TI NGHIN CU KHOA HC

PHN I: M U 1. Tn ti So snh gi cc cng ngh thi cng tng hm bng phng php Topdown 2. L do chn ti Nh c tng hm c t lu trn th gii, n tr thnh ph bin v gn nh l mt thng l khi xy dng nh nhiu tng. chu u do c im nn t tng i tt, mc nc ngm thp, k thut xy dng tin tin v cng do nhu cu s dng nn hu nh nh nhiu tng no cng c tng hm, thm ch cc siu th ch c 2-3 tng nhng c ti 2-3 tng hm. Cng ngh ny cn c dng thi cng cc ga ngm di lng ng, ng cao tc ngm Paris. Vic xy dng tng hm trong nh nhiu tng l iu rt bnh thng n tr nn qua quen thuc mi khi thit k v thi cng v n gii quyt c cc vn pht sinh do nh nhiu tng t ra. chu ni chung c nhiu s nh nhiu tng c tng hm cha phi l nhiu, nhng mt s nc v vng lnh th nh Hng Kng, i Loan, Hn Quc... th s lng nh nhiu tng c tng hm chim t l kh cao, s lng tng hm trong cc nh t 1 n 4 tng hm. Vit Nam ta, nh nhiu tng c tng hm cng ch mi xut hin gn y ti nhng cng trnh lin doanh vi nc ngoi hoc cc cng trnh vn 100% vn nc ngoi. Ta c th k n mt s cng trnh c tng hm TP. H Ch Minh , H Ni v gn y xut hin Nng, nhng s tng hm mi mc t 1 - 2 tng hm.

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Di y l bng thng k v d v nh cao tng c tng hm Vit Nam v th gii. : S tng ni 7 56 75 14 20 27 19 17 22 S tng hm 4 3 3 3 4 4 3 3 2 2 su o(m) 23 12 16 13,6 14,7 16,2 16,2 12,5 11 11

TT 1 2 3 4 5 6 7 8 9 10

Cng trnh Th vin Anh Quc Commerce Bank Frankfruit Central Plaza - Hng Kng Chi Thong - i Loan Chung Wei Tai Pao - i Loan Trung tm sch - H Ni Vietcombank - H Ni Sun way Hotel - H Ni TTHC Nng

Qua bng th d trn ta thy cc cng trnh thng c thng k t 1 --> 4 tng hm, chiu su h o t 5m --> 10m. Tt nhin trong tng lai s c nhng nh c tng hm su hn hin nay do nhu cu v cng ngh xy dng pht trin c th thi cng c v bo m yu cu v cht lng. Tng hm trong cc nh cao tng s l vn quen thuc trong ngnh xy dng trn th gii k c cc nc ang pht trin, n s rt ph hp cho cc thnh ph tng lai c thit k hin i, m bo c yu cu v mi sinh, mi trng v p ng s thch ca con ngi nh l nh c vn treo, thnh ph thng thong 3 chiu hay nhng cn h c thit k theo dng "bit th" trong cc nh nhiu tng. Ta c th ni rng tng hm trong nh nhiu tng l mt nhu cu khch quan v n c nhng u vit ta phi tn dng. 3. S cn thit ca tng hm trong nh nhiu tng :

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a. Do nhu cu s dng : Ngay t lu cc nc cng nghip pht trin, nhu cu v nh ca tng nhanh, cc phng tin giao thng cng tng ng k cng vi mc sng kh cao ko theo mt lot cc hon ng dch v, trong khi din tch xy dng li hn hp v th vic ra i ca nh nhiu tng l hin nhin. Mt khi nh nhiu tng ra i, n i hi x hi phi p ng nhng nhu cu do bn thn n sinh ra. Ni mt cch khc i, chnh l nhu cu ca c dn sng trong cc khu nh . V th vic xy dng tng hm ra i v pht trin mnh nhm :

Lm kho cha hng ho phc v sinh hot ca c dn trong to nh. Lm tng phc v sinh hot cng cng nh b bi, ca hng, qun bar...

Lm gara t, xe my.

Lm tng k thut gii quyt cc vn iu ho khng kh, x l nc

thi, lp t my mc phc v giao thng (thang my), cp nhit...

Lm ni c tr tm thi khi c s c xy ra nh chin tranh. cc ngn hng, kho bc n cn l ni ct tr ti liu mt, tin bc, vng,

qu v cc ti sn c gi tr cao ca quc gia. * Vit Nam : Tnh hnh cng khng ngoi xu hng pht trin ca th gii, ch c iu l ta lun i sau vi thp nin so vi cc nc tin tin. Cho mi ti nhng nm chn mi ca th k trc cc to nh nhiu tng mi c xy dng ti TP. H Ch Minh v H Ni, i km theo n l cc tng hm c thit k, thi cng theo cc k thut tin tin nht. Ngy nay, nhu cu v xu th ca tng hm l qu r rng i vi nh nhiu tng. S ra i ca n hon ton nhm p ng nhu cu va nu trc. b. V mt nn mng :

