_?_NGHl|NCuru KHOA HOC Thi cong dai mong khoi lan bang phiFang phap be tong lien tuc kit hap phan chia lap vai cap phoi va SLP toa nhiet khac Ngay nhan bai: 10/12/2013 Ngay sita bai: 15/12/2013 Ngay chap nhan dang: 30/12/2013 TAT: Trong thi cong be tong dai mong khoi ldn nha sieu cao tang noi rieng va ket cau be tong khoi Icin noi chung, van de quan trpng nhat la kilm soat diiac mJt hieu iJng nhiet thuy hoa xi mang khoi ma van phai dam bao dilpc tinh toan khoi, kha nang thi cong lien tuc va tinh chong tham cao cho cau kien. Bai bao the hien ket qua phan tich ly thuyet, ca scf khoa hpc ve qua trinh vat ly xay be tong kh6i ldn d giai doan dau dong ran va ket qua nghien ciJu thilc te qua trinh thi cong dai mong cong trinh sieu cao tang Lotte Center Hanoi, tii de xuat quy trinh cong nghe thi cong be tong lien tuc dai mong kh6i Icin nha cao tang va sieu cao tang bang phUPng phap be tong lien tuc ket hpp phan chia Ictp vdi cap phoi va stf t6a nhi^t khac nhau. Ket qua nghien ciiu co the tham khao, sil dung viec lap philong an cong nghe - to chiJc thi cong cac ket cau be tong dai mong khoi ldn dieu kien hau Viet Nam. TOM ABSTRACT In the cpnstruction of mat foundations of super high-rise buildings as well as other mass concrete structures, the most crucial issue is to control the cracking caused by the heat of cement hydration. Moreover, it is desirable for the concrete structure to achieve the unification property, uninterrupted construction and high water-repellent capability. This article reports the theoretical analysis, scientific fundamental of the physical process happened in the mass concrete during the initial stage of the hardening process, and the research result obtained from the construction of mat foundations pf the Lptte Center Hanpi. With these research findings, a prpcedure pf cpntinous construction of mat foundations for high-rise and super high-rise buildings is proposed. This procedure is established based on the countinuous cpncrete ppuring technique with multiple ppuring layers accprding different cpncrete mixtures and heat hydratipn. The research results can be used as a reference fpr establishing the cpnstructipn methpd and management of mat fpundatipns in the climate condition pf Vietnam. Keywprds: mat fpundatipn, mass cpncrete, heat hydratipn, cracking cpntrpl, super high-rise buildings. TS H6 Ngoc Khoa Khpa XSy dttng Dan dung va Cdng nghiep Trildng Dai hpc Xay dilng Email: hnkhpagiyahpp.cpm Ho Ngpc Khoa Mddau: Mong la mot trang nhufng ket cau chju lUc CO ban va quan nhat cCia cong trinh xay dung. Mong tiep nhan toan bo teii trpng phan ket cau ben tren va hoat tSi sir dung cua cong trinh, phan phoi va truyen xuong nen, quyet djnh den tinh on djnh va ben cua ci cong trinh. Doi v6i nha sieu cao tang thi phan ket cau mong cang the hien duoc vai tro quan nay. Trong thcJi gian gan day, d Viet Nam mot so cong trinh nha sieu cao tang da hoan dua vao sCr dung nhu Keangnam Hanoi Landmark Tower, Bitexco Financial Tower (TP. Ho Chi Minh); sap hoan nhu toa nha Lotte Center Hanoi; dang thi cong nhu VietinbankTower (Ha Noi). SUxuat hien cua cac toa nha sieu cao tang nhu la mot bleu tupng the hien su dang cap cua thj ve kien true va xay dung, phein anh phan nao sU phat trien kinh te cua Viet Nam. Dai mong nha sieu cao tang la ket cau be tong cot thep co kich thudc theo ci phuong va khoi tich rat ldn, den hang nghin m3, do qua trinh thi cong gap rat nhieu khd khan ve mat to chiJc va ky thuat de dJm bao tinh toan khoi, khS nang thi cong lien tuc va kiem scat niJt cua be tong. Van de lien quan den lUa chon cap phoi be tong, phuong an be tong va phuong an bJo dUSng be tong