tcxdvn 285 - 2002

www.

vnco

ld.vn

Tiu chun xy dng vit nam TCXDVN 285: 2002

Nhm

1. phm vi p dng 1.1. Tiu chun ny bao gm cc quy nh ch yu v thit k cn phi p dng khi lp,

thm nh, xt duyt cc D n thy li, bao gm: D n quy hoch, D n u t (Bo co nghin cu tin kh thi, Bo co nghin cu kh thi hoc Bo co u t), Thit k xy dng cng trnh (Thit k k thut, Thit k bn v thi cng hoc Thit k k thut-thi cng). Tiu chun ny thay th TCVN 5060-90 - Cng trnh thu li - Cc quy nh ch yu v thit k.

1.2. Thit k , b bao, cng trnh giao thng thu, cng trnh bin khng thuc phm vi iu chnh ca tiu chun ny.

1.3. Tiu chun ny p dng cho mi D n thy li thc hin trn lnh th Vit Nam, thuc mi loi hnh: xy dng mi, sa cha, phc hi, nng cp hoc m rng; khng phn bit ngun vn. Ch c php p dng nhng tiu chun khc vi tiu chun ny khi c s chp thun ca C quan qun l Nh nc c thm quyn.

1.4. Khi nghin cu, thit k cc cng trnh thy li ngoi vic tun th nhng quy nh ch yu nu trong tiu chun ny cn phi tun th cc quy nh trong cc Lut, cc vn bn di Lut, cc tiu chun TCVN, TCXD, TCXDVN, TCN, cc iu c quc t v cc tha thun m nh nc Vit Nam tham gia hoc k kt c lin quan n i tng thy li ang xem xt.

2. thut ngha, Phn loi v phn cp thit k cng trnh thy li

2.1. Gii thch mt s thut ng.

- Tt c cc cng vic "nghin cu, thit k" nu trong iu 1.1 c vit gn l "thit k".

- Tt c cc i tng nghin cu, thit k thy li nu trong iu 1.1 c gi chung l "D n thy li".

- Nhng hng mc xy dng c th trong D n thy li nh p, cng, nh my thy in, knh dn nc v.v... c gi chung l "Cng trnh thy".

- Cm t "Cng trnh thy li" trong tiu chun ny l tp hp tt c cc hng mc cng trnh thy c trong D n thu li.

- Cm u mi cng trnh thu li l mt t hp cc hng mc cng trnh thu tp trung v tr khi u ca h thng dn, thot nc; lm chc nng cp hoc thot nc, iu tit, khng ch, phn phi nc.

- H thng dn, thot nc l t hp mng li ng dn v cng trnh lin quan c mt trong d n.

- Theo thi gian s dng, cng trnh thy trong cc D n thy li c chia thnh cng trnh lu di v cng trnh tm thi:

www.vncold.vn Trang web Hi p ln Vit Nam

www.

vnco

ld.vn

TCXDVN 285 : 2002

4

+ Cng trnh lu di l cng trnh c s dng thng xuyn hoc nh k trong sut qu trnh khai thc.

+ Cng trnh tm thi l cng trnh ch s dng trong thi k xy dng hoc ch dng sa cha cng trnh lu di trong thi k khai thc ( quy, cng trnh dn, x lu lng thi cng, cu tm v.v...).

2.2. Ty thuc vo chc nng, cng trnh lu di c chia thnh cng trnh ch yu v cng trnh th yu:

a. Cng trnh ch yu l cng trnh m s h hng ca chng s nh hng trc tip n s lm vic bnh thng ca cng trnh u mi v h thng, lm cho chng khng m nhn c nhim v nh thit k t ra.

b. Cng trnh th yu l cng trnh m s h hng ca chng khng nh hng n s lm vic bnh thng ca cng trnh u mi v h thng, c th phc hi c trong mt thi gian ngn.

Danh mc cng trnh ch yu v cng trnh th yu qui nh Ph lc A.

2.3. Cng trnh thy li c phn thnh 5 cp thit k tu thuc vo quy m, a im xy dng cng trnh, mc nh hng tch cc ca chng n pht trin kinh t x hi, an ninh, quc phng v.v... cng nh tc ng tiu cc n ti nguyn, mi trng, tn tht v ngi v ti sn do s c ri ro c th gy ra. S khc nhau ca mi cp thit k c th hin bng h s an ton chung ca cng trnh v cc qui nh v kho st thit k. Cng trnh cp I c h s an ton chung ln nht v gim dn nhng cp thp hn.

2.4. Cp thit k ca cng trnh u mi, bao gm c cng trnh u mi trong khai thc bc thang l cp cao nht c la chn t cp xc nh theo nng lc phc v ca chnh u mi hoc t cp xc nh theo c tnh k thut ca cc hng mc cng trnh thy c mt trong cng trnh u mi:

a. Cp theo nng lc phc v c xc nh theo bng 2.1. b. Cp theo c tnh k thut ca cc hng mc cng trnh thy trong cm u mi

c xc nh theo bng 2.2.

2.5. Cp thit k ca h thng dn nc v cng trnh trn h thng dn nc cng l cp cao nht c la chn t cp xc nh theo nng lc phc v ca chnh on dn nc hoc t cp xc nh theo c tnh k thut ca cc hng mc cng trnh thy c mt trong on dn nc.

2.6. Cp thit k ca cng trnh u mi thng c xem l cp thit k ca cng trnh thy li. Cp thit k ca h thng dn nc v cng trnh lin quan thng bng hoc nh hn cp thit k ca cng trnh u mi v gim dn theo s thu hp phm vi phc v. V nguyn tc, cp thit k ca knh dn nc cp di phi ly nh hn cp thit k ca knh dn nc cp trn.


www.

vnco

ld.vn

TCXDVN 285 : 2002

5

Bng 2.1. Cp thit k ca cng trnh theo nng lc phc v

Cp thit k Loi cng trnh thy li

I II III IV V

1. H thng thy nng c din tch c ti hoc din tch t nhin khu tiu, 103ha

50 25 50 >15 25 >8 15 8

2. p b tng, b tng ct thp cc loi v cc cng trnh thy chu p khc c chiu cao, m

A

B

>100 >50

>60 100 >25 50

>25 60 >10 25

>10 25 >5 10

10 5

C >25 >20 25 >10 20 >5 10 5 3. Tng chn c chiu cao, m

A >40 >25 40 >15 25 >8 15 8

B >30 >20 30 >12 20 >5 12 5 C >25 >18 25 >10 18 >4 8 4 4. H cha c dung tch, 106 m3

>1000 >2001000 >20 200 >1 20 1

Ch thch:

1. t nn chia thnh 3 nhm in hnh: Nhm A- Nn l . Nhm B - Nn l t ct, t hn th, t st trng thi cng v na cng. Nhm C - Nn l t st bo ho nc trng thi do.

2. Chiu cao cng trnh c tnh nh sau: - Vi p vt liu t, t-: Chiu cao tnh t mt nn thp nht sau khi dn mng (khng k

phn chiu cao chn khay) n nh p. - Vi p b tng cc loi v cc cng trnh xy c chu p khc: Chiu cao tnh t y chn

khay thp nht n nh cng trnh.


www.

vnco

ld.vn

TCXDVN 285 : 2002

6

2.7. Cp thit k ca cng trnh thy li (tr cng trnh cp V) c th gim xung mt cp trong cc trng hp sau:

a. Cc cng trnh m thi gian khai thc khng qu 10 nm. b. Cc cng trnh thy cp I v II khng nm trong tuyn chu p (tr nh my thu in,

ng ng dn nc c p, ng dn nc vo tucbin, b p lc v thp iu p).

c. Cc cng trnh thy trong cm nng lng, h thng ti tiu nng nghip c th tin hnh tu b sa cha cng trnh m khng lm nh hng ng k n s lm vic bnh thng ca u mi thy li.

2.8. Cp thit k ca cng trnh thy li cn nng ln mt cp nu s c ri ro ca cng trnh dng nc, tch nc c th gy thit hi to ln v ngi- vt cht- mi trng, dn n thm ha cho cc khu dn c, khu cng nghip, cc h cha hin c, cc tuyn giao thng huyt mch nm h lu v.v...

Nhng p xy dng bng vt liu ti ch trn nn st yu bo ho nc trng thi do chy, chy c php nng ln mt cp so vi quy nh trong bng 2.2.

2.9. Cc cng trnh xy dng thuc chuyn ngnh khc c mt trong thnh phn ca D n thu li hoc cc cng trnh thy thit k c s giao ct vi cc cng trnh khc hin c (ng b, ng st v.v...), khi xc nh cp thit k cn phi i chiu vi cc tiu chun lin quan v c s ng thun vi c quan ch qun cc cng trnh .

2.10. Cp thit k ca cng trnh thu giao ct bo v phng l c xc nh nh cp ca cng trnh chu p (Bng 2.2) nhng khng c php thp hn cp thit k v tiu chun an ton ca tuyn .

2.11. Vic xc nh cp thit k cng trnh thu li theo bng 2.1 v 2.2 cng nh vic xut nng hoc h cp u phi gii trnh da trn nhng lun c xc ng trnh ln cp ph duyt D n quyt nh.

2.12. Nhng cng trnh thu li cp I c c im nu iu 2.8 hoc c vai tr then cht trong pht trin kinh t ca khu vc, hoc nh hng trc tip n an ton x hi (l ngun cp nc chnh, ngun nng lng ch o, cng trnh gim, phng l cho h lu v.v...), hoc xy dng vng c iu kin t nhin khng thun li (vng c bo lt ln, vng c iu kin nn mng phc tp, vng c ng t ln v.v...) nu thy cn thit, c quan thit k phi kin ngh xy dng Tiu chun thit k ring cho mt phn hoc ton b cng trnh ny.

2.13. Quan h cp thit k gia cng trnh ch yu - cng trnh th yu - cng trnh tm thi trong mt cng trnh u mi hoc h thng dn c qui nh trong bng 2.3.

Bng 2.3. Quan h cp thit k gia cng trnh ch yu - cng trnh th yu - cng trnh tm thi trong mt cng trnh u mi hoc h thng dn

Cp thit k ca cng trnh u mi hoc h thng dn

I II III IV V

Cp thit k cng trnh ch yu I II III IV V

Cp thit k cng trnh th yu III III IV V V

Cp thit k cng trnh tm thi IV IV V V V


www.

vnco

ld.vn

TCXDVN 285 : 2002

7

2.14. Cp thit k ca cng trnh tm thi c th c nng ln mt cp khi s h hng ca chng dn n cc hu qu sau: a. C th gy ra thm ha cho cc khu dn c, khu cng nghip tp trung, cc tuyn

giao thng huyt mch h lu. b. Lm mt an ton cho cng trnh lu di ang xy dng. c. Thit hi v vt cht gy ra khi s c ln hn nhiu so vi vn u t thm cho

cng trnh tm thi. d. y li thi gian a cng trnh vo khai thc, lm gim ng k hiu qu u t.

3. Nhng yu cu ch yu v thit k cng trnh thy li 3.1. Khi lp D n thy li phi cn c vo mc tiu pht trin kinh t x hi ca tng thi

k (ngn hn, trung hn v di hn) c hoch nh trong k hoch pht trin quc gia - vng lnh th, k hoch pht trin ca cc ngnh v quy hoch khai thc lu vc nhm xut phng n khai thc v s dng ti nguyn nc mt cch hp l nht.