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Ta thy nh nhiu tng thng c ti trng rt ln chn ct, n gy ra p lc rt ln ln nn v mng, v vy khi lm tng hm ta gim ti cho mng v mt lng t kh ln trn mng c ly i, hn na khi c tng hm th mng c a xung kh su, mng c th t vo nn t tt, cng ca nn tng ln (Khi ta cho t thi gian chu lc). Thm vo tng hm su nu nm di mc nc ngm, nc ngm s y ni cng trnh ln theo nh lut Acsimet nh th n s gim ti cho mng cng trnh v ng thi cng gim ln cho cng trnh. c. V mt kt cu : i vi nh nhiu tng khng c tng hm, su ngm vo t l nng (t 23m), n nh ca cng trnh khng cao do trng tm ca cng trnh trn cao. Khi nh c tng hm, trng tm ca cng trnh s c h thp lm tng tnh n nh tng th ca cng trnh. Hn na, tng, ct, dm sn ca tng s lm tng ngm ca cng trnh vo t, tng kh nng chu lc ngang nh gi, bo, lt ng t... d. V an ninh quc phng : Ti tr s cc c quan, cng s c tng hm th n s c s dng lm ni ct gi tin bc kim loi qu.... Cn nhng khu nh c th tng hm s l ni trnh bom n tt nht cho c dn mi khi xy ra chin tranh. 4. Mc ch nghin cu Hin nay c nhiu bin php thi cng tng hm cc cng ty xy dng p dng nhiu bin php thi cng khc nhau . Nhng cha c s so snh v cng ngh v chi ph xy dng khi p dng cc bin php thi cng vo tng cng trnh c th . Trong ti ny thc hin nhng cng vic sau:-

S b a ra hai gii php thi , tng thi gian thi cng cho mt cng trnh So snh chi ph xy dng cho hai gii php thi cng .

-

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-

Tng hp a ra gii php thi cng c thi gian thi cng ngn v chi ph thp hn.

5. Phng php nghin cu - Nghin cu ti liu v a cht cng trnh Nng Center . - Tham kho thc t v phn tch iu kin cc cng trnh c thit k v thi cng Nng v cc khu vc khc. - a ra hai gii php thi cng c th ln tng tin thi cng - Tim hiu v gi cc trang thit b v vt t mi trong thi cng tng hm - Da vo cc kin thc hc tnh chi ph xy dng 4. Kt lun Vic so snh gii php thi cng v chi ph xy dng cho bin php thi cng tng hm l rt cn thit , gip cho doanh nghip c th rt ngn c thi gian thi cng v gim chi ph xy lp . V vy tng kh nng cnh tranh ca doanh nghip vi cc i th cnh tranh trong giai on u thu cng nh em li nhiu li nhun cho doanh nghip .

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PHN 2

NI DUNG CA TICHNG 1 TNG QUAN V CNG NGH THI CNG TNG HMVic thi cng tng hm lun i i vi vic thi cng t v tng hm nm di mt t. Ngy nay vi cng ngh thi cng t c rt nhiu tin b ch yu nh vo cc my mc thit b thi cng hin i v cc qu trnh thi cng hp l cho php thi cng c nhng cng trnh phc tp, nhng a hnh kh khn. tin cho vic so snh, ta c th h thng cc cng ngh thi cng chnh nh sau y :

a. o t

b. X nh y

H 1 nh

1. Phng php o t trc sau thi cng nh t di ln : y l phng php c in c p dng khi chiu su h o khng ln, thit b thi cng n gin. Ton b h o c o n su thit k ( su t mng), c th dng phng php o th cng hay o my ph thuc vo chiu su h o, tnh hnh a cht thu vn, vo chiu su h o, tnh hnh a cht thu vn, vo khi lng t cn o v n cn ph thuc vo thit b my mc, nhn lc ca cng trnh. Sau khi o xong, ngi ta cho tin hnh xy nh theo th t bnh thng t di ln trn, ngha l t mng ln mi. m bo cho h h o khng b st l trong qu trnh thi cng ngi ta dng cc bin php gi vch o theo cc phng php truyn thng ngha l ta c th o theo mi dc t

