phần 2 ảnh hưởng của gió,dòng.Dear Thầy

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GVHD: NGUYN MNH HNG

Chng 1 Nguyn tc chung ca vic neo buc tu1.1 Tng qut : Cho n khi s ra i ca nhu cu vn chuyn s lng ln hng ha v nguyn vt liu bng ng bin, cc yu cu c bn ca mt h thng neo u ngn nga vic va chm ca cc tu khi neo u ti cu cng, khu neo u c ra i. Thut ng "neo buc tu " dng ch h thng m bo cho mt con tu c th neo u ti mt cng hay bn tu . Ni neo buc ph bin nht dnh cho cc tu bn ln l cu cng v sea islands , tuy nhin, vi cc hot ng khc ca tu nh chng buc tu mt v tr c nh, neo u phao, vt ni, vi cc tu v cc phng tin ngoi bin, nh tu cu h, tu lai, chng buc vi s lan, hay vic i qua knh, hay vic chuyn ti gia cc tu hay neo u mt khu vc no . Do phi c yu cu c bit i vi trang thit b, ph kin dnh cho cng tc neo buc tu. H thng cng h tr trong vic cp cu v ri cu ti bn tu. Thit b neo u phi c quy nh v thng nht tr n ton cu. Cc nguyn tc phi c tun theo, khng phn bit i vi kch thc tu, nhm mc ch hn ch vic di chuyn ca tu khi neo u trong mt gii hn c th chp nhn c, khi phn b mt s lng dy buc tu ph hp,v sao cho c th d dng x l bi cc cng nhn cng, v hn na sao cho tng thch vi cc iu kin ca gi, dng, thi tit, thy triu v cc hiu ng khc c kh nng tc ng n tu, trong sut thi gian tu ti neo u .

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Mu buc tu in hnh ti sea islands Tun th theo m hnh buc tu trn l s cn thit cho an ton ca tu, cng nh thuyn vin trn tu hay bn cng v mi tr ng.

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Gc ti u ca cc dy buc tu ti sea islands 1.1.1 Dy ngang (Breast lines) : - Dy ngang c lin kt vung vi ng trung tm dc ca tu vi cu cng nhm mc ch hn ch ti a s di chuyn ngang ca mn tu so vi cu cng. 1.1.2 Dy cho (Spring lines ) : - Dy cho nn c sp xp lch khong 10 0 so vi ng trung tm dc ca tu nhm mc ch hn ch ti a s di chuyn theo chiu cu tu. 1.1.3 Dy dc mi,li (Head and stern lines ) : - Dy dc mi ,li ty thuc vo gc ca n so vi trc gia tu, n c tc dng hn hoc t hiu qu hn so vi dy cho.

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1.2 Nhng lc tc ng ln tu khi tu ang neo u . - Cc lc chnh tc ng ln mt con tu ang neo u thng g y ra bi gi v dng,tuy nhin n cn chu tc ng nhiu yu t khc. - H thng thit b buc tu ca mt con tu phi chng li c mt s, hoc c th l tt c cc lc tc ng ca cc yu t sau y : Gi. Dng chy. Thy tr iu. Sng do tu khc gy ra Sng bin. Bng tuyt S thay i mn, trim,list . Sng bin, Sng do tu khc gy ra : - Trong trng hp c cc sng bin hay sng do cc tu khc gy ra xut hin trong khu vc cu cng hay vng ln cn ca khu neo u , lc ny lm cho tu b chng chnh,to ma st d gy ra hin tng t dy i vi tu cp cu tu. Thy triu,s thay i mn, trim,list : - Khi c cc hin tng ny xy ra th n to ra mt lc rt ln cho c c dy buc tu,cc bch hay cc phao neo..lc ny tc ng theo chiu ngang nh hnh di.

nh hng ca thy triu, thay i mn nc va trim,list Bng tuyt: - nh hng ca bng tuyt cng cn c xem xt khi tu neo u ti vng lnh. - Khi tu neo u trong vng ng bng c dng thy triu ,th c kh nng bng s b kt gia tu v cu. ,iu ny s to ra mt lc theo chiu dc tc dng ln tu v s kt hp gia bng v dng thy triu lm tng ln ca lc tc ng.

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1.3 Lc tc ng ca gi v dng : a. Gi: - phng thc tnh ton cc lc ny ta s cp phn sau: - Mc d ban u ta tnh ton da trn cc tu ln, sau chng ta ting hnh th nghim b sung vi cc tu nh hn v cho thy rng h s p lc gi v dng l khng thay i ng k cho hu ht cc trng hp th nghim khc nhau,tc l chng chung mt h p lc(h s lc cn).

Lc gi tc ng ln tu Hnh trn cho chng ta thy khi vn tc v hng tc ng ca gi khc nhau th lc nh hng ca n ln tu cng khc nhau.Trang5

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n gin, ngi ta chia cc lc tc ng ca gi ln mt con tu gm hai thnh phn sau: + Mt lc tc ng theo chiu dc tu,song song vi trc dc ca tu. + Mt lc tc ng theo phng ngang vung gc vi trc dc ca tu. + Hai lc ny ban u to thnh yawing moment. Vi mi phn din tip xc khc nhau th gi s gy ra nhng lc tc ng khc nhau ln tu. u tin khi mt cn gi va tc ng n mt phn b mt din tch n gi ca con tu, th lc theo chiu dc l tng i nh . Mt khc khi tc ng theo chiu vung gc vi trc dc tu th to ra mt lc ngang rt ln. i vi mt vn tc gi nht nh, tc ng ln mt tu VLCC th lc tc ng ngang ln nht bng gp 5 ln l c dc. V d: Mt cn gi 50 knot tc ng ln mt con tu du 250000 DWT khng ti: + Lc ngang ti a khong 300 tonnes (2943 KN). + Lc dc ti a khong 60 tonnes (589 KN). Mean Draft metres 6 7 8 9 Astern tonnes 47.8 47.2 46.7 46.1 Ahead tonnes 68 66.7 65.3 63.9 Transverse tonnes 303 283 263 244

Lc dc v ngang ti a ca gi tc ng ln tu 250000 DWT, 5m trim, 50 knot wind Nu gi tc ng vo hng mt phn t bt k ca tu, tc l khong cch t gia tu n mi hoc s au li: + Sinh ra c hai lc tc n tu,lc ngang v lc dc v cho n khi n tc ng ln c mn hng gi. - i vi mt vn tc gi bt k no khi tc ng vo hng mt phn t, th s hp thnh ca c hai lc ngang v lc dc ca n s nh hn so vi cc lc tng ng khi thi trc tip vo gia hoc mi. - i vi mt s tng hp c bit khi gi tc ng khng ngay chnh ngang mi,li hoc gia tu, m kt qu ca lc tc ng khng theo nh hng ca gi tc ng. - V d: Mt tu du 250000DWT, vi hng gi khong 45 0 so vi mi v cng chiu kim ng h,m kt qu l lc tc ng v khong hng 80 0 so vi mi.Trong trng hp ny nhng v tr m lc gi tc dng bi dch chuyn v pha trc so vi ng trc ngang ca tu ni gy ra cc moment o tu. trong phn ny quy c hng tc ng ca gi v dng l t ng trc bn phi ca mi tu l 0 0 v theo chiu kim ng h. SV: V VN HU