3.2. Vic la chn trnh t khai thc bc thang, quy m cng trnh, hnh loi cng trnh, b tr tng th, cc thng s chnh cng nh cc mc nc tnh ton in hnh cn phi c quyt nh trn c s so snh cc ch tiu kinh t - k thut gia cc phng n v c xt ti: a. a im xy dng cng trnh, cc iu kin t nhin trong vng chu nh hng

ca D n (iu kin kh hu, thy vn, a hnh, a cht cng trnh, a cht thy vn, tn kin to, mi trng sinh thi v.v...).

b. Nhu cu hin ti v tng lai cho ti tiu, cung cp nc, phng chng l, nng lng, vn ti thy, cng nghip, du lch v.v... c lin quan n ngun nc ca lu vc ang xem xt.

c. D bo v s thay i ch thy vn, ch l thng h lu sau khi xy dng cng trnh c xt n k hoch m thm cc cng trnh hoc h dng nc mi trn lu vc trong tng lai; D bo din bin lng dn, b sng, bi sng, b h, vng ca sng, vng ngp v bn ngp; S thay i ch lng ng bi xi bn ct thng, h lu; nh gi v xut bin php hn ch cc tc ng bt li.

d. Khi xy dng cc h cha cn phn tch nh gi nhng tc ng bt li sau y: - Nhng thit hi vt cht do ngp gy ra: mt t c bit l t nng nghip, cc

khu bo tn thin nhin, rng c dng, ti nguyn khong sn, c s vt cht kinh t- x hi- vn ho v s mt i cc a danh lch s, cc danh lam thng cnh.

- Nguy c dn n vic thu hp hoc lm mt i nhng vng dn c sinh sng lu i; nhng bt li v an ninh- x hi- dn tc- quc phng, hu qu do v p c th gy ra.

- Tnh kh thi v iu kin tin cy ca cng tc di dn ti nh c m bo s hn hn v mi mt ca ni mi.

- Vng chu nh hng h lu h cha do s thay i dng chy, bn ct v.v... d bo tc ng ca chng n lng dn, k, vng ca sng; nh gi li ch kinh t x hi sau khi xy dng cng trnh.

e. S bin ng mc tiu, nng lc v iu kin hot ng ca cc ngnh hng li hin c khi cng trnh thy li mi i vo hot ng nh: vn ti thy, ngh c,


www.

vnco

ld.vn

TCXDVN 285 : 2002

8

ngh rng, cc cng trnh thy nng, thy in, iu, cc cng trnh cp nc khc v.v...

f. Cc bin php bo m cht lng nc: dn lng h, ch v sinh thch ng vng quanh h cha, hn ch xm nhp cc cht c hi thng qua vic kim sot hm lng c hi khng vt qu tiu chun cho php.

g. Nhng iu kin khai thc tm thi v lu di ca cng trnh. h. Nhng iu kin v phng php thi cng; kh nng cung ng lao ng, vt t,

thit b v ngun lc t nhin phc v xy dng. i. S hi ha v kin trc, thm m ca bn thn cng trnh v s ho nhp ca chng

vi mi trng khu vc; Duy tr cc iu kin bo v thin nhin, cnh quan, v sinh mi trng sinh thi; Kh nng kt hp to thnh im du lch, an dng.

3.3. Khi thit k cng trnh thy li phi t c cc yu cu c bn sau: a. bn vng ca cng trnh v tho mn nhng iu kin khai thc i hi phi

p ng; Qun l vn hnh thun li, an ton; C gii php gim nh nhng tc ng bt li gy ra cho bn thn cng trnh v cc i tng b nh hng khc.

b. Gim st thng xuyn tnh trng cng trnh v trang thit b trong thi gian thi cng cng nh trong sut qu trnh khai thc sau ny.

c. B cc kin trc cc cm cng trnh u mi ph hp vi cnh quan xung quanh v kin trc c trng ca khu vc.

d. S dng vt liu ti ch mc ti a c th. e. Bin php thi cng ti u, thi gian xy dng hp l ph hp vi lch khai thc sinh

li, kh nng ca trang thit b hin c v cung ng vt liu xy dng; Kt hp gia c gii v th cng mt cch hp l.

g. T chc dn lng h v vng k cn; t chc n b di dn ti nh c v di di cc c s vt cht kinh t; Bo v nhng cng trnh kin trc vn ha lch s c gi tr trong vng ngp.

h. Tn dng khai thc hoc bo v cc m c ch trong lng h; Bo tn t nng nghip c gi tr mc cao nht c th; T chc bo v ngun thy sn.

i. Nhng iu kin cn thit p ng cho giao thng thy. k. Cung cp lu lng cn thit cng nh m bo ch vn tc, mc nc thun

li cho cc h dng nc hin c v mi trng sinh thi h lu. l. Cc bin php v phng tin bo m an ton khi thi cng v khai thc sau ny.

3.4. Khi thit k cng trnh thy li phi xem xt kh nng v tnh hp l v kinh t k thut trn cc mt: a. Kh nng kt hp mt s chc nng trong mt hng mc cng trnh. C k hoch

a cng trnh vo khai thc tng phn nhm pht huy hiu qu kp thi. b. C cu li cc cng trnh hin c v xut cc gii php ci to, khc phc

chng ph hp khi D n mi i vo hot ng. c. Quy chun ho b tr thit b, kt cu, kch thc v phng php thi cng xy lp

nhm y nhanh tin , h gi thnh v to thun li cho qun l sau ny. d. Tn dng u nc c to ra cc u mi thy li pht in v cho cc mc

ch khc.


www.

vnco

ld.vn

TCXDVN 285 : 2002

9

3.5. Cn phi nh gi tc ng mi trng v thit k tng th bin php bo v trn c s d bo s thay i ca chng sau khi hnh thnh h thng thy li.

3.6. Khi thit k cc cng trnh thy ch yu cp I, II v III phi b tr thit b kim tra- o lng quan trc s lm vic ca cng trnh v nn trong sut qu trnh xy dng v khai thc nhm nh gi bn vng ca cng trnh, pht hin kp thi nhng h hng khuyt tt quyt nh bin php sa cha, phng nga s c v ci thin iu kin khai thc.

Khi c lun chng tha ng, c th khng t thit b kim tra- o lng trong cng trnh cp III hoc ngh b tr thit b cho cng trnh cp IV.

3.7. Khi thit k cng trnh thy cp I, II cn phi tin hnh mt s nghin cu thc nghim i chng, hiu chnh, chnh xc ho cc thng s k thut v tng thm tin cy cho n nh: cc nghin cu v nn, vt liu xy dng, ch thy lc, ch thm, tnh trng lm vic ca cc kt cu phc tp, ch nhit trong b tng, ch lm vic ca thit b, hiu qu ca vic ng dng tin b khoa hc v cng ngh mi v.v... i tng v phm vi nghin cu ty thuc vo iu kin c th ca tng cng trnh v c xut ngay trong giai on lp Bo co nghin cu kh thi. Cng tc ny cng c php thc hin cho hng mc cng trnh cp di khi c lun chng cn thit.

3.8. Khi thit k cc cng trnh thy dng khi ln phi tnh n vic phn b hp l vt liu trong thn cng trnh, ph hp vi trng thi ng sut, bin dng, yu cu chng thm v.v... nhm gim gi thnh m vn m bo c cc yu cu k thut.

3.9. Cc cng trnh thy phi m bo cc tiu chun v n nh, bn, khng cho php nt hoc hn ch m rng vt nt, bin dng ca cng trnh v nn trong mi iu kin lm vic. ng thi phi tha mn cc yu cu gii hn v tnh thm nc, tc ng xm thc ha hc, c hc ca nc, bn ct v cc vt tri ni; tc ng xi ngm trong thn v nn cng trnh; tc ng ca sinh vt v thc vt v.v...

3.10. Khi thit k sa cha, phc hi, nng cp v m rng cng trnh cn p ng thm nhng yu cu sau:

a. Xc nh r mc tiu sa cha, phc hi, nng cp, m rng cng trnh, c th l: - Sa cha cng trnh hot ng bnh thng hoc ko di thi gian hot ng

trn c s cng trnh hin ti. - Nng cp cng trnh, trang thit b nhm ci thin iu kin vn hnh, qun l, tng

mc bo m, hoc ci thin mi trng hoc m rng nng lc phc v v.v...

b. Trong thi gian tin hnh ci to, nng cp cng trnh v nguyn tc khng c gy ra nhng nh hng qu bt li cho cc h ang dng nc. Cn nghin cu s dng li cng trnh c mc ti a.

c. Cn thu thp y cc ti liu kho st, thit k, thi cng, qun l, quan trc, s c xy ra ca cng trnh c, kt hp vi cc nghin cu kho st chuyn ngnh nh gi ng cht lng, tnh trng k thut, trang thit b, nn v cng trnh, lm c s cho vic la chn cc gii php k thut.

4. Cc ch tiu thit k chnh

4.1. Mc bo m ca cng trnh thy li phc v cho cc ngnh kinh t quc dn c


www.

vnco

ld.vn

TCXDVN 285 : 2002

10

xc nh theo bng 4.1.

Bng 4.1. Mc bo m thit k ca cng trnh thy li

Mc bo m (%) theo cp cng trnh

i tng phc v ca cng

trnh I II III IV V

Ch thch

1. Ti rung 75 75 75 75 75 - C th nng mc bo m ti ln trn 75% cho nhng vng c lng nc ngun phong ph, vng chuyn canh mang li hiu qu kinh t cao khi c lun chng tin cy nhng phi c c quan ph duyt D n chp nhn.

2. Tiu cho nng nghip

80 90 - Tn sut bo m ca h thng tiu ph thuc quy m ca h thng, dng cng trnh (t chy hay ng lc), kh nng tip nhn nc ca sng bn ngoi, hiu qu u t ca h thng tiu.v.v. do c quan thit k lun c v ngh.

3. Pht in a) H c lp

90

90

85

80

80

- Mc gim st cng sut, in lng, thi gian b nh hng trong nm (hoc ma) khi xy ra thiu nc ph thuc vo v tr m nhn ca nh my thy in trong h thng nng lng do ch u t n nh v cp cho c quan thit k

b) H s dng nc ti pht in

Theo ch ti - Khi nc dng cho pht in v ti trong ngy c s chnh lch, cn phi lm thm h iu tit ngy m iu tit li.

4. Cp nc a) Khng cho php gin on hoc gim yu cu cp nc

95

95

95

95

95

- Lu lng cp tnh ton c th l lu lng ln nht, lu lng trung bnh ngy hoc trung bnh thng v.v... do ch u t n nh v cp cho c quan thit k.

b) Khng cho php gin on nhng c php gim yu cu cp nc

90

90

90

90

90

- Mc thiu nc, thi gian cho php gin on cp nc cn cn c vo yu cu c th ca h dng nc do ch u t n nh v cp cho c quan thit k.

c) Cho php gin on thi gian ngn v gim yu cu cp nc

80

80

80

80

80

Ch thch: 1. Mc bo m phc v ca cng trnh l s nm lm vic m bo cng sut thit k (ring thu in

l cng sut bo m) trong chui 100 nm khai thc lin tc. 2. Vic tng hoc h mc bo m ch c php khi c lun chng chc chn v do c quan ph duyt D

n quyt nh. 3. Khi vic ly nc (hoc tiu nc) gy nh hng xu n nhng h dng nc hoc dn sinh, mi trng

hin c, c quan lp D n cn c lun chng v cc nh hng ny, nu gii php khc phc v lm sng t tnh u vit khi c thm D n mi trnh ln c quan ph duyt v cc ngnh ch qun c cc i tng b nh hng cng xem xt v quyt nh.

4. Cng trnh a mc tiu phi thit k sao cho mc bo m ca tng mc tiu phc v ph hp vi tiu chun nu trong bng ny.

4.2. Cc ch tiu thit k chnh v dng chy


www.

vnco

ld.vn

TCXDVN 285 : 2002

11

Khi xc nh cc ch tiu chnh v dng chy bng s liu thng k hoc tnh ton, cn d bo kh nng din bin ca cc ch tiu trong tng lai sau xy dng: do iu kin t nhin ca lu vc thay i, do k hoch khai thc tip theo dng chy trn lu vc, do s pht trin dn sinh kinh t ca vng v.v... c gii php k thut v quyt nh ng n nhm m bo an ton cho cng trnh, ko di thi gian phc v v tit kim vn:

a. i vi cng trnh cp V III thi gian cn d bo khng t hn 20 nm. b. i vi cng trnh cp II I thi gian cn d bo khng t hn 30 nm.