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nhin (Theo gc ca t). Hoc nu khi mt bng cht hp khng cho php m rng ta luy mi dc h o th ta c th dng c gi tng h o. u im Phng php ny thi cng n gin, chnh xc cao, hn na cc gii php kin trc v kt cu cho tng hm cng n gin v n ging phn trn mt t. Vic x l chng thm cho thnh tng hm v vic lp t h thng mng li k thut cng tng i thun tin d dng. Vic lm kh h mng cng n gin hn, ta c th dng bm ht nc t y mng i theo h thu nc c tnh ton sn. Nhc im Khi chiu su h o ln s rt kh thc hin, c bit khi lp t b mt yu. Khi h o khng dng h c th mt bng phi rng m taluy cho h o. Xt v mt an ton cho cc cng trnh ln cn hay cho nhng cng trnh xy chen th bin php ny khng kh thi, cn xt v chiu su h o khi qu ln nu dng bin php ny ta s phi c thnh nhiu t, nhiu bc v n nh cng nh an ton cho thi cng ta phi bn n. Qua thc t ta c th a ra cc phng n gi vch h o theo phng php thi cng c in nh : - o t theo dc t nhin, phng php ny ch p dng khi h o khng su, vi t dnh, gc ma st trong ln, mt bng thi cng rng ri m taluy mi dc h o v thit b thi cng cng nh cha t c o ln. - Dng vn c t thnh nhiu tng (Khng chng). H o c o thnh nhiu bc, m rng pha trn p dng cho trng hp khi vn c khng di chng mt ln hoc khi h o qu su, thi cng o t bng phng php th cng v khi c yu cu h o phi thng thong thi cng tng hm. - Dng vn c c chng hoc c neo, h o c o thng ng. Dng c c chng khi ct chng khng nh hng n thi cng tng hm, cn khi c s i hi thong ng trong h o thi cng tng hm ta phi dng neo, neo ny c neo trn mt t. Loi vn c c chng hoc neo dng khi p lc t ln.

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b. o c c khng chng t H : Chi s h u u o h : Chi s ngm ca c u u

a. o theo mi dc t t nhin

c. H thnh nhi t o o u ng c c ch khng chng n

e. Vn c givch c neo khi c thng thong cho h n o khi thi cng t h ng m

d. Vn c givch h o khng chng d ng khi cc ct chng khng nh hung n thi cng t h ng m

H 2 nhThit b thi cng o t : i vi cc loi h o ta va k trn, vic thi cng o t c th c tin hnh bng c gii hay th cng. Vi phng php thi cng c gii ta c th dng cc loi my o mt gu. C th l khi chiu su h o H 4m, ta dng my o gu nghch dung tch gu ph bin l 0,15m3 n 0,5m3 n c u im l ng trn o xung thp nn c th o nhng ni c nc v vic a vt liu ln t l d dng, nhanh gn. Khi nc ngm thp hn cao trnh my ng ta c th dng my o gu thun, n c th o c nhng h o kh su rt thch hp khi kt hp vi o v t ln xe vn chuyn i. Tuy nhin loi my ny yu cu ng i cho xe t vn chuyn phi di chuyn lin tc tn cng lm ng. Ngoi hai loi my chnh trn ngi ta cn c th s dng my o gu dy v my o gu ngom. Vi my o dy thch hp nht khi o mng su c nc, loi ny nng sut thp so vi my o gu

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thun v gu nghch. Vi my o gu ngom th s dng o nhng h o thng ng, n dng o trong lng ging, o h su c thnh cc vn c hay tng chn. N ch thch hp cho t ht yu hoc t ht ri. Khi o ch t rn ta phi lm ti t trc. Vi nhng cng trnh m khi lng o t khng ln, h o khng su ( 3 tng hm tr ln th vic p dng cc phng php truyn thng l khng kh thi v km v hiu qu v kinh t, chnh v l ngi ta a ra mt trnh t thi cng nh sau : Trc khi thi cng o t ngi ta tin hnh thi cng phn tng bao ca tng hm trc sau tin hnh o t trong lng tng bao ny n y tng hm (y mng). Trng hp mng ca cng trnh l cc khoan nhi thi ngi ta cng tin hnh thi cng cc cng lc vi tng bao. Phn kt cu chnh ca tng hm cng nh ca cng trnh c thi cng t di ln trn, t mng n mi (Bottom-up). Ta c th gi y l phng php thi cng tng trong t. Phng php ny c u im rt ln l khng cn dng vn c gi vch h o. Trnh t thi cng cng trnh vn theo th t nh xa tc l xy t di xy ln. p dng c phng php ny th tng bao ca cng trnh phi c thit k bo m chu c ti trng do p lc t gy ra vi n ng thi n iu kin thi cng tng bao bng phng php "cc barret". Nhc im ca n l thi gian thi cng di v phi thi cng xong tng bao, cc (nu c) ri mi n o t v xy cng trnh. Nu trng hp tng bao

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khng t chu p lc th ta phi c bin php chng tng bng cc h chng hoc bng neo b tng. Trn hnh 3 trnh by 3 giai on thi cng theo phng php tng trong t t di ln : Giai on u (Hnh 3a) ta tin hnh thi cng tng trong t t di ln, giai on 2 (Hnh 3b) ta tin hnh o t trong lng tng bao v giai on 3 (Hnh 3c) ta tin hnh thi cng tng hm t di ln.

o t

a)

b)

c)Cc phng php chng tng bao : Tng bao y c chiu su kh ln, chu p lc t cng kh ln nn cc phng php chng n gin mc II.1 khng p dng c, nu c th tin cy cng khng cao. V vy ta phi dng cc bin php chng tng bao nh sau : a. Dng h o v ct chng vng gia cc tng i din (Hnh 4a). H dm ny

thng lm bng thp hnh gm cc x ngang, dm vng v ct chng x ngang t ln tng, tng chu p lc t (chu un). Dm vng l b phn chu lc chnh (chu nn) lm nhim v chng gi cc tng i din. Ct chng c nhim v gi cho dm vng n nh (gim chiu di tnh ton).

