KHOA HOC CONG NGHE
NGHIEN C i r u H O A N THIEN P H l / O N G P H A P TESH \ 4 X A Y D l f N r CHU^ONG TRINH TINH TOAN BIEN H I N H >IAT C A T i S ^ H D I S T
SAU KHI C A T S 6 N G B A N G K E N H M 6 I TAI V t N G T R i t U d D O N G B A N G NA.M B O "
Le Vin Tuan Viin Ky thugt Biin T6m a t : Song uon khuc Idn Igi khd phd bien d Ddng bdng Nam Bg (DBNB). Trin sdng udn khuc xudt gqp gay bat lgt cho vifc khat thac Idng hgp ddng sdng nhu vdn di giao thong thuy, xdi Id thodt Id '^^^^'^fV-Chirditridognsdngconggdplheomnhthdccdlsdngcdthi^iq
'"y"h'^y'l'^ff«fcocaccangcudnhlodnbiinhinhldngd&,sdngcu^^
pfut^gphap nnh dugc tiung binh hoa cug Tg Gidm Hodnh (Tnmg Qudc), ldc gid hodn ihifnZmg PJ^ff^^-'^^dungchuangtrinhtinhhfdgngdpdungphiihgphantiongdilMinddngbLgc^
m^ong So Gon. Ket qua ung dmg cho thdy, dien biin sau cdt sdng bdng kenh mdi khd chdm, thdi gtan dien bien de M ddn cd thi thay thi sdng cong cH cd thi keo ddi hLg vdi thgp ky tiiy4n Snh --'""^I'P^-'triennhanhcdriphdicdgidiphdphS^^
Oau kenh mot can dugc ddo den gdn mgt cdt dn dinh Iheo quan hf hinh thdi « ^ <" ^ « """
Tukhda: Dong bdng Nam Bp, sdng uin khuc, kenh m6i, bdn ddo Thanh Ba. cit song cong.
Summary: Meandering river are quite common in the Southern Delias, some of these rivers occurs ab^rmal bends, so call Cl shape bend These abnonnal bends are a detrimeJal issue in nte^Z e^loiration of he river such as inland navigation, river bank erosion, flooding drainage Tmining 'ese abnormal bends could use a cut-off canal (pilot channel), howL th!re is nocJZZn procedures about,he morphological change. Rely on the theoiy of Xie Jian Heng (Chinese) author
^o-Vle.esthen,ethodo^gyandprogramingofanauto.calculalionwhichissui
the sourthern deltas. The application is used for Thanh Da Peninsula in Sal Gon River ThereZ shows that the development of cut-off canal occurs slowly the change of cut-off canaUo^^e
lasting in several decades In order to increase Ihe development ofcaL LrpJo^Xillrl K^llfZ" T ; ' " ' ' "^f" "' '^-<'-^<^^"-'^''ouldexcavaledneJyio tSsiable C
Keywords:soua,erndeUas,meanderingriver,pilotchannel, Thanh Da peninsula, cutoffmeander 1. D^T VAN Bt Bp Id nhftng khu vye ed nhilu dogn cong gip Cdc dogn sdng eong gip tin tgi khd pho biln d ^^- ^ ° ' vdi khu vye Dong bing Nam Bf edc hiyen sdng uon khftc d nudc ta, frong do (^BNB), cdc dogn sdng cong gip cd hf s l vflng dong bdng Bdc Bp vd dong bdng Nam «>."8 •<5m chft ylu tap frimg d hg chdu till sdng Ddng Nai - Sdi Gdn (SDN-SG) vd khu vye bdn ddo Cd Mau [11,121.131
Ngiy nhgn bdi: 13/10/2015 rK- i. • ' ''^ J'^ J-
Ngiy thdng qua phdn blpn: 14/11/2016 ^°'°" ^- ^°^ ^"8 «>ng gap ddp ftng myc Ngdy duyft (Mng: 28/12/2016 tieu phdng chong xdi Id, cdt ngdn Ip frinh ehgy
TAPCHfKHOAHOCVACONGNGH?TH0YL0ISfl36-2016 47
tdu, tidu ung vd thodt 1ft ludn l i nUdm vy quan trpng doi vdi cac dja phuang. Trong cic gidi phdp dupc lua chpn dh ehinh tirj cdc dogn sdng cong g ^ , gidi phdp gia eo bd ldm sdng cong ludn Id gidi phdp dupc lya chpn do cd uu dilm it ldm thay ddi Ufn trgng khu vuc chinh tri c i vd dpng luc ddng chiy vd vin dh pU ky thufit, ngodi ra, gidi phdp gia co bd sdng da cd nUlu ngWdn ctru vd bp cdng cy tinh todn. Nhupc didm cfla gidi phdp ndy Id khdng gidi quylt trift de cdc van dd cua sdng cong gip la cit ngdn Ip trinh ehgy tdu, tidu iing - thodt lfi vd can kinh pW thudng xuydn dl duy tu bao dudng cdc cdng trinh ke pUa bd ldm. Giai phdp cdt sdng cd till gidi quylt tit edc vin dd ndu tren my nhien trong thdi gian qua chua dupc lya chpn nWeu do nWlu nguydn nhdn trong dd cd nguyen nhdn vd cdng ey ho frp tinh todn vd dy bdo diln biln sau kW cit sdng.
Mft vdi cdng trinh cdt sdng tgi miln Bic dd khdng tfidnh cdng [6]. Tgi miln Nam, khu vye DBNB mft so cdng tiinh cit sdng chfl dfng hofc ty phdt dd dupc tiiyc Wfn nhung chua cd nghidn cuu vl ca sd khoa hpc.
v l chl dp dpng lyc vd Wnh tiidi cic dogn sdng cong khu vye DBNB cd nWlu dilm khic bift so VtW sdng khdng chju inh hudng cfla tiifly frilu [4], [10].
Ca chl tdc dpng dl chinh tii dogn sdng cong gip gim 3 ca chl chfl ylu [9]: (1) Bgt mom vd gia CO bd ldm sdng cong; (2) Ddo kenh tit vd duy fri hiyln sdng cft; (3) Md kdnh tit vd lip sdng eft. Trong dd co che (2) vd (3) lidn quan den hinh tiiftc cit sdng bdng kdnh moi.
