Nghien CLFU u'ng dung he dam d a di
chuyen xuong du'6'i (BRD) trong thi cong tang ham nha cao tang
Tran Hong Hai Ho Ngoc Khoa
Le Minh
ABSTRACT
In the development of the construction industry in big cities in Vietnam nowadays, many buildings have been designed and constructed with multiple basements. One of the issues that addresses attention from scientists and practitioners the most is the selection of the construction method for constructing basements in order to maintain project's requirements of safety, quality, time, and cost effectiveness. Every building has its own features of soil profiles and water tables. As a result, the selection of the construction method used in the construction of basements will vary.
This report will explore the construction method used in the construction of basements in the Lotte Center Hanoi project utilizing the Bracket Supported RC Downward technique. The report will also propose a construction procedure for this technique. The results obtained will be used as the basic for further studies to apply to the construction conditions of Vietnam.
TS Tran Hong Hai
Khoa Xay dimg, DHXD Ha Noi TS H6 Ngoc Khoa
Khoa Xay dung, DHXD Ha Noi KS Le Minh
Vien Khoa hoc cong nghe xay dung
MGI dau
Tfi6i gian qua, trong xu the fioi nfiap va toan cau hoa, kinh te - xa hpi cua dat nudc da CO nhQng bucifc phat trien manh me ve moi mat, dac biet trong cac llnh vi/c thuong mai, dau tir san xuat va phuc vu dan sinh. Su phat trien trong linh vuc dau t u xay dung co ban cung khong nam ngoai dong chay do va tat yeu la nhu cau ve dien tich xay dung cho muc dich 6, cho thue, van phong, thuong mai va dich vu ngay cang tang ca ve so lupng lan chat lupng. Kinh nghiem xay dung cua cac quoc gia tren the gidi da chCfng to r i n g vdi viec gia tang nhanh chong cua gia tri dat xay dung thi phuong an hieu qua nhat dudi goc dp kinh te cua dau t u la gia tang so tang cao va phat trien cac tang ham xuong long dat.
Mpt dac trUng co ban cua cac cdng trinh cao tang d cac thanh pho Idn cua Viet Nam la thi cdng trong dieu kien chat hep, xung quanh deu cd cac cdng trinh kien true va he thdng ha tang ky thuat dang sd dung, gay khd khan cho viec lua chpn giai phap thi cdng hd dao sau khi thi cdng xay dung tang ham cac cdng trinh nay. Ngoai nhufng khd khan ve t d chijfc thi cdng, van chuyen dat, khi thi cdng hd dao phai giai quyet cac van de anh hudng den trang thai dng suat bien dang cua dat nen xung quanh, cd the lam chuyen dich va lun, gay hu hdng cho cdng trinh dang thi cdng va cdng trinh lan can [1].
Ngoai ra, moi cdng trinh deu cd nhijng dac diem rieng ve cau tao nen dat, mat cat dja chat, cao dp muc nudc ngam, dac diem vj tri nen viec Ida chpn bien phap thi cdng cho phan ham cung rat da dang. Van de duoc cac chu dau t u va nha thau quan tam la lua chpn phuong phap thi cdng tang ham dam bao an toan, chat Idpng, tien dp va hieu qua kinh te.
Theo cac sd lieu cua nhieu nghien cdu [1, 2, 6], phuong phap thi cdng tang ham t d tren xuong (TOPDOWN) se gid on djnh dUdc hd dao trong sudt qua trinh thi cdng, han che dupc bien dang va lun ndt dang ke chp dat nen va cdng trinh lan can. Trpng phUPng phap TOPDOWN xay dung tang ham cd nhieu giai phap thi cdng van khudn va cpt chong cho san be tdng cpt thep. Sd dung he dam d d di chuyen xuong dudi BRD (Bracket Supported RC Downward) iam he chong dd van khudn la mdt phddng phap cd nhieu du diem vUdt trdi ve dp an toan, tien dp va chat Idpng, dac biet trong cac cdng trinh nhieu tang ham. PhUdng phap nay da duoc sddung de thi cdng 5 tang ham cdng trinh Lotte Center Hanoi. Day la cdng nghe mdi, lan dau tien duoc sd dung trong thde te thi cdng d Viet Nam. Do dd, viec nghien cdu sd lieu thde te, phan tich, tong hop de de xuat qui trinh cdng nghe va chi dan ky thuat thi cdng d mdc dp CO bcin lam CO sd ap dung cho cac cdng trinh tuong t d la het sde can thiet va ed y nghTa thde tien eao.