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H 4.a a1. Mbng hchng h o b hd ct nh t ng m

A

Ct chng b th ng p h nh

A D m T ng bao

a McA-A. Hgi chng 2. t t ng D m

Tha gi nh ng

Tha chng nh T ng ba o

Ct chng b th h ng p nh

Phng php ny c u im l n gin, d tnh ton, xung quanh rt tn vt liu lm x, dm, ct (c th thu hi 100%). Tuy nhin nhc im ca n l chim khng gian trong h o, khi thi cng, d b un vng gy kh khn cho qa trnh thi cng tng hm. Khi tng hm c thi cng xong th h chng ny s c d i v p lc ngang s chuyn vo khung nh (tng hm chu). Khi chiu ngang cng trnh ln th h chng tr nn phc tp v khong cch gia cc tng i din qu ln.

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TI NGHIN CU KHOA HC b. khc phc nhc im ca phng php trn ngi ta dng neo b tng gi

tng bao (Hnh 4b). Phng php ny c p dng khi ta cn khng gian thi cng trong lng h o. Vic t neo tu thuc vo lc cng m c th neo trn mt t hay neo ngm vo trong t. Trng hp neo ngm, khi o n u ngi ta khoan xuyn qua tng bao chn neo v c nh neo vo tng. Vi phng php ny tng gi vi ng lc trc nn hu nh l n nh hon ton. Khi tng hm c xy dng xong, tng c gi bi h kt cu tng hm, lc ny neo s c d i hoc li ty theo s tho thun ca ch u t vi cc cng trnh bn cnh. Nu tng bao h (khng lin kt vi kt cu tng hm) th cc neo s vn c gi nguyn v lm vic lu di, lc ny n cn c bo v cn thn.

t t nhin D neo y Mc n c ng m T h ng m x dng ang y

Neo y t ng hm

H 4b : Chng t ng bao bng hneo ng nh mTa thy c hai trng hp neo v chng u thi cng song song vi cng vic o t. o n u t neo hay t ct chng ti . Phng php ny tng bao hu nh khng chuyn v p lc t tc dng ln tng l p lc tnh. So snh gia hai phng php ta c th kt lun phng php dng ct dm chng h o d thc hin song n s gy nhiu cn tr cho thi cng trnh tng hm, ch cn nhng s sut nh c th xy ra s c ng tic. Vi phng php dng neo ngm m bo mt mt bng thi cng rng ri, thong ng song n i hi phi c thit k tnh ton neo v phi c thit b thi cng neo nh bm b tng, neo ng lc trc... phng php ny cho gi thnh kh cao ch nn p dng nhng cng trnh thc s cn thit n h neo ny.

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3. Phng php gia c nn trc khi thi cng h o : Khi cng trnh c thi cng nhng vng t ct, vic o t s gp kh khn v ct s l. Ngoi nhng bin php chng thnh h o nh nu trn ta cng c th p dng phng php gia c nn h o trc khi o t. N thch hp cho cng trnh co mt bng thi cng rng v chiu su h o khng ln. Ni dung ca phng php ny l trc khi thi cng o t ngi ta dng khoan v bm cao p pht va xi mng vo nn t xung quanh h o. Khi va xi mng rn chc s lm cho nn t c cng tng ln c th l tng h s dnh C v gc ma st trong ca nn t. Vi bin php gia c ny h o c th o thng ng hoc nghing theo gc kh nh.B xi mng ct m B xi mng ct m

V XM-ct a c b xung m o

H 6 : Gia c h tr c khi mng nh o o

u im ca phng php ny l thi cng n gin, gi thnh thp, to mt bng thi cng thong khng b vng bi h chng. Nhc im

Kh xc nh chnh xc cc thng s ca nn sau khi gia c. tin tng thp. i hi phi c mt bng xung quanh rng gia c vung c nguy c

trt.