4.2.1. Lu lng, mc nc ln nht tnh ton thit k v kim tra n nh, kt cu, nn mng, nng lc x nc ca cc cng trnh thy li trn sng v ven b, cc cng trnh trn tuyn chu p, cc cng trnh trong h thng ti tiu khi pha thng ngun cha c cng trnh iu tit dng chy c xc nh theo bng 4.2.

Bng 4.2. Lu lng, mc nc ln nht thit k v kim tra cng trnh thy

Cp thit k Loi cng trnh thy

I II III IV V

1. Cm u mi cc loi (tr cng trnh u mi vng triu); H thng dn - thot nc v cc cng trnh lin quan khng thuc h thng ti tiu nng nghip; Cng trnh dn - tho nc qua sng sui ca h thng ti tiu nng nghip

- Tn sut thit k % (Tng ng vi chu k lp li, nm)

0,10,2* (1000500)

0,5

(200)

1

(100)

1,5

(67)

2

(50)

- Tn sut kim tra %

(Tng ng vi chu k lp li, nm)

0,020,04* (50002500)

0,1

(1000)

0,2

(500)

0,5

(200)

2. Cng trnh u mi vng triu; Cng trnh v h thng dn thot lin quan trong h thng ti tiu nng nghip (tr cng trnh dn - tho nc qua sng sui ni im 1)

- Tn sut thit k % (Tng ng vi chu k lp li, nm)

0,2

(500)

0,5

(200)

1

(100)

1,5

(67)

2

(50)

Ch thch: * Tn sut nh p dng cho cc cng trnh c dng l phc tp thng xut hin min ni, trung du. Tn sut ln p dng cho cc cng trnh c dng l n nh thng xut hin vng ng bng.

1. Lu lng, mc nc ln nht trong tp hp thng k l lu lng, mc nc c tr s ln nht xut hin trong tng nm. Cht lng ca chui thng k ( di, tnh i biu, thi gian thng k v.v...) cn phi tha mn cc yu cu nu trong cc tiu chun tng ng. Cc s liu cn c x l v cng mt iu kin trc khi tin hnh tnh ton..

2. Nu pha thng ngun c nhng tc ng lm thay i iu kin hnh thnh dng chy hoc c cng trnh iu tit th khi xc nh cc yu t trong iu ny, cn phi k n kh nng iu chnh li dng chy ca cc cng trnh .

3. Nu pha h du c cng trnh iu tit, th m hnh x khng c ph hoi hoc vt qu kh nng iu tit ca cng trnh .

4. Nhng cng trnh thu li cp I c Tiu chun thit k ring nu trong iu 2.12 tn sut l kim tra c th tnh vi p=0,01% hoc l cc hn khi kt qu tnh ton tin cy c n nh c th trong "Tiu chun thit k".

4.2.2. Lu lng, mc nc thp nht tnh ton n nh kt cu cng trnh, nn mng


www.

vnco

ld.vn

TCXDVN 285 : 2002

12

c quy nh theo bng 4.3.

4.2.3. Mc nc ln nht tnh ton ch khai thc ca cc cng trnh cp nc t chy t h, p dng bnh thng c xc nh theo bng 4.2, tr trng hp c nhng quy nh khng cho php khai thc cc mc nc ny phng nga ri ro c th gy ra cho h lu, hoc tri vi nhng quy nh v bo v iu. Trong trng hp , c quan thit k phi kin ngh mc nc khai thc an ton cp c thm quyn quyt nh.

Bng 4.3. Lu lng, mc nc thp nht tnh ton n nh kt cu cng trnh, nn mng

Tn sut lu lng, mc nc thp nht (%)

Loi cng trnh

Cp cng trnhThit k Kim tra

1. H cha I, II, III, IV v V Mc nc cht Mc nc tho cn thp nht sa cha, no vt v.v...

2. Cng trnh trn sng I 99%

II 97%

III 95% (khng qui nh)

IV 95%

V 90%

3. H thng thot nc v cng trnh lin quan trong h thng ti tiu

I, II, III, IV v V Mc nc thp nht qui nh trong khai thc

Mc nc tho cn sa cha, no vt v.v...

Ch thch:

1. Lu lng, mc nc thp nht dng trong tp hp thng k l lu lng, mc nc c tr s b nht xut hin tng nm.

2. Khi cc h dng nc h lu yu cu phi bo m lu lng ti thiu ln hn lu lng theo quy nh bng 4.3 th lu lng thp nht c chn theo lu lng ti thiu . Mc nc thp nht tnh ton lc ny chnh l mc nc ng vi lu lng ti thiu ni trn.

3. Khi thit k cc cng trnh cp I, II cn phi xt n kh nng mc nc ny c th h thp hn do lng dn h lu b xi su hoc do nh hng iu tit li ca cc cng trnh khc trong bc thang s c xy dng tip theo.

4.2.4. Mc nc ln nht sng nhn nc tiu tnh ton ch khai thc cho cc cng trnh tiu nng nghip t chy hoc ng lc c xc nh theo bng 4.4.

4.2.5. Mc nc thp nht ngun (ti h cha hoc sng) tnh ton ch khai thc cho cc cng trnh cp nc, tiu nc c quy nh theo bng 4.5.

Bng 4.4. Mc nc ln nht sng nhn nc tiu tnh ton ch khai thc cho cc


www.

vnco

ld.vn

TCXDVN 285 : 2002

13

cng trnh tiu nng nghip

Tn sut mc nc ln nht sng nhn nc tiu tnh ton ch khai thc cho cc cng trnh tiu nng nghip (%)

Cp cng trnh Tiu t chy Tiu ng lc

I, II, III, IV v V Mc nc ngoi sng ln nht c th tiu t chy (1) 10% (2)

Ch thch: (1) Mc nc ngoi sng ln nht c th tiu t chy xc nh c bng cch kim tra kh nng thot nc ca u mi theo chui mc nc ngoi sng c nh gi l bt li nht xy ra trong 10 nm lin tc. Lng ma tnh ton chnh l lng ma tng ng xy ra cng thi gian, trong t nht c mt nm xy ra trn ma bng hoc ln hn trn ma tiu thit k. Khi kim tra iu kin trn, nu 9/10 nm (ng vi mc bo m p=90%), hoc 8/10 nm (ng vi mc bo m p=80%) hon ton tiu t chy c th quy m cng trnh la chn l ph hp vi mc bo m thit k. Nu khng bo m c iu kin nu trn cn tip tc tng khu din tho hoc kt hp gia tiu t chy vi cc bin php khc, hoc phi tiu hon ton bng ng lc tm ra phng n kh thi v kinh t - k thut nht. (2) nhng tuyn chu p quan trng, cc sng v.v... tiu chun ny c th thay i tu thuc vo cc quy nh an ton chng bo lt c th cho cc on sng ny.

Bng 4.5. Mc nc khai thc thp nht

Tn sut mc nc khai thc thp nht (%) Thit k Kim tra

Loi cng trnh

Cp cng trnh T chy ng lc T chy ng lc

1. H cha

I, II, III, IV v V

Mc nc cht

2.Cng trnh trn sng

I, II, III, IV v V

a) Ti nc, cp nc

Mc nc ca sng cp ngun ng vi tn sut nu trong mc bo m thit k bng 4.1, phi ly lu lng thit k

Mc nc ca sng cp ngun ng vi tn sut nu trong mc bo m thit k bng 4.1, phi ly lu lng thit k

Mc nc ca sng cp ngun ng vi tn sut nu trong mc bo m thit k bng 4.1, cng thm 5% vn m bo ly c 75% lu lng thit k

Mc nc ca sng cp ngun ng vi tn sut nu trong mc bo m thit k bng 4.1, cng thm 5% vn m bo ly c 75% lu lng thit k

b) Tiu cho nng nghip

I, II, III, IV v V

Mc nc ti thiu cn gi trong knh tiu theo yu cu sn xut nng nghip hoc mi trng

Mc nc b ht tng ng vi thi gian tiu m u v hoc tiu u v

(Khng qui nh)

(Khng qui nh)

c) Pht in I, II, III, IV v V

Mc nc khai thc thp nht

(Khng qui nh) (Khng qui nh)

(Khng qui nh)

Ch thch: 1. Mc nc khai thc thp nht nu trong mc (a) l mc nc trung bnh ngy c tr s thp nht xut hin trong thi on khai thc ca tng nm thng k. 2. Mc nc ti thiu khai thc nu trong mc (b) l mc nc thp nht cn gi cui thi on tiu nc m u v hoc tiu u v nhm tng hiu qu tiu do quy trnh khai thc n nh.

4.2.6. Lu lng mc nc ln nht thit k cc cng trnh tm thi phc v cng tc dn


www.

vnco

ld.vn

TCXDVN 285 : 2002

14

dng quai, knh dn... c xc nh theo bng 4.6.

Bng 4.6. Lu lng mc nc ln nht thit k cc cng trnh tm thi phc v cng tc dn dng

Tn sut lu lng, mc nc ln nht thit k cng trnh tm thi phc v cng tc dn dng (%)

Cp cng trnh

Trong 1 ma kh 2 ma kh I 10% 5% II 10% 5% III 10% 10% IV 10% 10% V 10% 10%

Ch thch:

1. Lu lng, mc nc ln nht trong tp hp thng k l lu lng mc nc c tr s ln nht xut hin trong tng ma dn dng. Ma dn dng l thi gian trong nm yu cu cng trnh phc v cng tc dn dng cn phi tn ti chc chn, khi xut hin tn sut thit k. Tn sut thit k c ly theo bng 4.6

2. Nhng cng trnh phi thi cng nhiu nm, khi c lun chng chc chn nu thit k vi tn sut nu trong bng c th gy thit hi cho phn cng trnh chnh xy dng v tn tht v ngi, ti sn vt cht h lu ln hn ng k so vi phn u t thm cho cng trnh dn dng th c quan thit k phi kin ngh tng thm mc bo m cho cng trnh ny.

3. Nhng cng trnh b tng trng lc c iu kin nn tt cho php trn qua th c quan thit k c th kin ngh h mc bo m ca cng trnh tm thi gim vn xy dng.

Tt c kin ngh nng v h tn sut u phi c lun chng kinh t k thut chc chn v phi c c quan ph duyt chp nhn.

4.2.7. Lu lng ln nht thit k chn dng c xc nh theo bng 4.7

Bng 4.7. Lu lng ln nht thit k chn dng

Cp cng trnh Tn sut lu lng ln nht thit k chn dng (%) I 5% II 5% III 10% IV 10% V 10%

Ch thch:

Lu lng trong tp hp thng k tnh ton l lu lng trung bnh ngy c tr s ln nht i vi dng chy khng b nh hng triu hoc lu lng trung bnh gi c tr s ln nht i vi dng chy chu nh hng ca triu xut hin trong thi on d tnh chn dng ca tng nm thng k. Thi on d tnh chn dng c xc nh ty thuc vo c im thy vn c th v khi lng cng tc nhng khng qu 30 ngy.

Cn c vo s liu o c thc t trong thi gian trc thi im n nh tin hnh chn dng (thng tin hnh o c lin tc t thi im kt thc ma l n thi im n nh chn dng), c quan thi cng hiu chnh li phng n chn dng cho ph hp thc t ca dng chy, thi tit, lch triu v trnh ln ch u t thng qua.

4.2.8. Hnh thc, mt ct, cao trnh phn xy dng d dang (hoc phn t thi cng) ca cc


www.

vnco

ld.vn

TCXDVN 285 : 2002

15

hng mc cng trnh thy lu di cn c quyt nh theo iu kin c th c xt n: Tin xy dng, iu kin kh tng thu vn, kh nng cung ng vt liu xy dng nht l vt liu ti ch, mt bng thi cng, nng lc v tc xy dng ca n v thi cng, bin php x l khi gp l ln hn tn sut thi cng hn ch thit hi cng trnh.

