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MAT THUY CHUAN QUY aOiC TRONG XAY DI/NG - DO CAO QUY UdC CONG TRl/dNG VA NHUfNG HE TQA DO KHONG GIAN SUf DUNG
TRONG TRAC DIA XAY Dl/NG CONG TRINH
PGS. TS. PHAM VAN CHUYEN TriJdng Dai hoc XSy diing Ha Noi
I. MAT THUY CHUAN QUY l/(JC TRONG XAY DUNG VA ©6 CAO QUY UdfC CONG TRUOlNG Do cao H la mdt trong ba ylu t l (x, y, H) de djnh vj diem trong khdng gian. V§y dp cao H la gl?
1. Mat dat tu* nhien
Nhln khai quat thIy mat dit gdm c6 29% luc dia va 71 % la bien ca. Nui cao nhIt gin 9km. Day bien sau nhIt gin 11 km. Gin dung, c6 the coi Trai dit la hlnh clu vdi ban kfnh 6.371km.
2. Mat thuy chuan (g§dit) 2.1. Mat thuy chuan (geoit) la mat nude bien trung blnh y§n t7nh tudng tuong k^o dai xuyen qua cac luc dja lam thanh mat cong khep kfn CO phap tuyin tai mil diem trung vdi phuong day dpi di qua diem l y
Vi§t Nam chpn glc cua mat thuy chuan tai Hon DIU, 06 Son, Hai Ph6ng.
Mat thuy chuan (gedit) la co sd de xac djnh dp cao cua cde diem thudc mat dit.
2.2. Dp cao cua mdt diem la khoSng each theo phuong day dpi ke \\S dilm l y din mat thuy chuan (geoit) (hlnh 1).
HA = AAO
Vf du: dinh nui Evoret cao 8.848m.
Dinh nui Phang xi Phang cao 3.143m.
mr\h1 C (tam trai dat)
Day bien ranh Mariana (Thai Blnh Duong) sau 10.911m.
2.3. Mat thuy chuan (geoit) cd hlnh dang rIt phUc tap, khdng ehfnh tic. Bdi vay trong thuc t l ngudi ta hay dung mat thuy chuan quy udc, thudng la mot mat ehfnh tic da dupe nghien cufu hoan thien trong toan hpe, vf du nhu mat Elip Xoit, mat phang...
3. Mat Elip xoit tron xoay Trai dit qudc t§ WGS-84
3.1. TU nam 1984 ca thi gidi da chpn mat Elip xoit trong xoay Trai dit qudc t l WGS-84 lam mat thuy chuan quy udc qudc t l va lam co sd de thanh lap he toa dd trie dia quIc t l WGS-84 (B, L, H).
3.2. Mat Elip xoit trdn xoay Trai dit qu6c t l WGS-84 co hai dac diem nhu sau:
Dac diem thU nhit vi kfch thudc. mat Elip trdn xoay Trai dit
quIc t l WGS-84 dupe tao thanh do hlnh Elip quay quanh true be b cua nd, kfch thudc cua hlnh nay nhu hlnh 2:
a. Ban true be: b
b. Ban true Idn: a = 6.378.137m.
e. Op det cue: a = (a- b)/a=17298.257.
Dac diem thUhai vi dinh vi: mat
Elip x6it tron xoay Trai dit quIc t l WGS-84 dupe djnh vi vao Trai dit nhu sau:
a. Tam cua mat Elip xoit tron xoay Trai dit qudc t l WGS-84 trung vdi tam C cua Trai dit.
b. True be b cua mat Elip xoit tron xoay Trai dit quie t l WGS-84 trijng vdi true quay thang dumg cua Trai dit.
3.3. Khi chpn mat thuy chuan quy udc la mat Elip x6it trdn xoay Trai dit quIc t l WGS-84 nhu tren thi trong pham vi toan t h i gidi d6 chenh giUa mat n^y vdi mat thuy chuin (geoit) cung khdng qu^
150m, dd Idch giufa phap tuyIn cua mat nay vdi phuong day dpi trung blnh tCr 3 din 4 giay, nhilu nhIt 1^
phut. NghTa la mat Elip xoit tron xoay Trai dit qudc t l WGS-84 gin gidng nhIt vdi mat thuy chuIn (geoit) va cung la gin gilng nhIt vdi mat Trai dit thuc. Do do ngudi ta gpi mat Elip xoit tron xoay Trai dit quIe t l WGS-84 la hlnh dang tong quat cua Trai dit.
