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

TCVN
TCVN 8419:2010
CONG TRiNH THUY LO'I - THII:T KI: CONG TRiNH
•
BAa vI: 80 SONG £)~ CHONG LO
.
HA NOI- 2010
Trang
Lai n6i d~u 4
1
Phl;tmvi ap dl,.!ng 5
2 £>inhnghia va phAn lol;ticong trinh bao v~ ba song 5
3 Tai Ii~u phl,.!cVI,.!thi~t k~ cong trinh bao v~ ba 6
3.1 Tai Ii~u dja hinh 6
3.2 £>jachAt oong trinh 7
3.3 Thuy van cong trinh va thuy h,rc 7
4 CAutl;tOva cac tieu chuan ky thu~t cua oong trinh bao v~ ba song 8
4.1 Ke lat mai 8
4.1.1 CAutl;tOcua ke lat maL 8
4.1.2 Vi triophl;tmvi va quy mo ke lat mai 8
4.1.3 Thi~t k~ chAn ke: 9
4.1.4 Thi~t k~ thAn ke 13
4.1.5 Thi~t k~ dinh ke: 16
4.2 Ke mo han 16
4.2.1 Ke me han clrng dU'Q'cSLrdl,.!ngtrong nhung trU'ang hQ'psau: 16
4.2.2 CO'sa cho vi~c thi~t k~ ke me han• 17
4.2.3 Cac thong s6 ky thu~t cO'ban cua ke me han clrng 17
4.2.4 Phl;tmvi ba song c~n bao v~ bAng ke me han 17
4.2.5 Vj trios6 1U'Q'ng.kich thU'cYccua ke me han 17
4.2.6 Kich thU'cYccO'ban cua ke me han dU'Q'cxac djnh nhU'sau
18

4.2.7 £>6ivcYike me han bAng dAt bQcdlL 22 .
4.2.8 Thi~t k~ lat mai g6c ke me han 22
4.3 Ke m~m 24
4.3.1 Thi~t k~ bai cAy chim : 24
4.3.2 Thi~t k~ me han cQc 26
TCVN 8419:2010 dU'Q'eehuy~n dOi tlJ' 14 TCN-84-91 theo quy
dinh tl;li khoan 1 ei!u 69 eua Lu~t Tieu ehu~n va Quy ehu~n ky
thu~t va di~m a khoan 1 eit\u 7 Nghi dinh sO 127/2007/Ne-Cp
ngay 1/8/2007 eua Chinh phu quy djnh chi ti!t thi hanh mOtsO
dit\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
NOngnghiep va Phat tri~n NOngthOndt\ nghi, TOngeve Tieu
ehu~n eo 1U'6'ngChAt 1U'Q'ngth~m djnh,
So
Khoa hoc va COng
nghe eOngbO.
b)
a
nhCl'ngvung chU'a c6 de, dl,J'avao tam quan trQng v~ kinh t~, chinh trj va xii h¢i d~ xac dinh cap
cOng trinh bao v~ ba sOng, theo quy djnh phap lu~t, tieu chuan, quy chuan hi~n hanh v~ xsy dl,J'ngva
vi~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 sOng
dU'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 cap
tU'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 cOtlV'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 thee
tuy~n chinh trj;
Ke m~m: la IOiilike khOng kin nU'ac (con gQi la ke xuyen thOng) nhAm giam tOc d¢ dong chay, gay
bOi lang va chOng x6i day.
BU'ac thi~t k~ cOng trinh bao v~ ba d~ chOng 10phai dU'Q'cti~n hanh theo cac quy dinh hi~n hanh v~
quan
Iy
dau tU' xay dl,J'ngcOng trinh. £>Oivai cac trU'ang hQ'p khan cap can thl,J'chi~n theo quy djnh hi~n
hanh tU'O'ng(mg trong cac trU'ang hQ'pkhan 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 thi
nghi~m mO hinh dOi vai tung cOng trinh Cl,lth!.
"£>e"trong tieu chuan nay la cOng trinh ngan nU'ac 10cua sOng ho~c ngan nU'ac bi!n, dU'Q'ccO'.quan
nha nU'ac c6 tham quylln phan IOiili, phan cap thee quy djnh cua phap lu(it, theo quy djnh tiili khoan
1
£>i~u3 cua Lu(it £>edi~u.
3 Tai litu phl}c
vI}
thiit ki cong trinh bao vt be;,
3.1 Tai
ntu 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 1/1000 d~n 112000 va khoang cach
giQ>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'
Iy
cua 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'p
khoan;
LU'6'icac hOkhoan, dao, xuyen tuy theo tlnh hlnh s~t la ba va dia tAng cua ba bliiiva long sOngma
bOtri Cl,lth€ld€lmOta dU'O'cdAy du tlnh hlnh dja ch~t, trong ph~m vi trl,l'Cti~p va vung anh hU'ang cua
cOngtrlnh 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 sOngcAn 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 gAn
cOngtrlnh) nhU'sau:
LU'uIU'O'ngIan nh~t (m
3
/s);
MI,l'CnU'ac 10Ian nh~t (m);
LU'uIU'O'ngt~o long (m
3
/s), (xem Phl,lll,lc
A);
Ml,l'cnU'ac(mg vai lU'u1U'Q'ngt~o long (m);
Ml,l'cnU'acki~t ling vai tAn su~t 95 % (m);
Ham IU'O'ngng~m cat Ian nh~t, trung blnh, nho nh~t (kg/m
3
);