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b. Dng:

nh hng ca underkeel clearance n lc tc ng ca dng ln tuSV: V VN HU

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Lc nh hng ca dng n tu phi c cng thm lc ca gi khi xem xt nh gi mt khu vc neo u. Ni chung s thay i lc nh hng ca dng ln tu trong mt gi tr vn tc v hng nh m hnh th nghim i lc ca gi th , lc ca dng phc tp hn nhiu, bi nh hng bi phn khong trng t ky tu n y. Hnh trn cho ta thy s nh hng ca lc dng ngy cng tng khi khong trng di y tu ngy cng gim. Phn ln cc cng, khu neo u thng c nhng nh hn g nhiu hoc t song song vi hng ca dng bng cch c th gim ti thiu lc nh hng ca dng. Tuy nhin, ngay vi mt gc tc ng nh nh (nh khong 5 ) c th to ra mt lc ngang rt ln v nn a vo xem xt, tnh ton. Trong nhng ln th nghim cho thy rng lc nh hng ca dng to ra bi mt dng c vn tc 1 knot tc ng pha trc mi ln mt tu du 250000DWT vi 2 m underkeel clearance th lc tc ng khong 5 T (49KN). Nhng vi dng 1 knot tc ng theo chiu ngang (90 0 ) c th ln ti 230 T ( 2256 KN). Vi dng 2 knot c th ln ti 14 T(137 KN) theo chiu dc,990 T ( 9712 KN) theo chiu ngang.

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1.4 Mt s m hnh buc tu chung. - M hnh buc tu cp n s phn b sp xp hnh hc ca cc dy buc tu, gia tu v cu cng... - Cn lu rng ngnh hng hi trc y c nhng tiu chun cho vic b tr h thng neo buc tu ti khu neo u.

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Tnh n cc mc nh hng bi cc yu t ca mi trng. Ngi ta phn b v xy dng cc khu neo u chung p dng ch yu cho cc khu vc neo u chiu nh hng bi nhiu yu t bn ngoi mt cch phc tp,v qua thit k cc trang thit b buc tu cho ph hp.

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Nhiu yu t bn ngoi tc la c nhiu yu t bn ngo i nh hng n vic buc tu, khng ch l mt yu t c nh m c nhiu yu t lun thay i mt cch phc tp. - i vi mt khu neo u nh hng bi cc yu t bn ngoi c th, tc l chu chi phi bi mt lc bn ngoi c th chim u th c hng hn nh vi mt dng chy mnh, gi ln, sng cao, vi s phn b ca cc v tr c xy dng cu cng ta c th sp xp, b tr cc dy sao cho hp l, nh bao gm mt dy li, dy mi, hoc tng cng dy ngang, dy cho c th c hiu qu h n. i vi nhng tu thuyn xuyn ra vo cng ny th c th xem xt trang b thm cc trang thit b buc tu hin i ph hp vi tnh hnh thc t cng ny. - Dy c xu hng chng li nhng lc tc ng ca cc yu t bn ngoi tt nht l hng ca dy t cng hng vi lc tc ng gy ra. iu ny c ngha l, v mt l thuyt, cc dy buc tu nn t theo hng ca c c lc ca yu t bn ngoi v hng tc ng nn t theo nhng v tr theo chiu dc tu , nh vy n s hn ch c cc lc bn ng oi tc ng n dy. Mt h thng buc tu nh vy khng c hiu qu trong thc t, t khi n khng c s uyn chuyn cho ph hp vi lc tc ng ca cc yu t bn ngoi khc nhau v cc v tr cc ct bch khc nhau ti cc bn cng khc nhau. i vi cc m hnh buc tu chung, n phi c nhng gii php khc phc v i ph vi cc lc tc ng ca yu t bn ngoi t bt k hng no. iu ny c th c gi quyt tt nht bng cch chia tch cc l c tc ng bng hai lc c bn : Lc theo chiu dc tu v lc theo chiu ngang tu v sau tnh ton lm th no chng li hi lc hiu qu nht. Theo iu ny mt s dy nn t theo chiu dc tu gi l dy cho ( spring lin es ) v mt s dy nn t theo chiu vung gc vi trc dc tu ngang gi l dy ngang (Breast lines). - y l nhng nguyn tc hng dn cho kh nng p dng ca mt s m hnh buc tu chung c p dng. - Mc d v r ca cc trang thit b ph trn thc t cc khu neo u khng phi lc no cng ph hp vi m hnh chung ta c th p dng ng nh vy.S gim hiu qu ca cc m hnh do s xp xp dy khc nhau t nhng dy buc u tin, iu ny c th hin qua hnh di y: + Trng hp 1 vi cch b tr dy chung ta thy cc dy s chu l c t hn. + Trng hp 3 vi cch b tr dy theo nhng v tr r rng th cc dy c v s chu lc nhiu hn. + Theo nh m hnh vi cng cc yu t nh hng nh vi vn tc gi 60 knot, tc dng th t theo ba hng khc nhau, hng o 0, hng 450, hng 90 0, v cng tc ng ln mt con tu trng ti 25000 DWT, nhng theo hai cch b tr dy khc nhau: v cho ta thy lc tc ng ln cc dy la khc nhau.nh hnh v di ta thy lc cng ca dy trong cch b tr dy trng hp 3 tng nhiu so vi cch b tr dy trng hp 1.Nh dy s 3 tng t 39.5 T 53.1 T, dy 4 tng t 39.9T -48.1T, dy 5 tng t 44.9T -88.4T, dy s 12 tng t 57.1T 70.3T, trong trng hp gi tc ng vi hng 90 0. -

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Phn tch m hnh buc tu

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nh hng ca gc ca dy n lc chu ti ca dy