1 . Khai quat ccr ban cdng nghe BRD (Bracket Supported RC Downward) thi cong san be tong tang ham trong phi/orng phap TOPDOWN
7.7. Thi cong tang hdm theo phuang phdp TOPDOWN
Theo phuong phap TOPDOWN, san cac tang ham duoc thi cdng t d tren xudng. Trinh t d thi cdng cua phUdng phap nay nhu sau: thi cdng cpc khoan nhdi va dat edt chong tam; thi cdng tddng trong dat; thi cdng dam san tang ham mdt (tren eung); chd be tdng san dat cudng dp, thao van khudn va he cot chong; dao dat tang ham mpt; thi cdng dam san tang ham hai. Sau dd, cac qua trinh cdng tac dddc lap lai den tang ham cudi cung. Sau khi thi cdng xong dam san tang ham t h d nhat, cd the tien
08.2012 SBHUiffll 7 3
hanh thi eong song song eac tang ham va cac tang npi d phia tren de day nhanh tien dp xay ddng [5, 8]. Ngoai viec han che anh hudng gay ndt, bien dang cho cac cdng tnnh lan can, phdong phap nay cd kha nang giam bdt djch chuyen cua dat xung quanh hd dao bang viee tap ra he ehdng can doi chp tudng ehan tai tdng cap trinh moi tang san vdi dp cdng dan hpi Idn.
IVIat khae khdng phai thi cdng he neo trong dat hoac he chong do trong Idng hd dao nhd trong phdong phap dao md, thi cdng t d d d d i len [T].
Trong qua trinh thi cdng, dat dddc dao bang cac may dao kich thddc nhd, van chuyen len bang gau thung thdng qua cae 16 md. Doi vdi cae cdng trinh Idn cd nhieu tang ham, khdi Idpng dat dap Idn, ngpai cac 16 md, ngudi ta thddng de mpt 6 m d e d kich thudc Idn gida san, du thuan Ipi cho viec thi cdng dap dat, dua dat len, cung nhu viec dua vat lieu, thiet bi xudng de thi cdng tang ham.
7.2. Thi cong vdn he vdn khudn cot chong ddm sdn tdng hdm
Thi cdng dam san be tong toan khoi cua cae tang ham, ke ca tang ham tren cung, bao gom cae cdng tac sau: thi cdng van khudn, edt ehdng; thi cdng edt thep; do be tdng dam san.
Can phai nhan thay rang, cdng tae thi cdng van khudn, edt ehdng cd nhdng van de khd khan, gay anh hddng den chat Idpng, tien dp va an tPan trpng thi cdng, nhd sau:
- Cpt ehdng ddpc dat tren nen dat, vi vay can ph^i CP bien phap ehdng lun chp he cpt ehdng. Thuc te thi cdng chp thay dp sd phdc tap ve nen dat trong cac khu dd thj va mde nddc ngam cao gay khd khan va tdn kem cho cdng tac gia ed nen dat. Trong nhieu trddng hpp vdi nen dat yeu, ph5i ap dung eac phddng phuong phap ddng cpc tre, dem da dam, da hdc. Trpng mpi trudng hpp, nguy cd mat dn dinh he ehdng, einh hddng den chat luong eau kien va an toan thi cpng la rat cap.
- Chi ed the dat van khudn dam san true tiep len nen dat vdi dieu kien: nen dat tdt, khd rap. Trong trudng hdp nay viec gia cd nen va phuong an thi cdng cung phai ddpc tinh tpan, thiet ke chat che, ddpc phe duyet thep qui djnh.
Nen dat p h i i ddpc gia cd dn djnh, dam bap dp cdng, khdng lun, phai dddc dam chat, do be tdng hoac lat gaeh. Cang xudng eac tang ham sau hdn, bien phap gia cd nen dat eang khd khan hon. Tren thde te rat it cdng trinh ap dung ddpc bien phap nay.
- Cdng tae dao dat tang ham chi cd the bat dau sau khi be tdng dam san du cddng dp cho phep thao he edt chong. Thdi gian chd dpi be tdng dat cddng dp cdng vdi thdi gian thap dd, van chuyen van khudn, edt chpng lam eham thdi diem bSt dau thi cdng dao dat, anh hddng den tien dp ehung eua cdng trinh.