£)U'angkinh h~t blnh quan cua bun cat day (mm);
£){>dOcm~t nU'ac mua la, mua nU'actrung va mua ki~t;
Ml,l'cnU'acthi~t k~ de, cao trlnh dinh de, cao trlnh bAigia (m);
TOcd{>dong chay Ian nh~t.
TrU'ang hO'Pkhu VI,l'Cxay dl,l'ngcOngtrlnh khOngco tr~m do thuy van, thl cAn phai tinh toan sOIi~u thl,l'c
do cua cac tr~m do
a
thU'O'ng,h~ lU'ugAn nh~t.
Tinh toan cac thOng sOthuy van, cac d~c trU'ngthuy II,l'CcAn thi~t d€lthi~t k~ tU'O'ngling vai cap cOng
trlnh.
Ngoai nhung tai li~u tren, con phai tuan thu cac quy djnh v~ tai li~u thi~t k~ cOngtrlnh 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.
1
0.5
1-
I
£>inh
ke
CHU DAN:
MN min: ml,l'Cmrae th~p nhAt;
MN TK: Mve mrae thiet ke ke;
m: ky hi~u mal

dOc
ke lat mai. tn s6 sau ky hi~u m gQi
Iii
h~ s6 mai
dOc
khOng
c6
"an
vi.
Cae kleh thl1ae gi tr~n ban v~ c6 "an vi
Iii
m.
Hinh 1 -
CAu
~o
ke
lat mai
a) Chan ke:
113
phan day
0
chan mai dOc, c6 tac dl,lng chOng x6i chan mai dOc va Jamn~n tI,ra cho
than ke.
b) £>inhke: la phan nAm ngang phia tren cung clla ke, c6 tac dl,lng bao ve than ke dOivai tac dong
clla 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,rc
nU'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~t
qua thi nghiem mOhinh thuy h,c k~t hoopvai quan trac, khao sat thl,J'Cdia. Khi I~p dl,J'an phai xac dinh
dung 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 sinh
mai 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
10
thl,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 thAng
bang 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 va
thi 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:
I"J
la h~ s6 6n djnh cho phep cua cOng trinh bao v~ ba dU'ooclay bang h~ s6 6n djnh cho phep
cua de c6 cap tU'O'ngdU'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).
m
2
- m~.cos2
8
0
1+m
2
trong d6:
m la h~ s6 mai d6c (khOng dO'nvj) 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:
CHUoAA(-
MN
min :
MI,I'C
nU'Ctc
ttrSP nfuft.
m, m1 : ky hi~u mai dOc trj sO sau ky hi~u m gOi
Is
h~ sO mai dOc khOng c6 cYan

