and shorten desgn tme. Ths paper adopts the HS software to smulate the uprghtng process. 15

12 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp 4. Smulaton descrpton Manual calculaton, the table method, experental formulas, and sem-emprcal formulas are used to calculate the rghtng force n tradtonal salvage engneerng. Whch have lmted sgnfcance n salvage engneerng because the process s slow and mprecse. Tradtonal calculaton cannot determne the exact necessary uprghtng force, so equpments must be contnually altered on ste. HS software can overcome the problems of tradtonal calculatons. The HS tools fall nto two groups nvolved n performng a hydrostatc analyss. One s the tool for buldng a model of a vessel, the other s the tool for analyzng the model. In phase one, the buoyant part of the hull must be defned n a manner sutable to the degree of precson requred. Internal subdvsons and tankage arrangements may be specfed as well as non-buoyant superstructure for calculatons. Phase two produces hydrostatc/stablty evaluaton data based on the model bult n phase one. Ths data may nclude tables and curves of hydrostatc propertes, stablty and tank characterstcs; or a smulaton-orented approach may be taken, subjectng the model to condtons of loadng and damage whle observng the response. Shp model qualty affects smulaton accuracy. Some prncples should be obeyed durng the modelng process: twsted hull lnes must be avoded to decrease computng errors; the changng actve model area must be encrypted to mprove soluton precson; the lne segment quantty n areas wth lttle changes n model ntensty should be controlled to expedate calculaton. There are two methods for HS software modelng: nterface operaton and an edtor program. Ths paper explores the edtor program method. The hull model must be establshed based on shp lnes plans. When creatng a vessel model, the buoyant part of the hull must be defned n a manner sutable to the degree of necessary precson. The hull s dvded nto dfferent sectons (The hull of a common shp can be represented by 1 frames, but shps wth more complex surfaces requre more frames); the longtudnal coordnate of every secton should be determned. The secton conssts of many ponts, whch can be obtaned by the transverse and vertcal coordnates of ponts. Then, compartment models are bult based on the compartment dagram. Here, compartment permeablty and cargo loads can also be set. Usng the shp n gure 9 as an example, orgn O crosses the area of the base plane, the mdshp secton, and the longtudnal md-secton, whch s 3 m from the stern. The axs drecton s as follows: Ox s the ntersecton of the base plane and the longtudnal mdsecton; the stern represents the postve drecton. Oy s the ntersecton of the base plane and the mdshp secton; the starboard represents the postve drecton. Oz s the ntersecton of the longtudnal md-secton and the mdshp secton; the postve drecton s over the base plane. Table 1 shows the shp s prncpal dmensons. g. 9 Hull and cabns 16

13 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, Table The prncpal dmensons of the ntact shp Length Overall readth Molded depth Weght (m) (m) (m) (ton) Smulaton scheme Accordng to related lterature and actual real salvages, some shps wll stll float on water although some compartments are damaged. The shp s profle lne, cargo, and superstructure affect the uprghtng process. Water flow, tde, and wnd are also mportant factors to consder [5-7]. In tradtonal calculatons for rghtng capszed wrecks, calculaton results are often naccurate because the equaton only analyzes certan stages of the uprghtng process [8-3]. The example used for ths study regards a shp wth a bg gash caused by a collson. The shp lsted to starboard, t had a trm of -.41, and an orgn draft of m. Three uprghtng schemes of uprghtng were evaluated. Scheme A: The compartments opposte to the damaged ones were unloaded. The damaged bulkhead was entrely cleared and rewelded. The damaged compartments were draned. Then, the shp lsted 18 to starboard. Scheme : The breaches n the damaged compartments were sealed. About 15% of the compartments volume was flled wth water, due to dranage technque lmtaton. Scheme C: The shp was rghted drectly. The breaches were not sealed and therefore water contnued flowng nsde out the compartments. As a result, the total amount of water changed durng the course of uprghtng. Durng the uprghtng process, the superstructure s not sealed and the same rghtng method was appled for comparng the three schemes. 5.1 Reserve buoyancy To ensure adequate reserve buoyancy t s necessary to verfy the counter-floodng calculaton. The reserve buoyancy of damaged shp s kn. The maxmum dsplacement of the damaged shp s kn. Thus, the shp could be rghted drectly. 5. Analyss on stablty of capszed shps 5 15 A Rghtng moment (KN.m) C g. 1 The statc stablty curves of capszed shps 17

