Tnrtmg Duv Dif Cong nghg thi cdng lap dat neo va nhCrng vin d l cdn gidi quylt Tgi cdc md him Id vCing Quang Ninh, tu tn^dc din nay da dp dgng ching giu eac dudng Id ddo trong dd vd t
Trang 1^ NGHIEN CCJa t)E XOfiT THIET Bj CONG NGHE THI CONG
NEO BE TONG COT THEP NHAM PHAT TRIEN AP DUNG CHONG LO BANG vi NEO
Up to now, anchor bolts used together with shotcrete has
been the lightweight supporting structure applied to the
underground constructions However, this type of the
supporting form has been so far not widely used in the
supporting works in mines in Quang Ninh coal basin One of
the main reasons is the limitation in their execution process
the reinforced concrete anchor bolts for increasing their
application in supporting works in mines
TS PHAM MINH e i / C
Vl$n khoa hpc Cdng nghi Md- Vinacomin
Bien t$p: TS Tnrtmg Duv Dif
Cong nghg thi cdng lap dat neo va nhCrng
vin d l cdn gidi quylt
Tgi cdc md him Id vCing Quang Ninh, tu tn^dc
din nay da dp dgng ching giu eac dudng Id ddo
trong dd vd trong than bang mOt s i logi vi neo,
nhu neo nem che, neo bd tdng c i t thep (BTCT),
neo Ing hd vd g i n day Id neo chat deo c i t
thdp (CDCT), trong d6, dd san xuit dugc chat
ddo thay t h i nh$p khiu
* Neo n§m che (hinh 1): la logi neo dan gian
v l elu tgo Phin cuoi thanh thep neo dugc xe
m6t ranh c6 ehilu ddi tir 20-30em De neo mang
tai, chi cin ddng mgt chiee nem vdo phan ranh
culi thanh neo Cd t h i su dgng biJa hoac khoan
khi ndn d l ddng neo Khod neo nem che mac du
elu tgo vd che tgo khdng phuc tap nhung d l
khod neo Idm vigc I n djnh can sy phu hgp ve dp
bin cua logi da vd dp Idn lyc tdc dpng De dam
bao yeu ciu tren Id tuang doi khd khan, vi the,
chP den nay neo ndm che it dugc dp dung
' Neo CO hQC (hinh 2): nguyen tac Idm viee
cua khod neo eung tuang ty neo nem che, dp
b i n cua dd qua eao hay qud t h i p deu khdng
thuan tien, do khod neo khdng md hoac khdng
bam dinh tit
* Weo ong ho (hinh 3) vd neo ong phong: Id
loai neo Idm viec theo nguyen ly ma sdt tren todn
bO thanh neo vdi thdnh lo neo
Khi dung mdy khoan ep Ing hd vdo Id neo,
Ing bj co, ndn tao lyc ep 6ng hd ludn cd xu
hudng md, dan ra, Idm cho than neo ma sdt vdi
Sllrarrf^TfTTfrnTfTTTfiTTTrr?
Hinh 3 Neo dng hd
thinh Id khoan Doi vo'i neo dng phdng, d l lim
viec, t^r\ bom dung dich de l i m phdng dng neo
* Neo BTCT va neo CDCT (hinh 4): l i lo?i
neo sy dyng chit b i m dinh l i vu'a bd tdng hoie
chat deo Vol neo BTCT, d l neo lidn k i t v<n
thinh Id neo phai bom, dun vu'a bd tdng vao diy
Id, sau dd lap thanh neo Khi vO'a be tdng ddng
Trang 2de dam bao on djnh khdng de dd chuyen vi vd biln dang
Dya vdo i>ng suit ngang cua khdi dd nguyen cung nhu coi su l i p day be tdng dam bao dp chat Idm cho neo du kha nang mang tai (1):
Hinh 4 Neo BTCT vi neo CDCT
eung, be tdng se gan thanh lo khoan vdi cot thep
hinh thanh khii be tdng c i t thep nhan tao, md
than neo trd thdnh cdt trong be tdng dd
Neo bdm dinh hay neo ma sat ve ca ban chat
bdm dinh dugc bo tri de lap day toan bp than
neo Tuy nhien, d l xdc dinh tai trpng cua neo,
