Nghien cvlu & Trao dd'i
LPNG DUNG MO HJNH THUY LIJC PHUC VU TINH TOAN THIET KE CAC CONG TRJNH 6 N DINH LONG DAN DOAN SONG DA
HA LU'U NHA MAY THUY DIEN HOA BINH
PGS.TS. Nguyin Tho Sao (Tru'6'ng DH KHTN)
ThS. Nguyin Kien Quylt, KS. Lu-ang Xuan Dai (Cty TVXD Difb-ng thijy, TEDI)
S
au khi Nha may Thuy dien Hoa Binh di vao khai th^c, long dan doan sdng Da phia ha luu dap thay ddi kh^ nhiSu, dac biet la doan phan lach gin ciu Trung Ha. D§ 6n dinh long d§n doan song nay phuc vu giao thong thuy va cac muc dich kinh tS khac, cin co giai phap cong trinh va cac giaiphip nay thwong duac thi/c hien tren mo hinh toan va vat ly. Bai nay trinh bay viec dp dung mo hinh toan 1 chiiu (HEC - RAS) va 2 chiiu (MIKE21C) vd md hinh vat ly dS tinh toan trwdng thuy dong lire.Si/phu hop kit qua cho thdy hieu qui cua mo hinh todn trong tu vin thiSt ki xay dung cong tnnh thuy
1. Dat van de
Song Oa chiem 55% lifgng nwdc cua he th6ng song Hong. Cach hgp lifu Thao-Da 57km ve phia thu-gng lifu la Nha may Thuy dien Hoa Binh. Cong trinh thuy (Ji$n H6a Binh (di v^o van hanh tu" nam 1991) CO nhiem vu chinh Id tham gia chong lu cho Thu do Ha Noi, hang nSm clit trung binh tif 4-6 tran lu, va hieu qua di4u tilt chong lu cho ha du rat ro rang. Ho Hoa Binh da lam thay doi co ban che do thuy li/c, thuy van, van chuyen bun cat, gay ra hien tu'ong xoi s3u long dSn tren song Da sau ho. Trong vdi nam t6'i khi cong trinh thuy dien San La di vao hoat dgng, gan nhu" toan bp lu'gng bun cat tao long cua song Da se du'oc giij" lai d hai ho nay, do do sy thay doi che dp thuy lye va bien doi long din d ha lu-u dap H6a Binh ch§c chin se diSn ra manh me han. Kem theo qud trinh xoi sau lan truyen la hien tu-gng ha thap myc nu'6'c, gay can tra giao thong thuy.
Doan s6ng phan Igch gan khu vyc cau Trung Ha c6 hinh thdi phCfc tap, chua on dinh, di§n bien thuy lye, x6i la b6' dang a tinh trang nghiem trpng, gay di chuyen luong tdu theo mua, anh hu-ang rit lan d§n dai song dan cu hai ben song. Theo thong le, dong chay thu'ong gay xoi a phia ba 16m doan song cong, tu-c dong chu luu phai a phia phai doan song nay.
Tuy nhien da nhieu nam nay, dong chtj luu ludn a phia trai doan song phan lach. Tren doan song nay, mot vai vi tri xung yeu da dugc gia co bing Idt mai, mot s6 vj tri co cac ke chinh trj dang chim. Viec chinh trj, on djnh long dSn phuc vu giao thdng thuy, ndng cao nang lye thodt lu a doan song nay la rat quan trpng trong khai thdo dong chay tren quy md todn tuyen song tu day v§ ha luu. Viec ndm bdt che dp thuy dong luc, dien biln cua long din co y nghTa rat thiet thye cho cong tdc chinh trj song khu vyc trpng diem ndy.
Trong dieu kien so lieu quan trie a khu vyc cdng trinh cdn han che, qud trinh dien biln ludng lach vd ket cau dong chay phue tap thi viec dua cdc mo hinh (ket hgp md hinh todn vd mo hinh vdt ly) vdo nghien CLFU ehl dp thuy lye doan thugng luu cau Trung Hd Id rat can thilt, Id ca sa danh gid, lya chon phuang an xdy dyng cong trinh mot cdch hi$u qua.