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4. Phng php thi cng t trn xung (Top-down) : phn trn chng ta trnh by phng php thi cng tng chn bng phng php "Bottom-up" ngha l thi cng t di ln theo cc phng php truyn thng. Trong phng php ny gi cho tng chn n nh khng b bin dng ngi ta s dng h ct dm chng hoc dng neo ngm. C hai phng php u bc l mt nhc im rt ln l chi ph cho cng tc chng v neo kh cao, ko di thi cng v i hi cc thit b tin tin. khc phc n, ngi ta a ra phng php thi cng t trn xung (Top-down). Bn cht ca phng php ny l : Bc 1 : Thi cng tng trong t v cc khoan nhi trc. Ct ca tng hm cng c thi cng cng cc nhi n ct mt nn. Bc 2 : Ngi ta tin hnh sn tng trt ngang trn mt t t nhin. Tng trt c t ln tng trong t v ct topdown. Ngi ta li dng lun cc l cu thang my, thang b, ging tri lm ca o t v vn chuyn t ln ng thi cng l ca thi cng tip cc tng di. Ngoi ra n cn l ca tham gia thng gi, chiu sng cho vic thi cng o t... Khi b tng t cng yu cu, ngi ta tin hnh o t qua cc l cu thang ging tri cho n ct ca sn tng th nht (1C) th dng li sau li tip tc t ct thp b tng sn tng 1C. Cng trong lc t mt sn tng trt ngi ta tin hnh thi cng phn thn ngha l t di ln. Khi thi cng n sn tng di cng ngi ta tin hnh b tng y nh lin vi u cc to thnh sn phm di cng, c cng l phn bn ca mng nh. Bn ny cn ng vai tr chng thm v chu lc y ni ca lc cimt. C hai phng php thi cng sn tng hm : Dng h ct chng hm thi cng (t ln cc nhi) h dm v sn tng hm. Dng ct chng tm (thng dng trong thc t l thp hnh ch I c gia cng t vo cc nhi, sau khi thi cng ct xong th d b.

Mi phng n trn u bc l nhng u im v nhc im ca n, p dng c phi tnh ton mt cch cht ch v khng nhng n lin quan n thi cng m c gii php kt cu na.

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u im ca phng php Top-down : Tin thi cng nhanh, qua thc t mt s cng trnh cho thy c th thi cng phn thn cng trnh ch mt 30 ngy, trong khi vi gii php chng quen thuc mi tng hm (k c o t, chng h dm tm, thi cng phn b tng) mt khong 45 n 60 ngy, vi nh 3 tng hm th thi gian thi cng t 3 --> 6 thng. Khng phi chi ph cho h thng chng ph. Chng vch t c gii quyt trit v dng tng v h kt cu cng trnh c bn v n nh cao. Khng tn h thng gio chng, cppha cho kt cu dm sn v sn thi cng trn mt t. Nhc im ca phng php Top-down : Kt cu ct tng hm phc tp. Lin kt gia dm sn v ct tng kh thi cng. Thi cng t trong khng gian kn kh thc hin c gii ho. Thi cng trong tng hm kn nh hng n sc kho ngi lao ng. Phi lp t h thng thng gi v chiu sng nhn to 5. Phng php thi cng semi Topdown : Bn cht ca phng php ny l : Bc 1 : Thi cng tng trong t v cc khoan nhi trc. Ct ca tng hm cng c thi cng cng cc nhi n ct mt nn. Bc 2 : Vi phng n ny ta tin hnh ch thi cng mt phn sn tng trt ngang trn mt t t nhin .Tng trt c t ln tng trong t v ct topdown. Vi phn sn c thi cng c tnh ton khi cng thi c th chu c p lc ngang ca t . Ngi ta li dng din tch phn sn cha thi cng lm ca o t v vn chuyn t ln ng thi cng l ca thi cng tip cc tng di. Ngoi ra n cn l ca tham gia thng gi, chiu sng cho vic thi cng o t... Khi b tng t cng yu cu, ngi ta tin hnh o t cho n ct ca sn tng th nht (1C) th dng li sau li tip tc t ct thp b tng mt phn sn nh tng trt. Khi thi cng n sn tng di cng ngi ta tin hnh b tng y nh lin vi u cc to thnh sn phm di cng, c cng l phn bn ca mng nh. Bn ny cn ng vai tr chng thm v chu lc y ni ca lc cimt. Sau ta thi cng vch tng hm v cc phn sn cn li theo trnh t thi cng t di ln theo cc phng php thi cng bnh thng

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Mi phng n trn u bc l nhng u im v nhc im ca n, p dng c phi tnh ton mt cch cht ch v khng nhng n lin quan n thi cng m c gii php kt cu na. u im ca phng php Semi Top-down : Tin thi cng nhanh, sau khi thi cng sn tng trn th ta khng phi mt qua nhiu thi gian ch b tng cng yu cu thi cng o t tng hm di v ta c th thi cng o t ti nhng v tr sn cha thi cng V khng gian thi cng rng ri hn phng php thi cng topdown n thun . Nh vy s gip ta d dng hn trong vn t chc thi cng hn iu ny rt quan trong trong vic rt ngn tin thi cng. Khng phi chi ph cho h thng chng ph. Chng vch t c gii quyt trit v dng tng v h kt cu cng trnh c bn v n nh cao. Khng tn h thng gio chng, cppha cho kt cu dm sn v sn thi cng trn mt t.Nhc im ca phng php Semi Top-down : tng t nh phng php thi cng topdown.