vi.
Cac kich thlJ'ac gi tr~n ban
va
c6 cYan
vi
Is
m.
Hinh 2 • Minh hot hinh thirc chan
ke
lat 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 xay
dl,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
ke
lat 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
h
ro
Khi tOc
~¢
dong chay nho hO'n2 mIs, ~lfcmg I~ch siu cach xa ba, khOng c6 VI,I'Csiu nAm trong
ph~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 dOetrj sOsau ky hi~u m gQi
18
h~ sO mai dOekhOng c6 <JO'n
vi.
Cae kleh thllae gi tr&n ban
va
c6 <JO'n
vi
18
m.
Hinh 2 • Minh hot hinh therc chin
ke
lat mai c.'IU'6'ngI,ch siu cach xa b6'
Khi dong chay thuc thAng vc\otuy~n ba, ~lfang I~ch siu gAn ba, c6 VI,I'Csiu nAm trong vung xiy
dl,l'ngkat 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
ke
lat mai c.'IU'6'ngI,ch siu nim trong vung xiy d.,ng
ke
e)
Vi
tri tha ~a: khi tha ~~ trong nlf6'c, vi tri vien ~a (Hinh 4) ~lfO'Cxac ~inh thee cOngthli'c (3)
-1

=
!L
h
CJ)
trong d6:
w
la tOcdOchlm 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);
h la do sau nU'oc (m);
d la dL1cmgkinh vien da (m).
u
t-<? .,
I
co
r'~\
!
,

,
Lb
h:\ :
, 'I
• " I
I \ I
;>;>;>;>;>;> : ~
.d;>;>;>
f) K~t cAu chan ke:
ThU'cmgSI1 dl,lng da hoc, rQ da, rOngda ho~c be chlm lam chan ke; trong mot s6 trU'cmghQ'pc6
th~ 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, khOibe tOngc6 lien k~t, ;
CAut~o chan ke bAng da tha rai dU'Q'cmOtei
a
Hinh 5;
O,5+1H
MNmin
CHO DAN:
MN min : MV'c nU'ac thllp nhllt.
m : ky hi~u mai
d6c
trj sO sau ky hi~u m gQi 18h~ sO mai
d6c
khOng c6 dO'n
vi.
Cac klch thU'ac gi tr~n ban
v~
c6 dO'n
vi
18m.

Hinh 5 - Chin
ke
bing
da d6
Truang hQ'pdU'ang kinh vien da thl,J'ct~ khOngdap ung yeu cau thi~t k~, c6 th~ dung rOngda,
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
ve
c6 c1O'n
vi
lei
m.
Hinh 6 - Chin
ke
bing rOng
Ket cau rOng c7U'Q'ctrinh bay
a
Hinh
7.
~ ~
CHO DAN:
Cac kich thll'c7Cgi tr~n ban
ve
c6 c1O'n
vi
lei
m.

-1
0
.
6
-
0
.
8
I-
Hinh 7 - Kit
cAu
rOng
TrU'cmg hQ'p c7ay chan ke nam
a
long song c6 trj s6 h~ s6 mai d6c nhe hO'n tl1 3 c7en 4
(m1
<
3 c7en4) can phai tha mOt lap rOng ho~c be chim c7ach6ng x6i (Hinh 8). ROng va be chim phai
tha c7;;lttai nO'ic7aysong c6 h~ s6 mai d6c bang tl,l' nhien tl1 3 c7en4.
CHO DAN:
MN min : Ml,I'c mlac thap nhat.
m, m1 : ky hi~u mai dOc, trj sOsau ky hi~u m gOi
la
h~ sO mai dOc khOng c6 dO'n
vi.
Cac kich thllac gl trAn ban
va
c6 dO'n
vi
la

m.
Hinh 8 • ChOng x6i chin
ke
bAng rOng hOfC be chim
4.1.4 Thi6t k6 than ke 1stmsi
Khi thh~t k~ than ke phai tuan theo nhung quy djnh sau:
a) K~t cAUva 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~c
khung 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 bao
tai dAt, da dO,
Khi tOc dQ dong chay Ian hO'n
5
m/s
va c6 yeu cau d~c bi~t v~ my quan ma
SLr
dl,lng v{lt li~u khac
d~ lam than ke, phai c6 can Clf kinh t~ va ky thu~t.
Khi tOc dQ dong chay nhe hO'n 1,5
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:
He