3.4. Dp cao quy udc quIc t l WGS-84 cua mdt dilm (H) la khoang each theo phuong ph^p tuyIn ke td dilm l y din mat Elip xoit trdn xoay Trai dit quIc t l WGS-84 (hlnh 3).
HA = AAO
Dp cao quy udc qu6c t l WGS- 84 nay con dupe gpi la dp cao trio dja qudc t l WGS-84.
Hinh 2
Hinh 3
4. Mat Elip xdit tron xoay Trai dat qudc gia Viet Nam-2000
4.1. TU nam 2000 Viet Nam da
chpn mat Elip xdit trdn xoay Tr^i dit
NGUdl XAY DUNG SO THANG 7 & 8 • 2014
MAT THUY CHUAN QUY l/OiC TRONG XAY Dl/NG...
qudc gia VN-2000 lam mat thuy chuan quy udc qudc gia, ddng thdi dijng lam co sd de thanh lap he tpa dp dja tam qudc gia VN-2600 (X, Y, Z) va he tpa dd trie dia qudc gia VN-2000 (B, L, H).
4.2. Mat Elip xoit tron xoay Trai d i t qudc gia VN-2000 co hai dac diem sau:
Dac diem thU nhit vi kfch thudc: mat Elip xdit trdn xoay Trai dit quIc gia VN-2000 cung dupe dac trung bdi ban true be (b), ban true Idn (a), dp det cue (a) hoan toan gidng vdi kfch thudc cua mat Elip x6it trdn xoay Trai d i t qudc t l WGS, cu the la:
a. Ban true be: b.
b. Ban true Idn: a= 6.378.137m.
c. Op det cue: a = (a-b)/ a
=1/2.98,257.
Dac diem thUhal vi djnh vj: mat Elip xdit trdn xoay Trai d i t qudc gia VN-2000 6uac djnh vj vao Trai d i t sao cho tren phin lanh tho Viet Nam thi phIn mat thuy chuan quy udc n^y g i n trung nhIt vdi mat thuy chuan geoit, khi l y cd tong blnh phuong cac khoang each tU mat thuy chuan quy udc qudc gia d i n mat thuy chuan geoit la be nhlt. Cu the luc nay la:
a. Tam 0 cua nd khdng trung vdi tam C cua trai dit;
b. True be b cua nd khdng trung vdi true quay thang dumg cua Trai dit.
NghTa la cd the coi nhu mat Elip xoit trdn xoay Trai d i t qudc t l WGS-84 da vC/a dupe tjnh tiln di mdt doan lai vUa dupe quay di mdt goe trong khdng gian de trd thanh mat Elip xdit trdn xoay Trai d i t qudc gia VN-2000. Do dd hai mat nay la ho^n toan khac nhau.
Hinh
4.3. 0 6 cao quy ude quoc gia VN-2000 cua mot diem (H') la khoang each theo phuong phap tuyIn ke tU diem l y d i n mat Elip x6it trdn xoay Trai d i t quIc gia VN- 2000 (hlnh 4).
H'A = AA'o
Op cao quy udc quIc gia VN- 2000 nay con dupe gpi la dp cao trie dja quIc gia VN-2000.
5. Mat thuy chuan quy u'dc trong xay di/ng va do cao quy udc cong trudng
5.1. Trong xay dung ngudi ta hay chpn mat thuy chuan quy^ udc cua c6ng trudng la mat phing nam ngang d dp cao trung blnh cua toan c6ng trudng. Ngudi ta cung thudng thilt k l sao cho mat phang nIn nha t i n g mot trung vdi dp cao trung blnh cua toan e6ng trudng nay.
5.2. Op cao quy udc cong trudng cua mot diem la khoang each theo phuong phap tuyIn k l tCr diem l y d i n mat thuy chuan quy udc cua edng trudng.
5.3. Trong xay dung phai thing nhlt l l y c i t cao cua c6ng trinh theo Nha nude Viet Nam da quy djnh tU 12/8/2000.
5.4. Oe thuan tien cd the sCr dung he dp cao quy udc, nhung phai thing nhlt chl dung mot he quy udc nhlt djnh cho toan bd edng trudng va nhlt qu^n trong t i t ca cac giai doan cua c6ng trinh.
