TIÊU CHUẨN THIẾT KẾ-CÔNG TRÌNH THỦY LỢI-THIẾT KẾ CÔNG TRÌNH BẢO VEN BỜ SÔNG ĐỂ CHỐNG LŨ

2.2 Phin loti cong trinh bao vt bc7sOng d6 chOng 10 COng trinh bao v~ ba sOng dU'Q'cphsn thanh 3 IOiilisau: Ke lat mai: gia cO tlV'C ti~p len mai ba sOng nhAm chOng x6i 10'do tac d¢ng cu

HA NOI- 2010

4.2.2 CO'sa cho vi~c thi~t k~ ke me han• 17

TCVN 8419:2010 dU'Q'eehuy~n dOi tlJ' 14 TCN-84-91 theo quydinh tl;li khoan 1 ei!u 69 eua Lu~t Tieu ehu~n va Quy ehu~n kythu~t va di~m a khoan 1 eit\u 7 Nghi dinh sO127/2007/Ne-Cp

ngay 1/8/2007 eua Chinh phu quy djnh chi ti!t thi hanh mOt sOdit\u eua Lu~t Tieu ehu~n va Quy ehu~n ky thu~t

TCVN 8419:2010 do Vien Khoa hoc thuy lQ'iViet Nam bien SOl;ln,

So NOng nghiep va Phat tri~n NOng thOn dt\ nghi, TOng eve Tieuehu~n eo 1U'6'ngChAt 1U'Q'ngth~m djnh, So Khoa hoc va COngnghe eOngbO

b) anhCl'ng vung chU'a c6 de, dl,J'avao tam quan trQng v~ kinh t~, chinh trj va xii h¢i d~ xac dinh capcOng trinh bao v~ ba sOng, theo quy djnh phap lu~t, tieu chuan, quy chuan hi~n hanh v~ xsy dl,J'ng vavi~c phsn cap cOng trinh xsy dl,J'ng;

c) Khi cOng trinh bao v~ ba cau thanh m¢t b¢ ph~n cua m~t cat de thi cap cOng trinh bao v~ ba sOngdU'Q'Clay bAng cap de d6

H~ s6 On djnh cho phep cua cOng trinh bao v~ ba dU'Q'Clay bAng h~ s6 On djnh cho phep cua de c6 captU'O'ngdU'O'ng

2.2 Phin loti cong trinh bao vt bc7sOng d6 chOng 10

COng trinh bao v~ ba sOng dU'Q'cphsn thanh 3 IOiilisau:

Ke lat mai: gia cO tlV'C ti~p len mai ba sOng nhAm chOng x6i 10'do tac d¢ng cua dong chay va s6ng;

Ke m6 han: nOi tu ba sOng nhAm hU'ang dong chay ra xa ba gay bOi lang va cai tiilo ba sOng theetuy~n chinh trj;

Ke m~m: la IOiili ke khOng kin nU'ac (con gQi la ke xuyen thOng) nhAm giam tOc d¢ dong chay, gaybOi lang va chOng x6i day

BU'ac thi~t k~ cOng trinh bao v~ ba d~ chOng 10 phai dU'Q'cti~n hanh theo cac quy dinh hi~n hanh v~quan Iydau tU' xay dl,J'ngcOng trinh £>Oivai cac trU'ang hQ'p khan cap can thl,J'c hi~n theo quy djnh hi~nhanh tU'O'ng(mg trong cac trU'ang hQ'p khan cap dU'Q'Cphap lu(it quy djnh

£>Oivai nhQ>ngcOng trinh bao v~ ba sOng quan trQng, d~c bi~t la d6i v6'i ke me han c6 th! thi nghi~m

mO hinh d! xac dinh cac thOng sO ky thu~t tOi U'Ulam cO' So' cho thi~t k~ Chu dau tU' quy~t djnh vi~c thinghi~m mO hinh dOi vai tung cOng trinh Cl,lth!