14 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp Statc stablty of the capszed shp determnes the dffculty of uprghtng (gure 1). Durng uprghtng, the shp begns to rotate when the rghtng force moment s greater than the rghtng moment. Negatve values of the curves represent the stablty of the shp n uprght condton. Negatve stablty s helpful durng the uprghtng process, because the shp s prone to return to the neutral poston wthout rghtng force. Then a moment n the opposte drecton s needed to mantan a steady speed, whch prevents the shp from beng damaged agan or from capszng agan. The proporton between the maxmum rghtng moment and the maxmum rghtng moment n the opposte drecton was.544,.546 and.395 for schemes A, and C, respectvely. In later phases of the process, the rghtng force moment n the opposte drecton and the rghtng force moment n the postve drecton were needed for schemes and C, respectvely. If the longtudnal load of the hull exceeds ts lmt stress value, there s a serous rsk for serous accdent and njury. Thus, from the strength analyss of the hull depends the success or falure of the salvage project. The varaton of the longtudnal strength were evaluated n nne postons along the hull, and -4.8,-13.6,-15.6,-3.94,-53.4,-61.88,-87.6,-13.87, and were the longtudnal coordnates of the nne selected sectons (gure 11). 5.3 The longtudnal shear forces durng uprghtng Shear force(kn) g. 11 Varaton of the longtudnal shear force of A Shear force (kn) g. 1 Varaton of the longtudnal shear force of 1 5 Shear force (kn) g. 13 Varaton of the longtudnal shear force of C The varaton of the longtudnal shear forces durng uprghtng process showed that the shear forces n the md-shp were relatvely small, whle heavy carryng capablty and small dsplacement near the front of shp produced greater shear forces. The shear forces at stern were relatvely bg, due to the superstructure and small dsplacement. In scheme, a large varaton of shear forces n the front half part of the shp at the begnnng of the project. In 18

15 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, scheme C, the damaged compartments of the bow had a greater water flow than other compartments, whch contrbuted to a large varaton of shear forces, and shear forces of mdshp decreased durng uprghtng. 5.4 The bendng moments durng uprghtng endng moment (KN) endng moment (kn.m) g. 14 Varaton of the bendng moments of A g. 15 Varaton of the bendng moments of endng moment (kn.m) g. 16 Varaton of the bendng moments of C Stll water bendng moment s the most mportant operaton for strength calculaton. gure 1 shows that the trends of bendng moment n dfferent longtudnal poston of hull were approxmately the same for schemes A and. In scheme C, early n the uprghtng, 94.7% of seawater n the peak tank was gone, whle the quantty of water nflow was very small. Durng uprghtng, the trm change of the shp was 1.48 ; the bendng moment of the hull wth the longtudnal coordnates , and reduced by 88.4%, 1.5%, and 99.5%, respectvely. The trends of bendng moment of the stern of scheme C were consstent wth scheme A and scheme. 5.5 The torques durng uprghtng Torque (kn.m) g. 17 Varaton of the torques of A Torque (kn.m) g. 18 Varaton of the torques of 19