4.3. Cc ch tiu chnh v kh hu.

4.3.1. Tn sut ma tnh ton xc nh nhu cu nc cn cho h thng ti c quy nh tnh vi p = 75%; khi c lun chng chc chn hiu qu kinh t do ti em li c th ngh nng tn sut ma tnh ton ln cao hn (xem ct ch thch bng 4.1).

Tn sut ma tnh ton xc nh nng lc tho dn cho h thng tiu nng nghip quy nh p = 1020% (xem ct ch thch bng 4.1).

4.3.2. Khi khng c hoc khng s liu o dng chy tin cy xc nh lng nc n cho cc h cha c php dng ti liu ma c tn sut tnh ton tng ng vi mc bo m nu trong bng 4.1 suy ra lng nc n.

4.3.3. Ch tiu tnh ton cho cc yu t kh hu khc c qui nh c th trong cc tiu chun thit k chuyn ngnh tu thuc vo tng i tng v trng hp tnh ton.

5. Ti trng, tc ng v t hp ca chng

5.1. Khi thit k cng trnh thy cn tnh n cc ti trng tc ng sau:

5.1.1. Cc ti trng thng xuyn v tm thi (di hn v ngn hn): a. Trng lng ca cng trnh v cc thit b c nh t trn v trong cng trnh. b. p lc nc tc ng trc tip ln b mt cng trnh v nn; p lc nc thm (bao

gm lc thm v lc y ni th tch phn cng trnh v nn b bo ho nc; p lc ngc ca nc ln mt khng thm ca cng trnh) ng vi mc nc ln nht khi xy ra l thit k trong iu kin thit b lc v tiu nc lm vic bnh thng. Ring cc hng mc nm trong tuyn chu p ca h cha, p dng cn cn phi tnh thm cc p lc nu trong mc ny ng vi mc nc dng bnh thng.

c. Trng lng t v p lc bn ca n; p lc ca nham thch (gy ra cho cc hm l, tuynen).

d. Ti trng gy ra do kt cu chu ng sut trc. e. p lc t pht sinh do bin dng nn v kt cu cng trnh, do ti trng bn ngoi

khc.

g. p lc bn ct. h. Tc dng ca co ngt v t bin. i. Ti trng gy ra do p lc d ca k rng trong t bo ho nc khi cha c kt

hon ton mc nc dng bnh thng, trong iu kin thit b lc v tiu nc lm vic bnh thng.

k. Tc ng nhit ln cng trnh v nn trong thi k thi cng v khai thc ca nm c bin dao ng nhit bnh qun thng ca khng kh l trung bnh.

l. Ti trng do tu, thuyn v vt tri (neo buc, va p). m. Ti trng do cc thit b nng, bc d, vn chuyn v cc my mc, kt cu khc (cn

trc, cu treo, palng v.v...), cht hng c xt n kh nng cht vt ti thit k. n. p lc do sng c xc nh theo tc gi ln nht trung bnh nhiu nm.


www.

vnco

ld.vn

TCXDVN 285 : 2002

16

o. Ti trng gi. p. p lc nc va trong thi k khai thc bnh thng. q. Ti trng ng sinh ra trong ng dn c p v khng p khi dn mc nc

dng bnh thng.

5.1.2. Cc ti trng tm thi c bit gm: a. Ti trng do ng t hoc n. b. p lc nc tng ng vi mc nc khi xy ra l kim tra. c. Ti trng gy ra do p lc d ca k rng trong t bo ho nc khi cha c kt

hon ton ng vi mc nc kim tra ln nht trong iu kin thit b lc v tiu nc lm vic bnh thng hoc mc nc dng bnh thng nhng thit b lc v tiu nc b hng.

d. p lc nc thm gia tng khi thit b chng thm v tiu nc khng lm vic bnh thng.

e. Tc ng do nhit trong thi k thi cng v khai thc ca nm c bin dao ng nhit bnh qun thng ca khng kh l ln nht.

g. p lc sng khi xy ra tc gi ln nht thit k. h. p lc nc va khi t ngt ct ton b ph ti. i. Ti trng ng sinh ra trong ng dn c p v khng p khi dn mc nc ln

nht thit k.

k. p lc pht sinh trong mi t do mc nc sng, h b h thp t ngt (rt nhanh). 5.2. Khi thit k cng trnh thy phi tnh ton theo t hp ti trng c bn v kim tra

theo t hp ti trng c bit: a. T hp ti trng c bn bao gm cc ti trng v tc ng: thng xuyn, tm thi

di hn, tm thi ngn hn m i tng ang thit k c th phi tip nhn cng mt lc.

b. T hp ti trng c bit vn bao gm cc ti trng v tc ng xt trong t hp ti trng c bn nhng mt trong chng c thay th bng ti trng (hoc tc ng) tm thi c bit. Trng hp ti trng c bn c xt thm ti trng ng t hoc n cng c xp vo loi t hp c bit. Khi c lun chng chc chn c th ly 2 trong cc ti trng hoc tc ng tm thi c bit kim tra. Thit k phi la chn a ra t hp ti trng c bn v t hp ti trng c bit bt li nht c th xy ra trong thi k thi cng v khai thc cng trnh.

6. Cc quy nh tnh ton ch yu

6.1. Khi tnh ton n nh, bn, ng sut, bin dng chung v cc b cho cc cng trnh thy v nn ca chng, phi tin hnh theo phng php trng thi gii hn. Cc tnh ton cn phi tin hnh theo hai nhm trng thi gii hn: a. Trng thi gii hn th nht - Cng trnh, kt cu v nn ca chng lm vic trong

iu kin khai thc bt li nht, gm: cc tnh ton v bn v n nh chung ca h cng trnh- nn; bn thm chung ca nn v ca cng trnh t; bn ca cc b phn m s h hng ca chng s lm cho vic khai thc cng trnh b ngng tr; Cc tnh ton v ng sut, chuyn v ca kt cu b phn m bn


www.

vnco

ld.vn

TCXDVN 285 : 2002

17

hoc n nh cng trnh chung ph thuc vo chng v.v... b. Trng thi gii hn th hai - Cng trnh, kt cu v nn ca chng lm vic bt li

trong iu kin khai thc bnh thng, gm: cc tnh ton bn cc b ca nn; Cc tnh ton v hn ch chuyn v v bin dng, v s to thnh hoc m rng vt nt v mi ni thi cng; V s ph hoi bn thm cc b hoc bn ca kt cu b phn m chng cha c xem xt trng thi gii hn th nht.

6.2. m bo kt cu v nn ca cng trnh thy trong tnh ton cn phi tun th iu kin sau:

Rk

mN.n

n

ttc =

Hoc m

k.n

N

RK nn

tt

= Trong : nc - H s t hp ti trng.

- Trong tnh ton theo trng thi gii hn th nht: nc = 1,00 - i vi t hp ti trng c bn;

= 0,90 - i vi t hp ti trng c bit; = 0,95 - i vi t hp ti trng trong thi k thi cng v sa cha. - Trong tnh ton theo trng thi gii hn th hai: nc = 1,00

K - H s an ton chung ca cng trnh; Bnh thng h s K khng c vt qu 15% gi tr nc.kn /m tr trng hp c nhng quy nh ring. Ntt - Ti trng tnh ton tng qut (lc, mmen, ng sut), bin dng hoc thng s khc m n l cn c nh gi trng thi gii hn. R - Sc chu ti tnh ton tng qut, bin dng hoc thng s khc c xc lp theo tiu chun thit k (TCVN, TCXD, TCXDVN, TCN). m - H s iu kin lm vic: xt ti hnh loi cng trnh, kt cu hoc nn, dng vt liu, tnh gn ng ca s tnh, nhm trng thi gii hn v cc yu t khc c qui nh trong cc ti liu tiu chun thit k hin hnh cho mi loi cng trnh, kt cu v nn khc nhau. H s iu kin ca mt s cng trnh thy in hnh qui nh ph lc B. kn - H s bo m c xt theo quy m, nhim v ca cng trnh. - Khi tnh ton trng thi gii hn theo nhm th nht: kn c xc nh theo cp cng trnh:

Cng trnh cp I ly kn = 1,25 Cng trnh cp II ly kn = 1,20

Cng trnh cp III, IV v V ly kn = 1,15 - Khi tnh ton theo trng thi gii hn th hai: ly kn = 1,00. - Khi tnh ton n nh cho nhng mi dc t nhin nm k st cng trnh khc c h s bo m ln hn: phi ly h s bo m ca mi bng h s bo m ca cng trnh .

6.3. Tr s ca cc h s sai lch v vt liu nvl v t n dng xc nh sc khng tnh ton ca vt liu v cc c trng ca t c nu trong tiu chun thit k qui nh ring bit cho mi loi cng trnh thy, kt cu v nn ca chng. Khi cng trnh s dng khi lng ln vt liu ti ch bao gm c vt liu t p,


www.

vnco

ld.vn

TCXDVN 285 : 2002

18

p v.v... sc khng tnh ton ca vt liu c xc nh thng qua x l thng k cc kt qu th nghim trong phng v nghin cu thc nghim ti hin trng.

6.4. Tnh ton theo trng thi gii hn th nht c thc hin vi ti trng tnh ton. Ti trng tnh ton bng ti trng tiu chun nhn vi h s lch ti n (bng 6.1). Ti trng tiu chun c nu trong tiu chun kho st thit k qui nh ring bit cho mi loi cng trnh, kt cu v nn ca chng.

Bng 6.1. H s lch ti (n)

Tn cc ti trng v tc ng H s lch ti (n) - Trng lng bn thn cng trnh (khng k trng lng t, lp o ng hm)

1,05 (0,95)

- Trng lng bn thn ca lp o ng hm 1,20 (0,80) - p lc thng do trng lng t gy ra 1,10 (0,90)

- p lc bn ca t 1,20 (0,80)

- p lc bn ct 1,20

- p lc : + Trng lng ca khi to vm

1,50

+ p lc ngang ca 1,20 (0,80) - Trng lng ton b lp t, trn ng hm hoc trng lng vng b ph hu v.v... (p lc thng ng do trng lng t gy ra)

1,10 (0,90)

- p lc nc trc tip ln b mt cng trnh v nn, p lc sng, p lc nc y ngc cng nh p lc nc thm, p lc k rng

1,00

- p lc tnh ca nc ngm ln lp o ng hm 1,10 (0,90)

- p lc nc bn trong ng hm (k c nc va) 1,00

- p lc mch ng ca nc 1,20

- p lc ca va khi pht xi mng 1,20 (1,00) - Ti thng ng v nm ngang ca my nng, bc d, vn chuyn cng nh ti trng ca cc thit b cng ngh c nh

1,20

- Ti trng xp kho trong phm vi bn xp d, hot ng ca cu ln 1,30 - Ti trng do gi 1,30 - Ti trng do tu thuyn 1,20 - Tc ng ca nhit v m 1,10 - Tc ng ca ng t 1,10 - Ti trng bc hng khi 1,30 (1,00) Ch thch:

1. H s lch ti do tu chy trn ng st, xe chy trn ng t, phi ly theo tiu chun thit k cu; 2. Cho php ly h s lch ti bng 1,00 i vi trng lng ca bn thn cng trnh, p lc thng ng do

trng lng ca khi t p, nu trng lng ca khi c xc nh t cc gi tr tnh ton c trng ca t (trng lng ring v c trng bn), cn b tng c xc nh t c trng vt liu (trng lng ring ca b tng v cc c trng khc) ph hp vi cc tiu chun th nghim, v tiu chun thit k nn hin hnh;

3. Ch s dng cc h s lch ti ghi trong ngoc n khi kt qu tnh ton th hin cng trnh trong tnh trng bt li hn.

6.5. Tnh ton theo trng thi gii hn th hai cho cng trnh, kt cu v nn c thc hin


www.

vnco

ld.vn

TCXDVN 285 : 2002

19

vi h s lch ti (n), h s sai lch v vt liu nvl v t n u ly bng 1,00 tr cc trng hp c qui nh c th trong tiu chun kho st thit k chuyn ngnh.

