tinh song tu gio theo spm 1984

Hng dn thc hnh K thut B bin Tnh cc c trng sng t gi theo SPM 1984

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TNH CC C TRNG SNG T GI THEO SPM 1984 Nghim Tin Lam

Khoa K thut Bin, i hc Thu li

1. Gii thiu Do cc iu kin hn ch v s liu o c sng, vic tnh ton sng bin hoc sng trong h cha t s liu gi thng c p dng bng cc cng thc kinh nghim. C kh nhiu cng thc tnh sng t gi nh Sverdrup v Munk (1944, 1946, 1947), Sverdrup-Munk-Bretschneider (SMB) (Bretschneider, 1952, 1958, 1970), Krylov (1966), Donelan (Donelan, 1980; Schawab et al., 1984; Donelan et al., 1985; Bishop et al., 1992), JONSWAP (Hasselmann et al., 1973), Kahma (1981), Dobson et al., (1989), SPM (CERC, 1973, 1975, 1977, 1984), Hurdle v Stive (1989), Young v Verhagen (1996). Trong cng thc SPM phin bn nm 1984 (SPM 1984) da trn c s cng thc JONSWAP c gii thiu trong Shore Protection Manual (CERC, 1984) v ang c s dng mt cch rng ri. Ti liu ny trnh by phng php SPM 1984 v cch p dng trong tnh ton cc iu kin sng nc su v sng su nc hn ch.

2. Tnh sng trong iu kin gi thi n nh

2.1. Xc nh gi v hiu chnh tc gi Trong 3 phin bn u tin nm 1973, 1975, 1977, SPM da trn cng thc SMB vi vic tnh ton gi bnh qun theo cosine v s dng vn tc gi b mt bnh qun m khng xt n nh hng ca cao hay s chnh lch nhit gia nc bin v kh quyn. Trong phin bn SPM 1984, gi s dng l gi tr trung bnh s hc c tnh ton cc gi trong khong hng gi 15 nh cng thc (1) v minh ho trn Hnh 1.

Hng gi

3F1

F2F3

F4F5F6

im tnh ton

F7F8F9

Hng gi

3F1

F2F3

F4F5F6

im tnh ton

F7F8F9

Hnh 1: Tnh ton gi


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9

1

19 ii

F F=

= (1) Vn tc gi o c c chuyn v cao 10 m so vi b mt s dng cng thc (2).

17

1010

zU U z = , vi z < 20 m (2)

0.8

1

1.2

1.4

1.6

1.8

2

0 5 10 15 20 25

Vn tc gi trn t lin, U (m/s)

H

s h

iu

chn

h v

n t

c gi

, R

L

Hnh 2: H s hiu chnh vn tc gi thi trn t lin

0.7

0.8

0.9

1

1.1

1.2

1.3

-20 -15 -10 -5 0 5 10 15 20

Chnh lch nhit khng kh v nc bin, (Ta-Ts) (C)

H

s h

iu

chn

h v

n t

c gi

, R

T

Hnh 3: H s hiu chnh vn tc gi do chnh lch nhit khng kh v nc bin

Ngoi ra, vn tc gi cng c hiu chnh bng 2 h s hiu chnh: h s RL hiu chnh s khc bit gia vn tc gi thi qua mt t (UL) v thi qua mt nc (UW), v h s RT cho nh hng n nh ca chnh lch nhit nc v khng kh. H s hiu chnh khi s dng s liu gi o c trn t lin c tra trong Hnh 2 v c ly RL=1 nu s dng vn tc gi trn bin. Dng RL=0.9 nu UL >18.5 m/s. H s hiu chnh n nh RT ph thuc vo chnh lch nhit nc bin v khng kh cho trong Hnh 3. Trong trng hp khng c s liu v chnh lch nhit gia khng kh v nc bin th c th ly gi tr mc nh l RT=1.1.