Ap dung cdng nghe BRD (Bracket Suppprted RC Downward) dam san be tdng edt thep cac tang ham cdng trinh se khSc phye
duoc nhdng van de neu tren, rut ngan ddoc tien dp thi cdng, dam bSo an toan, chat Idpng cdng trinh va ed kha nang ap dung rdng rai ddi vdi mpi dieu kien nen dat.
1.3. Khdi qudt ca bdn cong nghe BRD (Bracket Supported fiC Downward)
cot chong tam
ban ma lien ket
li
Hinh 1. Cau tao ban ma lien ket va goi ctS cija he BRD Cdng nghe BRD (Bracket Supported Reinforcement Cpncret Downward), duqc hieu la "dam dd di chuyen xudng dddi" thi cdng be tdng dam san tang ham trong phdong phap thi cdng t d tren xudng (TOPDOWN). Ban chat cua cdng nghe nay la sd thay the he edt chong van khudn dam san tang ham bang he dam d d lien ket qua cac gdi tda tren cae cpt ehdng tam. Sau khi be tdng dam du cddng dp, he dam d d se ddpc di chuyen xudng dddi den cap do thiet ke de phuc vu chp viec dp be tdng dam san tang ham tiep thep.
Cpt ehdng ehdng tam bang thep hinh thiet dien ehd H thi cdng cung vdi cpc khpan nhdi. Sd Idpng va kich thddc thiet dien cpc chong ddoc tinh toan dam bao on dinh eua tang ham trong sudt qua trinh thi cdng. Ket thuc qua trinh thi cdng cpc nhdi va tudng vay, dat tang ham t h d nhat dddc dao den cap dp thiet ke phu hdp cho viec lap ddng he dam dd. Dau tien cae ban ma dd toan bd tai trpng eua be tdng dam san, ban than he dam va cae Ipai tai trpng khae, bap gdm tai trpng thi cdng dddc lap ddng vdi cpt ehdng tam qua lien ket buldng. Gdi d d eau tao t d hai
toan bd tai trpng dam san be tdng tang ham va tai trpng thi cdng. Tren he dam dd lap ddng xa gd d d van khudn dam. Sau khi lap ddng van khudn day va thanh dam, van khudn san se lieri ket vdi van khudn thanh dam va cac gdi tiTa bd sung chay doc van thanh dam tren he xa gd da thi cdng (hinh 2). Van day dam thddng la van go ep, de tach rdi khdi be mat be tdng sau khi be tdng ddng ran. Tam van khudn san la loai tam chuyen dung bang hpp kim cd gia cddng cot thep de tang dp cdng. He tam khudn nay sau khi che tap, lap dat phai dam bao dn djnh, khdng bien dang dddi tai trpng cua san be tdng, ban than va tai trpng thi cdng ma khdng can he cpt ehdng dd. Sau khi be tdng ddng ran, tam se lien ket vdi be tdng, lam viec eung be tdng, khdng thao dd ra.
xa do van khu goi tua bo s
van knuon d
Hinh 2. Cau tao dam iS va van khuon dam he BRD Sau khi lap ddng xong van khudn dam san, cpt thep ddOc thi cdng theo thiet ke. Vdi muc dich lam tang sd lien ket gida cpt ehdng tam va be tdng dam, eac neo bang dinh thep ddpc han gia CP xung quanh cpt d vj tri tiep xue vdi dam be tdng. Cdng tae dp be tdng ddoc thde hien bdi may bdm be tdng qua cac 16 m d thi cdng.
De qua trinh bdm be tdng dddc thuan Ipi, ngddi ta sddung phu gia bdm va phu gia hda d^o de tang dp Idu ddng eua vda. He dam san cd the d dang san bdn eanh dam hoac san 2 canh dam (hinh 3).
Hinh 3. Be tong dam san tang ham sau thi thi cong bang he BRD bp phan: 2 ehan gdi ddtda vao ban ma, lien ket vudng goc vdi 2 dam gdi dd bang thep hinh thiet dien chdi.Toan bpgdi dded the trddt djch chuyen theo than cpt tam (hinh 1).
Dam d d BRD cau tao t d hai dam thep hinh thiet dien chd I cd gia cd ban bung va lien ket cdng vdi nhau bdi cae giang ngang. He dam dd tda tren cac gdi d d thay the he cpt ehdng, chju
Sau khi cdng tac dd be tdng ket thue, tiep tue cdng tac dao dat dddi tang ham t h d nhat.