Nhifm vy quan tipng nhit frong tiiilt kl cdng frinh dx song kieu nay la fr'nh todn bidn hinh ldng din dl dy bdo hifu qud cfla vifc cdt sdng:
Sy phdt friln md rpng cfla mdt cdt kdnh dan;
Wen Wnh Wnh thai cfla cdc dogn sdng cu. Mdti du, khoa hpe vl dpng lyc sdng vd cUnh trj sdng dd cd nhftng budc tiln nhit djnh frong tfi6i gian qua cflng vdi hS frp cfla cdng nghf thdng tin tfldng qua cdc phin mdm md hinh todn md phdng Wfn dgi, hiy nWdn, cdc phin
mim Wfn dgi ddi hdi rat nUeu so lifu diu vdo, tfldi gian Wfu chinh v i kilm djnh md Wnh, ydu cfiu cao vl trinh dO sft dyng md Wnh vd ddc bift khi md phdng chu trinh phdt friln hodn toan tft kU kdnh mdi rad rfng vd frd thdnh sdng Idn nhu trong tlilu kifn vftng ding bdng chju difli hudng thuy trilu cd thi kdo ddi hdng trim ndm la khd khd tU. Vi v§y, dl giai quylt vin dl nay, dflng giai phip fruydn flidng Id md Unh hda eac Wfn tupng ty nhien bdng cdc hf phuomg trinh dan gidn vd gidi chiing flieo phuang phdp gin dflng la phu hpp hon.
Dl phye vy cho vife tuih toan biln Unh Idng dan kdnh ddo va sdng efi sau kW tiln hdnh cdt sdng, GS.Ta Gidm Hodnh (Dgi hpc Vu Hdn - Trung Quic) dd phdt tridn phuang phdp tinh todn cdt sdng ddc thft cho edng tiinh cdt sdng fliuOc cW luu sdng Trudng Giang, phuang phdp tfnh toan dp dyng cho vftng thupng chdu flio sdng Trudng Giang. Phuomg phdp ndy dupc GS.Luang Phuang Hgu gidi tiiifu tiong cuon
"CU din ky tfiuat cdng tiinh cUnh tii sdng" [6].
Tuy nUdn, mft vai dilm hgn ehl cfla Phuong phip Tg Gidm Hoanh nhu: (1) Chua cd phin mem tinh todn tfieo hutJmg ty dfng hda; (2) Dilu kifn dp dyng cho vftng tiiupng chdu till sdng Trudng Giang khde bift nUlu so vdi vung DBNB nhu dp doe mft nude Idn, ldng sdng chii ylu Id cdt vi khdng phdi la bun sdt dinh xen lin eat mjn nhu d DBNB, dogn sdng dp dyng khdng chju tdc dfng do tfiuy tiiiu nhu khu vye DBNB. Ngodi ra, hf s l quan hf Wnh fliii on djnh cfla hiyln kdnh ddo cung khde bift so vdi vimg ngWdn cuu.
Vdi nhfing lfip lufin d frdn, trong bdi bdo ndy, ke tiifta edc nghidn cihi eua cWnh tac gid vl hf sd ty If quan hf hinh tfiii on djnh kdnh ddo cdt sdng, khdi nifm mtM "luu lupng khdi dfng"
cho kdnh ddo [9], bdi bdo hudng din mft phuang phap dupc dan gidn hda nhung cd df tin cfiy chip nhfin dupc vl khoa hpc de dy bio frong dii han tinh hifu qud cfla cdng tiinh cdt.
sdng vdi gidi phap kdnh mdi. Do dan gidn hda nUdu vin dl phftc tgp cua dpng lyc sdng bdng
« TAPCH(KHOAHOCVACONGNGH?TH0YLO1S636-2016
KHOA HOC CONG NGHE sa do don gidn ndn kit qud tiiu dupc cung cU
mang rauc dp udc tinh, cd till dp dyng frong giai dogn tUlt kl so bp.
Kit qua ftng dyng ehuong frinh cho rapt khu vye cy till tgi sdng Sai Gdn (Tp.HCM) cho fliiy, neu ip dyng co chl kenh mdi cho khu vye DBNB, khoang flidi gian dien biln tir kW kdnh mdi hogt dpng din kW kdnh phit tiiln tio fliinh sdng ldn du thay thi cho sdng eong efi khi Idu, ed flil din vdi ti&n ndm. Vi vay, kW dp dung Wnh tiiftc cdt sdng cin tinh todn cfin nhic, dl gia tfing tdc dO dien biln kdnh mdi can phdi cd tiidm ede gidi phip ho frp nhu ke md hdn hudng ddng hoac 1 ^ mpt phin sdng cfi, hodc phdi ddo kdnh moi gin din mdt cit In dinh cudi ciing.
Chuong frinh tinh todn mdc dft cdn cin phdi hoin fliifn fliem nhung cd uu dilm Id flidi gian tinh todn xft Iy nhanh, fliao tdc dan gidn, kit qud chuang tiinh tinh cd flil tin egy dupc vd cd flil dp dyng fliyc tien frong giai dogn tiiilt kl so bp.
Trong phin ddt vin dd cfla tdc gid, ndn tiinh bdy rd hom nhftng vin dl md tde gid tgp trung, nhung khdng till khdng dl efip din vin di dang ton tai Id gi. Cy till, ndn dua ra tgi sao khdng sft dyng dupc phuang phdp eua Tg Gidm Hodnh, hofic nlu dp dung phuang phdp cfla Tg Gidm Hoinh thi cd nhftng nhupc dilm gi v.v...NhOmg gl chua dupc gidi quyet frong dd vd dd Id vin dl tie gia giii quylt dupc....
Ve phuomg p h ^ ngUdn ciJtu, dl giii quylt van dd, tic gid sft dung phuang phip gi.
Hmh thftc trinh biy cfta bdi bdo ndn tdch thdnh cac phin chft ylu, dd la ddt vin dh (tdc gid dd trinh hay), phuang phip ngUdn cuu, kit qui v i fliio luan, kit lugn v i kiln nghj (nlu cd), rapt cich ngdn gpn vd xfle h'ch hon.