eae tdc gid [1], [2], [3] thyc hign nhieu thi nghigm
va thiy rang, khod neo (phan nam gan ddy Id
Hinh 5 Sa dd moi quan h$ gli/a tai trgng neo BTCT
vdi chiiu dii do^n thanh neo nam trong be tdng:
du^ng dOi - biiu thi c6t th6p bi chiy
Thanh neo ip 16-18mm, thanh phin X/C
1:0; 1:4:1: 3: 1:1 va 1:2
neo) vdi dudng kinh khac nhau, chi can dat d i n
chilu sau nhat djnh, 6\^Qfc bilu diin tai hinh 5
Tu k i t qua thyc nghigm [2], xdc djnh chieu
ddi khod neo phg thupc vdo thdnh phan be tdng
X/C, vdo dudng kinh thanh neo nhung chilu ddi
kfida khdng qud 30cm Khi thanh cot thep ndm
sdu han, vigc tang tai chi Idm cho thanh cot neo
bj chay va dut dut
Ngodi viee xdc dinh chilu dai khod neo bang
thyc nghigm, cae tac gia [1], [2], [3] cdn su dung
phyang phap giai tieh de tinh toan chieu dai
khoa neo
Khi biet tai trpng neo P (tinh vdi h$ s6 dy tri>
an toan k) Chilu dai khoa neo b trong neo BTCT
P<n.d^J,(,C + cj^f,) (1)
Theo Roghinxki P = TT.dt.n.13 r (2)
Tu dd biln ddi ta^eo chieu ddi khod neo I (3):
P
}>-Hayl = P ji.d.z
(3)
Trong dd
C - Lyc bdm dinh giO-a eit neo vdi be tdng;
khi thanh neo trdn tran 0 1 8 - 20mm thi C - IS
- 30kG/cm2 vdi mdc bd tdng 150 -250kG/em2
Khi thanh neo Id thdp gdn trdn thi C 25 -50kG/em2;
OH - Lfng suit phap tuyen do luc day hdng, c6 the Idy bang OH = A.y.H: A H$ s i day hdng -0,2 - 0,3 (Dp tdn cua ung suit khong nhOng chi phg thudc vao tinh chat dd (A) ma cdn phg thupe vdo dp eung eua c i t lieu be tong cung nhu phuong phdp dat thanh cdt neo);
fl - He s i ma sat giO-a thep vdi be tdng (fi = 0,4 - 0,5);
T - Luc bdm dinh thanh neo vdi be tdng, kG/cm2
Khi su dung neo hdng trong dd khdng chong gii> CO f< 3:
P<yy.nd,jAA^a,f,) (4)
Khi do chieu dai khod neo bd tdng Id:
Trong do:
[i] - Dp ben eat cho phep cua be tdng hoac
dd khdng bang nhau tai hdng khoi da; hai gid tri
dp ben cat nay ddu nhd;
f2 - He so ma sat giu'a be tdng vdi be tdng hoge da vdi dd;
4J - He s i tfnh tdi su tham gia cua dign tich
do anh hudng cua dp ben cat, lay bang 0,2 - 0,3
Trang 3cho tinh todn vd ching be tong giing dung khi
gieng khdng cd vanh chong trugt
Dudng kinh thanh neo dugc tinh theo (6):
4
Suy ra
(7) Trong do:
Op - Dp b i n keo tinh todn cua thep CT3 Idy
bdng 2100 kG/cm2
Nhu vgy, chilu ddi khod neo lien quan d i n tai
trpng, vd ehilu dai khda neo bdm dinh nam trong
mpt gidi hgn nhit dinh Trong tinh todn thiet k l
ching giO dudng Id bang neo BTCT hay CDCT
bang nguyen ly treo, d i m hay khod thi khod neo
ludn giu' vai trd quan trpng trong hg thong vi neo
- khii dd N l u chieu dai phan khod neo do thi
cdng khdng du, dp ben ciia vgt Ii0u khod neo
khdng dgt, khi dd khd ndng chju tai eua neo
khdng dam bao
Hinh 6 Kit ciu neo BTCT trong l5 neo
a-|»uf 4llJi!t> voj IT
Hinh 7 Binh nap vOa be tdng vio l6 neo
Theo hudng dan tinh todn thilt k l vd su dgng neo BTCT, CDCT [4], sau khi khoan Id neo, v§ sinh lo neo, e i n ehuan bj vgt ligu bdm dinh d l dua vdo lo neo Vdi neo BTCT la vigc bam vua
be tdng vdo Id khoan neo VO'a be tdng Id hin hgp xi mang, cdt, c h i t phg gia, chit dpn, nudc, sau khi djnh lugng dugc dua vdo thung trpn, may se trpn d i u cdc thanh phin cot ligu Thilt