"£>e" trong tieu chuan nay la cOng trinh ngan nU'ac 10 cua sOng ho~c ngan nU'ac bi!n, dU'Q'c cO'.quannha nU'ac c6 tham quylln phan IOiili, phan cap thee quy djnh cua phap lu(it, theo quy djnh tiili khoan 1

£>i~u 3 cua Lu(it £>edi~u

3.1 Taintu dja hinh

Binh dO cao d¢ ty Ie tu 1/2000 d~n 1/5000 dung d~ I~p tOng m~t bAng cOng trinh;

Binh dO cao d¢ ty I~ 1/500 tiili vi tri cOng trinh;

M~t cat ngang ty I~ dung tu 1/100 d~n 1/200, ty I~ ngang tu 1/1 000 d~n 112000 va khoang cachgiQ>acac m~t cat ngang la 20 m;

Cac mOc cao d¢, tQa d¢ kem thee c~c sO' hQa va sO lieu can thi~t;

£>Oivai giai dOiiln thi~t k~ ky thu~t thi cOng phai SLr dl,lng cac tai lieu dia hinh dU'Q'Cdo ve khOng qua

3 thang tinh d~n thai di!m d! thi~t k~

3.2 9ja chAt c6ng trinh

CAn phai I$p blnh dO va m~t cAt cfIatAng cac tai li~u thi nghi~m, cac d~c trU'ng cO'Iycua d~t ba, bAi,long sOng Vi~c khao sat dja chat cOngtrlnh dU'O'cquy djnh nhU'sau:

Bi~n phap tham do c6 th€l ti~n hanh b~ng hO dao, khoan tay, khoan may ho~c xuyen k~t hQ'pkhoan;

LU'6'icac hOkhoan, dao, xuyen tuy theo tlnh hlnh s~t la ba va dia tAng cua ba bliii va long sOng ma

bO tri Cl,lth€l d€l mOta dU'O'cdAy du tlnh hlnh dja ch~t, trong ph~m vi trl,l'Cti~p va vung anh hU'ang cuacOngtrlnh bao v~ ba sOng;

£){>sau tham do phai sau hO'nday long x6i O,2H (H la chi~u sau xoi tinh tlr m~t ba sOng cAn bao

v~)

3.3 Thuy van c6ng trinh va thuy I\lc

CAn thu th~p cac tai li~u thuy van dung cho thi~t k~ (it nhat cua 3 tr~m: thU'Q'nglU'u, h~ lU'uva t~i gAncOngtrlnh) nhU'sau:

LU'uIU'O'ngIan nh~t (m3/s);

MI,l'CnU'ac 10Ian nh~t (m);

LU'uIU'O'ngt~o long (m3/s), (xem Phl,lll,lcA);

Ml,l'cnU'ac (mg vai lU'u1U'Q'ngt~o long (m);

Ml,l'cnU'ac ki~t ling vai tAn su~t 95 % (m);

Ham IU'O'ngng~m cat Ian nh~t, trung blnh, nho nh~t (kg/m3);

£)U'angkinh h~t blnh quan cua bun cat day (mm);

£){>dOcm~t nU'ac mua la, mua nU'ac trung va mua ki~t;

Ml,l'cnU'ac thi~t k~ de, cao trlnh dinh de, cao trlnh bAi gia (m);

TOcd{>dong chay Ian nh~t

TrU'ang hO'Pkhu VI,l'Cxay dl,l'ng cOngtrlnh khOngco tr~m do thuy van, thl cAn phai tinh toan sO Ii~u thl,l'c

do cua cac tr~m doathU'O'ng,h~ lU'ugAn nh~t

Tinh toan cac thOng sO thuy van, cac d~c trU'ng thuy II,l'CcAn thi~t d€l thi~t k~ tU'O'ngling vai cap cOngtrlnh

Ngoai nhung tai li~u tren, con phai tuan thu cac quy djnh v~ tai li~u thi~t k~ cOng trlnh c6 lien quan

4 ciu t(lo va cae tieu chuin ky thu,t ella eong trinh bao v, bc7song

4.1.1 CAu t(lo ella ke !at mai

Ke lat mai gOmba bo ph~n chinh: chan ke, than ke va dinh ke (xem Hinh 1 - cau t~o ke lat mail

10.5

1-I £>inh ke

CHU DAN:

MN min: ml,l'C mrae th~p nhAt;

MN TK: Mve mrae thiet ke ke;