2. PHlTONG PHAP NGHIEN CUtJ 2.1. Dat bil toin
TUdt kd cong trinh cdt sdng cd nUlu cdng vide cin tiln hanh nhu xic djnh phuang tfiftc chmh tii, bd tri cdng frinh, tiiilt kl cic hang myc cdng frinh, xac djnh phuang phdp tfii edng, tinh todn Ufu qud vd ddnh gid tie dpng mdi frudng [7]...Trong bdi bdo ndy, eU tgp frimg iigUdn cthi vin dh quan tipng nhit frong tiiilt kl kdnh ddo Id tinh todn phfin luu vd tinh todn biln hinh Idng din cfta kenh ddo (Hmh 1) hrang ftng vdi 2 ca chl tdc d^ng Id ca chl (2) vd ca chl (3).
Van dl tufli todn phfin luu tuang dli dan gidn, nhung hnh toan chuyin dpng hftn cdt vd biln Unh ldng din Id khd phftc tgp. Phftc tgp nhit Id gidi quylt hpp ly 2 vin dl: Mpt Id phan cUa hftn cdt giua sdng cft vd kdnh ddo; hai Id phfin chia difn fr'ch xdi tiieo eUlu ngang vd cUlu tiling dftng flieo quan hf Wnh tiidi. Hifn nay, chua cd md Unh tinh todn ndo gidi quylt dupc mpt cich thda ding.
Htnh I. Phdn dogn tinh todn biin hinh long ddn sau khi cdt sdng
TAPCHfKHOAH0CVACflNGNGH?TH0YL(?ISfl36-2016 49
22. Sa do tong quit cho chinmg trinh tinh toin cit sdng
(l)Tdm Ids cdc btrde rinh todn chirdt:
- Tinh toin mdt cdt kdnh ddo theo ydu ciu khai tilde vd xdt din quan hf hinh thdi theo cic frj so ddc trang cho timg phdn vftng tfnh todn.
Tfnh todn luu Iupng sdng thupng luu kdnh Qo bdng luu lupng lfi 5% tft kit qua md Unh MDCE-l Icho mgng ludi sdng ngUdn cihi (ndu khdng cd, cd thi liy Qo bdng dipn ti'ch mdt cdt sdng nhdn vdi vfin tie khdi dpng hrong ftng vdi hat cdt Idng sdng cd dudng kfnh dso).
- Lay myc nudc d cfta ra kdnh bdng myc nudc frilu frung bmh, tinh todn phfin luu, kit qud fliu dupc Id luu lupng vd dudng mfit nudc trong kdnh sau thdi dogn At|
- Tfah todn vfin toe trong kdnh ddo cit sdne Vi
= Qk/Ak
- Tfah todn khoi lupng bftn cdt ldng din kdnh ddo bj xdi tiong flidi dogn At| flieo cdng fliftc (2-23).
Tinh todn phfin cUa dipn ti'ch xdi tixn mfit cdt ngang kenh, tiiu dupc mfit cdt kdnh ddo sau thdi dogn At|.
- Liy mfit cfit kdnh sau tiidi dogn Ati Idm dilu kifn bidn dl tinh todn cho flidi dogn At2.
- Tilp tyc phuong ph^ frdn, ve ly fliuyit phdi tien hdnh tinh todn tilp tyc cho din kW kdnh ddo tfidrig qua dupc todn bO luu lupng sdng vd sdng bj lip flii kit fliuc tinh todn. Thyc tl, fliudng dung lgi kW kdnh ddo flidng qua dupc 75% Qo.
(2) Sa dd khdi tinh loan cdt sdng bdng kenh m<5/. Xem Phy lyc I.
23. Hoin thifn phuomg phip tinh vi xay djrng Chiromg trinh ty dfng hda tinh toin cit sdng theo ca chl tie dpng bing kenh moi cho khu vuc dftno hin» v ns
cua ddng chiy on djnh v i phuong trinh lien tyc cfla bfln cit; kl flifta kit qui ngWdn cftu v|
Wnh tiiii In djnh kdnh dio cit sdng khu vye DBNB, ftng dyng khii mpm mdi "luu lupng khdi dOng" cho kdnh dio [9]; nhftng quan mfm xft ly mft so ylu to phftc tgp flieo dgng sa dl hda cho phft hpp vdi dilu kifn DBNB (myc 2.3), tde gid da xay dyng thufit todn (xem Phy lyc 1) va ehuong tiinh ty dpng hda tinh todn cdt sdng cong gip tiieo phuang tiiftc kenh mdi bdng ngdn ngft ForfrBn. Cfiu friic chuong trinh todn xem tiidm trong [9]. Chuang frinh ndy dupc dfit tdn Id CASO-2015.
*- Diu vdo chuomg frinh CASO-2015 ydu cdu:
Tdi lifu dja Wnh, dja chit, tiifty vdn, bftn cdt khu vye ngWen cftu.
Ydu ciu cua cdc ngdnh kinh tl - xd hpi doi vdi dogn sdng.
Quy hogch vl tiQ^ kenh ddo va ca cfal cdt saig c- Diu ra thu dupe cdc kit qud:
Mfit cit ngang kdnh dio tiiilt kl vi udc tinh qui tiinh phit tiiln cfta nd;
Luu lupng, dudng mfit nudc frong kenh ddo dudi luu lupng tiiilt kl.
d- Giao dipn man hinh chuang frinh CASO-2015
moi cho khu vye ding bing Nam Bf
a- Phin mim tinh todn: Dya Men phuong phdp y tiiuyet cfla GS.Tg Gidm Hodnh vdi nguydn ly CO bdn cfla fr'nh todn la gidi hf phuang frinh
e- Phgm vi img dtfng cua CASO-2015 Do sft dyng eie edng tiiftc kinh ngWfra vl quan hf hinh thai vi luu lupng khdi dpng viing anh hudng frilu DBNB cfta Vift Nam, phgm vi ftng dyng cfla nd cftng hgn ehl frong vflng DBNB Vift Nam.
so TAP CHI KHOA HOC VA CONG NGH? THOY LOl sfl 36- 2016
I KHOA HOC CONG NGHE 2.4 Mpt s^ qaan ni|m tinh toin v i sor do hda
cic vln de phuc typ khi xiy dmig chovng trinh tinh toin cit song i p dyng cho khu v^c Ding bing Nam Bp •
(1) Luu brgng linh todn cho sdng tivdc dra -vao
*ln/i t^a i w ^ go.-Xac finh Qo hfing luu lupng Ifi 5% qua mdt cit dogn sdng thupng lua Trong tiudng hpp kh&ig ed sl liai luu Iupng Ifi, cd flil lay di^ tich mdt cdt udt ngang bai dia Icmg sdng dogn thupng luu nhfin vdi van tie khdi dpng cfla hgt bfln cdt dso ldm luu hipng tinh todn Qo.
