VAT LIEU - M 6 | T R U - O N G - KY T H U A T HA T A N G
DANH GIA C H A T Ll/QNG CAC HE SQN PHU C H 6 N G AN MON K^T CAU THEP VUNG BI^N VIET NAM
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TS. NGUY£N NAM THANG TS. NGUYEN MANH H 6 N G KS. PHAN V A N C H U - O N G Vl?n KHCN Xay dyng
Tbm tit: Trong nhirng nim gin diy, nhiiu cdng trinh xiy dyng ngoii khai vi ven biin dwgc xiy dirng nhim phijc vu cho mgc tieu ciia Qudc gia li phit triin m^nh kinh ti biin, trong sd dd cic cdng trinh bing kit ciu thip chiim t^ 1$ Idn. Mic dii cic kit ciu thip cd wu diim li cwdng dd cao, ggn nhg va thdi gian thi cdng nhanh han so vdi kit ciu be tdng cdt thip (BTCT), nhwng chdng in mdn cho kit ciu thip trong mdi trirdng biin di dim bio dwgc tudi thg thiit ki li mdt vin di phirc t^p. Thyc ti d nwdc ta hiin nay tinh tr^ng in mdn giy hw hdng cic cdng trinh kit ciu thip li nghiem trgng, tdc dd an mdn khi nhanh. San phu la mdt trong sd nhO'ng biin phip hiiu qui thwdng dwgc lya chgn ip dgng di bio vi chdng in mdn cho kit ciu thip vung biin. Tuy nhiin, chit Iwgng cic h$
san phu bio vi kit ciu thip trong mdi trwdng biin li vin di cin dwgc xem xit k^ trwdc khi lya chgn ip dgng. Bii bio nay trinh biy mdt sd dinh gii bwdc diu vi chit Iwgng mdt sd logi san phu thwdng ip dgng bio vi kit ciu thip viing biin.
1. Tinh tr^ng an mdn k i t c i u thep trong mdi tru>dng b i i n Vift Nam
Tir cdc k i t qua khao sdt thgc trgng dn mbn kit c i u thdp trong mbi trudng biin Vidt Nam eb t h i rdt ra mbt s l nhdn xdt nhu sau:
Qud trinh dn mbn phd huy kit ciu thdp didn ra khd nhanh. Tai mbt s l cbng trinh cb hidn tugng gl thep cgc bb, d i m gl, bong trbc. MO-e db xdm thge cb sg khdc bidt giu-a cdc vung miln. Vi dg: d khu vuc Nha Trang t i c dp dn mbn thdp CT3 la 52,3pm/ndm, Kien Giang: 41,4|jm/ndm, thdnh phi Vinh:
39,3Mm/ndm, Hai Phbng: 31,46|jm/ndm [1].
Mgt s l cbng trinh thuy Igi Ble Hung Hai vd egm cbng trinh ngdn mdn, giO- ngpt, tidu ung sbng Ldn, Thai Binh, ede bb phdn dim bidn bj dn mbn ndng khbng cbn kha ndng Idm vide, ban mdt bj dn mbn tgo thdnh cdc lb vd rdnh [2].
c i u Nguydn Vdn Trbi ble qua sbng Hdn tgi Thdnh p h i Dd Ndng duge xdy dgng tu- ndm 1968, kit c i u bing thdp ong, ndm gin biin (cdeh biin 4,5 km), hidn nay cdc eiu kidn nhu: trg, dim ciu,... bj dn mbn Idm giam kha ndng chju tai ciia eiu (hinh 1, 2).
Hinh 1. ciu Nguyin Vin Trdi - Da Ning An mbn kit c i u thdp vung biin gdy ra thidt hgi kinh t l Idn, chi phi cho sua chO-a khdc phge eb t h i chiim tdi 30 -^ 70% mi>c d i u tu xdy dg-ng cbng trinh.
Hidn nay vd trong nhQ-ng ndm tdi ddy nhu ciu diu tu xdy mdi vd sua chO-a cbng trinh d vung biin se tdng mgnh, trong dd cbng trinh thdp ehilm ty trpng Idn. Vi v$y, ein thiit phai thin khai ung dgng cde giai
Hinh 2. Tinh trang gia dim ciu
phdp hidu qua d l bao v$ chong dn mbn cho kit c i u thdp vung biin Vidt Nam.