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Vi cc gi thit l s pht trin ca sng b gii hn v gi quan h cht ch vi vn tc ma st u* hn l tc gi o c U, v mi quan h gia u* v U cho vng bin h c p dng trc tip cho iu kin gi gii hn, cng thc SPM 1984 s i lng vn tc gi hiu chnh UA hiu chnh quan h phi tuyn thc o gia ng sut v vn tc gi theo (3)

1.230.71AU U= (3) vi 10T LU R R U= (4)

2.2. Cc i lng phi th nguyn thun tin cho vic tnh ton, cc i lng phi th nguyn sau y c s dng

cao sng phi th nguyn 2s

sA

gHHU

= (5)

Chu k sng phi th nguyn ppA

gTT

U= (6)

sng phi th nguyn 2A

gFFU

= (7)

Thi gian pht trin phi th nguyn A

gttU

= (8)

su nc phi th nguyn 2A

gddU

= (9)

2.3. Tnh ton sng nc su Cng thc SPM 1984 tnh ton sng nc su da trn c s cng thc JONSWAP v s dng vn tc gi hiu chnh UA nh sau Chiu cao sng c ngha

1

3 21.6 10SH F= (10)

Chu k sng ti nh ph sng

130.286pT F= (11)

Thi gian sng pht trin

2368.8Ft F= (12)

T (12) s tnh c gi hiu dng

32

eff 68.8tF = (13)

Sng c to ra vng nc su c th ba trng thi l b hn ch v gi, b hn ch v thi gian gi thi hoc l pht trin hon ton. Khi tnh cho vng nc nh (nh trong h)


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sng c th b hn ch bi gi ngn, tc l F < Feff. Khi cc gi tr HS v Tp c tnh trc tip t cc cng thc (10) v (11).

cc vng nc ln hn c th dng cc cng thc ny nhng thi gian gi thi c th hn ch cao sng. Nu thi gian trn bo nh hn tF, hay F > Feff, th trng thi bin s l b gii hn v thi gian gi thi v cc gi tr ca HS v Tp vn c tnh theo cc cng thc (10) v (11) nhng s dng chiu di gi hiu dng ( gi cn thit to cng cao sng nu thi gian gi thi v hn) tnh theo cng thc (13). Ngha l gi tr nh hn trong cc gi tr F bi Feff c dng tnh sng. vng nc rt rng ln v gi c thi gian thi lu th trng thi bin c th pht trin hon ton. iu kin ny xy ra khi c t v tF u ln hn tfull tnh theo (14). Vi iu kin sng pht trin hon ton th s dng cc cng thc gii hn trn cho chiu cao v chu k sng tnh theo (15) v (16):

t full = 7.15104 (14) HS = 0.243 (15) Tp = 8.134 (16) T cc cng thc (10) v (11) cho thy chu k sng c mi quan h gn gi vi cao sng nu gi c xc nh nh trong (17) v (18)

2320.9p ST H= (17)

hay 1 23 39.8p A ST U H

= (18) Cc bc tnh ton cc c trng sng nc su theo phng php SPM 1984 c th hin trong Hnh 4 v V d 1 km theo sau y.

V d 1: Tnh sng nc su Tnh cc iu kin sng to ra t vn tc gi U10 = 15 m/s thi trong thi gian t = 6 gi trn gi F = 100 km.

Bc 1: Tnh vn tc gi hiu chnh theo cng thc (3) vi gi tr mc nh RT=1.1 c vn tc gi hiu chnh UA = 20 m/s.

( ) ( )1.23 1.23100.71 0.71 1.1 15 22.3A TU R U= = = (m/s) (19) Bc 2: Tnh thi gian gi thi phi th nguyn t vi thi gian t c quy i ra giy v gi phi th nguyn F vi gi F c quy i ra mt

9.81 6 3600 949222.3A

gttU

= = = (20)

3

2 2

9.81 100 10 196922.3A

gFFU

= = = (21)

Bc 3: Tnh chiu di gi hiu qu Feff theo (13)

3 32 2

eff9492 1621

68.8 68.8tF = = = (22)

Bc 4: So snh F v Feff. V F > Feff nn sng b gii hn v thi gian gi thi v s s dng Feff thay th cho F tnh cc c trng sng:


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eff 1621F F = (23)

Hs = 0.0016 F Tp = 0.286 F

Hs = HsUA/gTp = TpUA/g

(F > Feff)?