Kt lun : Cng trnh Khu phc hp Nng Center l cng trnh c quy m ln c ch u t chia lm hai gi thu thi cng phn ngm v phn thn ring . Trong ti ny ta ch thc hin gi thu th nht l thi cng phn ngm : - Din tch sn tng hm 24994 - Quy m 4 tng hm - Chiu su o t 15,7 m Vi nhng phn tch trn v cng ngh thi cng tng hm th ta chn phng n thi cng tng hm theo phng php topdown hoc phng php semi topdown . la chn phng n hp l ta s t chc thi cng cho cng trnh theo hai phng n la chn phng n thi cng c thi gian thi cng ngn hn . v tnh chi ph xy dng cho hai phng n thi cng rt ra phng n c chi ph thp . Cui cng ta s kt hp hai yu t thi cng v kinh t chn phng n thi cng ti u cho cng trnh ny. CHNG 2 LP V LA CHN CC GII PHP K THUT - CNG NGH I. LA CHN GII PHP K THUT - CNG NGH TNG QUT 1. Cn c lp cc gii php k thut - cng ngh.

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- Da vo h s mi thu, p ng yu cu ca Ch u t vi cng trnh. - Da vo Lut u thu, cc ngh nh thng t vn bn hng dn lin qua, h quy chun, tiu chun xy dng Vit Nam, nc ngoi theo yu cu h s mi thu - H s thit k k thut, tin lng mi thu do bn mi thu cung cp. - Cn c vo a im xy dng, thc t mi mt ti khu vc thi cng, ln cn. - Cn c vo nng lc thc t ca nh thu . - Cn c vo chin lc cnh tranh ca nh thu . - Cn c vo hp ng kinh t c k kt gia Nh thu v Ch u t. 2. La chn gii php k thut - cng ngh tng qut : Cng trnh Nng Center l cng trnh dn dng cp I, phn ngm c quy m 4 tng hm .. Tng chiu su o t 15,7m , din tch mt bng xy dng l 5367,3m2, tng din tch sn 24994.2m2. Cc khoan nhi b tng ct thp , tng barret chn t bng b tng ct thp, chng thm bng ph gia hng Sika. Ngoi ra cng trnh cn c trang b cc h thng thit b k thut nh: thang my, h thng iu ha khng kh, h thng cp my tnh, cp in thoi, cp truyn hnh, h thng bo chy t ng, h thng cp in, cp thot nc, h thng phng chy, cha chy Cng trnh c xy dng nm v tr trung tm thnh ph, ba mt cng trnh tip gip vi ba tuyn ng ,mt mt gip vi nh dn. Cng trnh cn nm trn mt nn phc tp, c mc nc ngm cao . y l vn quan trng m chng ta phi quan tm trong vic la chn gii php cng ngh - k thut v t chc thi cng phi ph hp. Cng trnh c yu cu thc hin ng thi hn l 1000 ngy nh trong hp ng m bo c s dng cng nh kinh doanh ca ch u t. Do vy p ng yu cu ca ch u t th cng ngh thi cng c nh thu s dng thi cng cng trnh phi ph hp vi yu cu k thut c ra trong h s thit k. Cc loi my mc s dng trong thi cng cng trnh phi l nhng loi my hin i, c kh nng p ng vic thi cng phc tp ca cng trnh v c cng sut cao nhm m bo cht lng cng trnh. Qua vic phn tch nh gi tng qut v c im a cht khu t xy dng, v tr, quy m v c tnh s dng cng trnh cng nh kt hp iu kin thc t cng ty s a ra bin php v hng thi cng tng qut ca mt s cng tc chnh khi thi cng phn ngm cng trnh nh sau:

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2.1. cng tc trc t , o t , bin php chng thm: 2.1.1. cng tc trc t : - T chc nhn bn giao tim mc t Ban qun l cng trnh, C quan thit k, T vn gim st, vic bn giao ny phi lp thnh bin bn c ch k xc nhn ca cc bn lin quan. T c s tim mc bn giao t chc trin khai cc cng vic trc c k tip v lm c s nghim thu lu di trong qu trnh thi cng (lp bin php gi tim mc m bo thun li cho vic kim tra v s dng mc chun). Ngoi ra cn c cc cc chun xc nh trc nh v cng trnh. - B tr cn b trc a l 2 k s v 2 k thut vin c kinh nghim thi cng cc cng trnh tng t. - Vic chuyn tim ct c xc nh bng my kinh v, my thu bnh, my ton c in t, h thng dy cng, qu di, niv. - V tr cc tim ct v cc cao trnh khc c xc nh bng 2 my kinh v, 2 my thu bnh, 2 my ton c in t, h thng dy cng v qu di. - Tim ct cng trnh lun lun c kim tra trong sut qu trnh thi cng da trn cc mc c nh trn cng trnh v cc v tr ngoi cng trnh m bo kch thc v v tr theo thit k. - Trc khi thi cng cc cng vic phn sau phi c bn v hon cng cc phn vic lm trc nhm kp thi a ra cc gii php k thut khc phc nhng sai st c th c v phng nga cc sai st tip theo. Trn c s lp cc bn v hon cng phc v cho cng tc nghim thu thanh ton v bn giao cng trnh. Tt c cc dung sai v chnh xc cn tun th theo cc yu cu c qui nh trong cc tiu chun hin hnh c lin quan (TCVN 5724 - 1993, TCVN 5574 - 1991, TCVN 4453 - 1995) v cc quy nh v dung sai trong h s mi thu. 2.1.2. cng tc o t : - Thi gian thi cng: Thi cng vo ban m sau 20h ti, o t n u, vn chuyn t ht n . - o t gn tng khu. Khng o bng my ti cc v tr st mp tng vy, phn ny o th cng.