vdi nhOng kho khan va phufc tap dieu kien hau ndng am d Viet Nam, noi ma sU bien thien cua nhiet dp, dp am khpng thay doi lien tuc, khong chi thang, ma tham chi ngay. Qua trtnh xay dung cac cong trinh nha sieu cao tang d nUdc ta keo theo sU xuat hien (ap dung) cac cong nghe thi cong mdi hien dai, dd co cdng nghe thi cdng be tdng lien tuc dai mdng khdi Idn vdi viec sCr dung cap phdi be tong cung cudng dp nhUng cd tinh chat tda nhiet khac mdt cau kien. Day 1^ cdng nghe mdi, lan dau dupc ap dung oi.2oi4Bninn:[iBi g i thuc te thi cdng dViet Nam nhUng da cho thay dupc nhijfng Uu diem vuot troi viec kiem soat nut ilng suat nhiet de dam bao chat lupng cOa be tdng dai mong khdi Idn. Tuy nhien, viec tinh toan, thiet ke bien phap cdng nghe - td chdc thi cong duoc thUc hien bdi cac chuyen gia nUdc ngoai, ddi vdi cac chuyen gia nudc thi ly thuyet va kinh nghiem thuc tien ve van de han che. Do dd, viec nghien cufu cd sd ly khoa hpc va sd lieu thuc te, tCf dd phan tich, tdng hpp de de xuat qui trinh cdng nghe thi cdng co ban lam cP sd ap dung chp thi cpng cac ket cau tuong tU la het siIc can thiet va CO y nghTa thUc tien cao. 1. Cac qua trinh vat ly xiiy be tong d giai ctoan ctau ctong ran Viet Nam nam vung hau nhiet ddi gid mCia, vdi hai thupc tinh cP ban la ndng am va phan hda theo mua ro ret. Su bien thien cCia nhiet dp va am nhieu chu ky thdi tiet la rat Idn, chenh lech nhiet dp cd the dat 10 ^ 150C, dp am: 45 H- 50%. Cac yeu td hau: nhiet dp, dp am khdng khi, tdc dp gid, bufc xa mat trdi anh hudng rat Idn den qua trinh ddng ran cCia be tdng, cung nhu den cdng nghe thi cdng dedam baochat lupng va tri cac cdng nang thiet ke cua cau kien. Mot mat, khf hau ndng am thuc day qua trinh ninh ket va dong ran cCia vCfa be tdng, tang nhanh tdc dp phat trien cudng dp, rut ngan thdi gian thao van khudn. Mat khac, nhiet dp mdi trudng cao, dp am thap, tdc dp gid cao se lam tang nhanh qua trinh bdc hPi nudc, phat trien bien dang mem, hinh trudng nhiet dp va dng suat khong ddng deu be tdng d giai doan dau dong ran, anh hudng xau den cau true va sU phat trien cudng dp cuoi ciJng cua be tong [2]. Su ddng ran cua be tdng la ket qua cua hang loat cac qua trinh hda hpc, vat ly dien sau dd be tdng. DUdi tac dpng cua cac yeu td hau, xay cac qua trinh chuyen djch vat chat ben trpng be tdng, trao ddi chat gida be tdng va mdi trudng xung quanh va ket qua tiep theo, cd lien quan chat che vdi cac qua trinh tren la sU bien dang the tich cua bSn than be tong. Cu the, cd the liet ke: qua trinh mat nudc (bay hPi nudc); qua tnnh thay ddi the tich (bien dang mem: co va nd); qua trinh djch chuyen va thay ddi nUdc va ap luc hoi be tdng; qua trinh thay ddi nhiet dp be tdng; su hinh dng suat Idng khdi be tdng. Trong so cac qua trtnh tren, phai ke den mpt SP qua tnnh co ban nhU: qua trinh mat nudc, thay ddi the tich (bien dang) va thay ddi nhiet dp. Cac qua tnnh xay ddng thdi, lien quan lan nhau, chju tac ddng cua cac yeu td ben be tdng va cac yeu td t d mdi trudng ben ngoai. Qua trtnh mat nudc dan den cau true rong va bien dang mem be tdng, bien dang mem gay nuft mat be tdng; su thay doi nhiet dp Idng khdi be tong dan den sU ch#nh lech nhiet dp gida cac Idp be tdng vdi va vdi mdi trudng ben ngoai dan den nuft 92 BWniEifSIl 01.2014 eau true be tdng; ket quJ ed the anh hudng den eudng dp va eac tinh chat cd - ly cCia be tong vi sau. Nhieu tai lieu da nghien cilu va khang djnh van de [1,13,14,15]. De khac phuc nhufng van de tren can phai cd mdt giSi phap ve cdng nghe thi cdng va bao dudng be tdng phu hpp, theo kich thudc cua khdi be tdng. 2. TrUdng phan bo nhiet do, urng suHt dai mong be tdng Ithdi idn ichi dong r i n Theo [1,13], phan hda hpc cua xi mang pppclang thdng thudng ehufa nhieu cac khoang clinke va mdt lupng nho pha thuy tinh, CaO, MgO va kiem t u dp Na^O, Kp. Khi tac dung vdi nUdc, eac khoang clinke thuy hda tao eac khoang tinh the mdi cho cUdng dp va giai phdng nhiet. Cae phan ufng thuy hda la eae phan ufng tda nhiet. Luong nhiet tda sau thuy hda cua eac khoang CjA, C^S, C,AF, CjS, tUPng dng la 590,405,176, va 63 J/g. Nhu vay, ro rang lUpng nhiet tda phu thupc chu yeu vao phan cae khoang clinke, de han che lugng nhiet thuy hda cua xi mang phai hudng den giam phan CjA va C^S clinke. Trong be tdng khdi Idn, lupng nhiet tich tu du gay hieu ufng nhiet lam nuft khdi be tdng. Do be tdng khdi Idn thudng dung xi mang it tda nhiet, vdi lUpng n h i f t thuy hda sau va tUOng dng khdng qua 168 - 188 va 210 - 230 J/g, va han che toi da lUOng dung xi mang de gi^m tfch tu nhiet khdi be tdng. Trong qua trinh ddng ran, cau trijc be tdng dupc dan hinh va cd tinh dan nhiet thap. VI vay lupng nhiet thuy hda xi mang tda khdng kip thoat het ngoai va tfch tu long khdi be tdng, gay nen dp chenh lech kha Idn giufa cac ldp ben trpng va b l mat thoang. Theo thdi gian, nhiet dp khdi be tdng se giam dan tdi mdc dn djnh. Qua trinh thay ddi nhiet dp eua be tdng khdi Idn cd the chia lam giai doan: tang nhiet => giSm nhiet => dn djnh nhiet (hinh 1), nhi|t dd eao nhat Idng khdi be tdng cd the xac djnh theo cdng thdc: T™, = T, + T , (1) Trong dd:T^ - nhiet dp be tdng dd; T^j - nhiet dp phat nhiet Idn nhat cua chat ket dinh. Td nhiet dp J^ den T^^^ la giai dpan tang nhiet, sau dat den Tmax thi nhiet dd trpng be tdng giam dan gpi la giai doan giam nhiet, va cudi cung la giai doan dn djnh nhiet nhiet dp khdi be tdng dat gia tri dn djnh. Trong giai doan tang nhiet, nhiet dp cia be tdng tang lien tue khoang -f dau ddng ran hoac Bu hon theo khdi tich be tdng. Nhiet dp cCia phan be tdng phia khdng ngdng tang ISn cho den dat gia trj nhiet dp tdi da Tmax. Gia trj nhiet dp tdi da eua be tdng khdi Idn chiu inh hudng cCia nhieu yeu td, nhU: phan cap phdi be tdng; loai va lupng xi mang; nhiet dp vda be tdng do; nhiet mdi trudng; phuong phap thi cdng. Be tdng sCr dung xi mang cd nhiet thuy hda cang cao thi nhiet dp tdi da cang cao. Theo [10] sil dung eac loai xi mang pooclang tda nhiet thap va thay the mdt phan xi mang bang tro bay lam gicim gia trj nhiet dp tdi da eua be tdng khoi Idn. Khi dung Okg/m' xl Id cao hay tro bay thay the xi mang pooclang thudng, thi nhidt dp giSin tuong dng la 0,5°C -^ 1°C. Ngoai ra, viec sddung phu gia hda hpc nhu phu gia giSm nude, phu gia cudn khi, phu gia sieu d4o ngpai tac dung lam giam ham lugng xi mang, cdn cd tac dung lam giam nhiet dp bi tdng khdi Idn, dac biet la giai doan tang nhiet. Trong qua trinh tang nhiet, sutda nhiet chij yeu dien d cac Idp bi tdng be mat, bj lam ngudi bdi mdi trudng khdng khi. Tdc dp tda nhiet cua khdi be tdng t) le thuan vdi ty sd dien tfch be mat thoat n h i | t trdn khdi tich be tong (he sd bi mat thoang M ^ J . Theo [11], danh gia su khuech tan nhiet dp trpng khdi be tdng cd can cd vao mdc dp khuyech tan nhiet dp h^ (mVh), duoc xac dinh theo cdng thdc (2). ' =Z-p (2) Trong dd: K - d o dan nhiet (KJ/m.h.°C); C - nhiet rung rieng (KJ/kg.