Pham vi nghien CLPU tren md hinh 1 chieu dugc trai rong den cdc tram thuy van gan vd-i sdng Dd nhat tren cac sdng ndy cu the la; sdng Dd tu ddp Hod binh din ngd ba Thao-Da vdi chieu ddi 57 km, song Thao tu tram thuy van Phu Tho din din tram thuy van San Tdy vdi chieu dai 48km, sdng Ld tu tram Phu Ninh den nga ba Hong-Ld vdi chieu ddi 37 km, sdng Phd Ddy tu tram Quang Cu den ngd ba
Ngudi phan bi$n: TS. Dao Thanh Thuy
|soeA^lGK•'
Tap chi Khi tifdng Thuy van * Thdng 8/2^———^4=-
N g h i i n c ^ & T r a o doi '^m
L6-Phd Ddy vdi chieu ddi 29 km.
Phgm vi nghi§n cuu cue bp bdng md hinh 2 chieu vd md hinh vat ly Id doan phdn lach tren sdng Da, cdch cau Trung Hd ve phia thugng luu khoang 9km vd ve phia ha luu khoang 1km.
2. Cac mo hinh tinh toan
a. Mo hinh thuy dgng ILPC 1 chieu
Trong nghien CLFU ndy su dung chuang trinh HEC-RAS, Id mdt mddun cua SMS. HEC-RAS dugc phdt trien bdi Trung tdm Thuy van Cdng trinh (The Hydrology Engineering Center- HEC), qudn dpi My.
HEC-RAS ed the tinh todn trang thdi on dinh hoac khdng on dinh de xdc dinh myc nude vd van tdc ddng chay, bo sung cdc cdng trinh: de, dap, cau, cong, khu chua. H$ phuang trinh Id:
dt dx '
5 Q , 3 Q Z , g A ( ^ , S , ) = 0 (2) dt dx dx
Trong dd: Aj- dien tich mdt cdt ngang, Q-luu lugng, qi- luu lugng gia nhap khu giua, V- van toe ddng chay , Z- cao dp myc nude, Sf - dp doc thuy lye. Han ehl duy nhat cua HEC-RAS la khdng dua dugc tryc tilp mua vdo md hinh.
b. Mo hinh thuy dgng ILPC ILP&I cong 2 chieu Md hinh MIKE21C Id md hinh 2 chieu, giai tren ludi cong tryc giao, cd rdt nhilu uu t h i so vdi nhiJng md hinh cung chuc ndng. Ddi vdi cdc ung dung trong sdng, yeu cdu md phdng chinh xdc dudng bien vd dieu dd ddi hdi viec su dung ludi cong hodc ludi phi cau true (dang cdc phan tu huu han). Ludi cong trong MIKE21C ed nhung uu diem vugt trpi ludi phi cau true d diem sa dd tinh todn nhanh han rat nhieu, do sd diem ludi cdn it han nhung van md phdng dudng bao tdt han vd do dd kit qua tinh todn ed dp chinh xdc cao.
He phuang trinh dugc su dyng trong MIKE 21C nhu sau.
dt ds h dn h hR hR^ ds C h^
dt ds h dn h hR^ hR^ dn C h dH ^dp ^ dq Q ^ P
^Qdt ds dn R^ i?„
(3)
(4)
(5)
Trong dd: s, n- toa dp trong he toa dp cong; p, q- thdng lugng theo hudng s vd n; H- cao trinh myc nude; h- dp sau; g- gia toe trpng trudng; C- he sp Chezy; Rg, Rr,- ban kinh ccng cua dudng s va n, RHS - phan ben phai, md ta hieu tj-ng Reynold, lye Coriolis, ma sdt do gid, dp luc khdng khi.
Nhu vdy M1KE21C giai doi vdi thdng lugng md khdng theo cac thdnh phan van toe u, v nhu thdng le. Mpt thi manh cua md hinh ndy Id xet din hien tugng ddng chay thtr cdp (chay vdng) trong sdng.
Ddng chay vdng xuit hien tai ede doan sdng cong hay xung quanh cdc bai giua gay nen su l^ch hudng cua ddng sdt ddy so vdi ddng chinh vd do
vay cung gay nen sy lech hudng ung suit tilp ddy Ddng thu cap cd anh hudng ddng k l den hudng van chuyen bun cdt vd vi t h i anh hudng din sy thay doi hinh thai sdng. Do dd, viec tinh todn ddng chay vdng gdn lien vdi vi$e md phdng van chuyen bun cdt khi tiln hdnh md hinh hod hinh thdi sdng tren qui md Idn, qud trinh phdt trien xdi, sy luu dpng cua con cdt.