Cap dp dao dat thap hon cao dp san eua tang ham t h d hai, dam bcip viee thi cdng lap dat cae ban ma lien ket, cdng tac ha he dam dd di chuyen xudng dddi va eac cdng tac thi cdng khac sau dd ddpc thuan Ipi.
De phuc vu viee di chuyen he dam 6cl
7 4 8<Bnill19V 08.2012
xudng dudi, cac tdi xich dddc lap dat d trong cpt ehdng tam va tren cac he khung neo, dpc thep chieu dai cua dam dd, phia tren san tang ham da thi cdng. 56 lupng tdi xich xac djnh tren tong tcii trpng trong qua trinh di chuyen he dam dd va tJi trpng nang cua mdt tdi xich. Sau khi be tdng dam dat cddng dp thiet ke chP phep, he dam d d (bao gom c i xa gd) se tach khdi van day cua dam va di chuyen nhip nhang xudng dudi dpc theo than cpt ehdng tam bdi cac tdi xich, den cao dp cac ban ma lien ket da lap ddng. Cac cdng tae tiep theo lai dupe lap lai theo qui trinh tdOng t u de thi cdng be tdng dam san tang ham thd hai va tiep tue den san tang ham cuoi cung.
2. Nghien cuTu thUc te thi cong phan tang ham cong trinh Lotte Center Hanoi iJIng dung cong nghe BRD
2.7. GIO'I thieu cong tr'inh
Hinh 4. Mat bang thi cong CT Lotte Center Hanoi Cdng trinh Lotte Center Hanoi do Cdng ty TNHH Coralis Viet Nam lam chu dau td. Td van q u i n ly d d an: Cdng ty Lotte CIVl. Td van thiet ke (3 cdng ty): Doul International., LTD; Hankook Consulting structural Engineers, LTD va Saegil E&C Co., LTD. Hanil Mech Elee, Consultants. Td van giam sat: Vien KHCN xay ddng (IBST). Qui md cdng trinh: dien tich dat d d an - T4.094m^
dien tich san xay ddng - 8.827m', 65 tang ndi vdi chieu cao 267,05m va 5 tang ham (hinh 4).
Phan tang ham cua cdng trinh dddc thi cdng theo cdng nghe BRD.
2.2. Bien phdp thi cong phdn tdng hdm Ung dung cdng nghe BRD
2.2.1. Cdng tac dao dot
Cong tac dao dat tang ham ehia lam 6 giai doan, phdi hop chat che vdi qua trinh thi cdng be tdng dam san va chu trinh di chuyen he dam d d xudng dddi. Oat dddc van chuyen len bang gau - can true qua 4 16 m d va mpt khoang m d Idn d t r u n g tam cdng trinh.Tong khdi Idpng dat dao dat khoang 270.000m'.
Dot dau tien, dao dat tang ham den edt -2,000mm, tao dieu kien thuan Ipi cho viec van chuyen vat lieu, may, thiet bj thi cdng va lap dung dam d d (hinh 5). Cae dpt tiep theo chieu sau dao dat tdong ddong chieu cao tang ham tdong dng. Cot dao sau nhat d khu vdc dai mdng trung tam la -21,900mm.
2.2.2. Cong tdc lap dung he dam do Trddc khi lap dung he dam dd, tat ea che cdng tac chuan bj ve mat bang, may thiet bj, he thdng ky thuat phue vu thi cdng phai dddc hoan tat. Thd t u va qui trinh lap dung tuan thu theo ban ve phddng an thi cdng dupc thdng qua.
Dau tien cac ban ma thep day 21mm dddc lap ddng vao cac edt ehdng tam bang lien ket bu long ket hop han. Gdi d d va dam d d che tao t d thep hinh thiet dien chd I, nhap khau t d Han Qude. Kich thddc thiet dien gdi dd: 400x200x9x14mm va 600x200x11x17mm;
dam dd: 600x200x11x17mm. Dam d d ngang, dpc deu dddc lap ghep len gdi tda. Viec dao dat thap hon edt san khoang 2m tao dieu kien thuan Ipi chp viec van chuyen cau kien den vj tri lap ghep va cau lap cau kien vao vj tri lap ghep true tiep t d xe van chuyen (hinh 6, 7). He dam d d lien ket vdi tddng vay d nhdng vj tri dupc xac djnh trudc thep thiet ke bang bu Idng qua mpt ban ma han vdi ban thep dddc eau tap va dat sSn khi thi cdng tddng.
liii^
Hinh 6. Lap diing goi tUa len ban ma lien ket
2.2.3. Cong tdc Idp dung vdn khudn dam san Xa gd dd van khudn dam dang hpp t d hpp kim nhdm, kieh thddc thiet dien 150x150mm, bdde xa gd 200mm. Van khuon dam sd dung van gd ep, van thanh dddc gia cudng khung thep dam bao dn dinh trong qua trinh do va ddng ran be tdng (hinh 8).