(Hs>0.243) v (Tp>8.134)?

Nhp U10, F, t

Feff = (t / 68.8)/

t = gt/UAF = gF/UA

F = Feff

Hs = 0.243Tp = 8.134

ng: Sng pht trinb hn ch v thi gian

ng: Sng phttrin hon ton

UA =0.71 (RTU10)1.23

Kt thc

Bt u

Sai: Sng pht trin khngb hn ch v thi gian

Sai: Sng pht trinb hn ch v gi

Hs = 0.0016 F Tp = 0.286 F


(F > Feff)?

(Hs>0.243) v (Tp>8.134)?

Nhp U10, F, t

Feff = (t / 68.8)/

t = gt/UAF = gF/UA

F = Feff

Hs = 0.243Tp = 8.134

ng: Sng pht trinb hn ch v thi gian

ng: Sng phttrin hon ton

UA =0.71 (RTU10)1.23

Kt thc

Bt u

Sai: Sng pht trin khngb hn ch v thi gian

Sai: Sng pht trinb hn ch v gi

Hnh 4: S thut ton tnh sng nc su theo SPM (1984)


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Bc 5: Tnh Hs v Tp s dng cc cng thc (10) v (11)

1

3 321.6 10 1.6 10 1621 0.064sH F = = = (24)

1

330.286 0.286 1621 3.36pT F= = = (25) Bc 6: So snh Hs v Tp vi cc gi tr Hs v Tp ca iu kin pht trin hon ton trong cc cng thc (15) v (16). V Hs = 0.064 < 0.243 v Tp = 3.36 < 8.134, u nh hn trng thi pht trin hon ton nn trng thi ca sng l cha pht trin hon ton v b hn ch v chiu di gi.

Bc 7: Tnh Hs v Tp t cc cng thc (5) v (6)

2 20.064 22.3 3.27

9.81s A

sH UH

g= = = (m) (26)

3.36 22.3 7.69.81

p Ap

T UT

g= = =

(s) (27)

Vy p s cui cng l sng to ra c chiu cao Hs = 3.27 m v chu k Tp = 7.6 giy trong iu kin b hn ch v gi v thi gian gi thi.

2.4. Tnh ton sng trong iu kin su nc b hn ch Trong trng hp khu vc tnh ton sng c su hn ch, cng thc tnh ton sng theo SPM (1984) cho vng nc c su u d nh sau

13 24

34

0.005650.283 tanh 0.530 tanhtanh 0.530

SFH dd

=

(28)

13 38

38

0.03797.54 tanh 0.833 tanhtanh 0.833

pFT dd

=

(29)

Hn ch v thi gian gi thi

73537lim pt T= (30)

Nu thi gian gi thi nh hn tlim th sng b hn ch v thi gian gi thi v cc gi tr chiu cao v chu k sng cn phi tnh ton da vo gi hiu chnh suy ra t cc cng thc (29) v (30).

Cc bc tnh ton cc c trng sng khi su nc b hn ch theo phng php SPM 1984 c th hin trong Hnh 5 v V d 2.


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(F > Feff)?

Bt u

Hs = 0.283d1tanh(0.00565F /d1)Tp = 7.54d2tanh(0.0379F /d2)


d = gd/UAt = gt/UA

F = gF/UA

d1 = tanh(0.530 d )d2 = tanh(0.833 d )

Nhp d, U10, F, t

UA =0.71 (RTU10)1.23

Kt thc

Feff ={tanh-1[(t /537)3/7/(7.54d2)](d2/ 0.0379)}

F = Feff

ng: sng b hn chv thi gian gi thi

Sai: sng khng bhn ch v thi gian

(F > Feff)?