°C); p - khdi lugng rieng cua be tdng (kg/m^). Gia tri khuech tan cang cao thi khci nang t6a nhiet cang de dang hon. Gia trj khuech tan phu thudc vao loai edt lieu Idn sd dung thJnh phan be tdng. Su mat nhiet ciJa cac Idp be tdng phfa ngoai cd t h i tao nen chenh lech nhiet vdi cae Idp phfa gay ufng suat keo dCi ldn lam ndt be tdng. Giai doan nhiet cd the bat dSu sau 10 hoac lau hon, phu thudc vao khdi tfch cua k i t ciu. Ddi vdi cac k i t eau dai mdng Idn, qua trinh nhiet ed the keo dai hang thang. Trong giai doan nay, eac Idp be tdng phia se ngudi dan va co lai lam phat sinh dng suat keo be tdng. Qng suat duoc tfch tu theo thdi gian, cd the gay cac v l t ndt xuyen, rat nguy hiem cho k i t cSu [1], Ddi vdi cac ket cau be tdng khoi Idn (M^,, nhd) thi luong nhiet thoat cham, trang nhiet trang Idng kit ca'u lai cao, dan den su tao trudng nhiet dp khpng ddng d i u theo the tich, cd t h i anh huong den su hinh ca'u trde, chat luong va cuong be tdng. Theo [11] nhiet dp trang giai doan g i j m Hifih 1. Cac giai doan thay 46i nhiet Jo ciia he tong Ichoi \6nnhiet tai mpt vj tri bat ky each be i.^at mdt khocing x dupc xac djnh theo cdng thdc sau: I n ^ ^ e Vh^T (3) Ro Trong do: R,^ - nhiet dp tai vj tri each be mat mpt khoJng x (m); Rj - nhiet dp be mat (x = Om); e - CO sd cOa logarit tU nhien (e = 2,718); X - khoSng each tai diem khSo sat (m); h^ mufc dp khulch tan nhiet dp (mVh); Y - thdi gian cCia chu ky nhiet dp b i l n ddng ngay. Giai doan on djnh nhiet bat dau be tdng giSm nhiet den g i i trj dn djnh. Trong giai doan nciy, nhiet dp khdi be tdng tri dn djnh, sil thay ddi ve nhiet dp chCi yeu dien trpng pham vi Idp be mat be tdng dp sU thay ddi cCia nhiet dp mdi trudng. Trong thdi gian ddng rSn, theo khdi tich, lupng nhiet thCiy hda va mdc dp gId nhiet cCia cKu kidn ma gia trj cung nhu sU phan bd nhiet dp trpng khdi be tdng se khae d tdng vj trf. Ve nguyen tac, sU phan bd nhiet dp be tdng d mdi trudng nhiet dp cao dugc xac dinh bdi qua trinh nhiet - 1^ xay be tdng giai doan diu ddng ran. b l mat thoang cCia be tdng (Idp be mat), q u i trinh mat nhidt d i l n tuong dng vdi hd sd dan nhiet cua mdi trudng (trong dieu kien dp ^m lidn tuc thay ddi). (3 nhdng Idp phfa dudi - tuong ufng vdi he sd dan nhiet cua Idp be tdng phfa tren. Cdn d nhdng Idp be tdng canh khdi - sU mat nhiet phu thudc vao chCing loai va hd sd dan nhiet cda vat lieu lam van khudn. Trong [3], trudng nhiet dp va dng suat khdi mau be tdng dai mdng kfeh thudc 4600 x 4600 x 4000 mm dUOc phan tfch bdi phuong phap phan tuf hdu han va so sanh vdi k i t qui thue nghiem. Ket quJ nghien cdu cho thay nhiet khdi bd tdng dat gia trj Idn nhat d tudi 85 gid sau dd, khu vUe xung quanh tam khdi mdng la noi cd nhiet dp cao nhat, diem cao nhat cd nhiet dd 1^ 90,39°C (hinh 2a). Thdi gian dau nhiet dp phan bd kha deu tai cac diem Idng khdi bd tdng, nhUng cang v l sau vCing xung quanh tam khdi nhidt dp tang cap ciing vdi t h i tfch vung CP nhd lai. Khf vda be tdng v3n d dang Idng, khS nang ddi luu va truyen nhidt tdt nen nhiet dd phSn bd deu. Cang v l sau, be tdng bSt dau ddng rin, nhidt lugng ph^t tir phcin dng thuy hoa xi mang bj tfch tu Idng khdf va lam nhiet vung xung quanh t§m tang rat cao. Cfng suat khdi be tdng d thdi gian Siu sau chii y l u la dng suat nen, dng sutft keo chi xuat hidn chii y l u d mat thoang va xung quanh Ceic gdc canh vin khudn (hinh 2b). Khoing thdi gian nJy la giai doan tang nhidt khdi be tdng, phan be tdng phia cd xu hudng nd nhidt ndn dng suat phat sinh chO y l u khdi la dng suat nen. Trong dd d mat thoang vi gdc van khudn bd tdng bi giSm nhidt dp nhanh (ra mdi trudng khdng khf va qua Nhiet (°C) ^^ Lfng l u l l nhiei (kG/nV) 039S8e*001 - 8478718+001 • 917B4e-0Ol 3S6a7e+«)1 79609e*001 4S52eie>D01 - 43087e*001 S7DOOa+a01 a.TrirclngphSnhonhietdo bTririmg phan bo ling suat Hinh 2. Phan bo nhiet do, iing suat Jai mong be tong lihoi ISn thi cdng bJo dudng sau: Dua nhiet Tich tu khoi BT khdi be tdng Chenh lech nhiet d6 AT ngoai bSng dng k>Rbk chda nudc lanh de Phat sinh tfng s u j t kdo S Sy thay doi the tich can bang nhidt dp Hinh 