Van san la tam NT Deck b i n g tdn ma phang chieu rdng 600mm, chieu dai thep nhip san (6-^8m), dupc tang cdng bang khung sddn edt thep chay doc theo chieu dai tam tdn. Van san ddpc ke, lien ket len van thanh va cac gdi tda bd sung chay tren he xa go va song song vdi thanh dam. Dp cdng cua tam van san phai dddc tinh toan dam bao ehju dddc tai trong cua san be tdng, tai trpng ban than va cac tai trpng khac trpng qua trinh lap ddng va dp be tdng den khi be tdng phat trien du cudng dp chju Idc (hinh 9).
Hinh 5. Cao dat thi cong san tang ham thiJ nha't Hinh 7. Lap dung he dam do len goi tiia
I .. . J i: ,..;.ii__\:
Hinh 9. Lap dat tam khuon san (tam NT Deck) Sau khi lap ddng xpng he van khudn dam san, cdng tae lap dat edt thep, do be tong va bao dddng be tdng thde hien theo dung thiet ke va qui trinh ky thuat. Be tdng sd dung cho dam san la be tdng cd cap dp ben 30MPa, sd dung phu gia hda deo va phu gia ddng ran nhanh, dp Idu dpng (hay dp xde con) la 400-i-600mm. Sau 07 ngay, theo kiem tra thde te thi cdng, cddng dp be tdng dam san dat 95% cddng dp thiet ke, cdng tae ha he dam d d di chuyen xudng dddi ddpc tien hanh.
2.2.4. Cong tdc hg he dam da di chuyen xuong dudi
Sau khi do be tdng dam san, tiep tue cdng tac dap dat tang ham t h d nhat va t h d hai, dddi tam san viia 66 be tdng xong. Cao dp dap dat
08.2012 B^EiniiiifiX 7 5
Bang I.Chi dan bien Stt
1
2
3
4
5
6
7
8
9
10 Cong tac Thi congcockhoan nhoi, dat cot chong tam.
Thi cong tifdng vay, dat cac chi tiet lien ket, ban ma, thep cho.
Oao dat den cao dp thiet ke.
Lap dat he dam dS.
Lap difng van khuon dam tang ham.
L3p difng van khuonsantang ham.
Lap cot thep dam san tang ham.
06 be tong dam san tang ham.
Treo buoc he dam dd vao cac tdi xich.
Ha he dam dd xuong cao dp thi cdng mdi.
p l i a p , l<y t h u a t t h i c o n g t a n g h a m
Noi dung l.Oinh vi.
2. Thi cdng cpc khoan nhoi.
3. fiat cot chong tam vao cpc nhoi trong qua trinh do be tdng coc.
l.Dinhvi 2,Thic6ngti/dngvay.
3. fiat tru'dc cac chi tiet lien ket, ban ma, thep chd trong ti/dng vay.
1. Dao dat den cao dp thiet ke.
2. Van chuyen dat.
3. Thoat ni/dc ho dao.
4. Gia CO nen dat (neu can thiet).
1. Gia cdng ban ma, chi tiet; to hop goi dd, dam 6i!.
1. Van chuyen den vi tri lap dat.
3. Lap dat ban ma lien ket vao cpt chong tam.
4. Lap dat goi ddtira tren ban ma lien ket.
5. Lap dat dam dd len goi dd, 6. Kiem tra, nghiem thu.
1. Gia cdng xa go, tam khudn.
2. Lap dat xa go tren dam dd.
3. Rai van day dam.
4. Lap dat van thanh dam.
5. Kiem tra, nghiem thu.
1. Van chuyen tam van san den vi tri thi cdng.
2. Lap dat van san.
3 Kiem tra, nghiem thu
1. Van chuyen cot thep den vi tri thi cdng.
2. Lap dat cot thep dam san.
3. Kiem tra, nghiem thu.
l.ChetaoviJabetdng.
2. V/c viJa den vi tri do be tdng.
3.D6, sangatvOa.