6.6. Cc ni dung cn thit phi tnh ton, cc gi nh trng hp tnh ton, s tnh cho cng trnh v nn phi ph hp vi kh nng c th xy ra, tun th y cc tiu chun kho st thit k hin hnh v cui cng phi tm c li gii bt li nht. Trong nhng trng hp cn thit cn phi xt thm cc yu t sau: a. Trnh t thi cng v trnh t cht ti ca cc b phn cng trnh. b. nh hng ca cc tc ng ca nhit , co ngt v tc ng ca p lc thm t

bin. c. Cc bin dng phi tuyn n hi v do cng nh tnh t bin ca vt liu cu thnh

cng trnh v nham thch nn. d. Tnh ri rc ca cu trc thn cng trnh v nn ca chng ( nt n v.v...). e. Tnh khng ng nht ca vt liu xy dng, nham thch nn v tnh d hng ca

chng.

6.7. Khi tnh ton cc kt cu cng trnh trn nn b ln phi xt ti ni lc pht sinh trong chng do bin dng ca nn gy ra. ln v chnh lch ln phi nm trong gii hn cho php, khng gy bt li cho khai thc v bn, bin dng ca cng trnh, kt cu tng b phn hoc gia cc b phn vi nhau.

6.8. Nhng cng trnh dn, tho, x nc cp I, II phi tin hnh th nghim m hnh thy lc xc nh kh nng dn tho nc, kim tra ch thy lc, vn tc, p lc nc ln cng trnh, gii php ni tip cng trnh vi thng h lu, bin php gia c chng mi mn, xm thc v.v... xc nh hnh dng kch thc cc b phn, la chn phng n b tr tng th cm u mi mt cch hp l v kinh t nht. iu ny cng c php p dng cho cc cng trnh cp III c hnh dng ng dn phc tp m nhng ch dn tnh ton thy lc thng thng khng t c tin cy cn thit, ng thi trong thc t cha c hnh mu xy dng tng t khi c lun chng tho ng.

6.9. Tng t, khi cha c cc ch dn v phng php tnh ton tin cy xc nh trng thi lm vic v n nh ca cc kt cu phc tp, tnh trng thm trong nn v cng trnh, nh gi kh nng lin kt gia nn v cng trnh, xc nh mt s ch tiu c trng ca a khi v.v... cho cc cng trnh cp I v II phi tin hnh cc nghin cu thc nghim tng ng.

7. Nhng yu cu ch yu i vi cc cng trnh thu

7.1. p

7.1.1. Kiu v kt cu p cn la chn trn c s so snh kinh t - k thut cc phng n, tu thuc vo nhim v, thng s ca cng trnh, iu kin t nhin ti ch (thy vn v kh hu, a hnh, a cht cng trnh, kin to khu vc v ng t, vt liu xy dng ti ch v.v...), b tr tng th ca cm u mi, s t chc thi cng, thi hn thi cng, iu kin khai thc p, ngun nhn lc vt liu v trang thit b thi cng.

7.1.2. Khuyn khch p dng cc hnh loi, cng ngh xy dng p mi nhm khc phc nhng nhc im ca cc loi p truyn thng nh khi lng xy dng ln, thi gian thi cng ko di, tc thi cng b hn ch trong ma ma, nhit trong khi


www.

vnco

ld.vn

TCXDVN 285 : 2002

20

xy c rt cao v.v...

7.2. Cng trnh ly nc

7.2.1. Cng trnh ly nc phi m bo: a. Cp nc lin tc cho ng dn theo yu cu; b. C kh nng iu chnh v ch ng ngng cp nc vo ng dn khi cn tin

hnh kim tra, sa cha theo quy trnh vn hnh hoc trng hp gp s c; c. Phi b tr li chn rc, thit b hoc phng tin thu gom rc, bc phn vo, b

lng ct, hnh lang tho ra v.v... ngn nga v loi b bn ct, vt ni, c rc xm nhp vo ng dn.

7.2.2. Kiu kt cu v b tr tng th ca cng trnh ly nc cn phi la chn ph hp vi nhim v ca cng trnh v ty thuc vo kiu ng dn (c p - khng p - hn hp; iu tit v khng t iu tit); c im ca cng trnh thu nc (kiu c p - kiu khng p); iu kin t nhin: ch thy vn, dng chy bn ct, hnh thi b, s hin din ca c rc, vt ni, ch vn hnh v bi lng thng lu cng trnh.

Cn m bo nc vo ng dn c p khng ht theo khng kh v c tn tht ct nc t nht.

Thng thng ca ly nc c thit k gm mt s n nguyn khi cn thit c th tch ri tng n nguyn tin hnh sa cha hoc no vt.

7.2.3. Khi b tr cng trnh ly nc sinh hot t h cha phi xt n kh nng ti to ng b, cht lng nc hin ti v trong tng lai trn cc on quyt nh v tr t cng trnh; ng thi phi xem xt mc hm kh v s chy dn xit cng nh hm lng sinh khi dng mt bao gm c ru rong, to v tr ny.

7.2.4. Vic chn kiu cng trnh ly nc phi tu thuc vo cc loi mc nc in hnh trn sng v cao trnh mc nc yu cu t trong ng dn chnh, c xt n iu kin thy vn, a hnh v a cht ti ch.

Cng trnh ly nc khng p c s dng trong trng hp mc nc sng lun m bo cao hn cao trnh mc nc yu cu ca ng dn chnh. Trong trng hp mc nc sng ti tuyn cng trnh ly nc thp hn mc nc yu cu ca ng dn chnh th phi dng cng trnh ly nc c p.

Cho php thay th cng trnh ly nc c p bng trm bm thng qua so snh hiu qu u t.

7.2.5. Mc nc tnh ton thng lu cng trnh ly nc qui nh nh sau: a. Vi cng trnh ly nc khng p - Mc nc tng ng vi lu lng tnh ton

ln nht thit k v kim tra ti tuyn cng trnh c xc nh ph hp vi cc yu cu iu 4.2.1 ca Tiu chun ny.

b. Vi cng trnh ly nc c p - Mc nc tng ng thng lu p khi x lu lng tnh ton ln nht thit k v kim tra.

7.2.6. bo m iu kin vn hnh khai thc v phng nga s c cho bn thn cng trnh, cho ng dn - trang thit b cng ngh ca cc cng trnh pha sau cn trang b cc loi ca van thch hp cho ca nhn nc. Loi ca van, s lng, v tr c xc nh theo nhim v c th ca cng trnh.


www.

vnco

ld.vn

TCXDVN 285 : 2002

21

7.2.7. m bo nc a vo ng dn c trong cn thit phi d kin cng trnh lng ct cng cc thit b thch hp v c quyt nh trn c s tnh ton kinh t - k thut.

7.2.8. Khi thit k cng trnh ly nc phi tun th cc yu cu nu iu 4.11 phn 4 - Cc cng trnh cho c i v cng trnh bo v c.

7.3. B lng ct

7.3.1. B lng ct v thit b cn phi bo m: a. Gi li trong b cc ht bn ct c ln vt qu tr s cho php ly c nc

c trong ph hp vi yu cu cht lng. ln ca bn ct cho php a vo ng dn c xc nh thng qua tnh ton kinh t - k thut (tn dng lng ph sa c ch mc ti a; Hn ch hoc khng gy bi lng hoc xi l knh dn; Khng lm gim tui th trang thit b cng ngh di mc qui nh v.v...);

b. m bo cp nc c trong ph hp p ng biu dng nc; c. Ch ng loi b bn ct lng ng trong bung lng khi cn thit. Tn dng bin

php xi ra bn ct lng ng bng phng php thy lc.

7.3.2. Tnh ton b lng ct trn knh ca h thng ti phi cn c vo thnh phn bn ct ca nm c c trung bnh v kim tra kh nng lm vic ca b theo nm c c ln nht c xt n ch lm vic ca knh.

7.3.3. V tr b lng ct cn t trong phm vi cm u mi hoc u ng dn chnh c xt n cc iu kin sau: a. iu kin a hnh v a cht ti ch cho php b tr ng dn nc ti b lng

ct c kch thc v ch chy thch hp nhng ht bn ct c hi lng ng trong bung lng;

b. C kh nng x b bn ct lng ng ra khi bung lng hoc dn ng trong b no vt nh k bng c gii.

7.3.4. Vic chn kiu bung lng thau ra lin tc hoc nh k bng phng php thy lc hay lm sch bng c gii phi tin hnh trn c s so snh kinh t - k thut, la chn kiu bung lng da trn c s sau: a. Bung lng thau ra bng thy lc p dng cho nhng ni c lng nc tha

phong ph, tuyn thau ra c dc thy lc; b. Khi khng chnh ct nc xi ra ton b lp lng ng trong b cn s

dng bung lng thau ra kiu hn hp: bn ct ht nh c loi b bng phng php thy lc, bn ct ht ln c dn sch bng c gii;

c. Cc b lng ct kiu mt bung thau ra nh k ch p dng khi c php ngng cp nc hon ton hoc c php cp nc cha x l (th) trong thi gian thau ra.

7.3.5. Khi thit k cng trnh thu nc v ly nc cho h thng cp nc sinh hot v nc cho cc ngnh sn xut khc phi tun th yu cu ca cc tiu chun thit k mng li bn ngoi v cng trnh cp nc tng ng.

7.4. Cng trnh x nc, tho nc

7.4.1. Cng trnh x nc, tho nc phi m bo thc hin cc chc nng sau y:

a. i vi cng trnh x:


www.

vnco

ld.vn

TCXDVN 285 : 2002

22

- Cc cng trnh x lu di bao gm cc ca trn, l x, ng dn tucbin v.v... c mt trong u mi thy lc v cng trnh x l d phng phi nng lc m bo cho mc nc thng h lu khng vt qu mc nc qui nh khi x l thit k v l kim tra.

Thng thng cc cng trnh x l d phng ch lm vic khi mc nc thng lu bt u vt qa mc nc thit k ln nht. Khi khng c iu kin b tr cng trnh x l d phng ring bit th phi m rng cng trnh x chnh hoc nng p tng dung tch iu tit ca h cha, hoc kt hp c hai m bo x l kim tra an ton.

- Ch ng x nc theo quy trnh qun l khai thc.

b. i vi cng trnh tho:

- Tho cn hon ton hoc mt phn h cha hoc ng dn (knh) xem xt v sa cha cng trnh cng nh dn sch theo yu cu v sinh mi trng hoc rt nc phng s c cho cng trnh chu p;

- Xi ra bn ct;

- C th tham gia tho l.

7.4.2. Khi thit k cng trnh x nc, tho nc cn xem xt kh nng kt hp chng vi cc cng trnh khc trong cm u mi cng nh tnh n kh nng s dng chng x lu lng thi cng.

7.4.3. Lu lng x tnh ton trong qu trnh khai thc qua cc cng trnh x - tho - chuyn nc lu di ca cng trnh u mi cn xc nh xut pht t lu lng l thit k c qui nh khon 4.2.1 iu 4.2 v bng 4.2 c xt n s bin i ca n do tc ng iu tit li ca cc h cha hin c hoc h cha ang thit k v s thay i iu kin hnh thnh dng chy do nhng hot ng kinh t x hi trong lu vc.

Khi xc nh lu lng ln nht thit k v kim tra ca cng trnh u mi trn sng khai thc theo s bc thang cn xt n cp ca bn thn cng trnh, v tr ca n trong bc thang, nng lc x -tho - chuyn nc ca cm u mi bc trn ng vi mc nc dng bnh thng v mc nc gia cng (khi x l thit k v l kim tra), quy nh vn hnh khai thc cng trnh thu v h cha ca cc bc thang, dng chy nhp lu ca cc sng nhnh vo on sng thng lu tip cn vi cng trnh u mi ang thit k.

Khng ph thuc vo cp ca cng trnh u mi v v tr ca chng trong bc thang, qu trnh x - tho - chuyn lu lng v h lu ca trng hp tnh ton c bn khng c nh hng n vic khai thc bnh thng ca cc cng trnh thu lu di bc thang di.

