DIEN DAN KHOA HOC CONG NGHE
PHAN TICH "HOA SA MAC"
MONG TOA NHA CAO NHAT THE GI61
P G S . T S . N G U Y E N BAO HUAN
T()MTAT:
Bai bdo mo ta Igi ca qua trinh thiet ke mong Toa thap cao nhat the gioi d thanh pho moi Dubai Mong Toa Thap Burj la ban betdng CO sdon dgc Y phu kin mat be cpc khoan nhoi dudng kinh ldn ch sou vdo dd vdi mem kit tinh carbonat vd dd cdng dam cuoi kit trong lung dot tram tich. Bdi bdo tdm tdt day du so lieu dgc trung co ly cua dot/dd tuong dng cdc chieu sdu khdo sdt khdc nhau vdi nhdng ket qud thi nghiem trong phdng vd tren cong trudng; nhung ykien phdn tich ve khd ndng gidm tdi ma sdt vd do cung cua dia tang do qud trinh tdi trong gid tdc dgng theo chu ky. Cdc so lieu trich dan td cdc md hinh phdn tich so dugc dp dung de thiet ke ban dau cdng vdl phdn tich bleu chinh vd phan tich cdn nhac lua chgn cd qud trinh xem xet dugc tdm tdt trinh bdy dd mieu td mgt cdch chi tiet Ngodi ra, bdi bdo cdn de cap van de thiet ke khdc nhau Idm sao bdo ddm ben vung cuoi cung: - chu yeu dua vdo gidi hgn do lun tuyet doi vd do lun chenh lech, d'n djnh ngang ket cau thugng tang dudi tdc dgng cua tdi trgng gid hogc dgng dot nhieu hgn Id dua vdo khd ndng chiu tdi diing cho phep cua tong the cdng trinh.
Trong bdi cung trinh bdy chuang trinh chat tdi thi nghiem cbo cgc khoan cgc ong thep hinh dgt sdc chju tdi nguy hiem Idn nhat 64M, so sdnh vdi dng xd hien trudng thuc vd du bdo quan he dng suat bien dgng du dodn "vdng A"so vdi do Idn quan trac trong qud trinh xdy dung.
Dinh thap
Chop nbqa t h i p
M6DAU
6 t h i ky ndy, cu the d hien tai vd trong ca tuong lai cung khdng ai cd the da mo udc din xdy dung dugc mdt tda nhd chgc trdi hon t h i nay Du dn Burj Dubai cho thdy suphat trien xdy dung he thdng chilu cao ludn ludn true tilp lien quan tdi nhung phdt then mdi nhdt trong ky thuat nin mdng vd phd dja chdn, cdng nghe vdt lieu, ly thuyit kit cdu, ky thuat md hinh thf nghiem gid, phdn tfch vi tfnh, vd cdng nghe mdi xdy ldp.
Duan Burj Dubai tan dung nhiing tiln bd ky thuat trong cdc cdng nghe nin mdng, thiic day phdt trien cac kit cdu sieu cao. Tfnh din ngay hdm nay, Burj Dubai la cdng trinh kiln true cao nhdt t h i gidi - dugc thuc hien trong tdt cd cdc bg mdn khoa hgc, vd nd da trd thdnh mdt chdt xiic tac cho phdt trien hon niJa trong cdng nghe xdy dung sieu cao tdng tren todn
Hinhl: Thanh phd thing ddng Dubai {1}
t h i gidi. Dudn Burj Dubai Id mdt budc tiln trong viee dap irng nhung thdch thiifC cdng nghe tuong lai khdt vgng vuon cao vd xudng^sdu trong Idng ddt.
CAC PHAN TICH KIEM TRA OOC LAP
Md hinh dja chdt da sir dung trong phan tfeh kiem tra dugc tdm tdt trong Bang 1. Cdc thdng sd dugc udc dodn ddc lap tren co sd thdng tin sdn cd va kinh nghiem tir Du an Emirates (Poulos & Davis 2005).