Hinh 1 - CAu ~o ke lat maia) Chan ke: 113 phan day 0 chan mai dOc, c6 tac dl,lng chOng x6i chan mai dOc va Jam n~n tI,ra chothan ke

b) £>inhke: la phan nAm ngang phia tren cung clla ke, c6 tac dl,lng bao ve than ke dOi vai tac dongclla dong chay m~t va cac tac dong khac; dOngthai c6 th~ k~t hoopdU'ang quan Iy, bao ve

c) Than ke:113 phan k~ tCJtdinh chan ke tai dinh ke: than ke chiu tac dong clla dong chay, s6ng, ap h,rcnU'ac va ap h,rcdong tham

4.1.2 Vi tri, ph,m vi va quy mo ke hit mai

Vi tri, ph~m vi, quy mo ke lat mai phai xac dinh bAng tinh toan thuy h,rcva On djnh ho~c thee k~tqua thi nghiem mOhinh thuy h,c k~t hoopvai quan trac, khao sat thl,J'Cdia Khi I~p dl,J'an phai xac dinhdung vi tri, ph~m vi va quy mOclla ke lat mai;

Khi I~p thi~t k~ ky thu~t phai Cl,lth~ h6a kich thU'ac va phai can CLrvao nhung di~u kien phat sinhmai tCJtkhi I~p dl,J'an d!n khi I~p thi~t k! ky thu~t d~ c6 nhung bOsung, di~u chinh can thi!t;

TrU'ang hoopcan Xli' Iy dot xuat, Cl,lCbo, can can Cll' vao tinh hinh x6i 10thl,J'ct~ d~ xac djnh vi tri,ph~m vi va quy mO

4.1.3 Thilt kl chin ke 1st mai

Khi thi~t kit chan ke phai tuan thu nhCPngquy djnh sau day:

a) Kltt cau va v~t li~u xay dl,mg chan ke phai thea man yeu cau:

Dam bao 6n djnh cua chsn ke va cOng trinh;

Ch6ng dU'oocSI,J'keo trOi cua dong chay va dong bun cat day;

Phai thich (mg vai SI,J'bi~n hinh cua long sOng;

Phai ch6ng dU'oocSI,J'xam thl,J'ccua nU'ac;

Thu~n Iooicho vi~c thi cOng trong nU'ac

b) Cao trinh dinh chsn ke: dU'ooclay cao hO'n ml,J'CnU'ac ki~t (mg vai tan suat 95 %vai dO gia thAngbang 0,50 m DOng thai d6i chiltu vai ml,J'CnU'ac sOng t~i thai di~m khao sat phl,JCVI,JI~p thiltt kit ban vathi cOng d~ Il,J'achQn cho phu hoop

c) Kich thU'ac v~t li~u:

DU'ang kinh vien da bang da hOc tha rai dU'oocxac djnh theo cOng thli'c (1) va cOng thli'c (2):

trong d6:

cua de c6 cap tU'O'ng dU'O'ng;

U la lU'u t6c binh qusn thuy Il,J'cIan nhat thl,J'cdo (m/s);

K la h~ s6 dU'oocxac djnh theo cOng thli'c (2);

h la chi~u ssu cua vien da tinh toan (m);

d la dU'ang kinh vien da (m)

m2 - m~.cos2 801+m2

trong d6:

m la h~ s6 mai d6c (khOng dO'n vj) cua chsn ke;

mo la h~ s6 mai tl,J'nhien cua da tha rai trong nU'ac;

a la g6c hoopbai dU'ang mep nU'ac va hinh chiltu hU'ang chay cua dong nU'ac len mai dOc, dO;TrU'ang hOOpdong nU'ac huc thang vao tuyltn ba, lay K =0,6 dim 0,9;

H~ s6 mai d6c chsn ke khOng nen chQn nhe hO'n 1,5

d) Day chsn ke:

MN min : MI,I'C nU'Ctc ttrSP nfuft.

m, m1 : ky hi~u mai dOc trj sO sau ky hi~u m gOiIsh~ sO mai dOc khOng c6 cYanvi

Cac kich thlJ'ac gi tr~n banvac6 cYanviIsm.

Hinh 2 • Minh hot hinh thirc chan kelat mai c.1U'c7ngI\lch sau cach xa bc7

Khi dong chay thuc thAng vao tuy~n bat dU'ang I~ch sau gan bat c6 Vl,l'Csau n~m trong vung xaydl,l'ng ke, nltn keo chan ke tai I~ch sau (xem Hlnh 3)

CHO DAN:

MN min : MV'c nlJ'ac th~p nh~t.

m 1 : ky hi~u mai dOc.