bj ngp vu'a vdo l5 neo Id binh hinh trg (hinh 7) co kha nang chju dugc dp s u i t khi ndn 2-3 atm,
mpt d i u cd nap de ngp hdn hgp be tdng tiKt'\
dau cdn Igi n l i vdi dng d i n bd tdng De bom bd tdng vdo Id neo, su dgng khi nen dp suit 2-3atm Khi nen xuyen qua Idp be tdng vd thii ra ngoai kdm theo hon hgp vdo lo neo
Trong xdy dyng cdc cdng trinh nglm giao thdng, thuy dien, thuy Igi , vi$c ngp vua be tdng vdo l5 neo dugc ca gidi hod vd t y dgng hoa cao De ngp vCra be tong vdo IB neo sdu 5-7m ngudi ta khdng su dung binh ngp nhu hinh 7 ma
su dgng thilt bj t l hgp khoan, nap vua Sau khi khoan xong mdi lo neo, may khoan neo (boltec)
su dgng bom be tdng dp suit eao de phgt vOa
bd tdng vdo Id neo Sau khi ngp vua vao lo neo,
bp phgn ein mdy se dua thanh c i t neo vdo 16
De giu* cho thanh neo khdng bi tupt ra ngodi, tay ngp ty dpng be cong thanh neo, sau dd dung nut
gd hoge vai ehgn vu'a chay ra ngodi Hudng cam cua neo trong dudng 16 dupc bo tri theo hinh re quaL Cdc neo vudng gdc vdi mgt
Ip vd nghidng vdo phia tim 16 Neo noc Id neo chju tdc dpng cua t y trpng khoi dd va ludn eo xu hudng rai vdo tdm trai dit
Ngp vu'a be tdng vdo Id neo bang binh bam khi ndn Id mpt cdng vi0c phtpc tgp, khd khang (flnh chit lugng vua cung nhu muc dp l i p diy
va kha nang chen ehgt D i u tien, de ddng khi nen xuyen qua cac Id rdng trong vu-a ra vdi dan,
dp suit khi nen trong binh do bi ddng kin ndn tang len nhanh Khi ddng khi nen thing dugc sue can eua *ua be tdng, do dy tru the nang Idn nen vO'a be tong se phun mgnh Neu thao tac khdng dung qui trinh hoge d l vdi phun khong dung hudng, vua be tdng b i n vdo thiet bj thi cong vd ngudi trong guong se gdy nguy hiem Bgm phgt thdi diem d i u cd toe d | Idn se gay bgt n i y mgnh Vi>a bam Id dung djch khdng dge,
d l tgt tgi cdc Id doc ddng Ddy Id nguyen nhan
Trang 4Idm cho khod neo khdng dugc l i p day vd chen
chdt, Idm giam tai trpng neo
Qua trinh kiem tra tai trpng bang keo rut nhd
neo khdng phan dnh thyc t l tai trpng neo Dii la
nap vua be tdng bang binh bom (hinh 7) hay su
dgng bam tia cua mdy khoan ngp neo Boltec thi
v i n de thudng xay ra Id ddy Id khoan rlt khd bao
dam su l i p day VO'a be tdng chi dugc giu' lai khi
dua thanh neo vao va dung nOt d l ching vu'a
rai Theo nguyen |i? lam viec, neu chieu ddi khod
neo trong vung da ddn hoi khdng dam bao Itt <
Ineoc^ttvit, kha nang mang tai cua neo se bj giam
Nhu vdy, doi vdi mdi logi neo, loai chit bam
dinh, thilt bj vd cong nghg thi cdng cho thiy cdn
cd nhung v i n de can nghien ci>u, hodn thign d l
ddp ung yeu e l u nang eao san lugng vd gia
thdnh phu hgp, dd Id:
Ve v$t liiu:
- Neo BTCT la logi neo vdi nhieu uu ^ e m ve
kha nang chju luc, ve cung d p vat lieu, v l gid
thdnh Nhung cdng nghd ngp vO'a khdng phuc
tgp Kha nang l i p d i y khdng chde chan, dan den
su khdng dam bao dong deu v l tai trpng eua tdt
ca cdc neo
- Neo CDCT thi vdi chat deo, dieu kign bao
quan, thdi gian tuu kho vd ddc biet gid thdnh