Bt u

Hs = 0.283d1tanh(0.00565F /d1)Tp = 7.54d2tanh(0.0379F /d2)


d = gd/UAt = gt/UA

F = gF/UA

d1 = tanh(0.530 d )d2 = tanh(0.833 d )

Nhp d, U10, F, t

UA =0.71 (RTU10)1.23

Kt thc

Feff ={tanh-1[(t /537)3/7/(7.54d2)](d2/ 0.0379)}

F = Feff

ng: sng b hn chv thi gian gi thi

Sai: sng khng bhn ch v thi gian

Hnh 5: S thut ton tnh sng theo SPM (1984) khi su nc hn ch

V d 2: Tnh sng nc nng Tnh cc iu kin sng to ra t vn tc gi U10 = 15 m/s thi trong thi gian t = 6 gi trn gi F = 100 km trong khu vc c su nc bnh qun 15 m.


01/10/2008 8

Bc 1: Tnh vn tc gi hiu chnh theo cng thc (3) vi gi tr mc nh RT=1.1 c vn tc gi hiu chnh UA = 20 m/s.

( ) ( )1.23 1.23100.71 0.71 1.1 15 22.3A TU R U= = = (m/s) (31) Bc 2: Tnh su phi th nguyn, thi gian gi thi phi th nguyn t vi thi gian t c quy i ra giy v gi phi th nguyn F vi gi F c quy i ra mt

2 29.81 15 0.295

22.3A

gddU

= = = (32)

9.81 6 3600 949222.3A

gttU

= = = (33)

3

2 2

9.81 100 10 196922.3A

gFFU

= = = (34)

Bc 3: Tnh cc i lng trung gian trong cc cng thc (28) v (29)

3 34 4

1 tanh 0.530 tanh 0.530 0.295 0.209d d = = =

(35)

3 38 8

2 tanh 0.833 tanh 0.833 0.295 0.483d d = = =

(36)

Bc 4: Tnh chiu di gi hiu qu Feff t cc cng thc (30) v (29)

337

2eff

2

337

1atanh7.54 537 0.0379

1 9492 0.483atanh 108587.54 0.483 537 0.0379

dtFd

= = =

(37)

Bc 5: So snh F v Feff. V F < Feff nn sng khng b gii hn v thi gian gi thi v s s dng F tnh cc c trng sng. Bc 6: Tnh Hs v Tp s dng cc cng thc (28) v (29)

12

11

0.00565 0.00565 19690.283 tanh 0.283 0.209 tanh 0.0490.209s

FH dd

= = =

(38)

133

22

0.0379 0.0379 19697.54 tanh 7.54 0.483 tanh 2.750.483p

FT dd

= = =

(39)

Bc 7: Tnh Hs v Tp t cc cng thc (5) v (6)

2 20.049 22.3 2.51

9.81s A

sH UH

g= = = (m) (40)


01/10/2008 9

2.75 22.3 6.39.81

p Ap

T UT

g= = =

(s) (41)

Vy p s cui cng l sng to ra c chiu cao Hs = 2.51 m v chu k Tp = 6.3 giy.

3. Tnh sng trong bo Cc cng thc tnh sng phn trn p dng trng trng hp gi thi n nh. Tuy nhin, trong cc cn bo th vn tc v hng gi lun thay i theo thi gian nn vic s dng cc cng thc trn s c kh khn v khng cn ph hp. Vi cc trn bo nhit i nh thng xut hin nc ta, chng thng c phn b vn tc gi trong bo tng i n nh v c th m hnh ho da trn mt s thng s ca trn bo.

3.1. Phng php SPM 1984 Vi cc cn bo di chuyn chm, SPM 1984 a ra phng php tnh ton sng trong bo vng nc su khi bit cc c trng ca trn bo nh tc di chuyn ca cn bo, bn knh t tm bo n im xut hin vn tc gi ln nht trong cn bo v h p ti tm bo. Ti im xut hin vn tc gi ln nht ca cn bo, cao sng v chu k sng c ngha c th tnh ton theo (42) v (43) (Bretschneider, 1958)

5.03 exp 1 0.294700

fs

R

UR PHU

= + (42)

8.60 exp 1 0.1459400

fs

R

UR PTU

= + (43)

Trong

R Bn knh ca im xut hin vn tc gi ln nht trong cn bo (km) P gim p ca tm bo (mmHg) H s ph thuc vo tc di chuyn ca cn bo v gi. Vi trn bo di

chuyn chm c th ly = 1.