3. Co che gay niJt be tong khoi ldn gida eae Idp; van khudn) se cd xu hudng co, nhUng bj cac - Chia nhd khdi Idp phia cd nhiet dp cao hon kim gidva la be tdng, td chdc mach ngdng thi cdng, tdng nguydn nhan phat sinh dng suat keo ciia Idp khdi bang nhieu lan dd gian doan; bd tdng d nhdng vj trf nay. - Can bang nhidt dp gida cac Idp trung tam K i t quei phan tfch da md ta dugc qui luat va be mat khdi be tdng bang giai phap cdng thay doi va xac djnh dugc gia trj ciia nhiet va nghe thi cdng va b i o dudng. dng suat tai eac vj tri va thdi diem ddng ran khac 3. Cong nghe thi cong dai mdng khoi ldn ciia bd tdng, v l co b i n tuong dong vdi k i t bang phifcmg phap be tdng lien tuc l(et qua thirc t l bang phuong phap thi nghidm hop phan chia ldp vdi cap phdi va sil tda hien trudng. K i t q u i phan tich la eo sd d l thiet nhiet khac lap bien phap k i l m soat trudng nhidt dp va dng 3.1. Casdkhoa hgc lUa chgn cong nghe thi suat nhiet de chdng ndt cho be tdng khdi Idn cong thi cdng. Cdng nghd thi cdng dai mdng khdi Idn Qua eac ket qua phan tfch tren, thay rang bang phuong phap bd tdng lidn tuc k i t hgp nguyen nhan co bSn gay ndt trpng be tdng khoi phan chia Idp dd vdi cap phdi va su tda nhiet Idn la sU chenh lech nhiet dp (AT) gida eac Idp khac dugc ap dung lan dau tidn d Viet ben khdi bd tong vdi eac Idp ben ngoai Nam thi cdng dai mdng cdng trinh Lotte t i l p giap mdi trudng xung quanh. Khi dp chenh Center Hanoi. Dai mdng dugc thi cdng d tang lech nhiet dii Idn sd gay hien tugng co ham t h d cd kfeh thudc 92,7m x 44,1m, c h i l u gian khdng deu giiia Idp be tdng ed nhidt dp day dai mdng t d + 5,7m, khdi lugng bd tdng cap va Idp bd tdng ed nhidt dp thap hon. Qua 17.030m3. Odi vdi mdt k i t eau dai mdng kfnh trtnh CO gian lam phat sinh dng suat keo thudc sieu Idn nhu vay, cdng nghd thi cdng be tdng, va vUgt qua gidi ban keo tai p h i i dugc xem xet va lUa chpn vdi tieu chi quan thdi d i l m ciia be tdng thi sd gay ndt be trpng hang dau la kiem spat dupc ndt hieu tdng. Co che ndt dugc md ta tdm tat d hinh 3. ling nhidt thiiy hda xi mang khdi do. Ngoai ra, phuong an td chdc thi cdng dam bao Theo [8], be tdng khdi Idn bj ndt hieu chat lupng k i t cau, t i l n dp va thuan Igi cung dng nhiet thiiy hda xi mang cd dii y l u td can nghien cdu de cd giai phap thfch hgp. sau day: dieu kien can - dp chenh lech nhiet dp AT gida cac diem hoac eac virng khdi bd Phuong phap l i p dat dan dng thoat nhiet tdng vUgt qua 20°C (AT>20°C) va d i l u kidn dii bang kim loai be tdng, sau bom nude mddun chenh lech nhidt dp MT gida cae diem lanh qua dan dng de dUa nhiet ngoai da trpng khdi bd tdng dat khdng dudi 50°C/m cho hieu q u i thoat nhiet kha tdt va cd the (MT>50°C/m). be tdng lien tuc. Tuy nhien viec lap dat dudng dng va dam b i o bom nUdc lien tuc, thdng sudt Nhu vay, de kiem soat ndt nhiet qua dan dng gap nhieu khd khan.Trong trirdng be tdng khdi Idn can p h i i kiem soat ehdnh lech hgp x i y sU cd nhu t i c dng, dng bj bep, bj nhidt dp gida cac Idp be tdng, gida trung tam hd thi viec xd ly khic phuc tdn nhieu kinh phf va Idp be mat gidi han chp phep. Bi dat va cd the i n h hudng d i n chat lugng be tdng. dugc muc tieu dd, ed the ap dung eac bidn phap Phan Cmg thuy hoa xi mang - Giai phOng nhi$t ru'6'ng nhi^t d6 cao 01.2014B«ini:[|Bl Bing 1. Cap phdi vufa be tdng dai mong cdng trinh Lotte Center Hanoi I6p be tong Phia dirSi Phia tren UfVLbfCcickaUft Vat lieu cho I m ' b e tong T^le long li/tfng N/(X+Tro XM-i-Trobay Cat fia Xi mang Tro bay Niroic Phu gia bay) (kg) (kg) (kg) (kg) (kg) (lit) (sieu dio) 42% 39% 385 415 880 840 951 964 289 311 96 104 160 160 1,35% 1,35% Bing 2. K i t q u i nhidt dp khdi