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Qua ta thy mt s khc bit c bn v chc nng ca dy cho v dy ngang, chng ta phi hiu s dng cho ph hp. Hn ch ca dy cho i vi vic buc tu l ch trong hai hng (ng t rc v ng sau): Bn cht ca dy ngang l vung gc vi trc dc tu,v ch hn ch mt hng vung gc so vi cu tu,hn ch nh hng theo hng cu tu l nh cc fenders v cc ct bch dy ngang, mt khc cc dy ngang s chu lc tc ng di cu tu bi cc yu t bn di nh dng chy di, ch duy nht ng sau hoc ng trc th dy cho mi chu lc tng hp. Cc m hnh neo buc tu trong mt mi trng c nh c th kt hp cc dy dc li v dy dc mi, iu ny c th gip cn b ng ca s phn b lc theo chiu dc v chiu ngang. y l s hn ch ti u ha cho s phn b lc theo chiu dc tc l gim bt nh hng theo chiu dc tu ni m nh hng bi cc lc mi trng tc ng ln, trong khi bn cnh vn cn duy tr mt s hn ch do cc lc bn ngoi gy ra bi yu t mi trng. Cng c mt s la chn khc cho s phn b la chn cho vic buc tu vi lc dc chim u th l b tr thm nhiu dy cho hn. Hn na, hiu qu ca mt ng dy buc tu nh hng bi hai gc, t gc thng ng ca dy vi cc bch trn boong, v t gc ngang ca dy song song vi mn tu (nh hnh trn). Nu dy c d dc th chu ti ca lc ngang km. V d : Mt dy c hng vi gc thng ng 45 0 th duy nht ch c 75% hiu qu so vi mt gc 20 0. Tng t i vi gc dy ngang song song vi mn tu gc hp bi chng ln hn th s gim hiu qu trong vic chng li lc doc.

. a. m hnh buc tu chung ti cu cng. b. m hnh buc tu chung ti phao, cng trnh ni. c. mt s m hnh lai dt, chuyn ti. .

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1.5 Hng dn chung v vic buc tu : Ga nh rng mt tu ng neo buc th chiu nh hng bi gi ln v dng mnh n t nhiu hng khc nhau: - Cc dy buc tu nn c sp xp sao cho cng i x ng qua trc gia tu cng tt. ( Sp xp i xng s gip gimx ti tt hn khi sp xp khng i xng ). - Cc dy ngang nn c nh hng sao cho vung gc vi trc dc ca tu cng tt, v cng cch xa phia mi hoc li cng tt. - Cc ng dy cho nn c nh hng song song vi trc doc tu cng tt. - Cc dy dc li v dc mi th thng khng c hiu qu lm trong vic c nh tu neo buc tu cu cng. Cn cc dy cho v dy ngang th rt c hiu qu trong vic c nh cc phng tin neo u. Vi c s dng dy dc li v dy dc mi yu cu phi trang b thm hai ct buc tu. V iu ny gip lm gim hn ch mt cch tng th ca mt m hnh neo u khi m s lng dy c sn th c gii hn. iu ny l do chiu di ca dy v c tnh n hi ca dy cao v vic nh hng ca dy khng tt. Cc dy dc mi v dc li nn c s dng khi chng ta iu ng hoc trong trng hp cn thit do ia hnh ca bn tu, cu cng, nhiu lc tc ng tng, hay iu kin thi tit. i vi cc tu nh th cc trang thit b cu tu c thit k cho cc tu ln nn c th c dy doc li, mi bi v theo hnh dng ca cu cng. - Cc gc thng ng ca dy buc tu nn c gi gc nh nht. - Cc gc thng trong buc tu s gip cc dy c hiu qu hn tro ng vic chng li cc ti trng ngang ln tu, qua phn tch phn 1 v 3 trong hnh ( (phn tch m hnh buc tu ) ta thy rng mt tu c th c cch buc tu c hiu qu hn theo nh chiu di ca n. Mt d cng s lng dy nh nhau nhng trong trng hp mt s phn b ti trng ln tng dy trng hp mt tt hn v hn ch c sc ti ln tng dy. - Ni chung cc dy buc tu cng kch c, cht liu nn c s dng cho nhng dy u tin (dy buc u tin ). Nu c th c nn dng chung cho ta c cc dy, dy cho, dy ngang. - Nhng dy u tin c a ln b thng rt ln v tt nht, v dy ny rt quan trng, n gip nh hng ban u v gip cho qu trnh neo buc tu, thng thng nhn dy ny c tnh n hi cao v khng thch hp dn g cho nhng dy sau tr khi tt c cc dy cng loi nh nhau. - Cc dy buc tu nn c sp xp sao cho tt c cc dy dng nh nhau th nn s dng cng chiu di, ( khong cch t tu n ct bch trn cu). Tnh n hi ca dy thay i trc tip vi c hiu di ca dy v nhng dy ngn s chiu ti trng hn.

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1.6 ch trc khi chn phng n buc tu : Nhng hng dn trong phn 1.5 trn dng ti u ha vic neo buc tu, nhng trong tnh hnh thc t th chng ta kh c th p dng chng nh mong mn, bi v ty tnh hnh cc khu vc cng khc nhau, iu kin thi tit khc nhau, m chungd ta cn xem xt la chn mt phng n cho ph hp.Mt s hoa tiu, mong mun dng cc dy dc li, mi a tu ra vo cu bn, trong khi mt s ngi k hc c th dng dy cho lm vic ny, trong trng hp ny dy dc li, mi s dng tt khi cc im neo u gn tu, v cc dy ngang khng c s dng hoc s b tr cc ct bch cu cng khng ph hp, hay to ra gc thng ng qu mc trong iu kin y, nhng gc qu mc nh vy s lm gim kh nng chu ti ca cc dy. Gi mnh v dng n t mt hng c nh no c th lm cho vic sp xp dy buc tu khng i xng , iu ny c ngha l mt ni c th b tr nhiu dy buc tu h oc dy ngang pha mt u ca tu. Cc yu t khc cng cn c xem xt nh l di ti u ca dy buc tu. iu ny l mong mun d cc dy buc tu theo chiu thng ng nh hn 250. V d : nu nh cc vng chock ca tu l 25m v phia im neo u trn b, th v tr buc tu nn nh hn 50m theo chiu ngang v pha chock.