4. Dam be tong.
S.Baodi/dngbetdng.
6. Kiem tra, nghiem thu.
1 Xac dinh VI tri treo budc.
2 Treo budc he dam vao tdi xich.
3. Kiem tra
1. Kiem tra tong the he thong.
2. Kiem tra, xac dinh ci/dng dp be tdng.
3. Cat, giai phong ban ma khoi cot chong, tt/dng vay.
4. Dimg tdi xich ha he dam dd di xuong.
5. Can chinh he dam dd tai vi tri ban ma mdi.
t h e o phiTcfng p h a p BRD
Chi dan bien phap, ky thuat thi cong -Phe duyet phuong an thi cdng
- Cdng tac thi cdng cpc nhdi thuc hien theo TCVN 3262004 Coc khoan nhoi - Tieu chuan thi cdng va nghiem thu [3] va cac tieu chuan khac phu hpp.
- Thi cdng cpt chong tam dam bao tim cot, cao do va chieu sau ngam vao coc nhoi.
-Phe duyet phifpng an thi cdng
- Cdng tac thi cdng tudng vay thirc hien theo chi dan ky thuat thi cdng [7] va cac tieu chuan khac phii hop.
- Cac chi tiet, ban ma dam bao dung vj tri, cao dd va cau tao theo thiet ke.
- Phe duyet phucrng an thi cdng
- ficrt 1 dao den cot -2,000 so vdi cot mat san tang ham 1.
- Cac dot tiep theo dao theo tien dp thi cdng be tdng dam san tang ham.
- Cao dp dao tt/ng dot theo PA thi cdng, dam bao thuan lai cho cdng tac thi cdng ha he dam dd va an toan cho tifdng vay.
- fiao dat bang may dao loai nhd, van chuyen dat bang gau nang va cac thiet bj v/c khac phti hop.
- Phai cd bien phap thoat nifdc hd dao va gia co nen dat neu can thiet (ranh thu -f- bam, ha mifc nifdc ngam, ddng cpc tre,demdadam,demcat...)
- Xac nhan ban ve thiet ke ket cau, thiet ke mat bang he dam dd.
- Xac nhan xuat xii, chiing loai vat lieu, phifong thifc che tao, ke hoach va bien phap van chuyen.
- Phe duyet phifong an thi cdng.
- Lap dat ban ma vao cpt chong tam (lien ket bu long, han) va han ban ma vao chi tiet trong tifdng vay dung cao dp thiet ke.
- Kiem tra cao dd, dp nghieng, moi han ban ma.
- Lap dat goi, dam do bang can true. Dam dd lien ket vdi ban ma tifdng vay bang bu Idng.
- Kiem tra chat lifpng lien ket, cao dd, dp nghieng cua he dam dd.
- Xac nhan ban ve ket cau va cau tao van khudn dam.
- Xac nhan xuat xiJ, chung loai vat lieu, phu'ong thifc che tao.
- Phe duyet phifpng an thi cong.
- Thi cdng lap difng van khudn dam theo TCVN 4453:1995 Ket cau BT va BTCT toan khdi. Tieu chuan thi cdng va nghiem thu [4] va cac tieu chuan khac phii hop.
- Kiem tra chat lifpng, cao dd, kich thu'dc, dd on dinh van khudn dam.
- Xac nhan ban ve ket cau va cau tao van san.
- tii nhan xuat xif, chung loai vat lieu, nghiem thu.
- Phe duyet phifOng an thi cong.
- V/c tam san den vi tri thi cdng bang can true.
- Lap difng goi dd bo sung van san, tren xa go van khudn dam.
- Lap difng van san, lien ket vdi van thanh dam va gdi dd (lien ket khoan dc vit).
- Thi cdng van khudn san theo tieu chuan cua nha san xuat tam san va cac tieu chuan khac phu hdp.
- Kiem tra chat lifOng, cao dd, dd on dinh van khudn san.
-Xac nhan ban ve ket cau.
- Xac nhan xuat xu', chiing loai vat lieu, nghiem thu.
- Phe duyet phifOng an thi cdng.
- Van chuyen cot thep len san bang can true.
- Han cac ban ma va dinh vao cpt chong tam d vi tri lien ket vdi dam san be tdng theo thiet ke.
- Thi cdng cot thep theo [4] va cac tieu chuan khac phii hop.
- Kiem tra chat lifong, mdi ndi, neo cot thep.
