NHlN RR T H I Gldl
CONG NGHETHI CONG DAM BAN BAN LAP GHEP
TBONG HAY OUHG DOlMG CAO TOC VA DUMG TREN CAO
TS N G U Y I N TRQNG {>6NG T^ng cflng t y P^u t u ph^t tri^n aadnq cao tSc Vi^t N^m B^ (5iao t^idng V|n t i i
COng ngh$ thi cfing dSm bin ban l^p gh^p da diT^c d'ng dgng khi rfng rai t^l nhiju nirdc trfin thfi' gidi, cho phdp rut ngin thdi gian thi cfing, giim cao dfi daft d^p dddng din HM clu, dim bio my quan dfi thj... Bii vifi't gidi thi^u Ichil quit cOng ngh$ thi cfing dfi'm bin ban lip ghdp v i khi nang dng dgng cfing ngh$ niy t^l cic cfing trinh dudng cao tfi'c v i dudng tr§n cao d Vi@t Nam.
Gioi thidu Chung
Trong nhOng rtcim g^n day, cdng nghe thi cdng dSm bSn ban lip ghep da da^c iJTng dgng kha rpng rai tai nhieu nudc tren th^ gidi, dac bidt la d Phap.
Cdng nghe nay thich uTng cho tcit ca cac cdng trinh thdng dung nhu: c l u vaot, c l u can, him chui dan sinh, h i m dudng bd. cau qua sdng... Mdt logt Uu diem noi bat cija cdng nghe thi cong dam bSn ban l i p ghep nhu: rut ngan thdi gian thi cdng, gilm cao dd dudng dap, d i m b i o my quan dd thi, hgn che gian doan giao thdng trong qui trinh thi cdng... hijfa hen rang, cdng nghd nay se cd tfnh irng dgng cao trong xay diJng cac cdng trinh c l u tai Viet Nam.
Thdi gian qua, vdi si,r d l u tu manh me cija Chfnh phd nham nang cao dilu l<i$n cd s6 ha ting cua d I t nudc, nhilu di,r an xSy di,/ng c l u - dudng da dUdc triln khai thi,/c hidn nhu cSc tuyIn dudng cao tdc C l u Gie - Ninh Btnh, Tp H6 Chf Minh - Trung LUdng: hd thd'ng c l u can cua dudng vanh dai 3 H^
Ndi; cac cau vUdt tai cac niJt giao Chua Bdc - T§y Sdn, Lang Ha - Thai Ha, Nguyin Chf Thanh - Trin Duy Hung... Ddi vdi nhilu tuydn dudng, chilu dai phan c l u la tuong dd'i Idn, do dd tien dd thi cdng cau can se Snh hudng tri^c tilp tdi tiSn do tdng the cua cdng trinh. D l day nhanh t i l n dd thi cdng, ket cau nhjp phan o l u can thudng dUdc thi cdng b6i cac d i m djnh hinh (I, T, super T) c h i tao sin. Mdt nhudc dilm cua dgng ket cau nhjp nay la chilu cao k i t cau nhjp Idn, d i n d i n chilu cao dIt d i p cCia
dudng d i n d l u c l u Idn. M$t khdc, k i t c l u nhip dim I, T, super T thilu tfnh my quan dd thj do khdng thanh minh vi cd cdc gd (dim) chgy dgc suit thdn cdng trinh. VI vSy, d l i vdi nhOng dogn tuyIn qua cdc khu dd thj se bj hgn c h i v l tTnh khdng vd thlm my ndn k i t c l u nhjp duoc d l nghj thudng Id dim b i n d^ic due tgi chS. Vdi phuong phdp ndy, thdi gian thi cdng se ddi hOn nhilu so vdi vi0c sljr dgng cdc d i m dinh hinh. Cdng ngh$ d i m bdn bdn l i p ghdp Id mdt gill phdp cho phep dung hda nhOng nhiiflc dilm vd phdt huy nhOng Uu d i l m cua hai bidn phdp thi odng ndu trdn.