(2) Lua chgn cdng thuc tinh hdm lugng bim cdt la lung
Sft dyng cdng tiiftc tinh ham lupng bftn cit la Iftng cua Zhang R.C [11].
(3) Sa dd phdn chia bim cdt giira sdng vd kinh Do bftn cat la Iftng phfin bd khdng diu frdn flifty tnrc nai kU md kaih cit sdng, sy chdnh Ifch diy sdng vd diy kdnh ldm eho phdn bftn cit di vio
kenh se khac phin bim c& di vao sdng. Dl giii tpydt van dd niy idii x ^ dyng chuong trinh, tac gii l i ) ^ fdian mpt s6 gii tWit sau:
+ Trudng hpp cao trinh day kdnh ddo thip horn so vdi eao trinh day sdng thupng luu sdng cfi tU hdm lupng biin cat trong sdng vd di vdo kdnh eoi la nhu nhau, ngUa Id Sit=So.
+ Tnidng hpp cao dp diy kdnh ddo cao hon so vdi day sdng jAia thupng lmi, tU su phin cUa bun cat sd phy thupe vio gdc a. Id gdc hpp gifla fryc kdnh dao va chft luu ddng chdy sdng:
Ndu a<25'' tiii Sk=S„; nlu a>25'' tiii Sk=0,7So (gii thuylt trdn cung phft hpp vdi cdc ngUdneftu[13],[14]).
(4) Sa do phdn bd diin rich xoi kinh sau mdi ldp thdi gian
Nlu hiyln kdnh ddo Id dudng cong, coi kdnh eU xdi bdn bd Idm, bd ldi khdng ddi till vifc phfin cWa bftn cat tuan tiifl flieo Hmh 2a.
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Hinh 2a: Sa do rinh todn xdi sdu vd xdi ngang tiong kinh ddn htyin cong
Neu kdnh ddo cd hiyln tiidng, vifc phfin cWa bfln cdt flieo xu flil xdi Id hiin flieo quan hf hinh flidi flieo so do Hinh 2.b, phan xdi ngang cWa diu cho 2 pW'a bd.
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Htnh 2b: Sadd ti'nh todn xdi sdu vd xdi ngang trong kenh ddn tiiyen Ihdng
TAPCH(KHOAHOCVAc0NGNGt«TKlYL0IS636-2016 51
3. ONG DVNG THVC TE CHl/ONG TRtNH CASO-2015 CHO CONG T R I N H C A T SONG CONG GAP KHU VI/C BAN DAO THANH DA, S 6 N G SAI GON 3.1 Gidi thifn doyn sdng nghien ciru Ung dyng (jio I cdng trinh cdt s«ig fliyc tl dl chftng minh ring tinh khi tW vi dimg ddn ctia chuong frinh tinh todn vd dy bao cit sdng CASO- 2015. Thyc tl, tidy Id bdi todn gii dinh \i Wen nay cdng trinh Thanh E)a da dupc cdt sdng flieo ca chl kdnh tdt vi hai boi bd kdnh dd dupc ke bd hofic cd bj lin cW6n dh xdy dyng hg tang dpe bd sdng ndn tfnh ehit ty nWdn khdi% cdn dflng niia, tuy nWdn, myc tidu cfla tic gii muln sft dyng ca chl kdnh moi dl kilm tra tinh khi dyng cua chuang trinh CASO-2015 vi tfin dyng Igi bp sl lifu dja hhih, flifty hdi vdn cd sdn. Tuyin kenh mii (kenh ddo tit) di flieo hiyln Wfn hftu cfla kenh Thanh E)a, nhung viSri mfit cit hifin theo quan hf hinh flidi vdi 5=1,66 (ty If quan hf hinh flidi on djnh cho kdnh ddo cit sdng vflng hg chdu flio sdng E)lng Nai - Sdi Gdn, dieo [9]).
Etogn sdng cong gip frdn sdng Sii Gdn li mpt vdng sdng dgng n, cd hf so cong y =18, vdi cWlu ddi dogn cong Id 9000 m, khodng cdch eo sdng chl ngdn nhit Id 200m (dit liln) vd 500m
(tinh tiir 2 tive sdng). Vdng sdng niy fliufc phudng 27 vi phuong 28, qufin Bmh Thgnh, Tp.Hd CU Mmh (Mnh 4a). Trudc day, dl phye vy cho vipc giao flidilg flifty, vio ndm 1907 (cd tai lipu dl ndm 1898), ngudi PU^ dd tiln hdnh 1 ^ kdnh Thanh Da cfit sdng qua gdc eo hn (MonograpWe de la province de Gia Djnhl902, nguon internet). Xem Hinh 3a vd Mnh 3b.
3.2. Cor sddu-lifu a. Tdi lifu dja hinh:
^ Bmh dl ty If 1/1.000 khu vye bdn ddo Thanh Da do ndm 1998.
«iBmh do ty If 1/1.000 khu vye bdn ddo Thanh Da do tiidng 12/2003 [5].
b. Tdi lifu thuy vdn - biin cdt:
^ Mye nudc fliyc do tgi 3 vj fri fr^n sdng Sdi Gdn khu vye Bdn dao Thanh Da tiiyc Wfn bdt diu tiir 26/X din I l/XI/2003 ftng vdi tiidi k^
tiiiu cudng vd 23/27/X/2003 eho flidi kj- frilu tiimg binh [5].