mau be tdng thi ighiem Vitri Lln tien hanh Nhiet d tam khoi Nhiet Idp be mat Trung tam Lani 70,4 56,1 14,3 Lan 77,4 57,0 20,4 Lani 67,1 54,3 12,8 Lan 74,3 55,2 19,1 Lani 63,2 52,5 10,7 Lan 71,2 53,2 18,0 Canh bien Goc Thi cOng \&p d^ng vAn khuOn. bjimg tihin. t ^ cdch nN$t U p d^mg c6t th^p. h$ di6ng 60 c6t t h ^ , mdi che. thang. sdn cOng tdc. Ihi^t bj nhidt b& tfing. cdc chj tl^l d4t s i n Od, d i m tid tdng d e l , bd tdng It tda nhidt Chdnh lech L i p d3t 6ng bom bd tdng, t6 chi>c tr4n vd vdn chuydn vOd bdtdng Hinh 4. Phan bo cac Idp vdi be tong cd tfnh chat toa nhi^t khac theo chieu cao dai mdng cap phdi va su tda nhiet khic dugc lira chgn d l thi cdng dai mdng. Day la phuong phip k i t hop ap dung ddng thdi hai bidn p h i p : kiem soat nhiet dp c i c Idp bd tdng bang d i l u tiet sir trao ddi nhiet gida bd tdng vdi mdi trudng bdn ngoai thdng qua bidn p h i p b i o dudng va can bang nhidt dp gida cac Idp trpng khdi bd tdng bang phan chia Idp (dot) dp vdi c i c cap phdi be tdng Cling cap dp ben nhung cd su tda nhiet khae nhau. Ldp be tdng phia tren mat dai mdng c h i l u day m sddung xi mang pooc lang thdng thudng, vdi lupng xi mang -i- tro bay va lupng nhiet tda Idn hon rat nhieu so vdi Idp be tdng phfa dudi chieu day 4,7m sd dung xi m i n g tda nhiet thap, phu gia keo dai thdi gian ninh kit vdi Iggng xi mang -i- tro bay ft hon (hinh 4). B i n chat cua phuong phap la tao mdt Idp "can bang nhiet" d phfa tren dai mdng bang chfnh vat lieu la bd tdng. Be tdng - Idp "can Hodn thidn bd m$t bd tdng bdng bang nhidt" cd cap phdi d i m b i o k h i nang mdy xoa tda nhidt Idn hon so vdi phan be tdng edn lai Didu chlnh nhidt dd bdo d i r t n g (tdng, bdi ldp giO nhi$t) ben dudi, nham can bang nhidt dp gida Idp be Bdo di/d'ng giC^ nhidt bd tdng, mat v i cac Idp d trung t i m dai mdng.Trpng qui che mdt thodng bdng vdt lidu giO nhidt ttieo phmmg dn trinh b i o dudng, nhiet dp gida trung tam khdi va Idp b l mat, nhidt dp gida be mat be tdng va c i c Idp gid nhiet (nhidt dp b i p dudng be tdng) dupc k i l m spat va d i l u chlnh bdi vat lieu va so lugng Idp phii gid nhidt, can cd vao sd lieu nhiet do. Ngoai viec d i m b i o dugc k h i ning Kdt thOc bdo duCmg, thdo d d can bang nhidt gida cac Idp, phuong phap vdn Ithudn, vdi ll$u b i o dudrng, cho phep thi edng dd bd tdng lidn tuc, mdit^ khdng mach ngdng, d i m b i o tfnh toan khdi va k h i nang chdng tham cita k i t cau, tao dilu kien cho viec to chdc thi cdng va kiem soat chat Hinh 4. Quy trinh cong nghe thi cong dai mong khoi linbedotong lien tuc ket hop phan chia ldp vdi cap phoi va sir toa nhiet lugng bd tdng dai mdng tdt hon. khac Bd tdng dai mdng cdng trinh Lotte Center Mat khic, n l u dai mdng Idn, sd Idp dng nhieu chju c i c lilc gay tach trugt tai vj trf d l mach Hanoi dugc thiet k l cd eudng C4a (tidu thi hidu q u i thoat nhiet (dae biet tai nhOfng noi ngdng, tir dd lam tang chi phf vat lieu Idn rat c h u i n My ACI), t u len, dp chay 650 m m , sd dung each xa dau cap nUdc lanh) la rat thap, khd dap nhilu, ehua tfnh d i n vide thi cdng khd khan vi xl mang tda nhiet thap, mdt phan xi mang dUOc dng dugc ydu eau. mat dp cdt thep day dac. Ngoai phuong p h i p thay the bang tro bay vdi muc dfch lam g i i m Phuong p h i p chia nhd khdi dd eiia dai cung k l o dai dang ke thdi gian thi cdng dai lugng dung xi mang t d d d lam g i i m luong nhidt mdng vdi muc dich g i i m khdi lugng bd tdng mdng cic g i i n doan ky thuat va thdi gian xd thdy hoa. Cap phdi chi tiet vda be tdng Idp tren mdt lan thi cdng, g i i m lugng nhiet thiiy hda ly mach ngdng thi cdng. va duoi cua dai mdng t h i hidn d b i n g tdng khdi do, d l de k i l m soat