50 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 <1lm
0,15
m va vai IQccfIakYthu~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 gQi
la
h~ sO mai dOc khOng c6 (Jan
vi.
Cac kich thl16'c gi tr~n ban
vA
c6 (Jan
vi
la
m.
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~u
4.1.3 (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 -Y
treng 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 phep
cua de c6 cap tU'O'ngdU'O'ng;
do la h~ sO phv thuOc vao mai d6c thAn ke.
Khi m2 =
2
thi d
o
=
0.13
Khi 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 giCrachi~u dai va chi~U cao s6ng;
h
s
la chi~u cae s6ng dU'Q'cxac djnh thee ceng thLPC(5)
h

s
=O,0208. W
5l4
•
01/3
trong d6:
W la tOc dO gi6
(m/s);
D la da gi6 (km).
Tl1 kllt qua tinh toan thee hai di~u kien trem, chon trj sO dU'ang kinh viem da l6'n nhat d~ thillt ka thAn
ke.
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'cxac djnh theo khoan c) di~u nay, trong d6 trj sO do dU'Q'Clay giam di 25
% so v6'i trj sOghi
a
khoan c) di~u nay va phai bOtrf I~ thoat nU'6'c tham;
Viec thillt kll kllt cau thAn ke tuan thee quy djnh
a
khoan 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'acac tam b~ tong, khe co gian dU'Q'cnhat 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)
db
=
0,1
OSh,.~
~_y
!::-
(6)
Yb
-Y m.B
trong d6:
db
la chi~u day tam b~ tong (m);
h
s
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 cat
ho~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 cOng
thlrc (6)
trong d6:
P
n
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 k6t
hQ'p dU'ang quan Iy, bao ve, dU'ang giao thOng nOng thOn thi chi&u r¢ng dU'Q'cxac djnh thee yeu cau
quan
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 thoat
nU'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'
a
phan 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'sc7cho 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 va
cac 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'u
tOc 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,fC

nU'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'acac 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 va
phsn tich thee 4.2.2.
4.2.5 Vi tri, 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'ccOng nhU'
kinh nghi(lm
a
cac 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 hinh
thuy Il,I'cd~ xac djnh.
4.2.6 Kich thll't7c cooban cua
ke me
han (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 hsn
thi~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\li
ke
theo g6c Itch a
LO\li
me
hin
G6c Itch «(I(})
XuOi
< 90
0
Th~ng g6c
=
90
0
NgU'Q'c
>
90
0
Me han th~ng g6c vcYiba thU'ang dU'Q'cSLrdl,mg
a
vung c6 dong chay hai chi~u (vung chiu anh hU'ang
cua thuy tri~u),
a
vung chi c6 dong chay mQt chi~u, nen chon g6c I~ch ke t1165° d~n 80
0
•
b) Chi~u dai ke me han c(Png la khoang cach k~ tl1 ba t6'i tuy~n chinh trio
c) Khoang cach giCrahai me han la chi~u dsi tuy~n ba giCra hai gOc me han. Vi tri me han h~ lU'u phai

nAm trong ph~m vi anh hU'ang cua me han thU'Q'ng lU'u d~ tranh dong nU'cYcdam vao ba sOng. Khoang
cach giCrahai me han c6 th~ xac djnh nhU' sau:
Khi R ~ (5 d~n 6).B ; chon L
=
(3 d~n 4).l
t
.sina;
Khi R
<
(5 d~n 6).B ; chon
L
=
(2 d~n 3).l
t
.sina;
Khi ba IOi:chon L
=
(5 d~n 8).I
t
.sina ;
trong d6:
L la khoang cach giCra hai ke me han (m);
It
Is chi~u dai ke me han
a
thU'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 10msOng (m);
B la chi~u rQng long sOng theo tuy~n chinh trj (PngvcYiml,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'c

phep 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~u
dai me han.
Hltong dong chay
>
a) Ke me han da hOc
I
HltC1ngdong chay
>
szMNK
CHO DAN:
MNK: mllC
",lac
ke.
m : ky hi~u mai dOc, trj s6 sau ky hi~u m gQi
Is
h~ s6 mai dOc khOng c6 dO'n
vi.
Cac klch thU'6'c gi tr~n ban
vA
c6 dO'n
vi
Is
m.
Hinh 10 -
M,t cAt
ngang di6n hinh
ke
me
hin
d) Cao trinh dinh me han dU'Q'cxac djnh bai cao trlnh tliii g6c me han va dO d6c doc me han:

Cao trinh dinh tliii g6c me han clrng dU'Q'Clay b~ng cao trinh ml,t'CnU'oc lrng voi lU'u 1U'Q'ngtliio long
ho~c b~ng cao trinh bai gia;
Can chon th6ng nhat cao trinh dinh tliii g6c cac ke me han trong mOt he th6ng ke me han.
e)
£>0
d6c doc dinh ke me han thU'cmg dU'Q'cchQn tCP
0,01
d~n
0,005;
trU'cmg hQ'ptliii g6c me hEm,dinh
bai gia cao hO'n nhi~u ml,t'CnU'oc tliio long, c6 thf! chQn dO d6c dinh ke tCP
0,02
d~n
0,05.
t)
M~t cat ngang me han b~ng da hOcva b~ng dat bQc da thU'cmg c6 dliin9 hlnh thang.
C6 thf! tham khao PhV Ivc B cua tieu chuan nay df!
50'
bO chQn chi~u rOng dinh, dOd6c mai, dO d6c
mQi me han, sau d6 can phai tfnh toan kif!m tra Ondjnh va di~u kien kinh t~;
(] nO'ic6 nhi~u c!a hoc, me han ngAn (chi~u dai me han nhe hO'n
10
m) C!C)sau nU'ac Ian (Ian hO'n
15
m
(mg
vai ml,l'CnU'ac t~e long) t6c c!o dong chay Ian hO'n3
mIs,
nen dung me han bang c!a hoc;
(] nO'ixa me c!a, nen dung le~i ke me han bAng c!Atboc c!a; nen

SLY
dvng dAt thjt t~i chO c!~ lam ke
me han; phai thi~t k~ tang loc giCl'aloi c!Atva c!a hoc. C6 th~ dung vai loc c!ia ky thu~t he~c hai lap phen
nlia c!~tsat nhau lam tang loc.
g) Phai ki~m tra 6n c!jnh tl11Q'tcua me han thee cOng thl1c (8)
K=~~[K] (8)
P±T
treng c!o:
P la ap Il,I'cthuy c!ong c!U'Q'cxac c!jnh thee cOng thl1c (9)
treng c!6: ~ la h~ s6 c!c)ngIl,I'c,phV thuoc vae goc I~ch cua me han a, c!U'Q'cxac c!jnh thee Bang 3.
Bang 3 - Xae djnh h,
56
dqng life theo g6e I,ch eua
me>
hin
a (c!o)
15
d~n
25
> 25
c!~n
45
> 45
c!~n
90
~
0,6
c!~n
0,8
1,0

1,5
c!~n
2,0
'Yn
la trong 1U'Q'ngrieng cua nU'ac;
u la lU'ut6c ti~n gan thU'Q'ng lU'u me han;
h
z
la chi6u sau cot nU'O'c
tl11ac
me han;
a la goc I~ch cua me han c!U'Q'cxac c!jnh thee khean a) £>i6u
4.2.6;
T la Il,I'Cgay trU'Q'tde trong 1U'Q'ngban than me han gay ra c!U'Q'Ctinh thee cOng thl1c
(10)
treng C!O:
G la trQng 1U'Q'ngban than cua ke me han;
e
la goc hQ'p bai c!ay sOng va phU'O'ngngang; gia trj T mang dAu
(+)
khi c!ay sOng nghieng
cung chi6u dong chay va mang dAu (-) khi ngU'Q'cchi~u dong chay.
N la Il,I'cch6ng truQ't de trQng 1U'Q'ngban than me han gay ra c!U'Q'Cxac djnh thee cOngthl1c
(11) :
treng c!o:
G,
e
tU'O'ngtl,l' nhU'.cOng thl1c
(10);
f

la h~ s6 ma sat giCrame han va c!ay sOng, thU'c7nglAy tti
0,4
c!~n
0,6;
[K] la h~ s6 6n dinh che phep, dU'Q'cxac dinh thee khean a) £>i~u
2.1.
h) Phai xac djnh chi~u sau hO x6i tai hllln long sOng tllli mui me han thee cOng thLYC
(12):
a
U
2
&h
=
27.K
1
.K
2
.tg !!! -
30.d (12)
2
g
trong d6:
L\h Is chi~u sau hOx6i tai hllln (m);
1
d Is dU'6'ng kfnh hlllt cat long sOng (m);
J
U
m
Is lU'utoc tai gan dau me hsn (m/s), dU'oocxac djnh theo cOng thLYC
(13):