2. Cac giai phap ch6ng an mdn cho k i t c i u thep trong moi trirdng b i i n Vift Nam
So vdi BTCT thi k i t c i u thdp cb uu diim Id gpn nh? hgn vd toe db thi cbng l i p dgng nhanh han,
T9P Chi KHCN Xiy dyng - so 3/2011 37
VAT LIEU - MOI TRU'aNG - KY THUAT HA T A N G
nhung do phai true tiip chju tdc dbng cua mbi trudng biin nen logi kit eiu nay neu khbng duge bao vd tot se bj dn mbn rit nhanh. An mdn lam cho tilt didn cdc thanh cua k i t c i u thdp giam di, lam giam db tin cdy v l kha ndng chju tai ciia k i t c i u , Idm tdng kha ndng pha hogi gibn k i t eiu thdp. An mbn lam cho cdc eiu kien sdm bj phd hogi hodc phai sua chu-a nhiiu.
D l chong an mbn cho k i t c i u thdp vung biin thudng lua chpn dp dgng cdc bidn phdp ca ban sau:
- Su dgng cdc kim logi, hgp kim it bj dn mbn;
Thiit k l k i t c i u nhim giam thiiu cde nguy ca gdy dn mbn;
- Bao vd eatbt vd cdc bidn phdp didn hda khdc;
Su dgng cde Idp phu (kim logi, san) ching dn mdn cho kit eiu thdp, ben vdi mbi trudng.
Trong eac bidn phdp neu tren thi sir dgng cac hd san phu tgo Idp ngan each mdi trudng vdi be mgt Bang 1. Mgt sd hg san dwgc kien
thep Id bi$n phap bao vd hi$u qua vd thbng dgng nhit vi cd uu diem thi cbng dan gian, dp dgng cho cac k i t c i u cd kich thudc vd hinh dgng khdc nhau, eb tinh thim my cao, mbt s6 h$ san do tidu chuin ISO 12944 kiln nghj trong bang 1. Mdt khdc niu dung bidn phdp san phu thi cbng tdc bao tri cOng d l dang [3]. Vi t h i , hidn nay cd tdi han 80% b l mdt kim logi dugc bao vd bing san vdi cdc chung logi san r i t phong phu [5].
Ngdy nay, vdi sg- phdt then nhanh cua ngdnh ky thudt cdc hgp chit cao phdn tO ndi chung va nganh san ndi ridng, cdc loai chit tgo mang cd kha ndng bdm dinh tot tren thdp vd ehing dn mdn cao nhu- epoxy, polyuretan, furan, silicon, kha ndng ndng cao hdm lugng chit r i n vd vide su dgng ede dung mbi hogt tinh, cdc chat hoat dOng be mdt va phg gia ndng cao db bin nude cua mdng san, tao kha ndng sgn tren nen cb dp i m cao, da tgo nen nhu-ng h$ san ed kha ndng bao v$ cao vd ddng tin cdy, chIng dn mdn cho k i t c i u thep.
nghj tmng tieu chuan ISO 12944
Son lot Chat tgo
mang 1
s6
Idp 2
Chieu day MSK, pm
3
So-n phu Chat tgo
mang 4 Cho mdi trudnc Epoxy,
Polyuretan giau kem Etyl slllcat
1 1-2
1 1
40 80 40 80
Epoxy, Polyuretan
Epoxy, Polyuretan
S6 Idp 5
Chieu day MSK, pm
6
He son S6
Idp 7
Chieu ddy MSK, pm
8
Tuoi thp, ndm 5-15
9
>15 10 cd muc db an mdn C5-M
3 3-4 3-4 2-4
200 240 280 240
4 4-6 4-5 3-5
240 320 320 320
X
X X X Cho mdi trudng cd muc dp an mdn C4
Alkyd Cao su do hoa Epoxy Epoxy Epoxy, Polyuretan giau kem Epoxy, Polyuretan Etyl slllcat
1-2 1-2 1-2 1 1-2
1
1 1
80 80 80 160
80
40
40 80
Bitum Cao su do
hoa Cao su do
hoa Epoxy, Polyuretan Cao su do
hod, Polyuretan
Epoxy, Polyuretan
Epoxy, Polyuretan
2 2-3 2-3 1 2-3 2-3 2-3 2-3 3-4 2-3 2-3 2-3 2-3
160 200 160 120 200 160 200 240 280 160 240 120 200
3-4 3-5 3-5 2 3-5 3-4 3-4 3-4 4-5 3-4 3-4 3-4 3-4
240 280 240 280 280 200 240 280 320 200 280 200 280
X X
X
X X
X
