le van hung1.2011
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NG DNG PHNG PHP O CAO HNH HC TRONG QUANTRC VNG CA H DM THP KHU LN
KS. NGUYN VN XUNThS. L VN HNGVin KHCN Xy dng
Tm tt: D n239/05 - B Cng an c xy dng trn din tch 5,8ha l t hp a chc nngvi tnh k thut, m thut rt cao, nh thit k a ra gii php thit k h dm thp vi khu
nhp l 43m,cao 8m v c lp t cao 31m so vi chn cng trnh. H dm gm 4 dmthp c t ln 4 vch b tng ct thp dy 1.4m. Do phi ti trng ca 10 tng nn h dmthp b vng, cc nh thit k tnh ton gi tr vng d kin ca h dm thp. theo di v
a ra gi tr vng thc t ca h dm thp trong qu trnh cht ti, Trung tm T vn Trc av Xy dng c giao nhim v quan trc vng ca h dm thp ny. Cn c vo nhngyu cu kht khe v k thut v trang thit b cng vi c im kt cu ca h dm thp, Trung
tm T vn Trc a v Xy dng la chn phng php o cao hnh hc quan trc vngh dm thp trn. Bi bo ny nu chi ti t phng php quan trc h dm thp bng phng phpo cao hnh hc.
1. M t kt cu
H dm thp c thit k nm trong h kt cu ca nh A thuc cng trnh tr s B Cng an.
H dm gm 4 dm thp c t ln 4 vch b tng ct thp dy 1.4m, mi dm c khu nhp l
43m, cao 8m v c lp t cao 31m so vi chn cng trnh, h dm phi ti trng ca 10
tng pha trn.
Hnh 1.H dm thp
Vi dng kt cu dm thp, vic xc nh gi tr vng ca dm c p dng theo tiu chunTCXDVN 338:2005 Kt cu thp Tiu chun thit k.
2. p dng phng php o cao hnh hc xc nh vng h dm thpkhu ln
2.1. Phng php o cao hnh hc
Phng php o chnh cao gia 2 im bng mt tia ngm nm ngang ca my thy chun. Gi
s c 2 im A, B trn thc a. t mia trn cc im A, B, ti v tr c th ngm ti 2 im A, B t
my thy chun. Hiu cao h = HA-HB l chnh cao ca im B so vi im A, l hiu cc s c
trn mia t ti A v ti B qua my thy chun. Nu 2 im A, B cch xa nhau , ti mt trm my
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khng thngm ti c 2 im A v B ta vn c th o c chnh cao gia 2 im ny bng cch
o chnh cao lin tip tng cp im gn nhau. im trc ca cp im ny l im sau ca cp
imni tip to thnh mt tuyn o lin tip. Khi h = HA- HB=S - Tr; S l tng cc s c mia
sau Tr l tng cc s c mia trc. o cao hnh hc c tin hnh theo tng tuyn. Nhiu tuyn
ni vi nhau to thnh mt li cao. Khi trong li ct nht 1 im bit cao, tin hnh tnh
ton bnh sai li cao o c s c cao ca cc im cn li trong li.
T mc 1 ta thy xc nh gi tr vng h dm thp ta cn xc nh gi tr cao ca 2im u dm v cc im cn xc nh gi tr vng trn dm thp. Khi ta cn o ni cc im
quan trc vng dm thnh cc vng cao khp kn v ni cc vng khp kn cao khp kn
ny vi cc mc cao c s.
2.2. La chn cp chnh xc o cao hnh hc v thit b s dng
a. La chn cp chnh xc o cao hnh hc
Theo tnh ton ca thit k gi tr bin dng vng nh nht ca h dm l 1.9mm, do vy sai s
quan trc ca kt cu khng vt qu 1 mm. Vi chnh xc nh vy chng ti la chn cp
o cao hnh hc c chnh xc tng ng li cao hng II.
b. Thit b s dng
Vic quan trc vng h dm thp c thc hin bng my thu b nh chnh xc cao NA2.