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1.7 Gii hn khai thc : Mt kha cnh hn ch quan trng l s dch chuyn ca tu khi ang neo u ti cu cng. Khng c mt cch thc n gin no c th ni ra trc s dch chuyn ca tu, mc d iu ny thng c cho bi s tnh ton ca my tnh. S dch chuyn ca tu do lc tc ng ca mi trng co th vt qu sc chu ti ca loading arm or transfer hose trc khi sc vt qu gii hn chu ti ca dy buc tu.Tng t nh vy, gii hn v yu cu p dng cho cc cu tu, cbit cho cc trang thit b c bn trn b dng kt ni. iu ny chnh xc vi mt h thng dy tng hp. Theo nh cc iu kin khng tt ca mi trng, the loading arms and gangways c th b ngt kt ni trc vi iu kin gi v dng nh hn so vi s thit k c bn ca h thng dy buc tu. - Cc iu kin mi trng nn c xc lp cho mi cu tu v nn chi tit cho mi tu, c nhng check list an ton trn b. Ngoi ra, cc thuyn vin trn tu nn c thng bo v bt k v hn ch di chuyn ca tu do s khai thc bn ngoi ca cc trang thit b b nh hard arms, hose, fenders (gii hn nn) v gangways, v nhng tc ng khc. - Thut ng mana geable escalating events c p dng khi gii hn ca cc iu kin mi trng c thit lp v c tun th theo nhng nguyn tt sau: Cc loading arms in hnh c th c chn li hoc ly ra nu cn thit v dng kt ni khi tc gi 30 knots (15m/s) v vic chun b ri khi cu. Nhng con tu lai c th c yu cu gi nhng con tu vi tc gi khong 35 knotd (18 m /s). Gangway c thu li v tu sn sng ri cu khi c lnh ca thuyn trng khi tc gi t n 35 knotd (18 m /s). Cc dy buc tu nn gi tu mt v tr c nh khi tc gi t 60 knots (31m/s) v sc cng ti a ca mt dy bt k khng nn vt qu 55% MBL ca dy,50% dy tng hp, hoc 45% dy polyamide. Tuy nhin, iu ny c th vt qu gii hn ca h thng neo buc tu ca cng v mt tc gi thp hn c th thch hp khi thit lp mi trng gii hn. Vi tc gi 60 knots (31 m/s) lc cng ca dy s vt qu 60 -65% MBL v h thng ti c th b quay ngc tr li. Tu c th tro ng tnh trng nguy him. - Vi nhng con tu ang neo buc SPM ( single point mooring ) th cc gii hn an ton thc t c th tt hn nh vo s iu chnh ca cc thuyn vin n vic s l h thng ng ng v lm vic an ton hn l di chuyn tu. -

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1.8 Hng dn khai thc v gii hn ca vic neo buc tu : Trong qu kh, cc hng dn kha i thc v gii hn ca vic neo buc tu nhn chung c pht trin theo kinh nghim. Vi s pht trin ca khoa hoc cng ngh c bit l my tnh vi cc chng trnh c bit trong s kt hp pht trin tnh ton ngy cng chnh xc hn v h s tc ng ca gi v dng, vi s pht trin y ngi ta c th a ra cc gii hn khc nhau cho nhng loi tu khc nhau v kh nng neo u ca n ti nhng khu neo u khc nhau vi cc iu kin mi trng khc nhau. iu ny c m ta qua mt s m hnh v d di y. - Cc v d di : p dng cho tu 250000 DWT loi tnker neo u cc jetty vi nh hng ca gi v dng. H pht trin h thng neo u theo cc m hnh nh : dng dy nylon, dy bng kim loi, dy tng hp. - Hnh 1.8 vi 18 dy l dy nylon v vi mn kh ln nht, hay mn nc nh nht th loading arms nn c ngt cch ni vi tc gi khong 30 knots theo nh tnh ton th vi mn cao nht th c th ln ti 50 knots, qua ta thy gii hn ti ca loading arms c iu chnh khi mn thay i. - Hnh 1.9 vi 18 dy cp thp vi c phn ui l dy tng hp th loading arms c gii hn khng i vi vn tc gi 50 knots khi mn thay i. - Hnh 1.10 vi 14 dy cp c phn cui l dy tng hp v 4 dy la dy nylon th th loading arms cng c gii hn khng i vi vn tc gi 50 knots khi mn thay i, tuy nhin n c mt s thay i nhng nm trong gii hn chuyn ng ca cc loading arms v c th b qua. - Nhng hn ch trn to ra do s kt hp bi cc yu t gi, dng, v s th ay i mc nc, cc dy buc tu hnh dng tu v h ti. Thng tin ny c th s dng cho mt s vic sau : Quyt nh xem mt con tu c kh nng neo u trong mt khu vc cng vi iu kin mi trng d on trc khng ? Quyt nh khi no chuyn ti v khi no ngt kt ni vi loading arms. Tham kho xem xt cho vic tng hay gim mn. Quyt nh xem c nn cn s gip ca tu lai duy tr v tr neo u khng. -

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1.9 ch v dy khi neo buc : - Mc ch ca vic ch v dy l chc rng tt c cc dy phi cng u v chia u ti n mc c th v sao cho s chuyn ng ca tu khi neo u l hn Lc ko cng ca cc dy ( v d : cc ti trng ca dy, ti phi chu c lc tc ng ca cc yu t bn ng oi ) gim c s di chuyn ca tu v ci thin s phn b ti khi chiu di ca cc dy v c tnh ca n khc nhau ca cc dy c s dung. - ngn chn ti a s di chuyn ca tu ang neo u theo chiu dc cu tu, iu ny rt quan trng trong vic ch n cc dy cho v v s khc bit dy ngang. Ch v cc dy dc li, mi hin ti c vn c bit ( l mt trong nhng l do khng c khuyn khch ). Chng ta phi ch mt trong hai dy cho v ngang xem s nh hng ca chiu d c hay chiu ngang nhiu hn v quan trng hn. - V d : Nu mt tu ang neo u ngc dng ti cu cng v b tc ng mnh bi dng chy mnh, th nhng dy dc mi nn c ch v ko cng trc trong khi nhng dy dc li s b trng. Nhng quy t c chung sau y p dng khi n dy ang neo buc : Ni chung nhng ng day chng nn c thu u tin. Nhng dy chng c th gy ra s dch chuyn ca tu khi ang neo u khi t nhin c s tc ng ca yu t lc bn ngoi nh gi v dng m hai yu t ny lun hin hu. Ch duy nht mt dy nn c ch chnh sa mt thi im, bt k lc no cng nn xem xt hng ca cc dy, i khi n s thay i tc thi ti trng ln cc dy khc nhau c th tng. S thay i ng thi hai dy c th dn n tnh trng bt thng v c th gy ra hin tng qu ti cho cc dy khc. Bt k khi no mt dy cho cng c ch vi dy cho ngc hng vi chng cng nn c quan tm, nhng khng ng thi. v ch mt s thay i dy cho cng c th gy ra s dch chuyn ca tu ang neo u theo chiu dc cu tu. sc p ca cc fender cng nn c ch trong sut qu trnh lm hng cng nh s thay i ca thy triu. sc p ca cc fender cng c th b gy ra bi sc cng ca dy ngang . Nu sc p ca cc fender qu cc m khng phi do gi, dng gy ra th dy ngang nn c xong ra cho cng.