- Phe duyet phi/ong an thi cdng.
- Hoan thanh cdng tac chuan bl.
- Vifa be tdng che tao theo thiet ke cap phoi.
- V/c vda bang can true, may bom be tdng.
- Thi cdng do be tdng theo [4] va cac tieu chuan khac phii hop.
- Bao difdng be tdng dung qui trinh ky thuat.
- Thifc hien cdng tac kiem tra chat lifong trong sudt qua trinh do be tdng.
- Han chi tiet b cpt chong tam, thi cdng gia chong tren san de treo tdi xich.
- Lap dat tdi xich vao vi trL
- Treo budc he dam dd vao tdi xich dung vi tri.
- Kiem tra chat lifong tdi xich, an toan treo budc.
- Kiem tra chat lifpng ban ma ddtai vi tri mdi.
- Kiem tra cac vl trf neo budc, dp an toan cua toan bd he thdng, mat bang thi cdng.
- Kiem tra, xac nhan ci/dng dp be tdng cho phep di chuyen he dam dd theo thiet ke.
- Kiem tra sif sin sang lam viec cua cac tdi xich.
- Chi huy viec ha he dam dd bang hieu lenh thong nhat - Viec ha dam dd dam bao nhip nhang, eham, deu.
- Kiem tra dd on dinh, can bang cua he dam ddsau khi ha xuonq ban ma d vj tri mdi.
7 6 iSSSniKil^'^ 08.2012
den dddi edt san tang ham thd hai khpang 2m, dam b^p khdng gian thuan Ipi eho viec thi cdng ha he dam dd. Sau dd lap ddng cac ban ma lien ket cho gdi dd theo dung vi tri va cao dp thiet ke.
Hinh 11. He dam d8 di chuyen xuong duiii den vi tri ban mads chd san
Mdi mpt dam gida hai cpt chong tam dddc ha xudng bdi 2 tdi xich tai trong 10 tan, dupe lap dat trong cpt (hinh 10) va d dau dam, gan vi tri lien ket vdi tudng vay. Bdi vdi cac dam dd ed nhjp Idn, bo sung them mpt tdi xich treo bupc vdi dam qua 16 dat san d khpang gida dam. Tdi xich dddc lap dat tren khung gia lien ket vdi san be tdng. Tdi xich d edt ehdng tam trep budc vdi he dam d d tai gpi dd, tdi xich dat tren san be tdng theo bude tai vi tri ban tren cua dam.
Sau khi treo budc he dam vdi tdi xich, kiem tra dp dn djnh, chae chan, an tpan cua tPan bp he thdng, cac ban ma lien ket bj cat bd, cac gdi dd ddpc giai phdng, eac tdi xich ha dan, nhip nhang tdng he dam dd, bao gdm gdi dd, dam dd, xa go d d van khudn dam xuong vj tri cua ban ma mdi, cd the ha cung luc he dam d d cua mdt 6 san. Chu trinh dddc tien hanh den khi tpan bd he dam d d be tdng dam san cua tang ham t h d nhat ddpc di chuyen xudng dddi va lap dat tai vj tri thi cdng mdi, cd nhu vay den khi thi cdng den san tang ham eudi cung - tang ham t h d 5 ( h i n h l l ) .
Tren thde te, tien dp thi cdng be tdng dam san tang ham t h d nhat (khdng tinh cdng tae dao dat) la 42 ngay, cac tang ham cdn lai la 32 ngay
3. Qui trinh cong nlie va chi dan thi cong be tdng dam san tang ham theo phirong phap BRD
Thi cong cpc khoan nhoi. dat
cpt chong tam
L i p du'ng van khuon dam tang
ham 1
Dao dat tang ham den cao dp
thi^t ke
Thi cong tu'ong vay, dat cac chi t i i t lien ket
L^p dyng van khuon san t&ng
ham 1
Treo buoc he dlim do* vao cac
toi xich
Dao dat den cao do yeu cku
Lap dat c6t thep dam san l i n g
hSm 1
Ha he d i m da xu6ng cao do thi
cong mo'i
L i p dat h$ d i m do
Do be tong dam san t i n g h i m 1
Lap laj chu trinh thi cong cho den t i n g ham cuoi
H'mh 12. Qui trinh cong nghe thi cong tang ham theo phuong phap BRD Tren ket qua nghien cdu tai lieu va sd lieu
thde te thi cdng, qui trinh cdng nghe CO ban thi cdng tang ham cdng trinh theo phddng phap BRD (Bracket Supported RC Downward) dupc tong hpp va de xuat d dang sd dd khdi d hinh 12. Chi dan bien phap, ky thuat thi cdng the hien d ndi dung bang 1.