(hnh 2: My thu chun LEICA NA2 do Thu S sn xut).
Hnh 2. My Thu chun LEICA NA2
Bng 1.Mt s tnh nng k thut ca my NA2
ng knhGi tr phn
khong bt thuTnmy
NcSX vhng
phng
i
Khongcch ngn
nht
Btthudi
Bt thutrn
SSTP ochnh cao
1km i v v(mm)
Ghi ch
NA2Thu s
Leica 40x 0.9 mT
ng8/2 mm
S dngMicrometer:
0.3
2.3. Gii php thit k mc cao c s v mc quan trc vng dm
a. B tr, khoan gn h thng mc cao c s
Hai u h dm thp khu ln c gi ln 4 vch b tng rng 1.4m trn tng 9 ca 2 khi
nh hai bn. c c s chuyn cao vo cc mc quan trc vng ca h dm chng ti xy
dng h thng 3 mc chun quan trc c khoan su xung tng cui si, 3 mc chun c gi
nh cao v o ni vi nhau to thnh vng khp kn. Ti 2 khi nh hai bn uh dm chng ti
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khoan gn h mc ln vo cc ct chu lc ti tng 1 v tng 9 (v tr cc mc ln ti tng 1 v tng 9
tng ng vi nhau theo tng ct). T cao ca cc h 3 mc chun quan trc chuyn cao v o
cc mc ln ti hai khi nh u dm tng 1 sau t cao ca cc mc ln tng 1 chuyn
cao ln cc im ln ti tng 9. Ti mi chu k o chn ra mc ln n nh nht. T mc ln n
nh nht chuyn cao vo cc im o vng ca h dm.
b. Gii php thit k mc quan trc vng dm thp khu ln
* c im:
H dm thp khu ln l kt cu dng c bit, dm c cu to t nhng tm thp kh ln,
c lin kt vi nhau bi cc mi hn c bit. Khi thi cng xong dm c a ln trn cao
31m, sau sn chng g v sn chng chy. Khng ging nh cc cng trnh khc l c th t
trc tip mia ln cc i tng quan trc. H dm thp thi cng xong s khng t mia c ti v tr
cn quan trc. V vy ti cc v tr gn mc quan trc vng trn dm thp phi l loi mc c sn
mia trn . y l loi mc rt c bit, t trc n nay cha tng c cng trnh no s dng v
khng c bn trn th trng.
* Yu cu ca mc:
- Thp ch to mc c tnh cht ging thp ca dm;
- Sau khi hn gn mc vo dm thp, cc mi hnv sn chng g v sn chng chy;
-Thc chia vch ca mc khng c co dn theo thi gian;
- Cc k hiu trn mia phi r;
- Theo tnh ton ca thit k ti cc im y ca h dm u c gi tr v ng c th, v th
theo di gi tr vng ti cc v tr ny cn gn cc mc quan trc vng ti khi thp y h dm
theo ng v tr thit k (hnh 4).
* Thit k, ch to mc:
T nhng c im v yu cu ca mc. Cc cn b k thut ca Trung tm T vn trc a v
xy dng tm hiu, nghin cu v ch to ra loi mc p ng c cc yu cu kht khe k trn(hnh 3b).
a. Cu to mc chun quan trc b. Cu to mc gn trn h dm thpHnh 3. Cu to mc quan trc
Dm thp
V tr mi hn
Dy mia inva
Cht nh vmia
Thp gc
302
304
306
308
310
312
1
3
5
7
9
B tng
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Hnh 4. S b tr mc quan trc vng theo yu cu ca thit k
2.4. Phng php quan trc
Phng php o c s dng xc nh vng ca cng trnh l phng php o cao hnh
hc cp II.
Vic o vng c thc hin qua hai bc:
Bc 1.o li chun
Li chun l li gi nh cao ca mt mc chun v o ni cc mc chun vi nhau. Mc
ch ca vic o li chun l kim tra n nh ca cc mc chun. Vic o li chun c o
bng phng php o cao hnh hc chnh xc to thnh cc vng khp kn.