hon. Trong cdng trinh Lotte Center Hanoi, sau Be kiem chdng va hidu chinh c i c thdng sd phuong phap nay, can p h i i bd sung cae tam phan tfch, so sanh va tfnh t o i n , phuong an cong nghe trudc khf thi cdng, mdt thi nghidm chdng tham va mdt lugng thep kha Idn nham be tdng lien tue k i t hgp p h i n chia Idp dd vdi hien truong dupc thuc hien trdn khdi mau be Od. ddm bd tdng det 2, bd tdng tda nhidt blnh thi/dng 4SDiiniBIX 01.2014 Bing 2. Chi dan bidn phap, ky thuat thi edng dai mdng khdi Idn bd tdng lien tuc k i t hgp phan chia Idp vdi cap phdi va sU tda nhiet khic Cong tac Chi dan bien phap, ky thuat thi cong, tieu chuan ap dung Noi dung Lap PA CN-TC 1. Thf nghiem, tfnh toan Viec thi nghiem, thilc nghiem xac djnh cac thdng sd ky thuat phuc vu thiet ke bien phap cdng nghe - td chdc thi cdng thi cong 2. Lap, phe duyet PA cdng nghe-td chdc thi cdng. thflc hien theo phflong an cua ky sd phu trach. Thi cdng lap 1. Gia cdng, to hop tam khuon. Lfla chpn chdng loai van khudn (kim loai, gd, be tdng cdt thep) theo phflong an cdng nghe thi cdng. di/ngvan 2. Lap dimg van khudn mdng. Xac nhan ban ve ket cau va cau tao van khudn. khudn dai 3. Dd be tdng tudng chan dai mdng (neusitdung vdn Kiem tra tfnh toan he van khudn theo [6]. mdng. titmdn labi tong dt ttiep) Xac nhan xuat xfl, chung loai vat lieu, phfldng thflc che tao. 4. Kiem tra, nghiem thu Che tao van khudn tuan thu [6,8] va cac tieu chuan khac phu hgp. Lap di/ng van khudn tuan thu [6,8,9] va cac tieu chuan khac phu hgp. Van khudn bang BTCT thi cdng theo cac quy dinh trang [6]. Lap dat tam 1. Van chuyen tam giUnhietden vj trf thi cdng. Chung loai tam gifl nhiet theo phflflng an cdng nghe thi cdng (thfldng dung tam xdp polystyrene hoac polyurethane giO nhiet 2. Lap dat tam gid nhiet lien ket vdi van khudn day 4-5cm,cd khdi lflpng the tich >20kg/m',dpam < cdng vdi VK mdng. Xac nhan ban ve va phflong an thi cdng. mdng 3. Kiem tra, nghiem thu Jam vat lieu gidnhiet phai dflpc boc ap sat mat ngoai van khudn trflde ldc be tdng. Can cd bien phap che chan Thi cdng lap 1. Vdn chuyen cdt thep den vj trf thi cdng. Xac nhan ban ve ket cau, nghiem thu vat lieu va phe duyet phfldng an thi cdng. difng cdt thep 2. L3p dung cdt thep da mdng v a he gia dd cdt thep. Van chuyen va lap dung cdt thep tuan thu [6] va eae tieu chuan khac phu hdp. da mdng 3. Lap dat cac chi tiet dat san, chdn ngam dai Ndi cotthep (bang dng ren] dam bao eae yeu cau ky thuat theo [6,7] va eae tieu chuan khae phu hop. mdng. He gia ddeae Idp cdt thep dai mdng Sflfle ke tai nhflng vi tri dam bao khdng lam bien dang Idp edt thep phia dfldi. 12%). mat ngoai de chdng am vat lieu each nhiet 4. K.tra va nghiem thu. Kiem tra chat Iflong, mdi ndi, neo edt thep. LSp dat dung 1. Lcip dat thiet bi nhiet be tdng va nhiet Thiet bi nhiet dd tfl ddng vdi dau chfnh xac ±0,1"C. Thiet bj phai dflpc kiem tra hieu chuan. eg, thiet bj baodirdngbetdng. fiiem do, sd Ifldng dau do, lien ket dau vdi cdt thep tuan thu phflong an cdng nghe thi cdng. nhiet 2. LSp dat cac dung cu bao ve thiet bi nhiet dp. fiau phii cd dinh chac chan, dflpc bao ve, va each nhiet tuyet ddi vdi edt thep. be tdng 3. Kiem tra va nghiem thu. Cac dau nhiet dp be mat va d day khdi be tdng dflpc lap each mep ngoai eua khdi 100mm. Che trdn vda 1.Chuan bjvatlieu Xac nhan PA cdng nghe thi cdng va thiet ke cap phdi (2 cap phdi cho Idp be tdng cung cfldng dp, mflc dp tda nhiet betdng 2. Thiet ke cap phdi khac nhau). Kiem tra de dam bao thdng mach va khdng cd dau nao bi hdng. 3. Cap lieu (cdt lieu, nirdc, xi mang, phu gia) Lfla chpn tram trdn, xac nhan xuat xfl, chung loai vat lieu, phu gia. 4. Trdn vfla Chat IflOng vfla be tdng dap