Trng hp cp ch yu ca cng trnh u mi ang thit k thp hn cp ca cng trnh u mi bc trn, cho php tng nng lc x - tho - chuyn dn c lu lng kim tra ca cng trnh u mi bc trn m khng nng cp thit k cng trnh.

a. Mc nc thit k ln nht thng lu cng trnh u mi: l mc nc cao nht xut hin trong qu trnh x l thit k khi cc cng trnh x nc m hon ton, tt c cc tuc bin u lm vic, cc cng trnh tho, chuyn nc khc lm vic ch khai thc bnh thng.


www.

vnco

ld.vn

TCXDVN 285 : 2002

23

Khi khai thc trng hp ny cc hng mc trong cng trnh u mi k c phn ni tip thng h lu cng trang thit b phi bo m lm vic bnh thng, khng b hng hc.

Ti trng v tc ng ng vi trng hp ny c tnh theo t hp ti trng c bn.

b. Mc nc kim tra thng lu cng trnh u mi: l mc nc cao nht xut hin trong qu trnh x l kim tra khi tt c cc cng trnh tho nc, x nc, chuyn nc v.v... ni mc (a) v cng trnh x d phng u hot ng.

Khi khai thc trng hp ny cho php:

- Gim sn lng ca trm thy in (nu iu c li cho an ton cng trnh).

- Cng trnh ly nc lm vic khc iu kin khai thc bnh thng nhng khng dn n tnh hung s c cho cc i tng dng nc.

- Tho nc qua ng dn kn vi ch thy lc thay i (t khng p sang c p v ngc li) nhng khng dn n ph hng ng dn.

- Lng dn v mi dc h lu cng trnh u mi b xi l nhng s h hng ny khng e da ph hy cc hng mc chnh ca cng trnh u mi, cc vng dn c, cng nghip h lu.

- C h hng cng trnh x d phng nhng s h hng ny khng nh hng n an ton ca cng trnh chnh.

- Ti trng v tc ng ng vi trng hp ny c tnh theo t hp ti trng c bit.

7.4.4. thun li cho vic chun ho v tng kh nng lp ln khi cn thit, b rng ca l thot ch nht c ca van nn ly theo cc kch thc sau: 0,40; 0,60; 0,80; 1; 1,25; 1,50; 1,75; 2; 2,50; 3; 3,50; 4; 4,50; 5; 6; 7; 8; 10; 12; 14; 16; 18; 20; 22; 24; 30m.

Tng t, chiu cao ca l thot l 0,6; 0,8; 1; 1,25;1,5; 1,75; 2; 2,5; 3; 3,5; 4; 4,5; 5; 5,5; 6; 7; 8; 9; 10; 12; 15; 16; 18; 20m.

Ch thch: Chiu rng ca l l kch thc trong lng nh nht gia hai mt bn thng ng.

Chiu cao ca l c xc nh nh sau:

- Vi cc l mt- l kch thc t mt ngng n mc nc dng bnh thng.

- Vi cc l di su - l kch thc t mt ngng n trn ca l.

7.4.5. Vic quyt nh t lu ca cng trnh, vn tc lng dn h lu, ch ni tip thng h lu, kt cu cng trnh chnh, b tiu nng, sn sau, gia c b, tng chuyn tip v phn cch ca cng trnh x nc, tho nc phi cn c vo kt qu so snh ch tiu kinh t - k thut cc phng n.

B tr tng th v kt cu ca cng trnh x nc, tho nc, gii php ni tip cng trnh vi h lu phi bo m khi chng hot ng s khng gy nguy him cho cc hng mc cng trnh thy trong cng trnh u mi do xi nn. Dng nc x, tho khng c nh hng n hot ng bnh thng ca nh my thu in, knh giao thng thy, khng gy ra nhng bin dng lng dn bt li cho khai thc.

Bn thn cng trnh x nc, tho nc khi thit k cn phi xt n nhng tc ng bt li do lc thy ng, kh thc v hin tng mi mn do bn ct gy ra.

7.4.6. Kt cu ca cng trnh x nc, tho nc v cc b phn ni tip thng h lu ca


www.

vnco

ld.vn

TCXDVN 285 : 2002

24

chng c thit k vi cc trng hp khai thc c bn v phi kim tra li vi trng hp bt thng m bo an ton cho cng trnh v khng c php nc trn qua nh tuyn chu p, gm:

a. Cng trnh x nc, tho nc lm vic khi gp l thit k c m hon ton. Khi c lun chng tho ng cho php xt n kh nng mt s ca b kt;

b. Cng trnh x nc, tho nc lm vic khi gp l kim tra c m hon ton. Khng xt n kh nng ca b kt;

c. Do yu cu vn hnh khai thc, iu tit l hoc s c c th phi xt thm cc t hp m khc p ng mc tiu thit k v an ton cho cng trnh.

7.4.7. Khi thit k cng trnh x nc, tho nc cn phi lp quy trnh vn hnh cc ca. V nguyn tc th quy trnh ny khng c gy ra xi l ngoi d tnh thit k dn n phi b sung nhng bin php phng xi h lu.

7.4.8. Khi thit k cng trnh x nc, tho nc phi trang b ca van chnh v ca van sa cha.

Trc ca van chnh ca cng trnh x mt l van phng cng nh trc ca van chnh ca cng trnh x su (khng ph thuc vo dng ca van chnh) cn phi b tr ca sa cha - s c. Nhng cng trnh x mt c nhiu khoang cng loi cho php s dng ca van phng s c - sa cha loi di chuyn c gim bt s lng. Khi c lun chng tin cy cho php dng phai tm ln thay cho van phng s c.

Khi khng c kh nng tho cn l phn vo ca cng trnh x su th ngoi ca van chnh v van sa cha - s c cn phi b tr thm ca van sa cha (c th l phai sa cha) pha trc.

Khi ngng cng trnh x su thp hn mc nc h lu th phn sau mt ct ra ca cng phi b tr thm ca van sa cha loi di chuyn c.

7.4.9. Khi la chn kiu ca van v my nng phi cn c vo tc ln ca l, kh nng tch nc thng h lu, yu cu bo m lu lng ti thiu cho h lu, trong bao gm c trng hp ct t ngt mt phn hoc ton b ph ti ca nh my thy in quyt nh.

7.4.10. Khi ca van ca cng trnh x su l ca phng c din tch trn 60m2 song li c yu cu tho lu lng nh hn ng k so vi kh nng tho ca 1 l cng th phi thit k 1 l tho ring nh hn tha mn yu cu ny.

7.5. ng dn nc kn ca nh my thu in v trm bm

7.5.1. ng dn kn (c mt ct ngang khp kn) ca nh my thy in, trm bm phi m bo dn nc vi mi ch khai thc d kin trong thit k.

7.5.2. Vic la chn tuyn v mt ct dc ng dn nc c p v nguyn tc cn phi loi tr kh nng sinh chn khng trong ng dn khi lm vic.

7.5.3. Khi thit k ng dn nc v cng trnh lin quan cn phi cn c vo kt qu tnh ton thy lc. Nhng cng trnh cp I, II c hnh dng phc tp phi tin hnh nghin cu thy lc xc nh tn tht ct nc, xc nh mc nc cao nht v thp nht trong ng dn khng p khi dng chy khng u khng n nh, xc nh p lc


www.

vnco

ld.vn

TCXDVN 285 : 2002

25

nc ln nht v nh nht theo chiu di ng dn c p khi sinh nc va.

7.5.4. ca nhn nc ca nhng ng dn c p bng ng thp t h mt phn hoc h trn ton tuyn cp nc cho nh my thy in cn phi b tr ca van sa cha pha trc v ca van s c cho tng ng ng ring bit nhm m bo iu kin bo dng v ngt nhanh khi tuyn ng b v. Sau ca van s c phi c gii php cp khng kh cho ng ng. Ngoi ra cn d kin bin php bo v phng trnh cho nh trm khng b h hi hoc b ngp do v ng.

7.5.5. Khi xc nh mc nc ln nht tnh ton trong ng dn khng p phi xt n sng dng sinh ra khi ct nhanh lc s c hoc ct ng thi ph ti ln nht khi khai thc.

7.5.6. Tnh ton nc va ng dn vo tucbin, ng y trm bm cn xt cc trng hp sau:

a. Ct t ngt ton b ph ti ca nh my;

b. ng ph ti theo quy trnh khai thc cho n khi nh my t ton b cng sut.

7.5.7. Ca van sa cha - s c c vn hnh theo ch hon ton t ng. Ngoi ra, ca cn c thit k thm ch iu khin t xa v iu khin ti ch iu hnh trong nhng trng hp cn thit.

7.6. ng ng dn nc khc

7.6.1. Vic la chn kiu v kt cu ng ng dn cn phi tin hnh trn c s so snh kinh t - k thut cc phng n c xt n nhim v ca ng ng, tr s ct nc, t nn, iu kin lp rp v khai thc.

Khi thit k ng ng vng t ln t, t b sng nc, t bn, vng b ly ho v nguyn tc cn phi t ng trn mt t v khi cn thit phi c bin php gia c t nn.

7.6.2. Thng thng, khi thit k ng ng t h trn nn t phi cu to cc khp b b tr dc theo chiu di ca chng (k c on tip ni vi cc cng trnh xy c v.v...) m bo ln v bin dng nhit ca cc on l tch bit (c lp); hoc t trn mng b tng ct thp lin khi m bo cho ng ng ln u. Cho php thit k ng dn bng thp khng c khp b trong nhng iu kin thch hp.

7.6.3. Vic la chn kt cu ng ng dn (kch thc, hm lng thp, vt liu v.v...) phi lun chng bng tnh ton.

7.6.4. Khi thit k cc ng ng dn cn phi c bin php bo v chng g, n mn theo cc tiu chun hin hnh.

7.6.5. hai u v dc tuyn ng ng dn cn phi b tr cc ca quan st, thit b a nc lm y dn ng ng, thit b cp hoc x khng kh.

7.6.6. Vi ng ng dn bng b tng ct thp cn phi nh r tiu chun hn ch nt nhm m bo tui th ca kt cu theo cc iu kin n mn v chng thm.

7.7. Tuynen thy cng

7.7.1. La chn tuyn, kiu (c p hoc khng p) cng nh kt cu v hnh dng mt ct ngang ca tuynen cn phi cn c vo nhim v ca chng v tin hnh trn c s so snh kinh t - k thut cc phng n, c xt n: b tr tng th cm u mi; chiu su t di mt t; tr s ct nc; iu kin a cht cng trnh; ch thy lc ca


www.

vnco

ld.vn

TCXDVN 285 : 2002

26

tuynen; iu kin thi cng; nh hng qua li gia tuynen vi cc cng trnh b tr trn mt t v cng trnh ngm lin k.

7.7.2. V nguyn tc, tuyn tuynen thit k cn la chn l tuyn thng vi chiu di ngn nht. Trong iu kin a cht cng trnh v a cht thy vn khng thun, thi cng phc tp hoc cn p ng theo yu cu an ton cho php p dng tuyn tuynen khng thng.

7.7.3. Khi tuynen c nhim v tho lu lng khai thc lu di cn phi tnh n kh nng s dng chng tho lu lng thi cng.

7.8. H iu tit ngy m, b p lc ca nh my thy in, trm bm, thp iu p

7.8.1. Khi dung tch iu tit thng lu ca nh my thy in knh dn khng phi xt n vic to h iu tit ngy m. S thiu ht dung tch iu tit phi chng minh bng cc tnh ton kinh t - k thut.

7.8.2. H iu tit ngy m phi b tr trn tuyn knh dn hoc trn nhnh ca n, cng gn b p lc cng tt. Ty thuc iu kin ti ch c th s dng cc lng sng, vng trng t nhin lm h iu tit ngy m nhng phi xt n iu kin thm mt nc v kh nng b bi lp ca h.

7.8.3. Khi thit k h iu tit ngy m cho nh my thy in lm vic theo ch ph nh phi c bit quan tm n n nh, bn ca cc cng trnh ngn nc bng t v lp o bo v khi mc nc trong h b giao ng ln.