SV: V VN HU

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Chng 2 nh hng ca gi v dng n tu2.1 Gii thiu v nhng ch chung : Nhng nh hng da trn ti trng ca mi trng tc ng n nhng con tu nh gi v dng nn c ly t nhng d liu ca nhng m hnh th nghim thit k tu hoc nhng h s p lc cho nhng con tu du, tu gas s c cp trong phn ny. H s p lc ca gi v dng trong ph n ny l dnh cho nhng con tu VLCC (very large crude carrier ) v c tnh ton ban u cho nhng con tu 150.000 DWT. Gn y mt s d liu ca m hnh th nghim trn nhng con tu ch du hin i v t kt qu vi cc h s gn nh ging nhau, trong nhiu trng hp, y v chnh xc hn khi p dng cho nhng con tu nh hn v do c th s dng cho hng lot tu nh di khong chng 16.000 DWT. H s p lc cng c th p dng cho nhng con tu nh cng cp c hnh dng tng t nhau. iu ny c ngha l t l phn mn kh n chiu rng tu nn tng t nhau vi h s p lc ngang ca gi v mn nc n chiu rng tu nn tng t nhau vi h s p lc ngang ca dng. i vi nhng con tu ch kh, h s p lc gi p dng cho n hng bnh cha hnh cu trn boong trong khong 75.000 m 3 n 125.000 m 3 .

-

-

SV: V VN HU

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2.2 Mt s k hiu v ch thch : - Mt s k hiu v ch thch s dng trong ti liu ny : Al Khu vc gi theo chiu dc ( mnh tu ) trn mn nc At Khu vc gi theo chiu ngang trn mn nc A HL Din tch hnh chiu thng phn thn tu di mn nc A HT Din tch hnh chiu ngang phn thn tu di mn nc B Thang ngang Cxc H s p lc ca dng theo chiu dc. Cyc H s p lc ca dng theo ngang. Cxyc H s moment o ca dng. Cxw H s p lc ca gi theo chiu dc Cxyw H s moment o ca dng. Fxc Lc ca dng theo chiu dc. FYFc FYAc L c tc ng pha mi v li bi dng . FYFw FYAw Lc tc ng pha mi v li bi gi . Fyc Lc ca dng theo chiu ngang. Fxw Lc ca gi theo chiu dc. Fyw Lc ca gi theo chiu ngang. h cao trn mt nc / mt t k Yu t hiu chnh ca vn tc dng LBP Length between perpendiculars LOA Length overall MD MOULDED DEPTH MXYC Moment o ca dng MXYw Moment o ca gi S su ca nc tnh t mt nc T Mn nc trung bnh Vc Vn tc dng trung bnh vc Vn tc dng su VW Vn tc gi cao 10 m vw Vn tc gi cao h WD su ca nc c Gc tc ng ca dng c tnh theo trc dc gia tu W Gc tc ng ca gi c T trng ca nc w Khi lng ring ca khng kh ( m2). ( m 2). ( m 2). ( m 2). ( m).

(N) (N) (N) (N) (N) (N) (m) (m) (m) (m) (m) (m) (m) (m) (m) (m/s). (m/s). (m/s). (m/s). (m) ( 0 ). ( 0 ). (kg/m3). (kg/m3).

- Khi lng ring ca nc bin l 1025 (kg/m 3), v ca khng kh l 1,28 (kg/m 3). - 10 KN = 1 T, 1m/s = 2 knots

SV: V VN HU

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2.3 H s p lc ca gi v dng cho cc tu tanker trng ti ln. Ti trng ca cc yu t mi trng bn ngoi gy ra trn cc tu ch du ln ( trong phn ny p dng cho cc tu tanker trng ti ln t 150.000 n 500.000 DWT ) bi cc yu t gi v dng c th c tnh vi cc cch thc trong phn di y. Cc lc v moment pht sinh th sao cho phi ph hp vi cc s phn tch yu cu hn ch ca vic neo buc tu. Theo nhng h s khng th nguyn th c s dng trong sut phn ny : CX H s p lc theo chiu dc. CY H s p lc theo chiu ngang. CXY H s moment o. Cc ch s w v c th c dng ch gia gi v dng. nhng quy c v k h iu v h thng phi hp th c th hin trong hnh 2.1B di y. Nhng quy c v k hiu theo trc ca h ta tu vi hng lc tc ng ca gi v dng theo hng t o 0 n 180 0 t li cho n mi v ngc hng chiu kim ng h nh hnh 2.1B d i y. Vi nhng cc gc nh hng khc nhau t nhng hng khc nhau th lc ca gi v dng v h s p lc moment c th hin qua ng cong trong cc hnh t hnh 2.2B n 2.14B di y. H s gi th c bn c ly t nhng m hnh th nghim trng i hc Michigan vo nm 1960. Cc gi tr ca h s dng th c bn c ly t m hnh th nghim ti vin nghin cu hng hi h lan ( 1975 -1991). su ca nc 6T ly t hng dn thit k ca hi qun m. Nhng lc v moment c tnh s dng theo n v l N hoc NM ty theo nhng v tr tc ng theo chiu dc v ngang so vi trc dc gia tu. Hai ng cong mi tu c minh ha trong hnh 2.15B di y th hin s nh hng ca hnh dng elip hnh tr so vi mt thit k eli p truyn thng.

-

2.3.1 Nhng nhn t chnh nh hng n wind loads. - Cc gc ca gi th hin t o 0 n 1800 t li cho n mi. - Cc h s ch c gi tr duy nht cho cc tu c cu trc thng tng sau li. Cc h s v khu vc ( A T v AL ) nn c ph hp vi iu kin nhng con tu c th. Cc khu vc dc v ngang ( A T v AL ) nn c tnh ton t trn u v phn mn tu trn mt nc ca tanker. - S thay i mn kh ca tu c s nh hng nht trong vic thay i cc h s tc ng ca gi. sai lch trong cc h s gi cng mt phn do s khc bit ca phn thn tu v cu trc thng tng . 2.3.1.1 nh hng ca trim : - cc h s p lc ca gi gi s khi trim l zero trong iu kin y ti v iu kin 0.80 c dn ballast. Th nh hng ca trim l ln nht trn moment o v khi cc trim khc ng k t gi nh trn th c th hiu chnh n moment o nu cn thit.Trang24

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2.3.2 H s p lc ca dng : - Cc ng cong th hin p lc ca dng C XC ,CYC V CXYC trong hnh 2.5B n 2.14B theo nhng iu kin sau : Gc tc ng ca dng t o 0 n 180 0 t li cho n mi. T l su ca nc v mn tu (WD/T). 1.10 1.20 1.50 3.00 6.00 H ai hnh cong mi. iu kin ti trng ( mn nc = 100% mn v =40% mn) Trim = 0. 2.3.2.1 Vn tc ca dng : - Cc vn tc trung bnh ca dng ( V c ):nu tc ng trong mn nc ca tu th nn s dng tnh ton lc ca d ng v moment. Nu bit vn tc dng theo chiu ngang ca dng, th nh ngha theo gi tr vn tc dng nn c tnh theo cng thc sau :

V c2 =1/T 0T ( vc)2 ds Vc T vc s vn tc trung bnh ca dng (m/s). Mn nc ca tu. Vn tc dng su mn (m/s). su ca nc tnh t mt nc.