flng [6,8,9] va cac tieu chuan khac phu hpp. Nhiet dp cua vfla be tdng tnrde vao ket cau khdng dfloc vflpt qua 30"C, tdt nhat khoang 20-f25"C. Kiem tra tfnh thi cdng eua vfla va cfldng dp be tdng. Chap nhan ke hoach van chuyen: thdi gian, cfldng dp van chuyen, so Iflpng xe van chuyen, phan ludng giao thdng Van chuyen 1. Trut vda td thung trdn vao bdn xe van chuyen. vda betdng 2. Van chuyen den cdng tnrdng Kiem tra sfl phu hpp ke hoach van chuyen va nang suat dd be tdng tfnh den eac yeu td edng nghe: chieu cao Idp do, tir tram trdn 3. Kiem tra tinh thi cdng (do sut, chay) cua vfla. edng suat be tdng, thdl gian hoan mpt Idp dd, thdi gian bat dau ninh ket cua be tdng. den cdng 4. fiuc mau thf nghiem kiem tra cudng be tdng. Van chuyen vfla be tdng tuan thu [6] va cae tieu chuan khac phu hdp. Kiem tra dp sut tuan thu theo [4] va cac tieu chuan khac phu hop. trirdng fiuc mau thi nghiem tuan thij theo [5] va cac t/e khac phu hpp. Van chuyen 1. Trut vfla tif xe van chuyen vao thung chda may bdm. Xac nhan phflong an bom be tdng: chung loai, sd Ifldng, cdng suat, vi tri bom. Cd the ket hpp may bPm tinh va may vua be tdng 2. Van chuyen vfla trut vao vj tri dd. bdm dtd. bang may Lap dat he thdng dfldng dng bdm (lien ket, neo gifl chac chan, neu di tren cdt thep can I3p dat cac dung cu giim chan bdm den vitri ddng nhfl eac ban ke bang cao su). Kiem tra, nghiem thu. Bdm be tdng lien tue, khdng dflng qua - gid tranh tac dng, tuan thd theo [6] va cac tieu chuan khae phu hpp. be tdng Trong thfli tiet nang ndng, mat ngoai dng can che phu de ban che bdc xa mat trdi lam ndng vua lam cho dp Iflu ddng cua vfla giam nhanh fid, dam be 1.fid,san gat vda. Ky thuat be tdng theo phfldng an cdng nghe thi cdng dflde phe duyet, tuan thu (6,8,9) va cac tieu chuan khac phu tdng a m be tdng. hdp. flam be tdng tuan thu [6] va eae tieu chuan khae phu hpp. Kiem tra chat lflpng be tdng, vi tri cdt thep, cae dau nhiet dp va tinh trang van khudn sudt qua trinh be tdng. Biodirdngbe 1. Hoan thien be mat be tdng. Xac nhan phflong an bao dfldng be tdng. tdng dai 2. Trai cac Idp vat lieu che be mat be tdng theo phflong Xac nhan chung loai, chat Iflpng vat lieu gidnhiet, che phu. mdng an bao dudng. Hoan thien be mat be tong sau ket thuc cdng tac be tdng bang may xoa mat be tdng. 3. Theo ddi (do) nhiet be tdng. Bao dfldng giflnhiet cho khdi be tdng, han che AT gifla tam va be mat khdi theo [8,9] va eae tieu chuan khac phu hdp. 4. Thay ddi bien phap bao dudng neu can thiet Che be mat thoang cia khdi bang cac Idp vat lieu ket hpp: Idp (Idp dfldi) - Idp vinyl; Idp (Idp gifla) - Idp vat lieu gifl 5. XiJIy so lieu nhiet dp, xac ffinh AT, quyet djnh ket nhiet; Idp (Idp tren) - Idp vat lieu each am nhfl mang nilon. thuc bao dudng. Can cd ket qua nhiet dp de dieu ehinh che dp va quyet Smh thdi gian bao dfldng: -1- Trang thai phat trien va can bang nhiet (1-10 dau): kiem tra nhiet Idn nhat va kiem soat AT gifla tam va be mat khdi ludn thap hPn 25°C. fiieu chinh tang nhiet dp bio dfldng bang mpt Idp nilon bd sung. -1- Kiem tra nhiet dp d bien va gdc khdi, neu nhiet dp giam manh ( . bidn phap, ky thuat thi edng dai mdng khdi Idn do bd tdng lien tuc kit hgp phan chia Idp do vdi cap phdi va sU tda nhiet khic nhau Cong tac Lap PA CN-TC thi cong Thi cdng lap di/ngvan. dan bien phap, ky thuat thi cong, tieu chuan ap dung Viec thi nghiem, thilc nghiem xac djnh cac thdng sd ky thuat phuc vu thiet ke bien phap cdng nghe - td chdc thi cdng thflc hien theo. chi ddn bien phdp, ky thugt thi cong Trdn kit qua nghien cdu ly thuylt, co sd khoa hpc va sd lieu thi nghidm, thilc te thi cdng, qui trinh cdng nghe cP bin thi cdng dai mdng be tdng khdi