«t Kit qud luu toe tiiiye do tis ngdy 15/X din 22/X/200I tgi vj tii khdeh sgn Riverside vd qudn Hodng Tyl do Cty TVTL II tiiyc Wfn (dftng cho sl lifu ban diu).
Hinh 3a: Bdn do bdn ddo Thanh Da.
sdng Sdi Gdn (ngudn: Google Map 2015) Hinh 3b: Hinh dnh kenh ddo Thanh Da ndm 2008 nhin vephia hg luu (nguon: Internet)
4 Kdt qud luu Iupng vd vgn toe thyc do tgi
52 TAPCHrKHOAH0CVAC0NGNGH?TH0YLp.Sfl36-2016
I KHOA HOC" CONG NGHE cdc vi tri mat cit phmi hpp luu do luin dn thuc
Wfn frong hai dpt do gom ngiy 3/1/2014 vd 6/11/2013.
'^ Tdi lieu phfin tieh 30 mau bftn cat diy sdng tgi 22 mdt cdt ngang vdng quanh Ban ddo Thanh Da fliye Upn vio tiling X/2003. Mfit cit 4 vd 18 moi mfit cit cd 4 mau [5].
Lay mau vd phan tich mau bim cat la Iflng trong flidi ky do luu tdc X/2003. Sd Iupng mlu (Imlu/lgid/lmdt cdt) lgi 4 mdt cit Id 96 mlu [5].
3J.Phinmg in kenh dan va so Ufa dau vao 3.3.1. Sa do bo tri cdng trinh va phan dogn tinh todn
a) Tuyin kenh ddo:
Tuyin kenh dio sft dyng Igi tuyin kdnh dao dd cd frong fliyc tl: Vi tri ciia vdo tgi dilm A, cfta f*.tgi dilm G frdn Htoh 5. Tuyin kdnh ddo la dudng fliing ndi 2 dilm B vd G, ddi 1850m.
h) Mdt cdt ngang kinh ddo:
Vdi eo chd cit song bdng kenh mdi, img dyng kit qui ngUoi cuu v l quan hf hinh fliii kenh c^ song d Thanh Ba, xem xet dilu kifn ehgy tau tiea tuydn dudng thiiy cip 111, cd dp sau 3m ehgy d myc nudc 90%, mfit cfit ban diu ciia kdnh dio l i rait cit hinh thang, diy rpng 37ni, dp sau 5,75in, bl mfit rpng 60ni, mii die bdn cd he so m= 2. Mfit cdt kdnh dupc md phdng thdnh hinh chft nhgt, cUlu rpng dOm, cUdu sau 4,66m, tufin theo quan hf hinh thdi fliyc do tgi kdnh ddo cdt sdng Thanh Da, vdi ^
= 1,66 (xem Mnh 4) eom'
Htnh 4: Mdt cdt ngang kenh mdi (hinh thang) vd kenh mdi chd nhgt quy ddi
Htnh 5: Sa ddphdn chia dogn sdng tinh todn
TAP CHl KHOA HOC VA CONG NGH? THUY LOI Sfl 36 - 2016 53
c) Phdn dogn rinh loan:
Theo dieu kifn dia hinh vd tfnh chat ddng chdy, toan dogn cong dupc cUa Idm 8 dogn, trong dd ridng dogn sdng cong cfi cUa lira 5 doan, nhu Mnh 5 thi Udn:
- Doan thupng luu AB, dai lOOOm;
- E)ogn kdnh dao BG, ddi 1850ni;
- Dogn 1 sdng cfi BC, ddi 1000m;
- Doan 2 sdng cfi CD, dai 2172m;
- Dogn 3 sdng cfi DE, ddi 1562m;
- Dogn 4 sdng efi EF, ddi 2366m;
- Dogn 5 sdng cfi FG, ddi 2651 m;
- Dogn sdng hg luu GH, dii lOOChn.
- Nhu vfiy, ty If cdt sdng cfta dogn cong gip Thanh Da la: Kc=9751/1850=5,27.
3.3.2. S6 li$u diu vdo
Sd lipu diu vdo cfta chucmg trinh dya vio nln dja hinh ndm 1998 vd thfty vdn ndm 2003 dupc thi Ufn frong Bdng 1.
TT
Bang 1: Bing cic thdng so din vio chinmg trinh Ten thdng so
Boan sdng thupng lmi AB Be rpng trung binh ban diu Chilu sdu trung binh ban diu Chieu ddi dogn sdng thutyng luu Dogn sdng cong gap cu BCDEFG Be rpng tnmg btah ban diu phin doan 1 Chieu sfiu hung btah ban diu phdn doan 1 Chieu ddi phan dogn 1
10 11
Be rfng frung binh ban diu phdn dogn 2 Chieu sdu fr-ung binh ban diu phdn dogn 2 Chieu ddi phdn dogn 2
Be rfng frung binh ban diu phdn doan 3 12
13 14 16 17 18
21
Chieu sdu frimg binh ban diu phfin doan 3 Chieu ddi phdn dogn 3
Be rpng trung binh ban diu phdn doan 4 CWeu sdu hTmg binh ban diu phan doan 4 CWlu ddi phdn dogn 4
Be rfng frimg binh ban diu phfin dogn 5 Chilu siu frimg bmh ban dau phan doan 5
rhi°Ai. A^t . . ! . « _ A c
CWeu ddi phdn dogn 5 Dogn sdng hg luu GH Be rpng bung binh ban diu CWlu sdu frung binh ban dau
22 23 24
CWeu dii dogn sdng thupng luu Dogn kdnh cit sdng BG Bd rfng kdnh ban dau CWeu sdu frimg binh ban dan CWeu ddi doan kenh rat I Cic thdng so chunpr
54 TAP CHf KHOA HOC VA CONG NGH? THOY LOI sfl 36 - 2016
Ki hifu*
Bti hoti Lti Blo(l) hlo(l)
jam
Blo(2) hlo(2) _Lli2}_Blo(3) Wo(3) Ll(3) Blo(4) hla(4) Ll(4) Blo(5) hlo(5)
BU hoU LU
_LJL
Gii trj 250
12 1000 235 12,3 3106 275 12,8 2127 298 11,8 1562 251 12,8 2366 275 10,9 2651 295 11,13 1000 60 4,66 1850
Domyj m m m m m m m m m m m m m m m m m
m m m
KHOA HOC CONG NGHE TT