X X X X X X X Cho mdi trudng cd muc do an mdn C3
Alkyd Cao su do hoa Epoxy
1-2 1-2 1-2 1-2 1-2 1-2
80 80 80 80 80 80
Cao su do hoa Cao su do
hoa Epoxy, Polyuretan
2-3 2-3 1-2 2-3 2-3 2-3 2-3
120 160 80 120 160 120 160
3-5 3-5 2-4 3-5 3-5 3-5 3-5
200 240 160 200 240 200 240
X
X X X X X X
38 T9P Chi KHCN XSy dyng - s6 3/2011
VAT LIgU - MOI TRU'aNG - KY THUAT HA T A N G
Epoxy, Polyuretan gidu kem
Etyl silicat 1 1 1 1
40 40 80 80
Epoxy, Polyuretan Cao su do
hod Cao su do
hoa Epoxy, Polyuretan
2-3 2-3 2-3 2-3
160 160 120 120
3-4 3-4 3-4 3-4
200 200 200 200
X X X X 3. Xem xet c h i t lu>ang cac h f s v n phu bao v f chdng an mon cho k i t c i u thep
Dga vdo k i t qua nghien cuu cdc he san do tieu ehuin ISO 12944 kiln nghj trong phdng thi nghidm cung nhu xem xdt mbt so k i t qua tiJ- thge t l ung dgng, budc diu cb nhu-ng ddnh gid v l db bin mbt so hd san thbng qua ede ehl tidu ca ban nhu sau:
Bang 2. Mgt sd chi tieu ca ban cua cac hg san
— — ^ ^ ^ ^ I j e s o - n
Chi tieu -^—-—___
Do bam dinh, N/mm^ (TCXD 236:1999)
Kha nang chong an mdn (tieu chuan ISO 14993), chu ky
Do ben ndng Ignh, chu ky (TCVN 6934:2001)
Do tham ion dorua, 10'^mol/l (ASTM A943)
Od ben mil muoi, gid (ISO 7253) DO ben nhigt am, gid (TCXDVN 341:
2005)
Epoxy gidu kem - polyuretan 1.16-1.85 62-69 Ldn han 450
0.005- 0.01 560-940 720-648
Cao su do hod 0.43 - 0.47
45-50 9 0 - 1 1 0 17.4-24.5
277-305 120
So-n alkyd 0.38 14-22
54 38.5-48.5
120-198 24
a. Dd bim dinh
Kit qua thii- nghidm cho thiy hd san epoxy gidu kem polyuretan cb db bdm dinh vdi nin thdp cao nhit, dgt 0,16 1,85 N/mm^; ede hd san cao su do hod cb db bdm dinh 0,43 - 0,47 N/mm^ hd san alkyd cb db bdm dinh 0,38 N/mm^
b. Khi ning chdng in mdn
Cdc kit qua thir nghidm theo tieu ehuin ISO 14993 cho thiy: cde hd san epoxy gidu kem polyuretan eb kha ndng chong dn mbn cao nhit, chju dirge tir 62 din 65 chu ky thii- nghidm (tieu chuin JIS K5627 quy djnh san ehIng dn mbn phai chju dugc it nhit 28 chu ky thu nghidm); k l tiip Id cde hd san cao su do hod vd kha ndng ehIng dn mbn thip nhit Id hd san alkyd.
c. Dd bin ndng lanh
Ob bin ndng Ignh eua cdc hd san ddc trung cho dO bin cua mdng san dudi tdc d0ng cua thdi tilt khic nghi$t ning mua dbt ngbt diin hinh cua khi hdu nhidt ddi I m Vi$t Nam. K i t qua thu nghidm chirng td cdc h$ san epoxy gidu kem polyuretan ed db bin ndng Ignh cao nhit (450 chu ky), cdc hd san cao su do hod (90 110 chu ky), thip nhit Id hd san alkyd
(54 chu ky tuang duang vdi ydu ciu doi vdi san tudng ngodi).
d. Dd thim ion clorua
Dd chIng thim ion clorua eua mdng san phan dnh kha ndng ngdn can sg xdm nhdp eua ion clorua qua mdng san. Kit qua thu nghidm db chIng thim ion clorua eua cdc mdng san cho thiy: cde hd san epoxy gidu kem - polyuretan eb kha ndng chIng thim ion clorua cao nhit trong ede hd san thu nghidm, tiip theo la hd san cao su do hod, hd san alkyd kdm nhit v l tinh chit ndy. Diiu ndy cdng minh chung rd han cho kha ndng bao vd thdp ehIng dn mbn thip eua hd san alkyd trong mbi trudng tu nhien.