Bc 2. Dn cao t cc mc chun vo cc mc o ln
Mc ch ca vic dn cao vo cc mc o ln l xc nh cao thc t ca cc mc trong
chu k hin ti. Vic dn cao vo cc mc o ln c thc hin bng phng php o cao h nh
hc chnh xc theo mt hng. Khi ophi to thnh cc vng khp kn v tun th cc hn sai theo
quy phm hin hnh.
2.5. X l kt qu o
Sau khi o, kt qu c x l tnh ton bng cc phn mm chuyn dng trn my tnh. Li
cao o vng c bnh sai cht ch theo phng php s bnh phng nh nht. Trong li
chun c bnh sai ring chn ra mc chun n nh nht v da vo bnh sai tip li o
ln cng trnh. c kt qu l cao ca cc im mc quan trc vng dm p dng theo tiu
chun TCXDVN 338:2005 tnh vng ca h dm thp.
3. Kt qu o c tnh ton thc nghim
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Hin ti, Trung tm T vn trc a v Xy dng - Vin KHCN Xy dng quan trc vng
ca h dm thp khu ln c 11 chu k. Di y l kt qu tnh ton bnh sai ca chu k 1 v
chu k 11.
Kt qu tnh ton vng
Chu K1 (ngy 10/1/2010)
STT Tnim
Khong cchti u dm
phi(m)
Dm cao(m) Chnh cao TBso vi 2 imu dm (m)
vng sovi chu ktrc(mm)
vng sovi chu kgc (mm)
a b c d e f g h
1 D 1 38.34540
2 D 2 4.55 38.25443 -0.10897
3 D 3 12.95 38.24457 -0.15205
4 D 4 21.35 38.24904 -0.18081
5 D 5 29.75 38.21354 -0.24953
6 D 6 38.15 38.22548 -0.27081
7 D 7
Dmthp1
38.51429
8 D 14 38.58544
9 D 13 4.55 38.24372 -0.33898
10 D 12 12.95 38.24225 -0.33538
11 D 11 21.35 38.24287 -0.32969
12 D 10 29.75 38.21307 -0.35442
13 D 9 38.15 38.21637 -0.34605
14 D 8
Dmthp2
38.55968
15 D 15 38.58520
16 D 16 4.55 38.26148 -0.31185
17 D 17 12.95 38.25901 -0.29242
18 D 18 21.35 38.26460 -0.26492
19 D 19 29.75 38.25053 -0.25709
20 D 20 38.15 38.25099 -0.23473
21 D 21
Dmthp
3
38.4738522 D 28 38.32510
23 D 27 4.55 38.26302 -0.07897
24 D 26 12.95 38.25791 -0.11525
25 D 25 21.35 38.25032 -0.15401
26 D 24 29.75 38.24791 -0.18759
27 D 23 38.15 38.25133 -0.21534
28 D 22
Dmthp4
38.48356
Chu K 11(ngy 07/09/2010 )
STTTnim
Khong cchti u dm
phi (m)Dm cao(m)
Chnh cao TBso vi 2 imu dm (m)
vng sovi chu ktrc (mm)
vng sovi chu kgc (mm)
a b c d e f g h
1 D 1 38.34459
2 D 2 4.55 38.24783 -0.11480 -0.69 -5.84
3 D 3 12.95 38.23267 -0.16327 -1.19 -11.22
4 D 4 21.35
Dmthp1
38.23636 -0.19289 -1.49 -12.08
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5 D 5 29.75 38.20302 -0.25954 -0.97 -10.01
6 D 6 38.15 38.22068 -0.27519 -0.13 -4.37
7 D 7 38.51391
8 D 14 38.58350
9 D 13 4.55 38.23570 -0.34515 0.14 -6.17
10 D 12 12.95 38.22673 -0.34922 -0.63 -13.85