Cong nghO dim han chC 190 sin
Cdng nghd d i m b i n bdn ldp ghdp duoc ijfng dgng rdng rai tgi Phdp tiJ han 10 ndm nay vd duoc phdt triln bdi cdng ty Composants Prd-Contraints. Cdng nghd ndy Id sg ket hop Idm vide giOa d i m djnh hinh cd dgng chij T nguoc vd bd tdng bdn m§t c i u d l t | | cho. Cdc d i m T nguoc Id cdc d i m bd tdng dg iJng IOC, thi cdng bIng phuang phdp cdng trudc. Be tdng sCt dgng cho d i m thudng cd mdc C50 hojc C60. B§
Hinh t: m$t cit ngang &iSn hinh cija m^t cdng trtnh Ihu^C^^^
dudng cao t6c A65 (Phip) 3
K-HOA H T I ? S « t h a n g 11.2012
NHlN Rfl TH^'GI<3I
t6ng sii dgng cho b^n mat cdu thudng la C30 ho$c C35. Khi bd t6ng b^n m$t cau d^t cUdng dO tfnh toan, k^t ca'u nhjp l^m viec nhu mflt dim bin d$c dong nha't.
V l mat chju IL/C cua k§'t cS'u nhjp, c6 th^ chia iam hai giai doan sau:
Phdn di§n tfch dam tiep xtjc vdi bi t6ng bSn mat du d6 t^i ch6 duoc tao nham d^ dam bao sy lien kg't giOa bS tSng d^m va b§ t6ng ban mat du.
BUdc 2 (lip dft dim tdi cdng trUdng): trinh ty c l u iSp dim duoc b^t ddu hoac b6i dim bi§n, hoac bdi d i m giOa. Tuy nhi§n, nlu khdng c6 quy djnh khac thi th6ng thudng dm bien se dUOc dat d l u tiln.
Dim tilp theo duoc clu d i n , dat cgnh dim Xhil nhat sau d6 sang ngang vao vj trf cua n6 (hinh 4).
C l l ^
Hinh 2: nguy§n ly bd tri cd't thip trong dim vi bin m$l dim
Giai doan thi cdng: ling suat trudc trong cac philn dim ducjc tinh toan va bo tri d l chju md men u l n doc gay ra bdi tai trpng ban than dam cung nhU tTnh tai do be tong long cua ban mat c l u .
Giai do^n Ithal thic: d giai doan nay, mat cit iam vi§c la mat cat li§n hop giOfa dam bSn va be tong ban mat cau dd tai cho. Qng sua't trUdc tfnh cho mat dt li§n hop phai dD de chju mo men uon doc do tai trong ban than, ttnh tai va hoat tai gay ra. Cac dai thep (ky hi§u so 1 trong hinh 2) dUOc b l trf trong dam de chju mo men u l n ngang gay ra bdi tTnh tai va ho^t tai.
Cic budc thi cdng chi tiet
Budc 1 (che tao dim dU dng li/c trong nhi miy) bao gom: lap dat van khudn, cot thap; cang keo cap dy iJfng lUc; dd be tdng ddm; xCf ly nhiet de be tong dam d^t cudng do cao trong thdi gian ngSn; khi be tdng dat cUdng do tfnh toan, truyen dy yng lyc cho dam, van chuyen dam ra cho tap kit.
Hinh 4: trinh ti/ ciu Up dim
Khe hd giiJa 2 d l dim dUOc bjt kfn bdi gioang bIng mtjt roi tiep tuc dd mdt Idp viJa mdng len de dim bao trong qua trinh do, be tong khdng thd ehay qua khe nay.
[6p vih bjt
Hinh 3: mat cat ngang cDa dim bidn vi dim trong
Gioang tiing milt Hinh 5: chi bet xiS I'y khe hd giOa hai di dim
Tiln hanh lap dat cac dam tilp theo theo trinh tU tUdng ty cho den dam cuoi ciling.
Budc 3 (lip cdt thep vi dd bd tdng bin mat cau):
dau tidn, bo trf cac dai thdp trong khoang trong giOa hai dam, phfa trdn d l ddm (hinh 2). Tilp theo dat ludi thep dpc va ngang bSn mat du. Sau khi k i t thiJc viec dat ludi thep, tien hanh do be tdng ban mat du.