Uf Tc di chuyn ca cn bo (m/s) UR Vn tc gi n nh ln nht xut hin trong cn bo ti bn knh R (m/s)

max0.865 0.5R fU U U= + (44) Umax Vn tc gi gradient ln nht cao 10 m so vi mt bin (m/s)

( )max 0.447 14.5 0.31U P R f = (45) f H s Coriolis 2 sinf = (46) Vn tc gc ca Tri t (1 vng trong 23 gi 56 pht 4.09 giy) (s-1)

2 0.262523.93 = = (47)

V a l (rad)


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Cng thc (42) v (43) tnh cc c trng sng ti im xut hin gi ln nht trong bo. cao sng ti cc im khc c tnh ton da vo cao sng c ngha tnh theo (42) v c iu chnh bng mt h s suy gim trong Hnh 6. Chu k sng ti cc im tnh ton c tnh theo (48).

12.1 ssHTg = (48)

vi Hs v Ts l cao v chu k sng ti im tnh ton.

Hnh 6: Biu h s hiu chnh cao sng trong bo

3.2. Phng php Young (1988) s dng cng thc tnh sng nc su t ph JONSWAP, Young (1988) a ra khi nim gi tng tng v c tnh nh sau

( )2 2max max maxf f fF R aU bU U cU dU eU f = + + + + + (49) vi a = -2.17510-3, b = 1.50610-2, c = -1.22310-1, d = 2.19010-1, e = 6.73710-1, v f = 7.98010-1. Thng s t l c th tnh nh sau (Young v Burchell, 1996)


01/10/2008 11

max0.015 0.0431 1.30fU U = + + (50) Gi tr hiu chnh R tnh t R nh sau

3 322.5 10 log 70.8 10eR R = (51) n v ca Umax, Uf l m/s, n v ca F, R, R l m. Khi cao sng c ngha ln nht trong bo c th tnh theo (10) vi tc gi s dng tnh ton l Umax.

V d 3: Tnh sng trong bo theo SPM 1984 Tnh cc iu kin sng ti khu vc xut hin vn tc gi ln nht trong mt cn bo ti v tuyn 17 c p sut tm bo P0 = 940 mbar, bn knh gi ln nht R = 50 km, tc di chuyn ca cn bo l 50 km/gi. Ly = 1 v p sut vng khng c bo l Pn = 1013.25 mbar.

Bc 1: Tnh h s Coriolis f theo cng thc (46)

( )2 sin 2 0.2625 sin 17 3.14 /180 0.1535f = = = (52) Bc 2: Quy i p sut t mbar sang mmHg v tnh gim p tm bo

1013.25 7601.333224n

P = = (mmHg) (53)

0940 705

1.333224P = = (mmHg) (54)

0 760 705 55nP P P = = = (mmHg) (55) Bc 3: Quy i vn tc di chuyn ca cn bo t km/gi sang m/s

50 1000 13.893600f

U = = (m/s) (56) Bc 4: Tnh vn tc gi gradient ln nht cch tm bo bn knh R

( )

( )max 0.447 14.5 0.31

0.447 14.5 55 50 0.31 0.1535 47.0

U P R f = = =

(57)

Bc 5: Tnh vn tc gi n nh ln nht xut hin trong cn bo ti bn knh R

max0.865 0.5 0.865 47.0 0.5 13.89 47.60R fU U U= + = + = (m/s) (58) Bc 6: cao sng c ngha v chu k sng c ngha ti vng nc su xut hin vn tc gi ln nht ti bn knh R

5.03 exp 1 0.29

4700

50 55 1 13.895.03 exp 1 0.29 14.34700 47.60

fs

R

UR PHU

= + = + =

(59)


01/10/2008 12

8.60 exp 1 0.145

9400

50 55 1 13.898.60 exp 1 0.145 14.899400 47.60

fs

R

UR PTU

= + = + =

(60)

Nh vy, cn bo to ra sng c cao sng c ngha Hs = 14.3 m v chu k sng c ngha Ts = 14.89 giy ti vng nc su xut hin vn tc gi ln nht cch tm bo 50 km.