16 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp Torque (kn.m) g. 19 Varaton of the torques of C The uprghtng process s a rotaton process. The uneven dstrbuton of the transverse forces may cause the structure torson along the hull. The changng curves of torques n the three schemes are presented n gure 13. Scheme A has the maxmum torques, whle torques n scheme follow the same trend of A, but wth relatvely small values. In addton, the varaton curves of torques for A and are smlar to the statc stablty curves. The torques of and C under the ntal state and the neutral poston are unequal to zero, due to negatve ntal stablty. In scheme C, torques s greatly nfluenced by floodng water, and the trends of torques on the bow, md-shp and stern are the same respectvely, whle the maxmum negatve torque s produced on the stern of the shp. 6. Conclusons In ths paper, mathematcal models of rghtng force, floodng quantty and longtudnal strength were establshed based on the hydrostatcs theory for shps. The tree-dmensonal shp model was bult va HS to smulate the rghtng of capszed shps. The man results are as follows: (1) The stablty of the nverted shp can be reduced by unloadng stowage at a hgher level of shp, whch s benefcal to the uprghtng process. Three dfferent schemes of uprghtng processes were smulated by HS: scheme A, wth no water n the damaged compartment and for whch the damaged bulkhead was entrely cleared and rewelded; scheme, wth 15% of the volume of the compartment flled wth water due to dranage technque lmtaton; and scheme C, wth some water n the damaged compartment and breaches were not sealed. or scheme A, work tme ncreased due to the need of complete repar of damaged compartments, and the larger rghtng force moment was produced. or scheme, the tme for sealng damaged compartments was reduced, but the free water n the damaged compartments decreased the stablty of nverted shp, whch n turns reduced the dffculty of uprghtng, especally n comparson to A. Scheme C consderably reduced the tme of preparatory work, and decreased the stablty of nverted shp n some degree, but t also ncreased the dffculty of uprghtng due to floodng water. Thus, scheme was confrmed as the most reasonable. () Durng uprghtng, controllng the varaton of trm s benefcal. The longtudnal dstrbuton of weght, dsplacement and rghtng force should also be consdered. Adjustng ballast water reduces ptchng moton, but t can also produce bg shear forces. Superstructure also causes a local ncrease of shear force. (3) The uprghtng process s a rotaton process. The dstrbuton of torques along hull should also be calculated, especally for damaged shp wth large openngs. or shps wth negatve stablty, the torques stll need be consdered when the shp s pulled uprght completely. The torques vary complcatedly due to the water flowng nsde out the damaged compartments, so calculaton of the torques must be made to ensure the safety of hull. 13

17 Calculaton on the uprghtng process of a capszed shp De-we Pan, Cheng-xn Ln, Acknowledgments The authors thanks the anonymous revewers for ther valuable remarks and comments. Ths paper s funded by the undamental Research unds for the Central Unverstes ( , ), the Key Technology and Demonstraton of Helcoper Rescue Ablty Promoton of Severe Sea Condton(133858), and Natonal Sc-Tech Support Plan (14AK56). REERENCES [1] Ln, J.., R.. Wang,. C. Sun, 6, The salvage of the shp nheshanl68, Proceedngs of Chna Internatonal Rescue & Salvage Conference 6(CIRSC), Kunmng, Chna, pp (n Chnese) [] hao,.., 1988, The calculaton of subdvson and damage stablty of shp, J. Journal of dalan unversty of technology, 8(1), pp (n Chnese) [3] Ln,., T. L. L,. S. J, 1, Shp damage floatng calculaton, J. Journal of dalan unversty of technology. 14(1), pp (n Chnese) [4] L,. M.,, Study on the uoyancy Stablty Longtudnal Strength of Lumber Carrer and Smulaton of Damaged loodng, MA.Sc. thess, Dalan Martme Unversty, Dalan, Chna. (n Chnese) [5] Couser, P. R., 4, ON THE EECT O TANK REE SURACES ON VESSEL STATIC STAILIT, J. Internatonal Journal of Martme Engneerng. [6] uo D. H., He,. J. and Chen,. S., 1996, Determnaton of the ree Surface n a Lqud Tank, J. Communcatons n Nodmm Scence & Numakal Smukon, 1(3), pp [7] Ruponen, P., 7, PRORESSIVE LOODIN O A DAMAED PASSENER SHIP, Ph.D. thess, Helsnk Unversty of Technology, Helsnk, nland. [8] Vermeer,H., Vredeveldt, A.W. and Journée, J.M.J, 1994, Mathematcal Modellng of Motons and Damaged Stablty of Ro-Ro Shps n the Intermedate Stages of loodng, fth Internatonal Conference on Stablty of Shps and Ocean Structures, lorda, USA, pp [9] Mronuk, W., 1, The Influence of the loodng Damaged Compartment on the Metacentrc Heght Shp Type 888, J. Internatonal Journal on Marne Navgaton and Safety of Sea Transportaton, 4(4), pp [1] ao, T., 3, Hull grder strength, J. Marne Structures, 16, pp [11] Ivanov, L. D., 7, On the relatonshp between maxmum stll water shear forces, bendng moments, and rad of gyraton of the total shp's weght and buoyancy forces, J. Shps and Offshore Structures, (1), pp [1] ŽAJA, D., AMARIN, A., and HADJINA, M., 7, LONITUDINAL STRENTH O A CONTAINER SHIP, J. Eng. Rev., 7(1), pp [13] Khan, I. A., and Das., P. K., 8, Relablty analyss of ntact and damaged shps consderng combned vertcal and horzontal bendng moments, J. Shps and Offshore Structures, 3(4), pp [14] Pak, J. K., Thayamball, A. K., Pedersen, P. T. and Park,. I., 1, Ultmate strength of shp hulls under torson, J. Ocean Engneerng, (8), pp [15] e. W., Chen,.J., hang, H.Q., and Peng, H.,, Longtudnal strength of shps wth accdental damages, J. Marne Structures, (15), pp [16] Wang, D. N., and,. T., 1, A ref Introducton on HS Software n Wreck Removal Operaton, In: Proceedngs of the 6nd Chna nternatonal rescue and salvage conference, an, Chna, pp (n Chnese) [17] Lu,. H., Huang,. L., Huang,.., 6, Research on aded desgn software about salvage of sunken shp, J. Chna Water Transport(Academc Verson), 6(1), pp (n Chnese) 131