11 D 11 21.35 38.22525 -0.34581 -1.21 -16.1212 D 10 29.75 38.20152 -0.36465 -1.17 -10.22
13 D 9 38.15 38.20953 -0.35174 -0.38 -5.69
14 D 8
Dmthp2
38.55862
15 D 15 38.58350
16 D 16 4.55 38.25337 -0.31841 -0.56 -6.55
17 D 17 12.95 38.24384 -0.30630 -1.29 -13.88
18 D 18 21.35 38.24696 -0.28153 -1.78 -16.61
19 D 19 29.75 38.23544 -0.27141 -1.36 -14.32
20 D 20 38.15 38.24474 -0.24047 -0.60 -5.75
21 D 21
Dmthp3
38.47349
22 D 28 38.32339
23 D 27 4.55 38.25595 -0.08446 -0.83 -5.50
24 D 26 12.95 38.24415 -0.12769 -1.97 -12.45
25 D 25 21.35 38.23586 -0.16741 -2.21 -13.40
26 D 24 29.75 38.23314 -0.20157 -2.27 -13.97
27 D 23 38.15 38.24447 -0.22167 -1.13 -6.32
28 D 22
Dmthp4
38.48316
Biu vng ca dm thp s 3:
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BIU VNG DM S 3
-20
-15
-10
-5
0
5
TN IM QUAN TRC VNG
CK1
CK2
CK3
CK4
CK5
CK6
CK7
CK8
CK9
CK10
CK11
CK1 0 0 0 0 0 0 0
CK2 0.01 -1.28 -1.34 -2.05 -1.96 -0.42 0.45
CK3 0.27 -0.85 -1.12 -1.73 -2.03 -0.52 0.07
CK4 1.28 -0.86 -2.78 -4.05 -3.22 0.14 2.49
CK5 0.53 -2.98 -6.08 -7.78 -7.04 -1.76 1.88
CK6 0.98 -2.61 -6.25 -7.77 -6.53 -1.04 2.20
CK7 0.43 -3.68 -7.86 -9.84 -8.99 -2.61 1.63
CK8 -0.52 -5.68 -10.56 -12.49 -9.78 -2.27 2.08
CK9 0.15 -4.32 -10.26 -12.67 -10.81 -3.97 0.74
CK10 -0.21 -6.23 -12.86 -15.15 -13.32 -5.54 -0.42
CK11 -1.70 -8.11 -15.17 -17.64 -15.09 -6.25 -0.36
D15 D16 D17 D18 D19 D20 D21
c
3. Kt lun- Quan trc vng ca h dm thc cht l quan trc cao ca cc im u h dm v cc
im cn quantrc vng ca h dm;- Do c cu to v v tr c bit nn cc mc quan trc vng dm cn c thit k c bit
nhnu trn;- T nhng s liu quan trc v kt qu tnh ton cho thy: gi tr vng ca h dm thp th
hin ng quy lut bin dng vng ca h dm thp v u nm trong gii hn tnh ton ca thit k;- Nh vy phng php o cao hnh hc chnh xc cao hon ton p ng c cng tc
quan trc vng ca h dm v cc yu cu v chnh xc ca thit k;- C th s dng phng php o cao hnh hc chnh xc cao quan trc v ng ca cc
(hng mc) cng trnh tng t.TI LIU THAM KHO
1. NGUYN TRNG SAN, O QUANG HIU, INH CNG HA, Trc a c s - tp 1,2. PHM VN HI, NGUYN QUANG VIN, Kt cu thp - Cng trnh dn dng v cng nghip.
3. B Xy dng, TCXDVN 338:2005 Kt cu thp - Tiu chun thit k.4. B Xy dng, TCXDVN 271:2002 Quan trc ln cc cng trnh dn dng v cng nghip bng
phng php thu chun hnh hc.5. B Xy dng, TCXDVN 309:2004 Cng tc trc a trong xy dng - Yu cu chung.6. Trung tm T vn Trc a v Xy dng VinKHCN Xy dng, cng Quan trc chuyn v
v bin dng h dm thp khu ln.
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