V d 4: Tnh sng trong bo theo Young (1988) Tnh cc iu kin sng ti khu vc xut hin vn tc gi ln nht ca cn bo trn theo phng php Young (1988).

Bc 1: Tnh thng s t l theo (50)

max0.015 0.0431 1.300.015 47.0 0.0431 13.89 1.30 1.1935

fU U = + += + + = (61)

Bc 2: Tnh bn knh hiu chnh R theo (51)

( )3 3

3 3

22.5 10 log 70.8 10

22.5 10 log 50 1000 70.8 10 172645e

e

R R = = = (62)

Bc 3: Tnh gi tng tng F theo (49)

( )2 2max max max3 2

2 1 2

1 1 1

=1.1935 172645 (-2.175 10 47.0+1.506 10 47.0 13.89-1.223 10 13.89+2.190 10 47.0+6.737 10 13.89+7.98 10 )=388091

f f fF R aU bU U cU dU eU f

= + + + + +

(63)

Bc 4: Tnh gi phi th nguyn F

2 2max

9.81 388091 172347.0

gFFU

= = = (64)

Bc 5: Tnh Hs v Tp s dng cc cng thc (10) v (11)

1

3 321.6 10 1.6 10 1723 0.066sH F = = = (65)

1

330.286 0.286 1723 3.43pT F= = = (66) Bc 6: Tnh Hs v Tp t cc cng thc (5) v (6)

2 2max 0.066 47.0 14.96

9.81s

sH UH

g= = = (m) (67)

max 3.43 47.0 16.49.81

pp

T UT

g= = =

(s) (68)

Nh vy, cn bo to ra sng c cao sng c ngha Hs = 14.96 m v chu k sng Tp = 16.4 giy ti vng nc su xut hin vn tc gi ln nht cch tm bo 50 km.


01/10/2008 13

Ch su nc tnh ton trong trng hp sng nc nng l su trung bnh ca c vng nc m sng c to ra v pht trin. Do vy khng th dng cc phng php trn tnh ton sng trc tip ti chn cng trnh nu su trc cng trnh khc nhiu so vi su chung ca vng nc m sng hnh thnh m kt qu tnh ton phi coi l xa b sau tnh truyn vo.

Hurdle v Stive (1989) pht hin ra cng thc SPM 1984 c s khng nht qun trong vic chuyn tip gia 3 trng hp: sng ang pht trin nc su, sng pht trin hon ton nc su v sng pht trin vng nc nng. Hai tc gi cng ngh cng thc nhm iu chnh s khng nht qun trn.

Bi v vic xc nh cc gi tr ca U, F, t v hng gi mt cch chnh xc l rt kh, hn na, bn thn cc cng thc trn cng cha cc yu t bt nh nn mi kt qu tnh ton theo cc phng php kinh nghim nh SPM 1984 hay cc phng php kinh nghim khc ch nn coi l gn ng v cn phi c kim chng vi cc s liu o c thc t.

Ti liu tham kho CERC, 1984. Shore Protection Manual. 4th ed., 2 Vol., U.S. Army Engineer Waterways Experiment Station, U.S.Government Printing Office, Washington, D.C., 1,088 p.

Hurdle, D. P., and Stive, R. J. H., 1989. Revision of SPM 1984 Wave Hindcast Model to Avoid Inconsistincies in Engineering Application. Coastal Engineering, 12: 339 351

Massel, S. R., 1996. Ocean Surface Waves: Their Physics and Prediction. Advanced Series on Ocean Engineering, 11. World Scientifics.

Young, I.R., 1999. Wind Generated Ocean Waves. Elsevier Ocean Engineering Book Series, Vol. 2, Elsevier, Amsterdam.