7.8.4. Khi thit k b p lc cn c gii php m bo:

a. Nc i vo ng dn tucbin khng ht theo khng kh v c tn tht ct nc l nh nht;

b. Ngn nga vt ni v rc tri vo ng dn tucbin;

c. Ch ng ngng cp nc vo ng dn tucbin khi cn xem xt, sa cha hoc s c;

d. B tr thit b thch hp np khng kh vo ng dn tucbin khi tho cn v dn khng kh trong ng dn ra ngoi khi chng c lm y nc;

e. X nc tha cng nh vt tri ni v rc ri;

g. Loi b bn ct lng ng trong b.

Cn trang b ca van, phai sa cha, li chn rc, thit b dn rc cho b.

7.8.5. Khi xc nh cao trnh nh tng b p lc cn phi xt n tc ng ca sng dng pht sinh do ct t ngt ton b ph ti.

7.8.6. Khi xc nh mc nc khai thc thp nht trong b p lc cn phi xt n tc ng ca sng m pht sinh do ng ph ti ln nht.

7.8.7. Khi b p lc c cp nc bng ng dn khng t iu chnh, cn b tr cng trnh x t ng nm k b p lc. Cc cng trnh x ny phi m bo thot c ton b lu lng tnh ton ln nht ca nh my thy in hoc lu lng cn cp cho cc h dng nc h lu khi nh my thy in ngng lm vic c xt n cc ngun d tr ln cn.


www.

vnco

ld.vn

TCXDVN 285 : 2002

27

7.8.8. Khi b p lc c cp nc bng ng dn t iu chnh, trong trng hp cn thit cn b tr cng trnh x k b p lc cp nc cho nhng h pha h lu trong trng hp nh my thy in ngng lm vic.

7.8.9. Khi b tr b p lc trn nn t, c bit l trn t yu, cn d kin bin php phng ln khng u, hin tng trt c th xut hin do nc thm ra t b p lc lm suy gim cht lng nn.

Khi thit k b x ca trm bm cn phi d kin cc bin php nhm bo m:

a. Tiu hao ng nng ca nc chy ra t ng y;

b. Loi b bn ct lng ng trong b x;

c. Ni tip thun b x vi knh hoc vi ng dn.

7.8.10. Ni tip ng y vi b x ca trm bm c th thc hin theo cc hnh thc sau:

a. ng y bm nc trc tip vo b x. Ming ra ca ng y lun thp hn mc nc thp nht trong b mt khong cch an ton. Cui mi ng y c t mt van clap ngn dng chy ngc khi dng bm. Trng hp c bit khi khng c php h thp mc nc trong b x xung thp hn cao trnh y ca van clap th phi trang b thm mt van trn ng y ngn dng chy ngc khi tin hnh sa cha cc van clap;

b. Khi dng hnh thc xiphng ngc chuyn nc t ng y vo b x th ming ra ca xi phng phi nm thp hn mc nc thp nht trong b x. Xiphng c trang b van np kh t ng ph chn khng pht sinh trong xi phng khi dng bm, ngn nga dng chy ngc t b x v my bm.

Vic la chn phng n ni tip cn phi thng qua so snh kinh t - k thut.

7.8.11. S cn thit phi b tr thp iu p bo m cho cc t my pht lm vic an ton cn phi chng minh bng s liu tnh ton nc va.

7.8.12. Tnh ton thy lc ch chuyn i trong thp iu p phi tin hnh ch ngt v ng ph ti. Mc nc dng cao nht trong thp iu p c xc nh theo iu kin ct t ngt ton b ph ti. Khi mc nc thng lu phi ly mc nc ln nht, cn tn tht ct nc l tn tht b nht c th xy ra.

Mc nc thp nht trong thp iu p c xc nh theo iu kin tng t ngt ph ti ti a khi khai thc. Khi mc nc thng lu phi ly bng mc nc thp nht, cn tn tht ct nc ly theo tn tht ln nht c th xy ra.

7.9. Knh dn nc

7.9.1. Vic la chn tuyn, dng knh, cc thng s, tn tht u nc phi c lun chng bng cch so snh phng n c xt n: kh nng chuyn nc, kh nng p ng giao thng thy (nu c), khi lng cng tc xy dng v trang thit b, phng thc vn hnh iu phi nc, chi ph khai thc, yu cu bo v mi trng xung quanh v.v...

7.9.2. Nu khng c yu cu khng ch cao mt nc th knh cn b tr trong khi o hoc na o na p. Ch cho php s dng knh p nhng on c bit khi c lun chng ring. Khi xc nh bn knh cong ca tuyn knh cn m bo kh nng i li ca thuyn b v khng gy ra xi l lng dn.


www.

vnco

ld.vn

TCXDVN 285 : 2002

28

7.9.3. Cn d kin bin php chng ngp v snh ly ha vng t ven tuyn knh cng nh thc vt thy sinh pht trin trong knh.

7.9.4. Khi thit k knh trong nhng iu kin phc tp (trong t ln t, trng n, t cha mui d ha tan, trn sn dc trt l, nhng ni tuyn knh c th giao ct vi dng bn v.v...) cn xt n s thay i c trng ca t nn v t p trong thi gian khai thc sau ny v trong trng hp cn thit phi p dng cc gii php kt cu v cng ngh thi cng thch hp.

7.9.5. Lu tc trong knh c quyt nh theo iu kin khng gy xi hoc bi trong lng dn. Ngoi ra, cn d kin bin php phng nga tc nghn lng dn do rc ri, rong to, cy c ph mt.

7.9.6. knh khng b xi l v h hi c hc do ma, do dng chy, do thm mt nc cn d kin kt cu bo v thch hp.

7.9.7. dc mi knh phi xc nh t iu kin n nh mi dc.

7.9.8. m bo t tiu chun trong ca nc dng, cn phi d kin cng trnh lng ct hoc thay th bng gii php m rng kch thc on u knh. Hnh thc lng ct s c quyt nh thng qua lun chng kinh t - k thut.

7.9.9. Khi thit k knh cn tnh n kh nng phn on thun li cho vic kim tra bo dng nh k. Chiu di mi on c quyt nh theo iu kin c th c tnh n iu kin t nhin v cc yu cu khai thc sa cha.

7.9.10. Khi thit k knh cn xem xt kh nng s dng ngun nc b sung t sng sui giao ct. Lng dng chy b sung l lng nc c bn ca sng sui sau khi tr phn lu lng phi cp v h lu cho nhu cu v sinh mi trng.

7.9.11. Thng thng, dc knh cn b tr ng qun l kim tra thng xuyn tnh trng ca knh. Nhng ni knh i qua cc khu vc nguy him, t im dn c, cc cng trnh dn dng c th phi xt n vic xy dng hng ro cch ly.

7.9.12. Khi s dng ngun b sung t cc sng sui cn phi tun th cc iu kin sau:

a. Cc ch tiu cht lng nc tuyn ly nc phi ph hp vi yu cu ca tiu chun nc dng;

b. Lng dng chy rn v thnh phn ht ca n phi ph hp vi kh nng chuyn ti ca knh.

7.9.13. Tnh ton thu lc knh cn phi xt n ch chy khng n nh xut hin khi lu lng v mc nc thay i, nh hng ca nc dnh do gi, sng do gi v sng to thnh khi vn hnh ca van, vn hnh t my, cng trnh iu tit, trm bm, u thuyn v.v...

7.9.14. Trn cc on tuyn knh c iu kin a hnh, a cht khng thun li (a hnh b chia ct cc b, gp cc loi t d b xi, t yu v.v...) cn phi xem xt phng n thay th bng cu mng.

7.9.15. Thit k knh a chc nng phi tin hnh trn c s d bo nhu cu nc v yu cu cht lng thch ng cho cc h dng nc trong vng D n m knh c nhim v cung cp.


www.

vnco

ld.vn

TCXDVN 285 : 2002

29

7.9.16. Khi thit k knh kt hp vn ti thy phi cn c vo loi tu thuyn v c cu on tu xc nh cc mc nc tnh ton v kch thc ca knh ng thi phi xt n cc yu cu ca cng trnh u thuyn. Knh vn ti thy thng c thit k cho tu thuyn c th i li theo hai chiu. Dc knh cn b tr cc bn bi nhng v tr thun li.

7.10. Nh my thy in, trm bm

7.10.1. Vic la chn kiu nh trm ca nh my thy in, trm bm cn phi thc hin trn c s so snh ch tiu kinh t - k thut cc phng n, c xt n cc iu kin sau:

a. m bo cho nh my lm vic t hiu qu cao;

b. m bo cng trnh v thit b lm vic an ton, tin cy v thun li trong khai thc (thng xuyn v tm thi);

c. m bo i lng ct nc tc ng ln cng trnh v thit b cng ngh ph hp vi tnh ton thit k;

d. V tr nh trm trong b tr tng th cm u mi v kiu ca cng trnh dng nc chnh l hp l;

e. Ph hp vi dng t nn;

g. To thun li cho thi cng xy lp v cng tc phc hi - sa cha sau ny.

7.10.2. Gii php b cc phn di nc ca nh my thy in, trm bm phi tnh n bin php chia nh trm thnh cc n nguyn. Kch thc ca n nguyn tu thuc vo kch thc t my, dng t nn, gii php kt cu ca phn xy dng, bin dng cho php.

Cho php dng kt cu lin khi (khng chia ct) cho ton b phn di nc ca nh trm khi c lun chng tin cy. Kch thc sn lp my phi din tch sp t cc chi tit tho (lp) t mt t my ln nht v mt my bin p chnh. Cn tnh n kh nng s dng mt phn din tch ca gian my gim din tch sn lp my. Trong nh my ngm cn phi trit thu hp din tch sn lp my bng cch tn dng ti a din tch trn mt t tho lp.

7.10.3. Khi thit k phn nh trm ca nh my thy in kiu lng sng, kiu k p, phi xem xt cc phng n b tr nh trm tch ri hoc kt hp vi cng trnh x mt hoc x su, b tr t my ng hoc t my ngang. Vi nh my thy in kiu ng dn cn phi thit k nh trm ng ring bit dng h hoc ngm, hoc b tr gian my kiu ging vi cch sp xp t my thnh mt hoc hai hng.

Khi c lun chng tha ng, nhng nh my thy in t trong khe ni hp c th b tr t my thnh hai hng hoc theo mt cch sp xp thch hp.

7.10.4. Kch thc phn di nc ca nh my thy in, trm bm cn phi ly mc cn thit ti thiu xut pht t kch thc phn thng nc ca t my v b tr trang thit b theo yu cu cng ngh. Vic b tr cc phng sn xut, phc v v ph tr khng c lm tng kch thc phn di nc ca nh trm. Kt cu phn ngp nc phi c quy cch ha trn tt c cc n nguyn ca t my.

7.10.5. quan st tnh trng phn di nc ca nh my cn phi b tr cc ging v hnh lang quan st. Trong hnh lang nh my thy in, trm bm cn d tr hai li ra. Cc li phi c cu thang ring cch ly vi cc phng b tr bn trong nh my. nh


www.

vnco

ld.vn

TCXDVN 285 : 2002

30

ging hoc li vo ca nh my ngm cn b tr cao hn mc nc ln nht h lu 0,5m; ng thi phi c np kn nc (hoc ca) hnh lang khng b ngp.

7.10.6. kim tra v sa cha bung tucbin, bung ht v ng x cn phi b tr hnh lang tiu nc, ca cng tc v li i ring cch bit vi cc phng ca nh my; phi d kin thit b bm nc loi tr kh nng nh my b ngp do s c.

7.10.7. Cc ca nhn nc phi b tr cc khe lp t li chn rc, thit b dn rc, ca van sa cha, ca van vn hnh chnh hoc ca van sa cha - s c v.v... Phi b tr ca van sa cha - s c cui ng dn cp nc cho mt vi tucbin v trc ng dn vo bung ca mi tucbin.