25 26 27 28 29 30 31 32
Luu Iupng tinh toin
Ten thdng so He sd nhim sdng cu
Hp sd nhim kenh dio cit cong
Him lupng bun cit vio doan sdng thupng luu Cao dp mat nudc nga ba ha luu
Chenh cao myc nudc dilm phan vi hpp luu trudc kU cat sdng
Budc flidi gian tinh todn Hf sd cat sdn^
D"dig!kinh hat hftn cat d50% Ipt sang Pugg frpng khd ciia bvm cat
Ky hien*
_Qo_
nl JSL
So ZhI
Gii tri 2280 0,04 0,06 0,018 Delta_yo
Delta T Kc rho
;ho.phep
[f sd quan hf Unh fliai mdt cdt ngang kdnh ddo In 'MiKk the hodn todn sdng cft)
phan luu kjlm sodt Kpl=Qk/Oo
t™
4041
chfa hdm lupng bftn cit doan fliupng luu Hf sd sfta chfta hdm lupng bftn cdt dogn kdnh cfit Hf so sfta chfla hdm Iupng bun cat dogn ha luu
d50 els
+1,0 0,5
Don vj m7s
Kg/m' m
6,9 900 0,004
2%
ndm Kg/m'
mm
1,66 Kpl
Kfl -KJL Hp so sfta chCta him lupng bun cdt doan sdng eong
cfi Kl(l)=0.8; Kl(2)=0.9; KI(3)=0.95; Kl(4)=0.95;
Kl(5)=0.85
KU KI(I-5)
100 1,1 0,7 0,9 0,8-0,95
%
Chu y: Cdc ky hifu tiong Bdng I chi dugc su dung riing cho Chuang tiinh lgp tiinh ctia phdn mem tinh todn cdt sdng CASO-2015.
Trong dd:
- Ting luu lupng tufli todn Qo (luu lupng trung binh dgi difn cho dogn sdng fruik khi phan luu frong suit tfldi gian tinh todn md phdng) dupc flift ngUfm sft dyng cdng fliftc tinh luu Iupng khdi dpng cho kdnh ddo cit sdng (Qk^) do tdc gid dl xuit frong [9]. Gid fri Qk<i=Bod.hou.Vka=250xI2x0,76=2280 m'/s. Gid fri vgn tic khdi dpng V^ dupc tinh flieo cdng thftc Mirichulava vdi d5o=0,004mm.
- Myc nudc tgi mfit cit hg luu (mdt cit G) Zh = +lm Id myc nudc trung binh ting vdi luu Iupng frin bdi tai dilm ngd ba hpp luu, tgm lay tuong duong cao trinh myc nudc cao trung binh cfta trgm Phfl An (KjJ Vdn Thinh, 2009).
3. Ktj QUA VA THAO LUi^N 3.1. Ket qui tinh toin
3.1.L Quy tiinh tinh todn vd hifu chinh, kiem dfnh chutmg tiinh:
- Sau kU hodn fliinh phin khai bdo flidng s l diu vdo, kilm sodt loi vd tiln hdnh chay chuang frinh fr^n ca sd Unh tiiii dja hinh ndm 1998, bfln cat tfiyc do khu vye ngUen cftu tfiyc Ufn nim 2003.
- Neu cU chinh frj dogn sdng tiieo co chl kdnh tdt (dao kenh cit ttii mfit cfit cudi cung vd khdng duy tti long sdng cfl) flii sau kU tinh todn phdn luu vdo kdnh dao vdi mfit cdt diu tidn, sd tiln hanh kidm fra luu lupng vd myc nudc cd flida mdn yeu ciu khai fliac khdng. Nlu luu Iupng Qk 9^ Qkd flii cin gid fliiit lai mfit cdt kdnh vd tinh
TAP CHf KHOA HOC VA CONG NGH? THUY Lt3l sfl 36 - 2016 55
toin lgi tft diu dio den kU thda mdn dilu kifn Qk= Qkd- D I on d ^ kdnh dio cd thi tioi hdnh cdc cdng trinh gia CO bd kdnh.
- Nlu cdt sdng theo co chl kdnh mdi (vln duy fri Idng sdng cu) tW cin tilp tyc tinh todn biln Unh Idng dan din cuii thdi doan t|. Tiln hdnh kiem tra dieu kifn xdi cfla kdnh, nlu kdnh khdng xdi dupc tiii phdi gia tWit lgi mfit cit kdnh moi hofic bd tri thdm cic cdng trinh phy trp dd tdng luu lupng vio kdnh vi tinh toan lgi tu dau cho din kW thda mdn didu kifn xdi, mdi tiep tyc tinh toin cho thdi dogn t2.
Sau moi thdi dogn tilp theo diu thyc Wfn tinh toin vi kilm tra tlilu kidn phit triln ctia kdnh moi nhu vfiy.
Tftih toin cd thi dumg Igi d tiidi dilm kdnh dio tiidng qua dupc 75% Qo.
- KW kit tiiuc tinh toin, cin kilm tia dilu kifn quan hf Wnh flidi kdnh ddo d luu lupng Qk<|.
3.1.2. Xu&t dH lifu kit qud
Phin kit qud dgng sl lifu cfla chuong trinh sau dd dupc xuit ra tdi lifu djnh dgng excel vdi cdc flidng so diu ra nhu luu lupng, cWlu sdu mfit nudc, him Iupng bun cit, flil tich bun cit
theo tiing budc thdi gian tinh toin, thi ti'ch Ifly tich biin cdt, bl i$ng cic phin dogn sdng, kdnh tiieo tiing budc tinh toin, v§n toe tiung bhih mfit cfiL Dudi ddy li m^t so do thj kit qui tinh toin till Upn qud trinh diln biln v i mii lidn hf gifta cic thdng so ca bin hinh thdi Idng din vd luu lupng, bfln cdt cdng tiinh cit sdng. Xem Htoh 6.
Cic kit qud cUnh dupc phan ti'eh vd flil U ^ bing cae do tiij frong cdc hinh tft Htoh 7.1 din Htoh 7.4.