3. K i t qua tinh toan
a. So lieu dau vao cho mo hinh 1 chieu
Ndi Chung, md hinh 1 chieu vd 2 chieu deu ddi hdi so li#u dau vao Idm dieu ki$n bien ha luu Id myc
T a p chi K h i tifgfng Thuy v a n * T h a n g 8/2008
Nghidn cuTu & Trao fliDi
^nude vd dieu ki$n bien thugng luu Id luu lugng hodc van toe, ngodi ra can ed so lipu ve cdc cdng trinh nhu cau, de, dap tren sdng vd phuang thuc van hdnh cua chung.
Trong trudng hgp cua chiing ta, cin ed so li$u
tai cdc trgm thuy vdn: Hod Binh, Phu Thp, San Tdy Quang Cu vd Phu Ninh d l Idm bien cho md hinh.
So li$u tai Vipt Tri vd Trung Hd ndm trong khu vyc nghiSn cuu, dugc su dung de hieu chinh vd kiem chung md hlnh.
Bang 1. Cac dgc trwng lu chinh trong pham vi nghien cu'u
Tram
Hoa Binh Phii Tho Vu Quang Quang Cxi
Sdn Tay Trung Ha
Viet Trt
Dac tnfng quan t r i e
Q(mVs) Z(m) Z(m) Q(mVs) Z(m) Z(m) Q(mVs) Z(m) Z(m) Z(m)
Thang 8/1996 12400 22,61 19,50 6560 21,23 28,90 19900 15,09 17,70 16,85
Thang 7/2004 9910 20,65 18,55 6970 19,15 28,19 14800 13,69 16,53 15,49
Thang 8/2005 8160 19,77 18,12 3420 16,37 29,14 11300 12,26 15,41 14,03
* Chu thich:
Q - Luu lugng nude Z - Myc nude
Cdc trdn lu ndy bao qudt dugc cdc hipn tugng thuy vdn diln hinh, do vay cd t h i su dung cho tinh todn thuy lye. Vi cd 3 giai dogn tinh todn: hipu chinh,.
kiem dinh vd khai thdc, do dd so lieu cung phai ddp Crng yeu cau ciia 3 giai doan tren. Trdn lu 8/1996 Id
trdn lu Idn nhit dugc chpn de hipu chinh md hinh, cdc trdn lu cdn lai dung cho kiem djnh. Lu khai thde dugc thu phdng tu lu 1996, ung vdi cdc luu lugng Idn nhit tai Hda Binh Id: lu Idn 15150m^/s, lu trung binh 10800 mVs, lu tao Idng 6250 m^/s.
Bang 2. Quy trinh tinh toan Giai do^n
Hieu chinh tno hinh 1 ciii^u
Ki^m dinh mo hlnh 1 chieu
Khai thdc mo hlnh 1 chi'feu
Khai thdc md hlnh 2 chieu
mthShg
sdng l ) T h a o 2) HSng
3) DA 4 ) L 6 5) RDdy
l ) T h a o 2) Hong
3) DA 4 ) L 6 5) P.Ddy
l ) T h a o 2) HSng
3) DA 4 ) L 6 5) P.Day
1)DA
ThoTi gian, hoac dac diem dong chay
- Lu 8/1996
- Lu 7/2004 vA 8/2005
- Lu l(3n - Lu trung binh
- Lu tao Idng
-Lu Idn Lii tao long
Bi€n dung cho tinh toan 1) Phii Tho 2) Sdn TSy 3)HoABlnh 4) Phil Ninh 5) Quing Cii
I) Phu Tho 2) Sdn Tay 3)HoABlnh 4) PhO Ninh 5) Qu5ng Cii
1) Phii Tho 2) Sdn TSy 3)HoABlnh 4) Phii Ninh 5) Quang Cii
1) Tirm6 hlnh 1 chieu
T r ^ m hi6u chinh va Id^m chiJng
1) Trung Ha 2) Viet Tri
1) Trung HA 2) Viet Tri
Tap chi Khi tiftfng Thuy van * Thang 8/2008
Nghien ctfu & Trao ddi
b. Hieu chinh va kiem djnh mo hinh 1 chieu 1) So dd thuy luc
Sa do thuy luc (hinh 1) the hien ludi sdng tinh todn, trong dd ehi ra dp ddi sdng, cac bien, vj tri cdc mdt cdt ngang, ede cdng trinh: de, ddp, cau, cong..