Cc k hiu d su nc (m) d su nc phi th nguyn F gi (m) F gi phi th nguyn Feff Chiu di gi hiu dng (m) Feff Chiu di gi hiu dng phi th nguyn Fi Chiu di gi ca tia th i (m) g Gia tc trng trng (m/s) HS cao sng c ngha (m) HS cao sng c ngha phi th nguyn RT H s hiu chnh tc gi do s chnh lch nhit gia khng kh v nc bin RL H s hiu chnh tc gi thi trn t lin Ta Nhit khng kh (C) Tp Chu k sng ti nh ph sng (s) Tp Chu k sng phi th nguyn ti nh ph sng


01/10/2008 14

Ts Nhit nc bin (C) t Thi gian gi thi (s) t Thi gian gi thi phi th nguyn tF Thi gian gi thi nh nht sng khng b hn ch v thi gian pht trin (s) t F Thi gian gi thi nh nht phi th nguyn tfull Thi gian gi thi cn thit t trng thi sng pht trin hon ton (s) t full Thi gian gi thi cn thit t trng thi sng pht trin hon ton (phi th

nguyn)

tlim Thi gian gi thi nh nht sng khng b hn ch v thi gian pht trin (s) t lim Thi gian gi thi nh nht phi th nguyn U Tc gi (m/s) U10 Tc gi ti cao 10 m so vi mt bin (m/s) UA Tc gi hiu chnh (m/s) UL Tc gi thi trn t lin (m/s) UW Tc gi thi trn mt nc (m/s) Uz Tc gi ti cao z m so vi b mt (m/s) z cao so vi b mt (m)

2008 by Nghiem Tien Lam

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26283032343638404245

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1 1.5 2 3 4 5 6 8 10 15 20 30 40 50 60 80 100 150 200 300 400 500 600 800 1000

TON TNH TON CC C TRNG SNG NC SU

V

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t

c

g

i

h

i

u

c

h

n

h

,

U

a

(

m

/

s

)

gi, F (km)

SNG

PHT

TRIN

TI HN

0.1 m

0.15 m

0.2 m

0.25 m

0.3 m

0.4 m

0.5 m

0.6 m0.7 m

0.8 m 0.9 m

1 m

1.25 m1.5 m

1.75 m

2 m2.5 m

3 m

3.5 m4 m

4.5 m5 m

6 m 7 m

8 m 9 m10 m

11 m12 m

13 m14 m

15 m

17.5 m

20 m

1.4 s1.6 s

1.8 s2 s

2.2 s2.4 s

2.6 s2.8 s

3 s

3.5 s

4 s

4.5 s

5 s

5.5 s

6 s

7 s

8 s

9 s

10 s

11 s

12 s

13 s

14 s15 s

16 s

17 s18 s

19 s20 s

21 s22 s

20'

30'

40'

50'

1 hr

1.5

hr

2 hr

3 hr

4 hr

5 hr

6 hr

7 hr 8 hr 9

hr 10

hr 1

2 hr 1

4 hr 1

6 hr 18

hr 20 h

r 24

hr

30 h

r

Chiu cao sng c ngha, Hs (m)Chu k nh ph sng, Tp (s)Thi gian gi ti thiu, t (h)


01/10/2008 16

Mc lc

TNH CC C TRNG SNG T GI THEO SPM 1984.................................................1

1. Gii thiu................................................................................................................................1

2. Tnh sng trong iu kin gi thi n nh ............................................................................1

2.1. Xc nh gi v hiu chnh tc gi ........................................................................1

2.2. Cc i lng phi th nguyn .........................................................................................3

V d 1: Tnh sng nc su ...................................................................................................4 2.4. Tnh ton sng trong iu kin su nc b hn ch ..................................................6

V d 2: Tnh sng nc nng ................................................................................................7 3. Tnh sng trong bo................................................................................................................9

3.1. Phng php SPM 1984..................................................................................................9

3.2. Phng php Young (1988) ..........................................................................................10

V d 3: Tnh sng trong bo theo SPM 1984 ......................................................................11 V d 4: Tnh sng trong bo theo Young (1988).................................................................12

Ch ........................................................................................................................................13

Ti liu tham kho ....................................................................................................................13

Cc k hiu ...............................................................................................................................13

Ton tnh sng nc su theo SPM 1984............................................................................15

Mc lc.....................................................................................................................................16

tinh song tu gio theo spm 1984

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