Ket luan, kien nghj
Cdng nghe he dam dd di chuyen xudng dddi BRD (Bracket Supported RC Downward) thi cdng be tdng edt thep dam san tang ham trong phddng phap TOPDOWN la mdt cdng nghe mdi, uu diem ndi trdi cua nd the hien d nhdng diem sau: an tpan cho tddng vay va cac cdng trinh lan can vi giam ddpc sd chuyen vj;
an toan chp cdng trinh va ngUdi thi cdng vi sd chSc ehan cua he dam dd so vdi he van khudn cpt ehdng truyen thdng; day nhanh dddc tien dp thi cdng dp chii dpng trpng cdng tac dap dat, khdng phai ehd dpi thap edt chong; dam bao chat Idpng eau kien thi cdng (chat lupng be tdng, dp thang, phang cua dam san...).
Tuy nhien, cdng nghe BRD ehi hieu qua khi ap dung ddi vdi cdng trinh cd nhieu tang ham (3 tang trd len). Bien phap thi cpng ddi hdi phai tinh toan thiet ke ehi tiet. Trpng qua trinh thi cdng phai thde hien cdng tae kiem tra, kiem spat lien tue ve dp an toan, on djnh eua toan he thdng, dp ngieng cua ban ma, gpi dd, dam dd, chat Iddng cae mdi lien ket. Chi mdt sai sdt nhd ed the dan den mat an toan nghiem trpng cho cdng trinh va ngddi thi cdng.
Ngoai ra, gia thanh cua phdong phap edn cap do cau kien gdi, dam, tam khudn san chUa san xuat ddpc trpng nddc, phai nhap khau.
Cdng nghe m.di nen kinh nghiem thi cdng, quan ly ehda cd, do dd edn phai phu thudc vao nha thau nddc ngoai.
De CO the lam chu va dng dung hieu qua cdng nghe BRD vao thi cdng tang ham cac cdng trinh d Viet Nam, cac vien, trddng, cd sd nghien cdu can dau tU nghien cdu cdng nghe d mdc dp qui md hdn, dac biet la cac phddng phap tinh toan, thiet ke thi cdng. Cd the hdp tac vdi cac ddn vi nddc ngoai ed kinh nghiem ve thi cdng BRD de nghien cdu va chuyen giao cdng nghe
thi cdng. Cac don vj san xuat cau kien xay ddng can nghien edu ehe tao he dam dd va tam van khudn san khdng thao ddtai Viet Nam, tiet kiem ddpc chi phi so vdi nhap khau va ehu dpng ve thdi gian thi cdng. Van de sd dung cdng nghe BRD thi cdng tang ham phai dddc xem xet ngay trpng giai doan lap d d an va thiet ke ky thuat cua cdng trinh.
TAI LIEUTHAM KHAO
1. Oo flinh fiurc, Le Kieu (2004), Ky thuat thi cong. Nxb Xay dirng, Ha Npi.
2.06 Oinh Oac (2002), Thi cong ho dao cho tang ham nha cao tang trong Jo thi Viet Nam. Luan an tien sy ky thuat. Ha Noi.
3. TCVN 326:2004 Coc l<hoan nhoi - Tieu chuan thi cong va nghiem thu. Nxb Xay dung. Ha Noi.
4. TCVN 4453.1995 Ket cau be tong va be tong cot thep toan khoi.
Tieu chuan thi cdng va nghiem thu. Nxb Xay dung, Ha Ndi.
5. Trjnh Quoc Thang (2005), Khoa hoc cdng nghe va to chile xay dung. Nxb Xay dung, Ha Noi.
6. Nguyen Khac Tuan (1994), Tong l(et cdng nghe thi cdng phan ngam cac cdng trinh nha cao ting taiTp. Ho Chi Minh. Oe tai khoa hot cong nghe. Ha Ndi.
7. Nguyen Van Quang (2003). Chi dan thiet ke va thi cdng cpc baret, tudng trong dat va neo trong dat. Nxb Xay dung. Ha Ndi.
8. Ko4ep)KeHKO B.B. (2009), TexHOJiorHfl BOSEefleHiia noABewiHbix coopy*eHMit. MsflarenbOBO ACB, MpcKsa.