He thong sdng bao gom; sdng Thao, sdng Hong, sdng Dd, sdng Ld vd sdng Phd Ddy. Trong dd Sdng Thao dugc tinh tu tram thuy vdn Phu Thp tdi nga ba Trung Hd vd cd 25 mat cdt. Sdng Dd dugc tinh tu ddp thuy dipn Hod Binh tdi ngd ba Trung Hd vd cd 48 mdt cdt, ngodi ra tren doan sdng nghien cuu cdn bo sung them 6 mat cit tuang ung theo md hinh vdt ly (G1-G6). Sdng Hong dugc tinh tu ngd ba Trung Hd din tram thuy vdn San Tdy vd ed 20 mat cdt.
Sdng Ld keo ddi tu tram thuy vdn Phu Ninh tdi ngd ba Viet Tri, do vdo sdng Hong gan mat eat SHG12 vd cd 14 mat cdt. Sdng Phd Ddy trai ddi tCf tram thuy vdn Quang Cu din ngd ba Ld - Phd Ddy, do vdo sdng Ld cd 8 mat cdt. Ciu Trung Hd (14 nhjp, 13 tru vd 2 mo) cung dugc dua vdo sa do thuy lye ndy.
Hinh 1. So- do thuy lire the hien mang Iwm song trong mo hinh
R3>S£S Dotunsttan (in One)
Hinh 2. Mat cat cau Trung Ha the hifn trong s c do 2) Ket qud hieu chinh lu 8/1996
H§ so nhdm Manning liy bdng 0,025 d idng sdng vd 0,03-0.05 d hai ben bai sdng.
Ml* turic thift do va tloli t H i tMiig 8/1996 lai Vi4t Tri Mit aadc thiit dova liuli toaa thang 8/1996 tai Viet Tri
r-\.
/ \
^
r / \
\
' ^ / \
\ / V J -
V
IB III 65 E : s : 5 ! 21 JB 33; 365 3S3 KI U9 ITT 3SJ3J 561 ,=f96C 615 i;3 TOI T3 I a 3; 55 IB 111 B K : : s : 3 SI 308 3!7 K » j i:i m 41; SSJJJ m m a i t ;:; ;.ji ; a
Hinh 3. So sanh muv nircyc giCea thyc do va tinh toan tai Viet Tri va Trung Ha
Tap chi Khi tifcfng Thuy van * Thang 8/2008
ISrgWgn Clfu & Trao
Tu cdc kit qua tinh todn tren va so sdnh vdi doi tot, ca v l dp Idn vd pha lu len va lu xuong.
quan trie ta thiy cdc tinh todn cho kit qua tuang 3 ^^^^^^ ^.^^ ^.^/, / . ^^.^g Q/^OOS
Mic Di^ ibuc tbvQiCaliioBaitBDg 8/2005iaLTruiigHE9 Ivtut: [lUSc tliLC do VB t(Qh icoQ ibJQg SftOOJ QI vfii Trt
I 30 59 8S 117M l7S2042332<229l320]«3;S'l07 4 3 ( « 3 « 4 S 2 3 5 3 2 5 S l < l O ( 3 9 « S e ) 7 7 2 ( 1 33 63 97 129161 1932232372©3Z1333385417'M94S1313343377«)964167370i737
Hinh 4. So sanh mwc nw&c Myc nude thye do tai Trung Hd vd Viet Tri,
khdng tham gia tinh todn, chi dung de hieu chinh vd kiem djnh, nhung cho thiy phu hgp vdi kit qua tinh todn. Vipe kiem chung md hinh vdi trdn lu 2005 t h i hipn dung quy luat thuy lye cua ddng chay trong todn bd h? thong. TLP ddy cd t h i su dung md hinh HEC-RAS vd sa do thuy lye dd thilt lap d l tinh todn cho cdc phuang dn khai thdc tren md hinh vdt ly vd md hinh todn 2 chieu. Da sii' diing trdn lu 8/1996 cung cdc dilu kien bien nhu da ndi tren, rieng luu lugng Hod Binh dugc thu phdng theo dang lu 8/1996 vdi 3 trudng hgp: lu Idn (dinh lu 15150m^/s), lu trung binh (dinh lu 10800m3/s), lu tao Idng (dinh lu 6250m3/s).