Tdng qudt md hinh ndy hdi bao thii so vdl md hinh ban ddu da sir dung cho thilt k l . Ddc biet kha nang mang tai gidi han tai mui cgc bj giam cung vdi mddun dan hdi tai vdi Idp phfa tren va hien nay dugc gia thilt cd 1 Idp ddt tren cung hon ndm giira cdc Idp nay vdi gid trj mddun ddn hdi 1200 MPa tai do sdu dudi edt RL -70m DMD, thuc t l cho phep Id mure do biln dang trong nin ddt giam theo do sdu tang.
Cdch tilp can 3 budc sau ddy dugc sir dung cho
NGUdl XAY DI/NG s6 THANG 1&2 • 2011
PHAN TICH "HOA SA MAC"...
S6 ldp 1a 1b 2 3 4 5a 5b 6
B a n g 1 : Tdm tat m d hinh dja chdt d i i n g eho phdn tfch ddc lap khde n h a u Mata
CM bui chat trung binh cat bui r& x6p (Jin x6p fla vfli yiu din ylu vira Sa thach yiu
Sa thach/sa thach canxi Cannxi silic / kittinhyiu-vu'a Cannxl silic/kit tinh yiu fla vdl silic
Caoira
DMD +2,5(3in+1,0 -1 ,0 din-1,2 -1,2 din-7,3 -1,3 (Jin-24 -24 din -28,5 -28,5 din -50 -50 din -70 -70 & dudi niia
Eu mfitfun n6n khfing thoA ni/Oc
30 12,5 400 190 220 250 275 500
E' ni6(Tun n6n t h o ^ nilOc MPa
25 10 325 150 175 200 225 400
Ma s t i thdnh gidih^n kPa
- - 400 300 360 250 275 375
l\fc giei han mdi cpc MPa
- - 4,0 3,0 3,6 2,5 2,75 3,75
quy trinh kiem tra dde lap:
1. Cd the diing chUdng trinh phdn mim thuong mai FLAC de phdn tfeh he mdng eiia Toa thdp ed true ddi ximg. Mat bdng mdng quy ddi tuong duong la dien tfeh mot hinh trdn vd mdng cgc gdm ed ede cgc va ddt bao quanh nd dugc xem nhu mot mdng khdi quy udc. Do cirng dgc true eiia mdng khdi quy udc ldy tUdng dUdng bdng do cimg doc true coc vd ddt. Tdng hgp tTnh vd hoat tai duge gid thilt phan bd deu. Cae Idp dat duge gia thiet la vat lieu tudn theo quy tac mdi quan he Ung sudt eat vd img suat nen d bdt ky diem ndo trong khdi vat lieu duge the hien dudi dang vdng trdn Mohr - Coulomb vdi cac gid tri Mddun ddn hdi trong bang 1 vd ede gid trj lue dfnh lay bang 0,5 ldn eudng do nen vd han du bdo. Phdn tfeh djnh lugng mue dfch chfnh vd kiem tra Id phu vd sir dung chuong trinh phdn mem PIGS, tfnh nhdm cgc chi tilt hdn nUa (Poulos 2002).
! I I i.'~™!3
Hinh 2: Mo hinh mong hinh Ylien hdp cgc khoan nhdi co vo dng thep
2. Sir dung phan tfeh PIGS chl tiln hdnh cho mdng Thdp, de kiem tra do liin dp dung chUdng trinh thUdng mai FLAC. Trong phdn tfch ndy cdc cgc dugc md hinh rieng biet vd chii d l chiing dugc gia thilt mdi cgc Id chju taitrong Idm viec danh nghTa bdng 30MN. Do cirng mdi cgc dugc tfnh todn qua chUdng trinh DEFPIG (Poulos 1990) cho phep giQa tilt dien be trdn cgc va tilp xiic dudi ddt nin. Gid trj dd cirng cgc vdi mut do tai trgng tdng dugc gid thilt Id thay
ddi theo quy luat hyperbol, sir dung (Pr) he s6 hyperbolic bang 0,4.
3. Cudi eung thue hien ehudng trinh DEFPIG de phdn tfeh td hgp he mdng ea thap va nha quay va ddnh gid todn bd 926 ccpe. Mat khdc mdi coc dugc ddnh gid chju tai trpng Idm viee ly thuyet.