la van de chua that h i p dan vdi ngudi su dgng
Ve thiet bj thi cong:
- Neo BTCT khong ddi hdi thiet bj thi edng
chuyen dung khoan lo neo, khdng han ehe toe
dp chong giu Id, nhung thilt bj nap be tdng ddi
hdi muc d0 an todn cao; khd quan Iy toe dp phgt
vua vd su l i p day, d i xay ra nhu'ng bat trac
- Neo CDCT ddi hoi thiet bi, phg kien chuyen
dung, dong bp, dung chung loai (may khoan neo,
mdyxietneo, buldng neo ).Ddihdikythudtva
trinh dp thi cdng Dae bigt, thdi gian luu kho
ngan, dieu kign bao quan chat che, can thilt bi
bao dn d nhigt dp thip, it thay doi
Gan day, thay vi su dgng thdi chat deo, hay
si> dung binh ngp vu-a be tdng nhdm thudn tign
trong thi edng vd ha gid thdnh, mpt sd nai tren
t h i gidi vd trong nudc da hodn thien cdng tdc
ching giu neo BTCT theo hudng: 1) Su dgng
cdc thdi xi mdng khd; 2) Su dung thiet bj dun vij-a
ngp vdo lo neo
1) SO' dung cac thdi xi mang kho
Cdc hang Minova, Sika vd cdc nhd san xudt vat lieu be tdng tai Trung Qulc che tgo cae thoi
xi mang khd ddng gdi ed chieu ddi t u 250 -350mm, cd mdng ching tham, dugc bao ve bing bao polyethylen Khi thi cdng, lay thdi san phim ddng gdi ra khdi bao polyethylen va ngam vao nudc, d l cho nudc cd t h i tham du vdo san pham qua mdng, tao nen vu'a gdc xi mang thixotropie, khdng co ngdt Chit ho trg trong vua bao dam su co gian c6 the kiem scat dugc d l
on djnh vO'a vd kiem sodt sy hut nudc d l cung
d p ty Ig N/X toi uu, dgt cudng dp cao sdm Tinh lien k i t tong the cua vu'a cho phep su dung san pham trong dieu kign udt, thgm chi ca trong tnfdng hgp nudc ehdy tu trong Id khoan ra trong gidi han cho phep khdng lam trdi vO'a Dac diem cOa cac thdi xi mang khd nhu sau:
• Khdng dpc to, khong eo elorua;
• Khdng d n phdn loai khi d n van
chuyen;-• Cd the su dgng ngay;
• Khd nhanh vd r l t cung;
• Dp b i n culi cung cao;
• C6 the dung nhu Idp vu'a bu co ngdt;
• Khdng d n may bam hoac mdy trdn;
• Quy trinh lap dat nhanh vd dan gian;
• Thdi gian bat dau ninh k i t 12 phut, thdi gian kit thuc ninh k i t 60 phut, d nhigt dp 21*'C Khi nhigt do cao thi thdi gian tren ngan lai Thi cong Id khoan neo, Id khoan phai khoan
d i n chieu sdu qui dinh bang mdy khoan xoay dap hoac dap xoay vd phai kilm tra de bao dam sgch vd khdng bj vudng ket dd Cdc thdi xi mang ddng gdi phai l i y ra khdi bao lolyethylen vd ngdm vdo trong nude it nhat Id 1 phut vd khi thay edn c6 bpt khi thoat ra t u thdi xi mang thi phai ngdm den 03 phut Khi quy djnh ve lam udt thdi
xi mang hodn tat, lay thdi xi mang ra, cho vdo Id khoan Thoi xi mang phai cho vdo tan ddy Id khoan bang mpt thanh nhoi hoac vgt lieu de nhoi,
d i y thdi xi mang vao day 16 khoan neo Tat ea cdc thoi xi mdng djnh muc cho mpt 16 phai dugc dua vdo Id nhanh ehdng vd ngay cung mpt thdi gian Thanh neo dugc day vdo trong Id d l pha
vd bpc Cd the dung mdy khoan de ddy thanh neo, vua d i y vua xoay vdi t i c dp ti> 150
-4000v6ng /phut 6k dua thah neo vao day Id neo
2) Thay the binh bom be tong bang thiet bj
Trang 5nap dun be tong
Sir dgng nang lugng khi nen de phun be