c. Tinh toan tren mo hinh 2 chieu
Lu&i tinh todn va cdc tham so
Pham vi tinh todn md rdng v l phia thugng luu d l giam thieu anh hudng cua dieu kien bien, nhit Id khi cd gidi phdp chinh tri. Ludi cong dugc thiet idp vdi b l rpng doan sdng chia thdnh 87 d, chieu ddi chia thdnh 864 d (864 x 87), du chi tilt de ndm bit ehl dp thuy ddng lye cua miln tinh todn. Day Id mien cd dja hinh rdt phuc tap (h.5) vdi nhOng thay doi Idn ea v l dp sau lan be rpng sdng. True doan sdng cong lien tuc thay doi. Theo nhung ghi nhdn tu cdc dgt khao sdt cung nhu quan sat tren thye dja, Idng din doan sdng nay ed nhljng biln dpng rit ddng ke: ton tai nhilu doi cdt di ddng vd bat di ddng cung nhung ho xdi, ddc biet hd xdi ha luu cau Trung Hdsdu den 15m.
Hinh 5. Lw&i cong truv giao
Tap chi Khi tifdng Thuy van * Thang 8/2008
Nghidn cufu & Trao dd'i
Hinh 6a. Myc nw&c cwc dai trong lu l&n Hinh 6b. Van toe cwc dai trong 10 l&n
-25545
23530
23520
23510
23480
5300
0
10
ID S
5310
^
•.^^-.•^SHB
5330
| | x
#v
i^ • # J * ^ * !
^ ^ [ i i l W
S 5350
Z
Hinh 6c. Dong chay trong IQ l&n d. So sanh kit qua v&i md hinh vat ly
Nhu dd trinh bdy md hlnh 1 chilu dd cung cip cdc dieu kien bien cho md hinh 2 chieu vd md hinh vat ly, song dong thdi cung dua ra thdng tin ndm trong doan sdng gidi han bdi cdc bien. Viec so sdnh
kit qua ndy vdi kit qua nhdn dugc tCi' md Kinh vdt ly cho phdp ddnh gid lai tdc dung cua md hinh todn.
Bang dudi ddy dua ra kit qua so sdnh myc nude trong 2 trudng hgp lu Idn vd lu trung binh, ung vdi vj tri 6 gilng quan trie theo md hinh vat ly.
Bang 3. So sanh mwc nw&c quan trie (MH) va mwc nw&c tinh toan (NH)
Vjtrf
G I G2 G3 G4 G5 G6
L(in)
7700 5950 4550 3150 1650 0,00
Q =15150 mVs
HNH
(m)
19,07 18,84 18,77 18,71 18,39 18,33
HMH
(m) 19,03
18,8 18,75
18,7 18,38 18,33
SaisS' (m)
0,04 0,04 0,02 0,01 0,01 0
Q = 10800 m'/s
HNH
(m)
18,06 17,85 17,84 17,79 17,59 17,55
HMH
(m) 18,05 17,85 17,80 17,75 17,58 17,55
Sais£r(in)
0,01 0
0,04 0,04 0,01 0
6 Tap chi Khi ttfgfng Thuy van * Thang 8/2008
Nghidn citu & Trao doi
&'. chu hgp chinh xdc cua k i t qua tinh todn tren md hlnh todn vdi k i t qua do dac tren md hlnh vat ly that ddng ngac nhien, Cd the di tdi k i t luan rdng, md hinh vdt ly rat quan trpng doi vdi thilt k l cdng trinh, nhung chi nen su dung trong mpt so trudng hgp ddc biet do ehl phi cao, Md hinh todn vdi chi phi thap cd the dam nhdn vai trd ndy md khdng gdy ra sai s6 ddng ke,
4. K i t luan
Md hinh todn 1 chieu vd 2 c h i l u Id cdng cu hOu
ich cho viec nghidn cuu e h l dp thuy ddng lye doan sdng ndy vd thu nghipm cdc giai phdp cdng trinh trong tuang lai, Chi vdi cdc dieu kien tai bien nhung md hinh todn cho phdp nhdn d u g c buc tranh phdn bo myc nude vd ddng chay tren toan mien.
Sy phu hgp tot giO-a ket qua cua md hinh todn (ehi phi thap) vdi k i t qua md hinh vdt ly (chi phi cao) cho thay uu t h i cua md hinh todn, Kien nghi trong thilt k l cd t h i dp dung md hinh todn, ehi s u dung md hinh vdt ly trong mdt so trudng hgp r i t dgc bipt.
Tai lieu tliam khao
1. HEC-US Army Corps of Engineers, "River Analysis System-Manual", 2005 2. DHI, "MIKE 21C- Scientific Reference Manual", 2005,