Hinh 3 • Vi d\l hinh thirc chan kelat mai c1U'c7ngI,ch sau nim trong vung xay d.,ng ke

e) Vi tri tha da: khi tha d~ trong nU'6'c, vi tri viltn da (Hinh 4) dU'Q'cxac djnh thee cong thfrc (3)

-1.- = !L

Khi tOc~¢ dong chay nho hO'n2 mIs, ~lfcmg I~ch siu cach xa ba, khOng c6 VI,I'Csiu nAm trongph~m vi xiy dl,l'ngka, nen keo dc\ichin ka tai ch6 mai ba c6 he s6 mai dOctu 3 ~~n 4 (xem Hinh 2);

CHU DAN:

MN min : Mile m,ae thap nhat.

m, m1 : ky hi~u mai dOe trj sO sau ky hi~u m gQi 18 h~ sO mai dOe khOng c6 <JO'nvi

Cae kleh thllae gi tr&n banvac6 <JO'nvi18 m.

Hinh 2 • Minh hot hinh therc chin kelat mai c.'IU'6'ngI,ch siu cach xa b6'

Khi dong chay thuc thAng vc\o tuy~n ba, ~lfang I~ch siu gAn ba, c6 VI,I'Csiu nAm trong vung xiydl,l'ng kat nen keo chin ka tai I~ch siu (xem Hinh 3)

CHU DAN:

MN min : Mile nllae thap nhat.

m1 : ky hi~u mai dOe.

Hinh 3 • Vi d\l hinh th(rc chin kelat mai c.'IU'6'ngI,ch siu nim trong vung xiy d.,ng kee) Vitri tha ~a: khi tha ~~ trong nlf6'c, vi tri vien ~a (Hinh 4) ~lfO'Cxac ~inh thee cOngthli'c (3)

-1 - = !L

trong d6:

w la tOc dOchlm cua vien da thee chi~u th'ng dung (m/s); voi trQng 1U'Q'ngrieng cua da la 2,65

T/m 3 thl: w =4,2.d (m/s);

u la lU'utOcthl,J'cdo cua dong nU'oc(m/s)

L la khoang cach nAm ngang k~ tli vi tri truoc va sau khi tha vien da (m);

f) K~t cAu chan ke:

ThU'cmgSI1 dl,lng da hoc, rQ da, rOng da ho~c be chlm lam chan ke; trong mot s6 trU'cmghQ'pc6th~ SI1 dl,lng Ong buy, trong tha da hoc; bao tai dAt ho~c bao tai cat t~o mai, phia ngoai dU'Q'cbao v~bAng da hoc, rQda, rOngda hoac cac tAm, khOi be tOng c6 lien k~t, ;

CAu t~o chan ke bAng da tha rai dU'Q'cmOteiaHinh 5;

O,5+1HMNmin

CHO DAN:

MN min : MV'c nU'ac thllp nhllt.

m : ky hi~u mai d6ctrj sO sau ky hi~u m gQi 18 h~ sO mai d6c khOng c6 dO'nvi

Cac klch thU'ac gi tr~n ban v~c6 dO'nvi18m.

Hinh 5 - Chin ke bing da d6

Truang hQ'pdU'ang kinh vien da thl,J'ct~ khOng dap ung yeu cau thi~t k~, c6 th~ dung rOng da,rOngdAt set ho~c rOngcat, Iam chan ke (Hinh 6);

CHO DAN:

MN min : Ml,I'c OlI'c7Cthap nhat.

m 1, m2 : ky hi~u mai dOc.

Cac kich thll'c7Cgi tr~n ban vec6 c1O'nvilei m.

Hinh 6 - Chin ke bing rOngKet cau rOng c7U'Q'ctrinh bay aHinh 7.

CHO DAN:

MN min : Ml,I'c mlac thap nhat.

m, m1 : ky hi~u mai dOc, trj sO sau ky hi~u m gOilah~ sO mai dOc khOng c6 dO'nvi

Cac kich thllac gl trAn banvac6 dO'nvi lam.