Phan tfch FLAC & PIGS lun chl cho mong Toa thap
Do su khae biet ve hinh ddng giUa mdng thyc t§
vd mdng trdn tuong duong, chl xem xet sd lieu Idn nhdt vdl muc dich de so sanh. NhOng ket qua do liin trung tdm mdng Tod thdp nhdn duge la:
- Do liin 72,9mm theo md hinh mdng khdi quy udc eiia chUdng trinh phdn mim FLAC;
- Dp liin 74,3mm theo md hinh todn bd 196 coc eiia chuong trinh phan mem PIGS. VI vay mac du ede md hinh tiep can hodn todn khdc nhau nhung ket qua tfnh todn do liin duge ghi nhdn kha tiem can. Cac gia thiet udc doan mddun dan hdi dat nen dudi mui cgc anh hudng den ket qua tfnh todn gid trj do lun.
VD theo phan tfeh PIGS thi dp liin tfnh toan tai trung tam toa thap se tang den khoang 96mm vdi gia thiet gid trj Mddun ddn hdi EO = 400 MPa dudi eao trinh RL -70m DMD (Mddun dan hdi ddt nin chfnh xac hdn bang 1.200 MPa).
Phan tfch PIGS lun cho mong ca toa nha
Hinh 3: DUdng bao tinh toan ddng mdc lun mong toa nha So lun (mm) khoang cach(m)
NGUdl XAY DUNG SO THANG 1&2 • 2011
PHAN TICH "HOA SA MAC"...
Hinh 3: Cho thdy dudng bao do liin tfnh todn cho toan bd vung mdng tod thdp vd nhd qudy. Cd the thdy rdng gid trj do liin Idn nhdt tap trung tai trung tdm ciia khu vuc mdng toa thap.
Hinh 4: Md ta mat eat dae trung do liin qua trung tam mot phdn viing mdng tod nhd. D i l u ddng lUu y d mat cdt nay Id dp liin gidm nhanh khi ra ngodi vimg mdng khu vue tod thdp: gid trj do liin ddi vdi phan Idn viing nha qudy giam cdn 10 den 12mm.
naspm f^a. m f» ^^pmfm
I
»-
10-
^ ***^
Hinh 4: Mat cat do lun tinh toin gua trung tam toa Thap
Ghi chu: tdtrai qua phai cac coc M353, P317, P205, P193, PI84, P51, P38P6, P194, P250, P683, P701, P814
Do liin tfnh toan ca qud trinh tham tra ddc lap dugc cho la kha hgp ly so vdi nhung gid trj do liin tU thiet ke ban dau cho tod thdp theo bdo edo tren.
CAC ANN H l / d N G TAI TRONG TUAN HOAN Cd the thdy cdc dnh hudng tai trgng tudn hodn qua cdc k i t qua 4 khdo sat Id:
- Thf nghiem nen tudn hodn 3 true.
- Thf nghiem cdt vdng true t i l p tudn hodn.
- Thf nghiem tudn hodn do cimg thdng thudng khdng ddi (CNS).
- Thdng qua ddnh gid ddc lap cdc phdn tfch ly thuyet - nang lue eiia ngUdi tham tra.
Cac thf nghiem nen 3 true tudn hodn cho thdy rdng cd vdl kha ndng suy giam dp eung vd dp lue tfch luy vugt qud dp luc Id rdng du thUa, trong khi cdc thf nghiem eat true t i l p cho thdy cd s u giam eudng dp cat du, mac dii nhtmg thf nghiem nay da thuc hien vdi cudng dp b i l n dang Idn khdng dai dien cho cdc dilu kien hien trudng d u k i l n .
Thf nghiem do cirng khdng ddi thdng thudng CNS (Constant Normal Stiffness) cho thdy khdn^ cd kha nang ndo giam ddng ke gid trj ma sdt tudn hoan, miin Id img sudt cat vdng tudn hodn duy tri trong pham vl d u k l l n .
Sau ddy Id mot phdn tfch ddc lap cdc hieu ung tdi trong tudn hoan theo phUdng phdp md ta cua Poulos (1988) vd thue hien qua chuong trinh phdn m i m SCARP (Static and Cyclic Axial Response of Piles).