U
m
=
U'[1+( 0.2+~
n
Trong cOng thLYC
(13):
U
o
Is lU'utOc binh quan tllli m~t cat trU'ac khi c6 me hsn LYngvai lU'utOc tlllo long (m/s);
b
k
la chi~u dai hlnh chiltu ke me han Ian m~t cat ngang sOng (m);
Is chi~u dai ke me hsn (m);
a Is g6c lech ke me hsn (do);
B Is chi~u rong m~t nU'ac LYngvai lU'u 1U'Q'ngtlllo long (m)
K
1
Is he sO xac djnh thee cOng thLYC
(15):
Trong cOng thLYC
(15):
b
k
va u
m
:
xac djnh thee cOng thLYC
(14);
9 la gia tOc trQng trU'6'ng (m/s

2
);
e
=
2,714,
he sOcua In(LOc na pe hay gQi 10ga na pe);
K
2
Is he sO dU'oocxac djnh theo cOng thtic
(16):
Trong cOng thtic
(16):
e
=
2,714;
he sO cua In(LOc na pe hay gQi LOga cO'sOtl,l' nhilm);
m Is he sO mai dOc mUi me hsn;
Khi ke me han csng dsi, do co hep dong chay cang Ian thl chi~u sau hO x6i csng Ian. Dt\ bao dam 6n
dinh mai mUi ke me hsn, can thiltt kit lap dem chOng xci cho mQi trU'6'ng hOOp.C6 tht\ bO trf lap dem
chOng xci bAng rOng da thee quy djnh
a
Bang 4. Phai bOtrf dem chOng xci trong phlllm vi 1/3 chi~u dsi
ke me han kt\ tl1 mUi ke
tra
vso b6' sOng.
Bang 4 - Quy djnh bO tri lap dtm chOng x6i bing rOng dil
Khu VIlC
Tir chan ke vso than ke TiP chan ke ra sOng
TOng chi6u dsl rOng
Phfa mUi

1 m d~n 2 m 8 m d~n 9 m 10m
Phfa thU'oonglU'u
1 m d~n 2 m
8 m d~n 9 m 10m
Phfa h~ lU'u
1 m d~n 2 m
6 m d~n 7 m 8m
Khi chOng x6i bang be chim rong rao c6 chi~U day tl1 0,15 m d~n 0,20 m, danh chim bang da hOc c6
th~ bO trf be chim nhU' Hinh 11.
i) f)U'cmg kfnh vien da hOc nam
a
m~t ngoai dU'oocxac djnh theo cong thLPC(17)
d 0,36 ~ '1 . U
ml
5,45 . K . h 0,14
trong d6:
U
ml
la lU'u tOc ti~n gan dau me han, dU'ooclay bang lU'u tOc trung binh m~t cAt t~i me han ling v6'i
mlic nU'cYcthi~t k~ de (m/s);
K la h~ sO di~u chinh lU'u tOc khai dOng lay bang 0,6 d~n 0,9;
h la dO sau kl! tl1 mllC nU'6'c
10
thi~t k~ de t6'i hon da tinh toan (m); ThU'cmg kil!m tra 6n djnh cua
vien da t~i dinh me han nam
a
phfa mOi;
l') -
h~ sO 6n djnh cho phep lay theo quy djnh t~i ml,lCkhoan a) f)i~u 2.1;
TrU'Crng hOOpdU'Crngkfnh vien da thllc t~ nhe hO'n dU'Crngkfnh vien da yeu cau theo cong thlic (17),

phai dung rQ thep bQc m~t ngoaL Can bQc rQ kl! tl1 mOi ke vao ba song it nhat 5 m.
4.2.7 aOi vai ke me) hsn bAng dAt bQc dil
Phai thi~t k~ tang IQc ngU'oocgiQ>amai dat va da. C6 thl! lam tang IQc ngU'oocbang hai l6'p phen nCra
tU'O'idan kfn, vai dja ky thu~t, (xem Hinh 10, b).
4.2.8 Thi6t k6 lilt mili gOc ke me) han
Phai thi~t k~ lat mai gOc ke me han, t6ng chi~u dai lat mai gOc ke lay bang chi~u dai ke me han v6'i
3/4 chieu dai phan lat mai nam
a
thU'oonglU'uva mOt phan tU' chieu dai lat mai nam
a
h~ lU'u (Hinh 11);
Yeu cau thi~t k~ lat mai gOc ke phai tusn theo cac quy djnh tU'O'ng(Pngv~ ke lat mai cua tieu chuan
C6 thl! ma rOng gOc me han d~ nOi ti~p thu~n dong v6'i bCr,nhU'ng chieu rOng cua gOc khong
VU'Q't
qua 8 Ian chieu rOng cua dinh ke me han d6.
CHU DAN:
Cae kleh thU'c7e
gi
tr6n ban va
c6
(Jan vi Is m.
Hinh 11 -
80
tri dtm chOng x6i bing be chim
4.2.9 Trinh t\l'thi cong
kit
mo han
a)
Tl"U'cmghQ'plo~i ke me han del:
Tha rOng hoac d~m chOng x6i;