Ph^m vl ip dung
Cdng nghe dam ban ban lap ghep cd the sii dung vdi chieu dai nhip dao dong ty 6 den 30 m. Be day
S«thang 11.2012 g f j I g W * ^ ^
NHlN Rn TH^' Gldl
Hinh 6. Ihi cdng him chui din sinh bing cdng ngh$ dim bin chi lao sin
tdng cdng cua dim vi ban mat du dd tgi chd, vdi k i t c l u nhip gian dOn, vao khoang 1/28.
Cdng nghe nay dUOc yng dung de thi cdng c l u cheo, cau cong cung nhU tat ca cac cdng trinh thdng dyng nhU: c l u vUOt, cau can, ham chui dan sinh, ham dudng bo, c l u bac qua sdng.
Ve mat ket c l u nhip, cd t h i ap dung cdng nghd dam ban ban l i p ghep cho nhjp giSn ddn, nhjp sidu tTnh ngam hai dau cung nhU k i t cau nhjp lien tyc (thi cdng bang each lien tgc hda cac nhjp tTnh djnh).
i/u nhUdc didm
Uu didm: vdi ty 10 giOa chilu cao k i t c l u nhjp va chieu dai nhip la 1/26, c l u kien d i m ban ban l i p ghep cho phdp cdng trinh cd dd mSnh cao, giup giam chieu cao d I t d i p dudng dan d l u c l u va ndng cao tfnh my quan. Do dd, cdng nghe thi cdng c l u bang dam b i n ban l i p ghep r l t phij hop cho xay dung c l u cgn qua cac khu dd thi. D l i vdi cac cdng trinh c l u vuot. c l u can, qua trinh thi cdng cd thd tien hanh song song vdi qua trinh khai thac dudng.
Viec cau l i p d i m thudng dyoc t i l n hanh vao ban dem. B6 b§ tdng bSn mat c l u va cac hgng myc khac cd the t i l n hanh vao ban ngay ma khdng phii gian dogn giao thdng. Mot yu dilm Idn cija cdng nghd nay la rut ngin dang ke thdi gian thi cdng. Cac dam dyoc due trong nha may nen tdc dp san xult cao, chat IUdng dUOc dam bao. Cdng nghe nay cdn
phO hop vdi nhDng cdng trinh ma vi0c btf tr(, Q\H phdng m$t bIng phyc vy thi cdng phyc tgp va tfirt kdm, do khdng ddi hdi m$t b&ng d l dOc d i m . Khdn{^
c l n sii dyng van khudn trong qua trinh dd bd tdng"
b i n m$t c l u ; khli luong bd tdng dd tgi chd ft hon nhilu so vdi vide thi cdng d i m b i n truyin thdng, do dd giam thidu nguy cO d nhifim do rd rl bd tdng.
Nhupc didm: khdu dd vUdt nhjp nhd hon so vdi cac d i m bdn l i p ghdp khdc nhy d i m super T. TSng chi phf xdy lip trong trudng hop cdng tn/dng d qui xa nha may sin xult dim.
m\m
Cdng nghd thi cdng d i m b i n ban l i p ghdp tuy cdn mdi md nhyng da thd hidn dyyc nhilu yu didm.
Tgi Vidt Nam, vdi nhu c l u hodn thidn hd thdng dudng cao tdc vd xdy dyng c l u vU(fX tgi d o nilt giao thdng trong cdc khu dd thj ngdy mdt gia tang, cdng nghd ndy se giup rut ngIn t i l n dd thi cdng v i d i m bao tfnh m5' quan cho cdng trinh. Ngodi ra, vdi phUdng phap thi cdng dOn gidn, thdi gian thi cdng duoc rut ngln ddng kd ndn cdng ngh$ d i m b i n bdn l i p ghdp se giup gidm tdi da dnh hudng d i n cdng ddng •
Tai lieu tham khao
11] G6rard Gu6nt, -Pdnphirique Parisien-Les LBas brertt b couverture; Chantiers de France. N^SS!, 6.2006. *,
[2] J6r6me Herv6, Techn/tjue rapide pour rdaliser tes d^8S M taUier; Le Monlteur. 20.4.2004
[3] Piftrre Deloiien, -Potrfres-da/tes pour couverture courbe'. \M,
Monlteur. 3 8,2001 i [4] Renaud Montes, 'Un nouveau mode de realisation de teMsf",
Les Composants Pr§-Contraints, 2.2002
ro I K ' M f ? A * H n ' r S^ thdng 11.2012