7.10.8. Khi thit k lp bc (o) ca gian hm ngm, tuynen cn phi tun th nhng yu cu ca cc tiu chun thit k ng hm thy cng tng ng.

7.10.9. Khi thit k nh trm ngm, phi d kin nhng hnh lang v ging giao thng lin lc c th c gii ha vic vn chuyn thit b, vt liu v i li ca nhn vin qun l. ng thi phi d kin li i b hoc cu thang tng li thot ra bn ngoi cho cc nhn vin qun l khi c s c.

Nu c th nn thit k hnh lang vn chuyn nm ngang. Hnh lang v ging vn chuyn phi ni vi sn lp my. ng cp lin lc cn kt hp b tr trong hnh lang v ging vn chuyn.

Trong nh trm ngm phi b tr h thng thng gi m bo cho nh my hot ng bnh thng.

7.10.10. Cc phng sn xut ph (bao gm c h thng du), khi khng c yu cu c bit cn phi b tr chng trn mt t.

7.10.11. Thit b phn phi in p ca my pht v nhu cu t dng, trm iu khin trung tm trong trng hp t ngm cn b tr kt hp trong gian my nhng khng c lm tng kch thc mt bng chnh. Trng hp cn thit c th lm ngch ring b tr thit b v my mc.

7.10.12. Ch thy lc trong tuynen tho vi mi trng hp khai thc phi duy tr ch chy n nh c p hoc khng p. Ch chuyn i t c p sang khng p hoc ngc li trong tuynen tho ch c php xy ra trong mt thi gian ngn khi c lun chng tha ng.

Phi d kin a khng kh vo tuynen tho trong mi ch lm vic.

7.10.13. Khi thit k trm bm phi m bo cp lng nc theo yu cu ca biu dng nc.

Lng nc cn v biu dng nc c xc nh thng qua tnh ton cn bng thy li ton h thng c xt n:

a. Cc thng s thy vn ca ngun cp nc;

b. Cc thng s tnh ton ca h thng thit k: lng nc cn cp v ch dng nc, tn tht lng nc trong h thng bm chuyn, kh nng dn v iu chnh ca h thng, s khai thc c chp nhn v.v...;

c. Lu lng ca ngun cn li x v h lu phi p ng yu cu cho cc h dng nc v yu cu bo v mi trng.


www.

vnco

ld.vn

TCXDVN 285 : 2002

31

7.10.14. Khi thit k ch lm vic ca cc trm bm c cng sut ln hn 10.000KW, cn xem xt kh nng s dng mt phn hoc ton b cng sut trm vi t cch l mt h tiu th iu chnh cng sut b ca h thng nng lng.

7.10.15. Khi thit k kt cu b x ca trm bm cn to ra ch chy thun bng cch lm tn dng chy, phn b li v gim nh lu tc.

7.11. H cha nc

7.11.1. Khi thit k h cha cn phi gii quyt vn di dn ti nh c, n b thit hi sn xut nng nghip; Bo v t nng nghip khi b ng ngp; Bo v bng bin php cng trnh hoc di di cc im dn c, cng nghip, vt kin trc, di tch lch s kin trc, ng x, ng ng dn du kh, ng dy ti in, thng tin lin lc v.v...; Cht dn rng, v sinh lng h; Khai thc ti nguyn khong sn; to iu kin khai thc vn ti thy, thy sn; Bo v v s dng hp l ti nguyn nc, thy sinh vt, rng v cc ngun ti nguyn khc.

7.11.2. Khi thit k h cha cn phi:

a. Lp cc Bo co nghin cu nh gi tc ng mi trng v d bo v s thay i mi trng sinh thi xung quanh vng h v lu vc do vic hnh thnh h cha c xt n cc yu t thy vn, a cht, a cht thy vn, ng thc vt trn cn v di nc, nng nghip, sinh thi v cc yu t khc, trong c vic lp d bo v cht lng nc, ti to b, s bin i ca mc nc ngm v cc tnh cht ca t theo tiu chun hin hnh;

b. Tnh ton phm vi mt thong ca h cha, vng ngp thng xuyn v vng bn ngp c th khai thc;

c. D kin cc bin php khc phc khi than bn v cc khi vt cht khc b y ni khi h cha tch nc.

7.11.3. Dung tch bi lng ti thiu ca h cha c xc nh tu thuc vo cp ca h cha nu trong bng 2.2. Thi gian dung tch bi lng ca h cha b lp y trong iu kin bnh thng khng c t hn quy nh nu trong bng 7.1.

Bng 7.1. Thi gian tnh ton dung tch bi lng ca h cha b lp y

Cp ca h cha Thi gian tnh ton dung tch bi lng b lp y

Cp V, IV 50 nm

Cp III 75 nm

Cp II v I 100 nm


www.

vnco

ld.vn

TCXDVN 285 : 2002

32

Ch thch:

1. Dung tch bi lng ca h cha xem nh b lp y khi cao trnh b mt bn ct lng ng trc tuyn chu p t bng cao trnh ngng ca nhn nc chnh.

2. Qu trnh bi lng ca h cha cp I, II cn xc nh thng qua tnh ton thy lc hoc th nghim m hnh.

3. C bit, khi c lun chng kinh t - k thut tha ng c php chn thi gian dung tch bi lng nh hn quy nh bng 7.1. Trong trng hp ny nht thit phi c bin php hn ch bn ct lp trc ca nhn nc bng gii php cng trnh nh xy dng thm cng x ct hoc c bin php no vt nh k. V tr, qui m cng x ct ca h cha cp I, II c quyt nh thng qua th nghim m hnh thy lc.

7.11.4. Trong trng hp dng chy ma l c lng nc tha phong ph cn phi xem xt phng n b tr cng x ct gim bt dung tch bi lng, tng dung tch hu ch. Cng ny c kt hp lm nhim v dn dng thi cng v rt nc h khi c nguy c s c.

7.11.5. Lu lng, lu tc, ch vn hnh ca cng x ct ty thuc vo c tnh bn ct cn x, tc rt nc cho php ca h cha sao cho m bo y c bn ct lng ng trc cng v h lu m khng gy ra tnh trng st mi cng trnh t v b dc.

7.11.6. Mc nc thit k ln nht v mc nc kim tra ca cc h cha lm nhim v cp nc, pht in c xc nh trn c s iu tit l phn dung tch t mc nc dng bnh thng tr ln. Khi h c t dung tch phng l th mc nc ny c xc nh trn c s iu tit l phn dung tch t mc nc phng l tr ln. Lng nc x v tho qua cc cng trnh trong tuyn chu p ca h cha phi tnh ton theo m hnh l bt li nht v nh l hoc tng lng l c xt n kh nng xy ra l kp do nh hng ca ma bo (nu tng xy ra trong vng D n).

7.12. Cng trnh bo v h cha v h lu cm u mi

7.12.1. Phi d kin cng trnh bo v h cha v h lu cm u mi ( bao, cng trnh gia c b v.v...) nhm bo v ti a cc vng t c gi tr, cc i tng kinh t quc dn (thnh ph, x nghip cng nghip, t nng nghip, ci thin iu kin v sinh ca ao h v.v...) khi b ng ngp v l b.

7.12.2. Vic thit k cc cng trnh bo v c thc hin theo cc tiu chun thit k tng ng hin hnh.

7.12.3. Khi tiu nc cho vng c bo v cn phi tnh n kh nng iu tit ti ch mt phn dng chy gim bt quy m ca trm bm.

7.12.4. Khi thit k gia c b phi d bo s chuyn dch v xi su lng dn (nu c), s ti to b v s m bo n nh chung ca c on tuyn phi bo v.

7.12.5. vng t c bo v khi b ngp ng, cn phi d kin thit lp mng li h khoan quan trc din bin ca nc ngm.


www.

vnco

ld.vn

TCXDVN 285 : 2002

33

7.13. Cng trnh cho c i v cng trnh bo v c

7.13.1. Khi thit k u mi thy li trn sng, h cha hoc ao m ni a vng c gi tr thy sn cn phi d kin xy dng cc cng trnh cho c i, cng trnh bo v c. n thit k cc cng trnh ny cn ph hp vi yu cu, tiu chun bo v ngun li thy sn.

7.13.2. bo tn ngun c d tr trong khu vc, cc cng trnh cho c i phi bo m ng cho loi c qua li thng xuyn hoc qua li theo ma.

7.13.3. Khi thit k cng trnh ly nc ao h nui c cn phi d kin t cc dng c chuyn ngnh ngn nga c lt vo cng trnh ly nc.

Ph lc A

Danh mc cc cng trnh ch yu v th yu A1. Cc cng trnh thy c xp vo cng trnh ch yu gm:

a. , p cc loi.

b. Tng bin, tng chn, cng trnh cho c i trong tuyn chu p.

c. Cng trnh nhn nc, ly nc v x nc, thot nc.

d. Knh dn cc loi v cng trnh trn knh.

e. Trm bm; Trm thy in; ng dn nc; Tuynen. g. B p lc v thp iu p.

h. Cng trnh gia c b v chnh tr sng; Cng trnh thng tu (u thuyn, nng tu, p iu tit).

i. Cng trnh thy cng trong t hp xy dng nh my nhit in.

A2. Cc cng trnh thy c xp vo Cng trnh th yu gm:


www.

vnco

ld.vn

TCXDVN 285 : 2002

34

a. Tng phn cch.

b. Tng bin v tng chn khng nm trong tuyn chu p.

c. Cng trnh x d phng.

d. Cng trnh gia c b nm ngoi cm u mi; Cc cng trnh bo v c.

e. Cc ng mng cho b mng lm nghip, g cy xui v h lu.

Ch thch: Tu thuc mc tn tht c th gy ra khi b h hng hoc kh nng xy dng li gp nhiu kh khn, mt s cng trnh th yu khi c lun chng thch ng c th chuyn thnh cng trnh ch yu.

Ph lc B

H s iu kin lm vic ca mt s cng trnh thy

Cc loi cng trnh v cc loi nn H s iu kin

lm vic m

1. Cng trnh b tng v b tng ct thp trn nn t v na cng. 1,00

2. Cng trnh b tng v b tng ct thp trn nn .

a) Khi mt trt i qua cc khe nt trong nn 1,00

b) Khi mt trt i qua mt tip xc gia b tng v hoc i trong nn c mt phn qua cc khe nt, mt phn qua nguyn khi.

0,95

3. p vm v cc cng trnh ngn chng khc trn nn 0,75

4. Cc mi dc t nhin v nhn to 1,00

Ch thch: Trong cc trng hp cn thit, khi c lun chng thch ng, ngoi cc h s nu trong bng, c php ly cc h s iu kin lm vic b sung xt ti c im ring ca cc kt cu cng trnh v nn ca chng.

Mc lc

Trang

1. Phm vi p dng 2

2. Thut ng, Phn loi v phn cp thit k cng trnh thy li 2

3. Nhng yu cu ch yu v thit k cng trnh thy li 6

4. Cc ch tiu thit k chnh 9

5. Ti trng, tc ng v t hp ca chng 15

6. Cc quy nh tnh ton ch yu 17

7. Nhng yu cu ch yu i vi cng trnh thu 20


www.

vnco

ld.vn

TCXDVN 285 : 2002

35

7.1. p 20

7.2. Cng trnh ly nc 21

7.3. B lng ct 22

7.4. Cng trnh x nc, tho nc 23

7.5. ng dn nc kn ca nh my thu in v trm bm 26

7.6. ng ng dn nc khc 27

7.7. Tuynen thy cng 27

7.8. H iu tit ngy m, b p lc ca nh my thy in, trm bm, thp iu p

28

7.9. Knh dn nc 29

7.10. Nh my thy in, trm bm 31

7.11. H cha nc 33

7.12. Cng trnh bo v h cha v h lu cm u mi 34

7.13. Cng trnh cho c i v cng trnh bo v c 35

Ph lc A- Danh mc cc cng trnh ch yu v th yu 36

Ph lc B- H s iu kin lm vic ca mt s cng trnh thy 36


tcxdvn 285 - 2002

Documents