e. Dd bin mu mudi
Theo tieu chuin ISO 12944, ede hd san cao su do hod ehl nen dp dgng trong mbi trudng cb muc db xam thgc C3 vdi tuli thp trung binh. Trong mbi trudng cb muc dO xdm thuc C4, tuli thp bao vd cua cdc hd san ndy ehi d muc thip. Do db, cin nghidn cuu biin tinh hd san ndy d l ndng cao d l bin nhi$t I m eua chung, bdi vi kha ndng chju mu muli cua hd san ndy khd cao. Cde hd san epoxy gidu kem - polyuretan cb t h i dp trong mbi trudng xdm thgc C3,
T9P chi KHCN Xiy dyng - s6 3/2011 39
VAT LIEU - MOI TRU'aNG - KY T H U A T HA T A N G
C4 vdi thdi hgn bao vd cao, mbi trudng C5-M vdi tuli thp trung binh. Hd san alkyd cd d | ben nhi$t i m qud thip (< 48 h), khbng dgt ydu cau bao vd k i t c i u thdp trong mbi trudng khi quyin biin (thip nhit la C3), do db khbng ndn dp dung trong mbi trudng ndy.
f. Dd bin nhiit im
Kit qua thO nghid^ eho thiy dp ben nhidt I m phg thubc nhieu vdo logi chit tgo mdng san. Hd san alkyd cb dp bin nhidt i m thip nhit (24h), diiu ndy lien quan din tuoi thp ngdn cua hd san alkyd trong thue t l khi su dgng d l bao vd cdc k i t c i u thdp. Cdc hd san khdc thudng eb db bin nhidt i m han hin hd san ankyd diin hinh nhu hd san cao su do hod, ddc bidt Id he san epoxy gidu kem - polyuretan.
4. Kit luan
Mbi trudng biin Viet Nam cd tinh chit xdm thge mgnh doi vdi k i t c i u thdp. Muc dp anh hudng ciia mbi trudng Idn k i t c i u thdp d ede vung miln cb su khdc bidt.
Tinh trang an mbn k i t c i u thdp vung biin Viet Nam Id nghiem trpng. De dam bao tuoi thp thiit k l cin phai dp dgng cdc giai phdp bao vd chIng dn mbn, md san phu Id mbt trong nhu-ng giai phdp cd t h i lua chpn dp dgng.
Xem xet eac eh? tidu ea ban ve kha ndng bao v$
kit c i u thdp cua cdc hd san nhu db ben nhidt i m , mu muli, db chong thim ion clorua, kha ndng chong dn mbn, db bin nhidt i m cua mbt so hd san thbng dgng
cho thiy hd san epoxy gidu kem polyuretan cd d$
ben cao va kha ndng bao v$ k i t cau thdp trong mbi trudng xdm thgc vung bien rat tot, tiip d i n Id cdc h$
san cao su do hod vd hd san alkyd.
Cdn cu vdo yeu c i u bao v$ chong dn mdn, mu-c db anh hudng cua mbi trudng, dang k i t c i u thdp dl Iga chpn dp dgng hd san phCi hgp ddp ung ydu eiu d i r a .
TAI LigU THAM KHAO
1. NGUYEN MANH H O N G vd ctv. Bao cdo tong ket de tdl nghien cuu ung dgng son bao vf ket ciu thep vung ven bien Viet Nam, Ha N&, 2007.
2. OO VAN HO-A, VO T H A N H HAI, NGUYEN DINH TAN.
Thgc trgng an mdn cua van thep cdng trinh thuy Ig^i.
Hpi nghi khoa hpc toan quoc lan thu hai ve sg co vd hu- hdng cdng trinh xay dgng. NXB Xiy dgng. Ha N^i, 2003.
3. NGUYEN VIET H U $ , VO B I N H HUY vd ctv. SOT xi mang vd ket qud dp dgng trong dieu kien Vigt Nam. Bia do giim dinh de tai cap Nha nwac, ma sd 48D.02.02.
Ha Ngi, 1988.
4. NGUYEN THj BiCH THUV vd ctv. Lga chpn, xdy dyng tieu chuan vd cdng nghd son phd bao v# thich h^p trong mpt sd mdi trudng ddc biet cho cdc cdng trinh giao thdng. Bio do nghigm thu de tii, Viin Khoa hgc vi Cong nghg Giao thong v$n tai, Hi Ndi, 1997.
Ngiy nh$n bai:15/8/2011.
40 T9P chi KHCN Xiy dyng -so 3/2011