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- Cng tc o t tin hnh song song vi bin php top-down, chi tit xem bin php thi cng top-down v bn v. 2.1.3. Bin php h mc nc ngm , thot nc mt: S dng h thng rnh, h ga, my bm v ng kim lc h mc nc ngm v thot nc b mt. H thng ging lc ng knh nh b tr st nhau theo ng thng trn ton b mt bng. Nhng ging lc nh ni lin vi my bm chung. + Thit b Gm mt b kim lc, mt ng ht tp trung trong nc ni ng kim lc vi my bm. - My bm dng vi thit b kim lc h nng l my bm ly tm c chiu cao ht nc ln (8-9 m ct nc). - Kim lc l nhiu ng thp c ng knh nh di ti 10m gm 3 phn: on ng trn, on lc v on cui. - ng ht tp trung nc gm nhiu on ng thp lp rp vi nhau. Nhng ng ny c u t ni vi on ng thu nc. + Nguyn l hot ng - H kim lc thng ng sao cho u kim lc ng v tr thit k. - Dng ba g nh cho kim cm phn u vo t. Ming ng ht nc ni vi my bm cao p. - Cho bm nc vo trong kim lc, di p sut ln nc c nn vo trong kim lc, y van vnh khuyn ng li v nn van hnh cu xung, nc theo cc l rng nhn phun ra ngoi. Vi p sut ln, cc tia nc phun ra lm xi l t u kim lc, ko theo t, bn chy ln mt t. Do b xi u kim, t b no ra v cun i. Di sc nn do trng lng bn thn, kim lc t t chm xung su cn h. Khi ngng bm, nc ngm v t xung quanh chn cht kim lc. - Hot ng ca kim lc: ng ht nc ni vi h thng ng gom nc v ni vi bm ht. Khi bm ht nc ln, nc ngm ngm qua h thng lc vo y van vnh khuyn m ra, trn vo ng c ht ln. ng thi do p sut nc ngm, van cu ng li gi khng cho bn ct vo trong khu lc. 2.1.4. Bin php chng thm:

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Cng tc chng thm cho cc cu kin b tng c chng ti c bit lu trong sut qu trnh thi cng. a. Chng thm y tng hm : + Vt liu - SIKAPROOF-MEMBRANE: Mng mng chng thm n hi cao (khong 1,5kg/m2 cho 3 lp). - SIKA LATEX: Cht kt ni v ph gia chng thm cho va (khong 0,8lits cho 1 lp va dy khong 20mm). + Chun b - B mt b tng phi c lm phng, nhn. - Lm bo ho b mt bng nc sch (Khng ng nc). + Phng php thi cng - Qut 1 lp lt SIKAPROOF-MEMBRANE c pha long vi 20-50% nc bng bn chi hoc phun ln b mt cn chng thm (mt s dng 0,2-0,3 kg/m2). - i lp lt kh hn(t 1-2h) mi qut tip 3 lp chng thm SIKAPROOFMEMBRANE (khng pha nc vi mt s dng 0,6 kg/m2). - Lng 1 lp va SIKA LATEX dy 30mm lm lp bo v. b. Chng thm thnh tng hm : + Vt liu - SIKA LATEX + nc + xi mng (t l 1:1:4 theo khi lng) lm lp kt ni. - SIKA LATEX/nc (1/3 th tch) v xi mng/ct (1/3 khi lng) lm lp va trt. +Chun b - B mt b tng thnh tng hm phi c lm phng, nhn v bo ho nc. + Phng php thi cng - Qut 1 lp kt ni SIKA LATEX chng thm ln b mt b tng, i lp kt ni kh hn(t 1-2h) mi trt lp va SIKA LATEX.