Nu khng bit vn tc dng theo chiu ngang ca dng, m bit vn t c su nc bit nn c hiu chnh theo cc yu t trong hnh 2.16B c vn tc trung bnh theo mn nc ca tu.

2.3 .3 Nhng nhn t chnh nh hng n current loads. - Underkeel clearance th nh hng ln n h s p lc ca dng. - ln ca lc tc ng ca dng v moment cng nh hng bi hnh dng v cu trc phn pha mi tu. 2.3.3.1 nh hng bi chiu di v chiu rng tu (L/B) : - Cc chng trnh th nghim ch yu gia t l chiu di v rng tu (L/B) trong khong 6.3 v 6.5 n nhng con tu VLCC. Tuy nhin cc con tu VLCC hin nay thng c t l t 5.0 -5.5 . - Vi nhng con tu VLCC (L/B 5.0) tng dn theo chiu dc h s p lc ti a 25 30% l c d kin cho gc tc ng ca dng ( n mc ti a l 150 ). 2.3.3.2 n h hng ca trim. - Trim ban u l zero nhng thc t s khc. - Tuy nhin s nh hng ca trim s c chnh xc khi h s o ca dng khi ballast ni nc nng. Ch y nn thc hin khi h s o ca dng theo iu kin khi trim vt qu mt .SV: V VN HU

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Hnh 2.1B: Quy c v k hiu v h trc ta .

SV: V VN HU

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Hnh 2.2B: H s p lc ca gi theo chiu dc (C XW)

SV: V VN HU

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Hnh 2.3B: H s p lc ca gi theo chiu ngang ( C YW)

Hnh 2.4B H s moment p lc ca gi gy o tu

SV: V VN HU

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Hnh 2.5 B: H s p lc ca dng theo chiu dc (C XC ) Loaded Tanker WD/T = 1.1

SV: V VN HU

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Hnh 2.6B: H s p lc ca dng theo chiu dc (C XC ) Loaded Tanker WD/T = 1.2

SV: V VN HU

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Hnh 2.7B: H s p lc ca dng theo chiu dc (C XC ) Loaded Tanker (WD/T = 1.5)

SV: V VN HU

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Hnh 2.8B: H s p lc ca dng theo chiu dc (C XC ) Loaded Tanker (WD/T = 3.0)

SV: V VN HU

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Hnh 2.9B: H s p lc ca dng theo chiu dc (C XC ) Loaded Tanker (WD/T > 4.4)

SV: V VN HU

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Hnh 2.10B: H s p lc ca dng theo chiu ngang (C YC ) Loaded Tanker

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Hnh 2.11B: H s moment p lc dng quay tu (C XYC ) Loaded Tanker

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Hnh 2.12B: H s p lc ca dng theo chiu dc (C XC ) Ballasted Tanker (40%T)

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Hnh 2.13B: H s p lc ca dng theo chiu ngang (C YC ) Ballasted Tanker (40%T)

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Hnh 2.14B: H s moment p lc dng quay tu (C XYC ) Ballasted Tanker ( 40%T, Based on Midships )

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Hnh 2.15B: Variation in bow configuration

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Hnh 2.16B: Hiu chnh vn tc dng theo h s (k)

SV: V VN HU

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2.4: V d tnh ton lc tc ng ca gi v dng i vi tu VLCC . V d: Tm p lc gi, dng v moment p lc gi, dng gy o tu ln mt tu tanker trongj ti 280000 DWT vi cu trc trc mi l cylindric al. Vi tu tanker y ti vi mn nc lc l 22,3 m, v neo u khu vc c su l 24,5 m. a, Vn tc gi l 34m/s cao 20m so vi mt nc, tc ng theo gc 30 0 so vi mi, tc gc 1500 theo nh quy c trong ti liu ny. b, Vn tc trung bnh ca dng l 1,03 m/s ( 2 knots). Hng ca dng l 10 0 so vi mi, tc gc 1700 theo nh quy c trong ti liu ny. Cc k hiu quy c nh trong hnh 2.1B, v phn 2.2 . a, Tnh ton ti trng ca gi : Step 1: Xc nh yu t chung ca tu : - cho tu tanker 280000DWT trong iu kin y ti. + AL = 3160 m2. + AT = 1130 m2. + LBP = 325 m. Step 2: Vi gc tc ng ca gi l 150 0 . + CXW = - 0,73 ( Hnh 2.2B ). + CYW = 0,31 ( Hnh 2.3B ). + CXYW = -0,032 ( Hnh 2.3B ). Step 3: Tnh ton vn tc gi cao 10m so vi mt nc t vn tc gi cao 20 m.

Vw = vw ( 10/h)1/7+ + +

Vw vwh

= vn tc gi cao 10 m ( m/s).= vn tc gi cao h (m/s).

= tnh t trn mt nc/ mt t (m).

Vw = 34,0 ( 10/20)1/7=.>

Vw = 30,9m/s.

SV: V VN HU

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+ Cng thc p lc gi v moment p lc gi nh sau : =>

FXw FYw FXYw

= CXw w Vw2 AT = CYw w Vw2 AL = CXYw w Vw2 AL LBP

FXw = ( -0,73) (1,28) (30,9)2 (1130) = - 504 (KN). FYw = ( 0.31) (1,28) (30,9)2 ( 3160) = 599 (KN). 2 FXYw = ( -0.032) (1,28) (30,9) (3160) (325) = -20082 (kNm).

b, Tnh ton ti trng ca dng : Step 1: Xc nh yu t chung ca tu : - cho tu tanker 280000DWT trong iu kin y ti. Step 2: Vi gc tc ng ca dng l c = 1700 . - V c t l WD/T = 1,10 Theo cu trc mi cylindrical ta c. + CXc = 0,00 + CYc = 0,67 + CXYc = 0,15 ( Hnh 2.5B ). ( Hnh 2.10B ). ( Hnh 2.11B ).

Step 3: Cng thc p lc dng v moment p lc dng nh sau : =>

FXc FYc FXYc FXc FYc FXYc= = 0

= CXc c Vc2 LBP T = CYC C VC2 LBP T = CXYC C VC2 L2BP T ( 0.67) (1025) (1,03)2 ( 325) (22,3) ( 0.15) (1025) (1,03)2 (325)2 (22,3)(KN). = 2640 (KN).