18 De-we Pan, Cheng-xn Ln, Calculaton on the uprghtng process of a capszed shp [18] Lu, H. M, and u,.., 4, The desgn and realzaton of the auxlary desgn software of layout for salvage boat, In: The 4 Salvage annual Symposum, Haerbn, Chna, pp, (n Chnese) [19] Lu, H. M., u,.., Lu., L,. H., Duan,., and Hu, P., 6, PDA Applcaton and Empolder n the eld of Rescue Salvage and Dvng, In: The 6 Salvage annual Symposum, Kunmng, Chna, pp (n Chnese) [] Huang,. K., ang, H. P., Wang,. M., and Ln,. T., 5, Research on the Auxlary Desgn Sohware Model of Rghtng Sunken Shp, In: The 5 Salvage annual Symposum, Chongqng, Chna, pp (n Chnese) [1] Deng,. T., 6, Chuanbo alun, Chna communcatons Press, ejng, Chna, pp. 3-5.(n Chnese) [] Chen,. R., Jn, C. M, and Wang, C. M., 3, Engneerng flud mechanc(nd edton), Hgher educaton press, ejng, Chna, pp (n Chnese) [3] Sheng,.., and Lu,.., 3, Prncple of Shp, Shangha Jao Tong Unversty Press. Shangha, Chna, pp. -3. (n Chnese) [4] Ma,. W., 1999, Calculaton of Damaged shp on stll water, MA.Sc. thess, Wuhan Transportaton Unversty, Wuhan, Chna. (n Chnese) [5] hang, H. L.,, Engneerng of underwater ol recovery and refloated for unhong shp, In: Proceedngs of the nd Chna nternatonal rescue and salvage conference, Nngbo, Chna, pp (n Chnese) [6] Cong, P. S., and hou,. Q., Jn J 7 Salvage, 5, Chna Rescue and Salvage, (11), pp (n Chnese) [7] Wang, D. N., and hou,. Q., 9, Jao hua 16 rab Dredger Salvage, In: The 9 Salvage annual Symposum, Wuhan, Chna, pp (n Chnese) [8], 1974, US Navy Salvage Report: Suez Canal Salvage Operatons n 1974, 36, Department of the Navy Naval Sea Systems Command, Washngton, D. C. [9] hao, M.., 1995, Analyss of rghtng force durng salvage of Changzheng shp, J. Marne Technology., pp (n Chnese) [3] Sun,. C., Wu, J. C., and hang,. Q., 8, Salvage of Neftegaz 67 wth HUA TIAN LON, In: Proceedngs of the 5nd Chna nternatonal rescue and salvage conference, Dalan, Chna, pp ( n Chnese) Submtted: Accepted:.6.16 De-we Pan Cheng-xn Ln, lch_xn@16.com h-je Lu Transportaton Equpments and Ocean Engneerng College Dalan Martme Unversty De-png Sun Marne Engneerng College, Dalan Martme Unversty 13