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- Trt lp va SIKA LATEX (khong 40lt/m3 va) dy 30mm lm lp bo v. 2.2. Cng tc ct thp : 2.2.1. Cc c im thi cng chung cho tt c cc cu kin : - Thp trc khi dng phi c th nghim ko th vt liu xc nh cng thc t. Th nghim ny phi c s cng nhn ca gim st k thut v phi c cn b gim st k thut ng mi c s dng. Bin bn nghim thu cng tc ct thp ngoi ni dung nh: s lng, chiu di, ng knh v v tr t cn phi km theo chng ch mu th. - Ct thp c gia cng sn theo thit k ti xng, xp theo tng loai ng knh v b nh du vn chuyn ti v tr thi cng bng cu. Khi vn chuyn ct thp trong cng trng, nh thu s b tr cn b hng dn cng nhn cch bo v thp khi bin dng, h hi. Thp lun c bo qun cch mt t ti thiu 45cm. Thp c xp thnh l theo ng knh v c bng k hiu d nhn bit bng mt thng, d s dng. - Ti chn thit b nh cu thp s t bng bo s thanh ng vi chiu di v ng knh thanh thp cho php trong mt ln vn chuyn cng nhn bit v b buc ng qui cch. - Hn ni ct thp v cc chi tit t sn bng que hn E42 hoc loi c cng tng ng. - Ct thp phi v sinh sch trc khi a vo lp dng. - Buc cc con k c sn bng XM vi khong cch 300 - 500mm m bo chiu dy lp b tng bo v theo thit k.. - Ct thp ai ca cc cu kin phi c buc hoc hn vo ct thp ch chu lc. Tng loi ct ai phi o ct, un th kim tra li kch thc chnh xc, m bo chiu dy lp b tng bo v trc khi sn xut hng lot.. Khi hn, buc, mt phng ct ai phi vung gc vi trc dc ca ct thp. - Ct thp ch nh ra ngoi phm vi b tng phi c c nh bng thanh ngang trnh rung ng lm lch v tr thp ch. Khng b cong thp ch mi v tr. 2.2.2 Thi cng ct thp mng :

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- Trc khi lm thp mng cn kim tra cc trc nh v mng theo cc chiu ngang, dc v nh du bng sn ln b tng lt. - Gia cng ct thp mng ti xng v sau vn chuyn n cng trng bng xe chuyn dng, ct thp sau khi gia cng c b thnh b v nh s cng nhn d nhn bit v tr lp dng. - Trong qu trnh lp dng ct thp mng, phi c bit ch n thp neo ca u cc. Phi m bo chiu di neo ca thp ny. Nu khng phi hn ni. 2.2.3 Thi cng ct thp ct - Trc khi lm thp ct cn kim tra cc trc nh v ct theo cc chiu ngang, dc v nh du bng sn ln tng hoc sn. - Ct thp ct c ni buc. Khi ni buc ct thp Khng c trng qu 30% mi buc trn cng mt mt ct v phi c kim tra nghim thu trc khi thi cng phn tip theo. - Thi cng lp dng ct thp ct c th s dng th cng, kt hp vi cu dng treo thp trong khi c nh, buc v c nh ct i. Trc khi lp t ct thp cn phi dng cc thit b trc c nh v sn tim, mc , vch xung nn b tng. Sau khi c nh bng buc, iu chnh ct thp ch cho ng kch thc theo thit k ri mi buc ct ai. Sau khi lp t ct thp cho tng cu kin ct nh thu s li s dng thit b trc c kim tra li v tr, tim ct, mp ct trc khi nghim thu. - Trong khi thi cng lp dng ct thp ct phi s dng gio lm sn thao tc. Chn gio phi c neo vo sn. Sn thao tc phi chc chn, phi c lan can an ton cng nhn c ch ng v ta vng chc trong khi thi cng. - Buc cc du thp ch lin kt gia ct v tng theo thit k. - Ct thp ct l ct thp theo phng ng, hn na chiu cao ca thanh thp l ln nn trong qua trnh thi cng lp dng ct thp ct cn c bin php c nh ct thp theo phng ng. C th trong trng hp ny nh thu s s dng h thng cy chng thp n vng chng theo hai phng. 2.2.4 Thi cng ct thp dm : - Thi cng ct thp dm: v c chiu di v kch thc dm ln: khi lng thp cho mt dm rt ln chnh v vy khng th t hp ct thp dm di t ri cu ln ng v tr c m phi t hp thp trn sn v trn ng v tr.

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- Cu thp ln ng v tr thi cng. S dng h sn cng gia cng nh hnh k thp chnh ca dm, sau lng ct ai c gia cng sn vo, nh v tm mt vi v tr chnh ca ct ai ri tin hnh buc ct thp ai vo ct thp ch. - Khi hon thnh khung chnh ca ct thp dm mi tin hnh buc con k. Vic buc con k b tng phi tho mn chiu dy lp b tng bo v nu trn v phi m ba chiu dy lp b tng bo v l u . Con k phi oc buc cng v khng dch chuyn. - Sau khi hon thnh khung thp dm, dng con ln, kt hp vi cu dch chuyn ct thp dm vo ng v tr. Trong qu trnh dch chuyn c bit ch trnh va chm ct thp vo thnh cp pha. 2.2.5 Thi cng ct thp sn :- Thi cng lp thp di sn: Vic lp dng lp thp di hon ton tun theo thit k

v theo TCVN 4453-95. - S dng con k b tng vi li