= = 192101 (kNm). Nu vn tc dng cho 30% ca mn nc, nh vy gi tri vn tc trung bnh ca dng tnh ton nh di: Step 4: Hiu chnh vn tc dng theo hnh 2.16 B vi DW/T = 1.10 Ta c. K = 0.948

SV: V VN HU

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Step 5: tnh ton gi tri vn t trung bnh . VC = K v c VC = 0,948 1,03 = 0,976 m/s . s dng li cng thc phn step 3: FXc = CXc =>

FYc FXYc= = =

c Vc2 LBP T = CYC C VC2 LBP T = CXYC C VC2 L2BP T(KN). = 2227 (KN).

FXc FYc FXYc

( 0.67) (1025) (0,968)2 ( 325) (22,3) ( 0.15) (1025) (0,968)2 (325)2 (22,3)

0

= 169671 (kNm).

Tng hp ca lc tc ng ca gi v dng c thng k sau: Theo nh bn tng tnh ton sau ca ti trng gi v dng tnh ton trn v cng nh nh hng ca gi v dng cho nhng iu kin khc nhau. Ti trng ca gi trn tu tanker 280000DWT vi vn tc gi 34m/s cao 20m. Wind Angle of Attack 1800 - 655 0 0 1500 - 504 599 - 20082 1200 - 228 1,216 - 52700 900 28 1390 - 71500 600 196 1303 - 10300 300 449 830 - 90300 00 511 0 0

Full Load FXw in kN FYw in kN MXYw in kNm

Ti trng ca dng trn tu tanker 280000DWT vi t l WD/T = 1.10, Cylindrical bow. Current Angle of Attack Full Load FXc in kN FYc in kN MXYc in kNm 1800 v 2,57 m/s - 809 0 0 1700 v 1,03m/s 0 2522 192101 900 v 0,514 m/s 72 3200 25514

Cc gi tr trong hai bn trn ly t nhng v d tng tSV: V VN HU

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2.5: Lc dc v ngang ln nht theo nhng tiu chun tc ng ca cc yu t bn ngoi. - lc tc ng ca gi v dng i vi t u ch du, vi iu kin y ti, v iu kin ballast, vi nhng iu kin y n s c iu chnh. Vi nhng taud ch kh ha lng, duy nht iu kin l thay i mn trong qu trnh lm hng. 2.5.1 Lc dc v ngang ln nht trn nhng con tu ch du. - vi nhng con tu ch du 160000 DWT tr ln th nhng lc ln nht theo nhng cng thc sau: Vi iu kin full load: + Fx max = 0,550 ATF + 0,0425 d LBP ( KN) + FyF max = 0,1506 ALF + 0,2320 d LBP ( KN) + FyA max = 0,2839 ALF + 0,2482 d LBP ( KN) Vi iu kin Ballast :( mean draft = 0,02 Lbp + 2m ) + Fx max = 0,498 ATB + 0,0923 ( 0,01 L2BP + LBP) + FYF max = 0,284 ALB + 0,0520 ( 0,01 L2BP + LBP) + FYA max = 0,319 ALB + 0,0524 ( 0,01 L2BP + LBP) (KN) (KN) (KN) (10) . (11) . (12). (m2). (m 2). (m2). (m 2). (7) (8) (9)

d = mn nc y ti (m) ATF = phn din tch ngang trn mt nc vi iu kin full load ATB = phn din tch ngang trn mt nc vi iu kin Ballast ALF = phn din tch dc trn mt nc vi iu kin full load ALB = phn din tch dc trn mt nc vi iu kin Ballast

2.5.2 Lc dc v ngang ln nht trn nhng con tu kh ha lng 75000m3. - vi nhng con tu kh ha lng trn 75000m 3tr ln th nhng lc ln nht theo nhng cng thc sau: + Fx max = 0,557 AT + 0,0425 T LBP ( KN) (13). + FyF max = 0,331 AL + 0,2320 T LBP ( KN) (14). + FyA max = 0,2839 AL + 0,2482 TLBP ( KN) (15). 2.5.3 Lc dc v ngang ln nht ln nhng con tu kh ha lng trn 125000m 3 - Vi tu kh ha lng 125000 m3(cc tanker hnh cu)th lc theo cng thc sau: + Fx max = 0,597 + FyF max = 0,345 + FyA max = 0,365 AT + 0,0425 T LBP AL + 0,2320 T LBP AL + 0,2482 TLBP ( KN) ( KN) ( KN) (16). (17). (18).

SV: V VN HU

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2.6 Nhng phng hng quyt nh nhng yu cu hn ch cho vic neo buc dnh cho tu Tankers v kh ha lng theo nhng tiu chun yu t bn ngoi. - khi thao tc thc t iu ny thng rt cn thit cho vic c lng tnh ton cc trang thit b buc tu ca tu khi ting hnh neo buc vi kin thc r rng v tu v cu cng a ra nhng quyt nh cho ph hp. 2.6.1: Nhng yu cu ti thiu ca vic neo buc vi tu ch du trn 16000 DWT. 2.6.1.1: H thng dy . - spring lines: S MBL = 1,992 ATB + 0,369(0,01 LBP + LBP ) (19). - Breast lines: BR MBL = 1,476 ALF + 1,291 TLBP S = Tng s dy cho. BR = Tng s dy ngang. MBL = minimum breaking load of each line (Kn) T (m) = mn nc ma h. (20) .

2.6.1.2: H thng dy Synthetic. - Tng t nh h thng dy trn, nhng S MBL v BR MBL tng 20% vi dy nylon v 10% vi cc dy synthetic khc. 2.6.2: Mc yu cu ti thiu ca dy cho dnh cho tu ch du 16 KDWT khi khu vc gi tc ng theo chiu dc. - khi chiu di tu, rng, v su bit th s quyt nh la chn h thng d y cho theo cng thc sau: S MBL = 1,992 DB 0,0398 LBP + 19,9B + 40 + 0,369(0,01LBP +LBP) Vi ATB = BD -0,02 LBP +10B +20 10B +20 L din tch thng tng kin trc (21)

2.6.3: Mc yu cu ti thiu ca dy ngang dnh cho tu ch d u 16 KDWT khi khu vc gi tc ng theo chiu ngang. - khi chiu di tu, mn nc ma h, v su bit th s quyt nh la chn h thng dy ngang theo cng thc sau: BR MBL = LBP [ 1,550(D-T) + 1,291T + 2,0664] + 517 Vi ALF = 1,05 LBP ( D-T ) +1,4 LBP + 350 DT L mn kh vi iu kin full load. 1,4 LBP + 350 L din tch thng tng kin trc. (22)