Kit qud cuoi cftng eho tiiiy: Dl kdnh din phit trien den mfit cdt cuoi eiing (thdng qua khodng 98% tdng lira Iupng), eiia vdo dogn sdng cu bj ddng, cdng trinh ein ttii qua 222 ndm ldm vifc. Mfit cdt kdnh sau 222 nfim phdt friln, c6 kich fliudc B=283m, h=12m.
Kit qud tinh todn ty If phfin luu dupc flil Wfn fr«n Hinh 7.1 vd Hinh 7.2 vdi fri sl ngdy cdng ldn vd khi kenh din frd flidnh sdng cUnh flii ty If phdn luu dgt 100%.
Hinh 7.3 vd Hinh 7.4 flil Ufn qui frinh xdi ctia kdnh frong qud tiinh phdt frien, tiidi gian diu rit mgnh md, khi kdnh xdi din mure df ndo dd sd gidm din vd di den on djnh.
25( 0(m'/5) 2000 N 1500 1000
500 J 0 —
P i F i
N 106 121 1 136 1
—Qy(m3/s|
—Ql<m3/s)
NSm
»^ ID i-l VO iH in VD CO CT rH rt r i rt rH rvj
L
Tyle phan luu Kpl(%)
Hinh '.I: Tuang quan luu lugng sdng cH vd
kenh ddo cdt sdng theo thdi gian Hinh 7.2: Diin bien ty If phdn chia luu lugng vdo kenh dan Kpl=Qy/Qo
56 TAP CHf KHOA HOC VA CONG NGH? THtJY LOI sfl 36-2016
KHOA HOC CONG NGH6 (ni^
Biin dong thi tich xoi • bdi cit sdng
Hmh 7.3: Bien ddng the tich xoi boi trung lmh ndm theo budc thdi gian phdt trien cua kenh ddo cdt sdng 3.2. Thio lu|n ket q u i v i chinmg trinh ti'nh Hinh 7.1 thi Udn sy tucmg quan gifta lira lupng kdnh din vd sdng eft, tiieo flidi gian kdnh dan sd phdt friln vd lin dt sdng eft, flidi gian dl kdnh din cd flid fliay flil hodn todn sdng cu Id 222 nfim. Con so ndy phdn dnh hrong doi cUnh xdc tinh Unh phdt tiiln kdnh ddo vflng DBNB nhu cUnh Kinh Thanh Da dupc ddo tft nfim 1907 din nay mdi tiidng qua dupc khodng 12% luu lupng; kdnh Chp Ggo (ddo tft ndm 1876, din nay dd 139 ndm vln cdn sgt Id bd hromg doi mgnh); kenh Quan Chdnh B I ddo ndm Ty Dftc tiift 8, hic 1856, den nay dd gin 160 ndm mtii hromg dli In djnh)... Hifn hipng kenh ddo phdt tiiln chfim Id do DBNB chju dnh hudng cfla flifly hilu khd mgifli, dp doe thfly lyc vd dp die dja hinh rat bd, ddng chdy nguin ngdy cdng suy gidm do dnh hudng vifc xdy dyng h i chfta. Cdc hi so kich tiiutjc mfit cit euli cung cfla kdnh ddo Bk=283m, hk = 12m, diu thi Ufn khd tdt quan hf hinh tiidi vd quan hf cfla B, h vdi Q nhu kit qud nghidn curu tiong [9]. Cflng cUnh vi thi d vflng DBNB khdng tfiieh hpp lira vdi ftng dyng ca chd kdnh mdi. Trudng hpp vln sft dyng gidi phdp kdnh moi ein cd gidi phdp ho tipr tap tiimg ddng chdy qua kdnh mii nhu md hdn hofic ildp mft phin Idng sdng cu hofic ddo kenh mii gin tdi mfit cit In djnh cuoi eflng.
Hinh 7.4: Bien ddng chieu rdng vd chieu sdu cua kenh ddo cdt sdng theo thdi gian Vd Chirong trinh tinh, tft Iy tfiuylt ca bdn chung vl cdng tiinh cit sdng tiong sdch gido khoa, ludn an dd xdy dyng thdnh cdng budc diu chuang tiinh phin mim CASO-2015, ty d$ng hda tinh todn ftng dyng cho cdng tiinh cdt sdng cong gip vftng DBNB.
Ket qui tinh toin eho cdng tiinh gid djnh tgi dogn cong gip Thanh Da frdn sdng Sdi Gdn cho phdp ngudi dung rflt ra nUlu sy nhfin tiifte quan frpng vl cdc Ufn tupmg vfit if xiy ra frong qud frinh cit sdng, nhu diln biln phdn cUa luu Iupng sau kU cit sdng, phfin cUa bfln cdt, chl d$ tiifly dpng lyc tai tiing phan dogn sdng trong cdc tiidi dilm khde nhau, gifta sdng cfi vd kdnh ddo mtii. Kit qui tinh todn cho ngudi tiiilt ke hinh dung dupc ehu tiinh dh kdnh cdt phdt tiiln din mfit cit cuii cftng hofic kdnh cfi bj suy fliodi flianh hd dch frau (oxbow), tft dd ra quylt djnh chip nhgn hay dilu chinh tWit kl.
Chuang trinh tinh todn do cd nWlu gid tfiilt don gidn hda, dp ehinh xde cd tfil chua cao, song dam bdo cho kit qui hpp ly vd cd mftc df tto egy chip nhgn dupe, hodn todn cd tfil ftng dyng frong tfiilt kl ea sd cua giai dogn Bdo cdo ngUdn cftu tidn khd flii hofic bio cio khd flii cfla cic dy dn chinh frj dogn sdng cong gip theo htoh fliuc cit sdng, loai Unh sdng khi pho biln d khu vye DBNB.
TAP CHf KHOA HOC VA CONG NGH? T H O Y LOl Sfl 36 - 2016 57
KHOA HQC CONG NGHE 4. KtT LUAN VA KI^N NGHf
4.1.Ketln$n
Bdi bdo dd gidi tUfu chuong trinh CASO- 2015 de sft dyng trong udc tinh Upu qua cdng trinh cit sdng viing DBNB theo Unh thftc kenh mii vd dy bdo qui frinh di&i biln sau kU cit sdng.