eo da than me han; vi tri dO da thee khoan e) ei~u 4.1.3;
BQc rQdel (nl!u c6);
Lat mai va gOc me han.
a)
Tl"U'ang hQ'p lo~i ke me han dat bQc del:
Tha rOng hoac d~m chOng x6i;
Thi cong hai ba vAy bang da;
Thi cong tAng IQc(dU'6'i muc nU'6'c ki~t);
f)~p loi dat tai cao trinh thi~t k~;
Thi cong tAng IQcphan nam tren ml,l'CnU'6'c ki~t;
Lat da thAn mo hEmphAn nam tren ml,l'CnU'6'c ki~t;
BQc rQda (n~u c6);
Lat mai va gOc mo han.
4.3 Thi6t k6 ke
m6m
Ke m~m (can dU'Q'cgQi la ke xuyen thong can dong gAy bOi) c6 th~ dU'Q'cphAn thanh hai lo~i: bai cAy
chim va mo han CQC;
4.3.1 Thi6t k6 bii
cay chim
a) Bai cAy chim thU'ang dU'Q'c
SLr
dl,lng d~ can dong, h~n ch~ x6i CI,ICbOt bOi lap I~ch phl,l ho~c phOi
hQ'p vai mo han cling d~ bao v~ ba song. Thi~t k~ bai cAy chim thU'ang
SLr
dl,lng cAy cO thl,l, Cl,lm cAy
tre nguyen canh la Chi nen
SLr
dl,lng bai cAy chim trong cac
trU'ang
hQ'p sau:

f)O sAu mlic nU'6'c song ling vai
10
ti~u man: Nho hO'n
15
m dung cAy cO thl,l; Nho hO'n 6 m: dung
Cl,lmcAy tre;
TOc dO dong chay binh quAn nho hO'n 2,5 m/s;
Ham 1U'Q'ngbun cat Ian hO'n 0,5 kg/m
3
.
b) Khi
SLr
dl,lng bai cAy chim d~ lap hO x6i ho~c h;;ln ch~ x6i CI,ICbO
a
khu ba song dang bj x6i la
m~nh, uy hi~p an toan cua de, can tha bai cAy chim h~t ph~m vi hO x6i ho~c ph;;lm vi ba song dang bj
x6i la.
c) Nen
SLr
dl,lng bai cAy chim phOi hQ'p v6'i mo han cung nham bao v~ mOt sO mo han m6'i xAy dl,l'ng
trong he thOng mo han dl,l' ki~n ho~c nham nAng cao long song d~ giam khOi 1U'Q'ngcua mo han cung.
Chi k~t hQ'p
SLr
dl,lng bai cAy chim v6'i mo han cung khi da c6 mo han cung
a
thU'Q'ng lU'u trong h~
thOng mo han. Chi~u dai bai cAy chim cAn Ian hO'n 20 m so v6'i chi~u dai ke mo han cung dl,l' ki~n; theo
chi~u rOng can bOtri tOi thi~u tll' 8 d~n
10
hang Cl,lmcAy 10;;livll'a va nho.

d) Khi
SLr
dl,lng bai cAy chim gAy bOi d~ keo dai duoi bait d~ lap l;;lch phl,l ho~c bao ve chAn ke lat mai,
ph~m vi can tha bai cAy chim phl,l thuOc vao ph~m vi can bao v~ nhU'ng tOi thi~u phai bao gOm tll' 8 d~n
10
hang Cl,lmcAy theo phU'O'ng dong chay.
e) Quy cach Cl,lmcAy quy djnh nhU' sau:
CAy cO thl,l gOm cac lo~i cAy nhU' nhan, vai ho~c xa Cll', c6 dU'ang kinh tan rOng 6 tai 8 m, cao
tll' 6 d~n 8 m
t
buOc
a
goc mOt rQthep kich thU'ac 2 m
x
1 m
x
1 m chua 1,6 m
3
da hOc;
Cl,Im cay Vlfa gOm 6 cay tre tU'O'inguyen canh, Is c6 dU'ang kinh tan rQng tlf 4 m d~n 5 m, cao tlf
4 m dim 5 m, gAn
a
gOc mQt rQthep chlia 0,5 m
3
da hOc;
Cl,Im cay nho gOm 4 cay tre tU'O'i,nguyen canh la haec csnh xs Clf ghep I~i c6 tan rQng tlf 3 m dAn
4 m, cao tlf 3 m dAn 4 m, gan mQt rQ thep
a
gOc, chlra
0.3