tdng, do khd khan eua vigc 1dm chu dugc qua
trinh bam phgt nen chit lugng vd dp lap day,
kha ndng chen ehgt khd bao dam Nap be tdng
bang phun khi nen, do su dgng ddng khi d l day
vua ra khoi binh phun nen ddng phun do bj tae
dong eua kich thudc hat, trpng lugng ban than
hgt, mue dp bam dinh giu'a cdc hat nen hon hgp
be tong khi bay vdo 16 bj phdn tan, phan Idp Tgi
phin khod neo - phin sat day Id neo be tdng
ehu y l u la cat, bpt dd mjn vd mot lugng xi mang
xi mang nhd [5] C i t ligu thd, bd khung chju luc
cua be tdng ndm d phan giu'a hoac dudi neo, do
do dg t>en cua be tdng phan khod neo khdng cao
so vdi phan thdn va dudi neo Mat khde, do be
tdng khdng l i p d i y day Id nen chilu ddi khoan
bj gidm v.v dan den sy dam bao dac tinh ky
thuat cua khod neo khdng ehac chdn
D l thay the ddng chay phdn tang cua hdn
hgp be tdng thdnh ddng chay roi, nhilu hdng c h i
tgo mdy thi cdng da san xuat cae thiet bj nap be
tdng theo dgng dun Nguyen ly Idm vigc cua may
nap vua be tdng tuang t y cdc thiet bj "xay,
nghien thit" su dung d l xay hay bam thit Hdn
hgp bd tdng tuai duge nap vdo binh hinh trg,
trong dd cd dgt mpt trg xoan cycloit Khi taic
xoay hon hgp be tdng tuoi theo cdc ranh xodn
d l dun ra ngodi Toe dp xoay cua tmc quyet djnh
d i n chieu cao nap vd vigc dun h i t s i lugng be
tdng tuai trong mdy dun Thiet bj dun be tong
gidi thigu tren hinh 8
May dun vu'a be tdng hoat dpng theo kilu tmc
xodn nen khdng sinh bui, an toan trong qud trinh
ngp vi>a Vu-a dugc day trdn ddy 16 neo Chilu
Hinh 8 l\AAy dun vCra tii tdng vio l5 neo
Hinh 9 Ddng vQ^ bi tdng ra khdi miy dun
ddi khod neo dugc l i p ehgt kin bang vOa be tdng nen chilu ddi vd dp b i n be tdng ludn ehac chan Vdi mdy ngp dun be tdng, nen chieu ddi khi tinh toan khod neo cd t h i loai bd he s i du' tri> 1,3-1,4, tilt kigm dugc chieu ddi du phdng
Id neo cung nhu chieu dai neo d y tru sai so khi thi cdng
Thilt bj dun gon nhg, an todn eho ngudi dilu khiln Higu qua kinh t l do thilt bj nay mang lai Idn, dd la vigc rut ngan chieu ddi Id, chilu dai thanh neo , cdi thign dang ke ve moi trudng, an todn trong thi cdng, khdng ddi hdi nguyen eong ngng nhpe nhu khi ngp vija bang khi nen vv
Tdm lai:
De cai thign dilu ki0n lao dpng, an toan, giam thilu tdc dpng khdng t i t d i n mdi trudng, tilt kiem chi phi vd giam gid thdnh ching Id bang vi neo BTCT, vat ligu - xi mang thdi khd va thiet bj nap vua be tdng dugc nghien cuu gidi thieu la nhu'ng vdt lieu thiet bj da va dang dugc su dung nhieu trong xdy dyng cdng trinh ngam va md Vdi vdt lieu vd thilt bj thi edng tren se gdp phan
de phdt trien neo BTCT ngdy mgt rpng rdi hon trong ngdnh Than./
Tdf lieu tham khao
I.Kazimierz Podgorski, Wladyslavi/ Podgorski,
1969 Obudowa Kotwiov\/a \A^robisk Gomiczych.,
V^davmictvx) "Slask"
2 B M PoauHCKuu HpoeKmupoeaHue upaoiem
)Kene3o6errK}HH0u Kpeno 1971 MocKsa Hesopa
3 S H CeMeecKuu tUmaHaoeaa Kpen M
Me-Tannypmsflarr
4 Huung dan si> dung neo BTCT ket hop be
tong phun kho - TKV; HiKmg din s u dung neo
CDCr-TKV
5 Sika Rokkon CVN; Meyco Masterbond -Gidi thigu san phim