SV: V VN HU

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2.6.4: Nhng yu cu ti thiu ca vic neo buc vi tu kh ha lng. - Nhng yu cu c bn cng tng t nh nhng phn trn: - Vi tu kh ha lng 75000 m 3 S MBL = 2,228 AT + 0,170 TLBP BR MBL = 2,012 AT + 1,291 TLBP - Vi tu kh ha lng 125000 m 3 . S MBL = 2,388 AT + 0,170 TLBP BR MBL = 1,898 AT + 1,291 TLBP

(23) (24) (25) (26)

2.7 Bi ton v d tnh ton MBL cho mi dy buc tu: + + + V d: Tm sc ti ti a cho mt dy buc tu i vi mt tu ch du 90000 DWT vi ballast tanks tch ring. Vi gi 60 knots t hng bt k vi dng theo tng loi sau: Dng 3 knots vi hng o0 1800. Dng 2 knots vi hng 1o0 1700 Dng 0,75 knots vi hng 90 0

A, Thng s v tu : - LBP = 234,0 m. - B = 39,6 m. - D = 20,6 m. - d = 14,0 m. - ATF = 755 m2 - ATB = 1044 m2 - ALF = 2492 m2 - ALB = 4200 m3

(at design draft d ) (at ballast draft ) (at design draft d ) (at 6,7m draft = 0,02 LBP + 2m )

B, Lc ti a tc dng ln tu : - Theo nhng cng thc (7), (8), (9), (10), (11), (12), ta c: + Fx max = 0,550 ATF + 0,0425 d LBP ( KN) + FyF max = 0,1506 ALF + 0,2320 d LBP ( KN) + FyA max = 0,2839 ALF + 0,2482 d LBP ( KN) Vi iu kin Ballast :[ mean draft = 0,02 Lbp + 2m (IMO draft)] + Fx max = 0,498 ATB + 0,0923 ( 0,01 L2BP + LBP) (KN) + FYF max = 0,284 ALB + 0,0520 ( 0,01 L2BP + LBP) (KN) + FYA max = 0,319 ALB + 0,0524 ( 0,01 L2BP + LBP) (KN)

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GVHD: NGUYN MNH HNG

Ta c : - Full load : + Fx max = + FyF max = + FyA max = - Ballast IMO: + Fx max = + FYF max = + FYA max =

415 + 139 = 554 ( KN). 375 + 760 = 1135 ( KN). 707 + 813 = 1520 ( KN). 520 + 72 1193 + 41 1340 + 41 = 592 = 1234 = 1381 (KN). (KN). (KN).

C, Yu cu ca dy cho theo cng thc (19). S MBL = 1,992 ATB + 0,369(0,01 LBP + LBP ) - Ta c : S MBL = 2080 + 288 = 2368 (KN). - Vi tu c tng s l 4 dy cho (S = 4 ), Vy MBL yu cu cho mi dy l. MBL = 2368/ 4 = 592 (KN) = 60 ( Tonnes Force ). D, Yu cu ca dy ngang theo cng thc (20). BR MBL = 1,476 ALF + 1,291 TLBP - Ta c: BR MBL = 3678 + 4229 = 7907 Kn. - Vi tu c tng s l 8 dy ngang (S = 8 ), Vy MBL yu cu cho mi dy l: MBL = 7907/8 = 988 KN (= 101 Tonnes Force ). Vi tu ch khi ha lng 75000 m3 ( tanks hnh lng tr): A, Thng s v tu : - LBP = 220,0 m. - D = 22,4 m. - T = 8,0 m (Mn nc ballast trung bnh ) . 2 - AT = 1003 m ( mn nc ballast trung bnh). 2 - AL = 3844 m ( mn nc ballast trung bnh). B, Lc ti a tc dng ln tu s dng theo cng thc (13), (14), (15). + Fx max = 0,557 AT + 0,0425 T LBP ( KN) + FyF max = 0,331 AL + 0,2320 T LBP ( KN) + FyA max = 0,2839 AL + 0,2482 TLBP ( KN) => + Fx max = 559 + 75 = 634 ( KN) . + FyF max = 1272 + 408 = 1680 ( KN) . + FyA max = 1488 + 437 = 1925 ( KN) . C, Yu cu ca dy cho theo cng thc (23). S MBL = 2,228 AT + 0,170 TLBP - Ta c: S MBL = 2235 + 299 = 2534 KN - Vi tu c tng s l 4 dy cho (S = 4 ), Vy MBL yu cu cho mi dy l. MBL = 2534/ 4 = 634 (KN) = 65( Tonnes Force ).SV: V VN HU

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D, Yu cu ca dy ngang theo cng thc (20). BR MBL = 2,012 AT + 1,291 TLBP - Ta c: BR MBL = 7734 + 2272 = 10006 ( Kn). - Vi tu c tng s l 10 dy ngang (S = 10 ), Vy MBL yu cu cho mi d y l: MBL = 10006/10 = 1000 KN (= 102Tonnes Force ). Vi tu ch khi ha lng 125000 m3 ( tanks hnh lng tr): A, Thng s v tu : - LBP = 274,0 m. - D = 25 m. - T = 9,0 m (Mn nc ballast trung bnh ) . 2 - AT = 1382 m ( mn nc ballast trung bnh). - AL = 7122 m2 ( mn nc ballast trung bnh). B, Lc ti a tc dng ln tu s dng theo cng thc (1 6), (17), (18). + Fx max = 0,597 AT + 0,0425 T LBP ( KN) + FyF max = 0,345 AL + 0,2320 T LBP ( KN) + FyA max = 0,365 AL + 0,2482 TLBP ( KN => + Fx max = 825 + 105 = 930 ( KN) . + FyF max = 2457 + 572 = 3029 ( KN) . + FyA max = 2600 + 612 = 3212 ( KN) . C, Yu cu ca dy cho theo cng thc (25). S MBL = 2,388 AT + 0,170 TLBP - Ta c: S MBL = 3300 + 419 = 3719 KN - Vi tu c tng s l 4 dy cho (S = 4 ), Vy MBL yu cu ch o mi dy l. MBL = 3719/ 4 = 930 (KN) = 95( Tonnes Force ). D, Yu cu ca dy ngang theo cng thc (26). BR MBL = 1,898 AT + 1,291 TLBP - Ta c: BR MBL = 13518 + 3184 = 16702 ( Kn). - Vi tu c tng s l 1 4 dy ngang (S = 14 ), Vy MBL yu cu cho mi dy l: MBL = 16702/14 = 1193 KN (= 122 Tonnes Force ).

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