Hinh 8 • ChOng x6i chin kebAng rOng hOfC be chim4.1.4 Thi6t k6 than ke 1st msi

Khi thh~t k~ than ke phai tuan theo nhung quy djnh sau:

a) K~t cAU va v~t Ii~u lam than ke phai bao dam cac yeu cau:

eam bao On dinh cua than ke va cong trinh;

ChOng dU'Q'c51,1'keo troi cua dong chay va 56ng;

ChOng dU'Q'cx6i ngam ba song do dong thAm;

ChOng dU'Q'c51,1'pha ho~i do cac v~t troi

b) V~t Ii~u lam than ke:

ThU'cmg dung la da hQc lat, da lat chit m~ch, da xay, be tong; da lat trong khung da xay ho~ckhung be tong, be tong cOt thep,

Khong nen dAp dAt t~o mai ke; dOi vai nhung vi tri mai ke bj 5~t 10'CI,lCbQ, c6 th~ t~o mai bang baotai dAt, da dO,

Khi tOc dQ dong chay Ian hO'n5 m/s va c6 yeu cau d~c bi~t v~ my quan ma SLrdl,lng v{lt li~u khacd~ lam than ke, phai c6 can Clf kinh t~ va ky thu~t

Khi tOc dQ dong chay nhe hO'n1,5 m/s va thai gian ng~p nU'ac it, c6 th~ ap dl,lng bi~n phap trOng

c) K~t cAu than ke bang da hQc lat khan dU'O'cquy djnh nhU' sau:

He50 mai dOc than ke thU'cmg bang 2 d~n 3 va phai dl,l'a vao tinh toan On djnh than ke;

£)a hOc phai xilp <1(mg va chen ch~t;

DU'ai lap <1ahOCla lap IQc,thU'6'ng lam bang <1adam day tll' 0,10 m <1lm0,15 m va vai IQccfIakY thu~t;Kilt cau thAn ke bang <1alat khan <1U'Q'cme ta treng Hinh 9;

CHU DAN:

m2 : ky hi~u mai dOc, trj sO sau ky hi~u m gQilah~ sO mai dOc khOng c6 (Janvi

Cac kich thl16'c gi tr~n banvAc6 (Janvilam.

Hinh 9 - Kit cAu thAn ke

£)U'cmg kinh da lat thAn ke dU'Q'cxac djnh thee hai di~u ki~n:

ChOng dU'O'ctac dOng cua dong chay: dU'ong kinh vi~n da dU'Q'cxac djnh thee khean c) £)i~u4.1.3 (kich thU'ac v~t li~u);

ChOng dU'Q'ctac dOng cua s6ng: dU'ang kinh vi~n da dU'Q'cxac djnh thee cOng thLPC(4)

"'

d = 11.do.hs.ifi. Y

Yef -Ytreng d6:

d la dU'ong kinh vi~n da (m);

'1 la h~ s6 6n djnh che phep cua ceng trinh bae v~ ba dU'Q'Clay bang h~ s6 6n djnh che phepcua de c6 cap tU'O'ng dU'O'ng;

do la h~ sO phv thuOc vao mai d6c thAn ke

Khi m2= 2thi do= 0.13Khi m2 =3 thi do = 0.11

Ya.Y la trQng 1U'Q'ngri~ng cua da va cua nU'ac (T/m 3);

A la ty sO giCra chi~u dai va chi~U cao s6ng;

hsla chi~u cae s6ng dU'Q'cxac djnh thee ceng thLPC(5)

hs=O,0208 W 5l4• 01/3

d) Kat cau thAn ke bAng da chit m~ch dU'Q'cquy djnh nhU' sau:

f)U'ang kinh vi~n da dU'Q'c xac djnh theo khoan c) di~u nay, trong d6 trj sO do dU'Q'Clay giam di 25

% so v6'i trj sO ghi akhoan c) di~u nay va phai bO trf I~ thoat nU'6'c tham;

Viec thillt kll kllt cau thAn ke tuan thee quy djnh akhoan c) dit\u nay;

Can phai ki~m tra On djnh day nOi theo cong thlrc (6)

e) Kat cau than ke bAng tam b~ tong dU'Q'cquy djnh nhU' sau:

C6 th~ dung cac tam b~ tong thU'ang ho~c b~ tong cOt thap duc san ho~c dO t~i ch~ tr~n mai b6'

sau khi da lam xong tang loc ngU'Q'c;

Phai bO trf cac khe co gian giCl'a cac tam b~ tong, khe co gian dU'Q'c nhat ch~t bAng h~n hQ'p cat

-nhl,J'adU'ang ho~c day day tam -nhl,J'adU'ang

C6 th~ chon kfch thU'ac cac tam b~ tong nhU' sau:

B~ tong thU'ang: 0,5 m x 0,5 m x 0,2 m ho~c 1,0 m x 1,0 m x 0,2 m;

B~ tong cOt thap: 2,0 m x 2,0 m x 0,1 m

f)Oi v6'i ke cap III, chju tac dOng m~nh cua d6ng chay va s6ng, can ki~m tra dO day tam b~ tong

theo cong thlrc (6)

Yb -Y m.B

trong d6:

db la chi~u day tam b~ tong (m);

hs la chi~u cao s6ng tfnh theo cong thlrc (5) (m);

Yb la trong 1U'Q'ngri~ng cua b~ tong (T/m 3);

Y la trong 1U'Q'ngri~ng cua nU'6'c(T/m 3);

~

m la he sO mai dOc;

B la chit\u rOng tam b~ tong (m);

L la chi~u dai tam b~ tong thee chi~u vuong g6c v6'i dU'ang ba (m);

r, la h~ sO On djnh cho phap dU'Q'cxac djnh thee quy djnh t~i f)i~u 2.1.

Vai mai ba la dat thjt ch~c nen chQn chi&u day lap IQCb~ng da dam day 0,10 m Vai mai ba la catho~c pha cat, nen chQn chi&u day lap IQCla 0,15 m C6 th~ dung h~n hQ'p cat - s6i d~ lam lap IQc,trU'ang hQ'p nay b& day lap cat IQCdU'Q'Clay b~ng hai Ian chi&U day lap dam.

f) Phai kit\m tra On djnh chOng day nOi cua than ke b~ng da h¢c chit m~ch va tam be tOng theo cOngthlrc (6)

trong d6:

Pn la ap h,rc day nOi cua nU'ac tac dl,mglen da ho~c tam be tOng (T/m 3);

db la chi&u day lap gia c6 (m);

Yb la trQng 1U'Q'ngrieng cua lap gia cO(T/m 3);

a la g6c nghieng mai ba so vai m~t phAng nam ngang

4.1.5 Thi6t k6 dinh ke

Bll r¢ng dinh ke thU'ang dU'Q'Clay bang 1,0 m d6n 2,0 m, be tOng lat dinh ke day 0,3 m Truoang hQ'p k6thQ'p dU'ang quan Iy, bao ve, dU'ang giao thOng nOng thOn thi chi&u r¢ng dU'Q'c xac djnh thee yeu cauquan IY.

Tuy d~c dit\m cau t~o cua ke va khu VI,PC,c6 tht\ bO tri ranh tho~U nU'ac dQc dinh ke va cac ranh thoatnU'ac ngang mai ke

Chi~u day va cau t~o tang IQc ngU'Q'ccua phan dinh ke dU'Q'Clay tU'O'ngtl,PnhU'aphan than ke

4.1.6 Trinh t\l'thi cong ke lat mai

Thi cOng phan than ke;

B~t mai ba sOng;

Thi cOng phan than ke va dinh ke

4.2.2 CO'sc7 cho vi,c thi6t k6 kit me) hin

Nhat thi~t phai khao sat va phAn tich tinh hinh diAn bi~n cua dong sOng t~i khu Vl,l'Ctrvc til!p bj x6i la vacac khu Vl,l'Cbj anh hU'ang v~ phia thU'O'ng lU'u va h~ luu tren cac mat sau dAy:

Tai li~u dja hinh va Sl,l'di~n bil!n theo thai gian gOm cac m~t c~t ngang sOng va binh dO;

Sl,I' diAn bil!n m~t bling I~ch sOng, bai sOng;

Qua trinh x6i la ba va cac qua trinh thanh t~o bai bOi;