ChUdng trinh Phdn tfch cd sii' dung nhilu gia thiet don gian hda, cimg vdi cdc thdng sd khdng d i dang do dugc hodc suy dien dugc tU nhung sd lieu sdn cd (Vp tfnh khdng ddng nhdt ciia ddt, cdc b i l n ddi tfnh chdt cd ly eua ddt, b i l n dang lau ddi khi ddt t i l n ddn den trang thai phd hoai...). K i t qua Id cae phan tfeh chl mang tfnh ddnh gid so bd. Bdi le viec phdn tfch todn bo he t h i n g mdng Id khdng thfeh hgp vdl
ChUdng trinh SCARP, nd chl xem xet mdt coc ddn dien hinh cd dudng kfnh 1,5m, ddi 48m (gia t h i l t coc ddn tudo). Cdc k i t qua dugc sirdung de thdm dd ede dnh hudng ciia tdi trgng tudn hodn tUdng doi hieu qua ddi vdi trudng hgp tai trgng tTnh.
Ngudi ta nhdn thdy rdng cd the xay ra hao hut kha nang mang tdi cgc khi tai trgng tuan hoan vugt qua khoang ± 10MN (lOOOt).Do hao hut sUc chiu tai Idn nhdt khoang 15-20% (gdy ra do giam do ma sat thdnh). Kha ndng mang tai bj hao tdn gay anh hudng tUdng ddi khdng nhay cam den tai trong trung binh, trU khi tai trong trung binh vucrt qua khoang 30MN(3000t). Ngudi ta du doan rdng, tai gia trj tai trgng binh qudn bang vdi tai trgng lam viec va theo mot tdi trgng tudn hoan khoang 25% tai trong lam viec, s u gia tang do liin rdi vao khoang 27% tuong irng cho 10 ehu ky tai trpng.
TU tac dung cae cgc chl djnh dugc tfnh toan theo phdn tfch k i t cdu PTHH thUdng mai ABAQUS, ngudl ta da dua ra de nghj rdng tai trgng tuan hoan ciia mdng thdp Burj khdng vugt qua ± 10MN(1 OOOt). Nhu vay, gia thiet rang anh hudng ciia chat tai tuan hoan khdng tac ddng lam giam dang ke kha ndng chju tai dgc true ciia cdc cgc, vd dnh hudng cung khdng Idn lam den sUe chju tai ede cpc va do lun ed ve la khd hdp ly.
THI NGHIEM THU" TAI COC
Bang 2: Y l u td thf nghiem sd bo cpc Ky
hl$u cgc TPI TP2 TP3 TP4
TP5 TP6 TP7A
DiAng kinh cgc (m) 1,5 1,5 1,5 0,9
0,9 0,9 0,9
Chlgu dai cgc (M) 45,15 55,15 35,15 47,10
47,05 36,51 37,51
Phun vffa thanh cgc (No-Yes)
No No
YesNo
Yes
No No
Lo^i lam thi nghiem cgc
chju tai Compression Compression Compression Compression (cyclic) Compression Tension Lateral Du an Burj Dubai tien hdnh hai chuong trinh thf nghiem nen tTnh cgc, dd la:
-Thf nghiem s d b d bay cgc tai thf nghiem nen tTnh gdp 2 ldn tai trong lam viec.
- Thf nghiem kiem tra tdm cgc edng trinh tai nen tTnh gdp 1,5 lan tai trgng lam viee, thue hien giai doan thi cdng dai trd (8 cgc tuong img khoang 1 % eiia tdng sd 926 cgc).
Ngodi ra, cdn thf nghiem tdi trong dong b i l n dang Idn PDA, gdm 10 cgc (D1,5) edng trinh thap cong 31 cgc (D 0,9) cdng trinh nhd qudy, khoang 5% tdng sd cgc cdng trinh.
Thf nghiem sieu dm sonic kiem tra chdt lugng betdng cgc dugc tien hdnh tren mot sd coc edng trinh. Luu y, d ddy thir nghiem nen tTnh Id muc tieu quan trgng chi'nh. 1^