m
3
da hQc.
f) Phai ki~m tra 6n djnh cua Cl,lm cay theo c6ng thlic (18):
3
G (U
2
)4
-~25-
G
m
g.H
trong d6:
G Is trQng 1U'Q'ngcua rQ da (kg);
G
m
Is trQng 1U'Q'ngcua Cl,lmcay (kg);
u Is lU'utOc binh quan m(it cat luc tha Cl,lmcay (mls);
H Is dQ sau nU'ac t~i vi tri tha cay (m);
9 Is gia tOc trQng twang
(m/s
2
).
g) Cac Cl,lmcay phai dU'Q'ctha thee hinh hoa mai (Hinh 12).
CHO DAN:
a 18chi~u
rOng tan
Cl,Im cay.
Hinh
12 -

Quy cach thi bii cay chim
h) CAn xac djnh hieu qua gay bOi nhU' sau:
Xac dinh lU'u tOc sau khi tha Cl,lm cay theo cong thCrc (19):
u= Q(1-P}
=
uo{1-P}
F
trong d6:
Q
Is lU'u 1U'Q'ngling vai mllc nU'ac thi~t k~ de (m
3
/s);
uo Is lU'utOc binh quan m(it cat ngang khi chU'a c6 bii cay chim ling vai mllC nU'ac thi~t k~ de
(m/s);
P la h~ s6 kin nU'ac, la ty s6 di~n tich bai cAy tren m~t cAt ngang va di~n tich m~t cAt ngang trong
khu Vl,J'C~U'ang vi~n tha bai cay;
F la di~n tich m~t cAt ngang sOng t~i vi tri tha bai cay chlm (m
2
).
Sau khi xac ~inh lU'u t6c khi ~a co bai cay chim thee cOng thLYC(19), ~Oi chi~u vai lU'u tOc khai
d¢ng cua vung cat
a
vi tri cOng trinh ~~ danh gia kha nang gay b6i. LU'u tOc khai ~¢ng cua bun cat ~ay
~U'OOCxac c!jnh thee cOng thLYC(20):
trong ~o:
U
kd
la lU'u tOc binh quan thuy ll,J'cIan nhat thl,l'c do luc tha bai cay chim
(m/s);
h la chi~u sau cua vien da tinh toan (m);

d la ~U'angkinh binh quan cac h~t ~ay sOng (m).
Xac ~inh ~¢ dang ml,l'CnU'ac thee cOng thLYC(21)
trong ~o:
Z la ~¢ dang ml,J'cnU'ac (m);
P, u : tU'O'ngtl,J'nhU' trong cOng thLYC(19);
kc la h~ s6 thu h~p 16ng dan, la ty s6 giCra hinh chi~u cua bai cay chlm va chi~u r¢ng m~t
nU'ac
sOng LYngvai ml,J'C
nU'ac
thi~t k~ ~e.
i) Quy trinh tha bai cay chim va di~U ki~n ap dl,Jng
Tha Cl,Jmcay tCJ'16ng sOng vao ba;
Tha Cl,Jmcay tCJ'phia h~ lU'u trU'ac, thU'oonglU'u sau;
Nen U'Utieu ap dl,Jngtrong nhCrng ~i~u ki~n khAn cap, de dang bi ~e do~ bai
nU'ac
10khOng th~ tri
hoan dU'ooc.
4.3.2 Thi6t k6 m6 him cqc
a) ThU'ang
Sl1
dl,Jngme han coc trong trU'cmg hoopsau:
Chi~u dai me han Ian hO'n 50m;
Kha nang chOng x6i cua ~at ba thap;
Co thi~t bi dong coco
b) N¢i dung cac thOng sO cO' ban cua me han coc: phai ~U'OOcxac djnh tU'O'ng LYngvai quy dinh neu
trong f)i~u 4.2.3 tieu chuAn nay.