Kdt qui vipc kp dyng chuong trinh tinh toin dh tWet ke mpt cdng trinh thyc tl, liy bdi canh Ii
^>gn cong gip Thanh Da fr^ sdng Sii Gdn.
Chuang tiinh CASO-2015 dd chay frong 300 thdi dogn, moi flidi doan At=lndin, tiln hdnh xen ks tinh todn phan luu vd biln hinh ldng sdng, thu dupc kit qud du<7c trinh bdy trong cdc htoh tft Hinh 7.1 din Htoh 7.4. Kit qud cuii cung cho fliiy: Dl kdnh din phdt triln den mfit cdt cuoi ciing, sdng cfl bj ddng, cdng frinh cin trii qua 222 ndm ldm vifc. Mfit cdt kdnh sau 222 ndm phdt friln, cd kich fliudc B=283 m, h=l2iii, luu lupng thdng qua la 2280 m /s, sdng cfi bj lip hodn todn phin diu.
^^^m
Kit qua umg dyng cho thiy eie kit qui tfnh toin md phdng ed thi tin c§y dupc d mftc udc tinh, phft hpp vtii dilu kipn DBNB, chuong trinh CASO-2015 li khi tiii, cd till ftng dyng trong thyc te chinh tq dogn sdng cong g&>
vftng DBNB d giai dogn tUlt kl so bf.
4.2. Kien ngh|
Do cic cdng tiiifli chinh tij dogn sdng cong gip chua dupc thyc Ufn nUlu d khu vye dnh hudng frilu DBNB, vi vgy chua cd nUlu kinh ngUfm dl hpc hdi vd so lifu dl kilm djnh chuong frinh tinh. Vi v$y, cin tilp tyc ngWen ciiu dl hodn tiiifn md htoh CASO-2015.
NgUdn cftu Idm rd hon diln biln cdc cdng trinh chtoh trj theo hinh tiiftc cdt sdng dd fliyc Ufn, cin Idm rS horn xu flil dien biln vd tinh khde bift so vtW sdng khdng chju dnh hudng thfty trilu.
Dl tdng df chfah xde cho chuong frinh, flidng sl luu lupng Qo cin dupc tiung btoh hda tdi tflng chu kjr frilu frong flidng ho|c frilu frong ngdy.
TAI L i f u THAM K H A O
DdngNa, Sdi Gon va d,nh huang cdc gidiphdp kp Ihu^tphdng chdng sgt Id gidm nhe /A.e« ,«„re« .d«g C«« ^ « ^ , Dy dn dilu fra CO bdn, Vif n KH nifty Lpi miln Naif
^'^' N L T B ' ^ - T r ? V T ' ' " " •=*" •""*' * ^ ^^"6 ^-^y trilu vflng bin ddo Cd Mau - m S N L ' - 2005" ^^ '"" """^ ""^ '' "'''' "^''^ 2°°^' ^'^^ ^ - hpc thuy lpi
^'^' ifdn""™ ^ " T ' ' l-'"!^"" *="" ""^ ^ ^"^ °^"^ Nai phin hg du edng frtoh flifty m £ N 1 • ' " '"' ""^ """ """^ '^'^ '' ''^"^ »8hf 2005, Vipn Khoa h ^ TTifty i j
[5]. Cdng ty CP Tu vin flifty loi 2-HEr2 nntid -i n. .1 ^i , i
Da. Binh Thank To HcJut - f - ^' ^ '*" ^'^" '" "^"S sgt Id bdn ddo Thanh '^ mnn ingnn, ip.HCM, Bao eao ngUdn cftu khd thi
^'^' K J Z g " S ; N p [ ' ^ ° ' ^ " ^ ^ ' ° ° ^ ^ ' ^ ^ ' ' ^ ^ - ^ ' ' ^ ^ ' ^ - ^ ^ ^ ' ' ^ ^Chlnhtrisdn,
TAPCHIKHOAHOCVACONG NGH? THOY Lt?l sfl 36-2016
KHOA HOC CONG NGHE
[8][9].
Hoing vdn Huan (2005), Nghiin cuu di xudt cdc gidiphdp khoa hgc cdng nghf di dn djnh '^gddn hg du sdng Ddng Nai -Sdi Gdn diphdt tiiin kinh ti xa hdi vimg Ddng Nam bg, De tai cap nhd nudc tfiupc chuong trinh.
Ld Vdn Tuan (2015), Nghiin cuu ca chi Idc dgng di chudi tii dogn sdng cong gdp tiong vung chiu dnh huang cua thuy triiu, Lufin dn tiln sT ky tfiuat, Vipn Khoa hpc Thfty lpi tmenNara.
[10]. Ld V3n Tuin, Hoing Vdn Huan, Luang Phuong Hgu (2010), "NgUdn cftu dfic frung hinh tfldi long dan cie doan sdng cong gip frong vftng chju anh hudng tiifty frilu", Tuyin tap Hgi nghi khoa hoc Ca hgc Thuy khi loan qudc ndm 2010, Hgi Ca hgc Viet Ngm
[11]. Zhang R.C (1996), Tuyin tap cdc bdi vidt, Nhi xuit bdn Thfty Ipi - Difn luc Tiung Quic Bdc Kinh, 1996. e v , [12]. Xie jian Heng (1997), Dien bidn ldng sdng vd cUnh fri sdng. Nhi xuit bdn Thfty lpi - Difn
lyc Trung Qudc, Bdc Kinh, 1997.
[13]. Laura Jagaru Tiron, Jerome Le Coz, Mireille Piovansal. (2009)- Flow and Sediment procecess in a cutoff meander of the Danube Delta during episodic flooding- Geomorphology 106(2009), 186-197.
[141, SUelds, F.Douglas, Jr. (1987), Management of Environmental Resources of Cutoff Bends Along the Tennessee Tombigbee Waterway, Miscellaneous Paper EL-87-12 US Aimy Engeener Waterways Experiment Station, Vicksburg, Mis.
TAPCHfKHOAH0CVAC0NGNGH?TH0YH)ISfl36-2016 59