Ban dO phsn bO lU'u tOc dong chay tren mat bling, mat c~t ngang, m~t c~t dQc (ban dO phsn bOIU'utOc hai chi~u, ba chi~u)

TCI'tai li~u va phsn tich tren, can phai rut ra quy lu~t diAn bi~n cua do~n sOng, dl,l' bao xu th~ phat tri~n,tOc dO phat tri~n, quy mO phat tri~n cua vi~c x6i la va bOi I~ng tU'O'ng LYngv6'i ch~ dO lU'u IU'O'ngva ml,fCnU'6'c

4.2.3 Cac thOng 56 ky thu,t cO' ban clla ke mo hin c(rng

Cac thOng sO ky thu~t phai dU'O'cxac djnh bao gOm:

Ph~m vi ba sOng can bao v~ bling ke me han;

SO IU'O'ngva vi tri cac ke me han;

Kich thU'6'c cO' ban tren m~t bling cua ke:

Cao trinh dinh;

Chi~u dai;

Goc I~ch;

Khoang cach giCl'a cac me han

K~t cau cua me han;

V~t li~u lam me han

4.2.4 Ph\lm vi bc7sOng cAn bao v, bAng ke mo hin

Vi~c xac djnh ph~m vi bao v~ ba sOng can bao v~ bling ke me han phai dl,l'a vao tai Ii~u khao sat vaphsn tich thee 4.2.2

4.2.5 Vitri, s6 1U'Q'ng,kieh thU'oe ella kit me) hin

Vi tri, sO 1U'Q'ng,kich thU'6'c cua ke me han phai dU'Q'cxac dinh tren cO' sa tinh toan thuy Il,I'c cOng nhU'kinh nghi(lm acac ke khac co di~u kien tU'O'ngtl,l';

£>Oiv6'i nhCl'ng ke l6'n, quan trQng, hoac trong di~u ki(ln di~n bil!n phLYCt~p, phai thi nghi~m mO hinhthuy Il,I'cd~ xac djnh

4.2.6 Kich thll't7c coo ban cua ke mehan (llIVC xac (linh nhll' sau

a) G6c I~ch (a) cua ke me hEm la g6c hQ'p bai tn,lc me han va phU'O'ng cua dong chay (Png v6'i ml,l'C

nU'O'ct~o long £>U'Q'cphep chon g6c I~ch (a) hQ'p bai tl\lC me han va tuy~n ba dU'Q'cnOi tl1 gOc me hsnthi~t k~ va me hsn h~ lU'u ti~p d6 £>Oiv6'i me hsn cuOi cung cua h~ thOng me han la tuy~n ba, dU'ang

ba h~ lU'u

C6 th~ phan lo~i ke me han c(Png thanh ba lo~i neu trong Bang 2

Bang 2 - Phin IO\liketheo g6c Itch a

b) Chi~u dai ke me han c(Png la khoang cach k~ tl1 ba t6'i tuy~n chinh trio

c) Khoang cach giCra hai me han la chi~u dsi tuy~n ba giCra hai gOc me han Vi tri me han h~ lU'u phainAm trong ph~m vi anh hU'ang cua me han thU'Q'ng lU'u d~ tranh dong nU'cYcdam vao ba sOng Khoangcach giCra hai me han c6 th~ xac djnh nhU' sau:

Khi R ~ (5 d~n 6).B ; chon L= (3 d~n 4).lt.sina;

Khi R < (5 d~n 6).B ; chon L=(2 d~n 3).lt.sina;

Khi ba IOi: chon L= (5 d~n 8).It.sina ;

trong d6:

L la khoang cach giCra hai ke me han (m);

It Is chi~u dai ke me han athU'Q'ng lU'u (m);

a la g6c I~ch me han dU'Q'cxac dinh theo khoan a) di~u nay (dQ);

R la ban kinh cong ba 10m sOng (m);

B la chi~u rQng long sOng theo tuy~n chinh trj (Png vcYiml,l'CnU'cYct~o long (m)

Khi vi tri me han dU'Q'cxac djnh thee tinh toan tren I~i n~m vao hO x6i sau ho~c ba sOng qua 10m, dU'Q'cphep djch chuy~n vi tri me han v~ thU'Q'ng ho~c h~ lU'u, nhU'ng ph~m vi djch chuy~n phai nhe hO'n chi~udai me han