5.5. Trong h i so c6ng trinh phai ghi rd dp cao cua cac bp phan c6ng trinh la thupc he thing dp cao nha nude hay thupc he thing dp cao quy udc edng trudng.
5.6. N I U theo he thing dp cao quy udc thi phai ghi rd trong h i so cong trinh: mat thuy chuan quy udc edng trudng dupe chpn nhu t h i nao? 6 dau? (ghi dja chl cu the, rd rang). Dp cao cua mat thuy chuan quy udc cong trudng la bao nhieu?
(so vdi mat thuy chuan geoit).
5.7. Op cao dupe d i n d i n edng trudng td m l c dd cao nha nude g i n nhlt nao? 0 6 cao cua m l c nha ni/dc nay la bao nhieu?... phai dupe ghi cu the trong hd so edng trinh.
5.8. Tren cac cong trudng xay dung ngudi ta thudng danh d I u mat thuy chuan quy udc edng trudng bing son mau dd d cdt cao quy udc +1m tren t i t ca cac cdt va tudng
nha.
5.9. Mat thuy chuan quy ude c6ng trudng, dp cao quy udc cong trinh vUa co y nghTa khoa hpe vUa CO y nghTa thuc tiln, kinh t l , ky thuat, anh hudng d i n ddi sdng hang ngay cua dan sinh. Bdi vay, ngudi ky suxay dung phai rIt chu y dilu nay, phai co bien ban ban giao mat thuy chuan quy udc edng trudng va dp cao quy udc c6ng trinh hpp phap giura c^c ben li§n quan va luu truf can than.
6. K i t luan
6.1. Trong trie dja c I n phan biet su khac nhau giura cac loai mat sau day:
- Mat thuy chuan (ge6it);
- Mat thuy chuan quy udc quIc t l la mat Elip x6it tron xoay Trai d i t quIc t l WGS-84;
- Mat thuy chuan quy udc qudc gia cua Viet Nam la mat Elip x6it tron xoay Trai d i t quIc gia VN - 2000;
- Mat thuy chuan quy udc edng trudng thudng la mat phang n i m ngang.
6.2. Tuong Ung cd cac loai dp cao sau day:
- 0 6 cao (tuy§t dli);
- Op cao trie dja quIc t l WGS- 84 la dp cao quy udc cua toan t h i gidi ke tU nam 1984;
- Op cao trie dja quIc gia VN- 2000 la dp cao quy udc cua Viet Nam ke tCr nam 2000;
- 0 6 cao quy udc edng trudng.
6.3. Chl cd dp cao dupe tfnh theo phuong day dpi, cac dp cao quy udc con lai d I u dupe tfnh theo phuong phap tuyln.
11. NHCfNG HE TOA DO KHONG GIAN THl/G(NG DUOC SU* DUNG TRONG TRAC DIA X A Y DUNG CONG TRINH
1. Cac khai niem
1.1. Trong trie dja, de xac djnh vj trf khdng gian ba chilu (3D) cua tCmg diem, ngudi ta thanh I3p cac he tpa dp khong gian nhu he tpa dp dja tam, he tpa dp trie dja.
1.2. TU nam 1984, toan t h i gidi sir dung:
a. He tpa dp dja tam quIc t l WGS-84 de djnh vj diem trong kh6ng gian.
b. He tpa dp trie dja quIc t l WGS-84 de dinh vi diem tren mat NGUdl XAY DUNG SO THANG 7 & 8 - 2014
MAT THUY CHUAN QUY U d ^ T P n M Q XAY D O N G . . .
dat tu nhien.
1.3. TU nam 2000, Viet Nam sCr dung:
a. H§ tpa dp dja tam quIc gia VN-2006 de djnh vj diem trong kh6ng gian thupc lanh tho Viet Nam.
b. He tpa doc trie dja quIc gia VN-200b de djnh vj diem tren mat d i t tu nhien thu6c lanh tho Viet Nam.
1.4. Bin he tpa dp kh6ng gian ke tren (a, b, c, d) la hoan toan khac nhau:
- Hoac la khac nhau v l y l u t l de djnh vj diem:
+ Y I U t l de djnh vj diem la doan thang vu6ng goc.
+ Y I U t l de djnh vj diem la goc cue.
- Hoac la khac nhau v l vj tri cua g l c tpa dp:
+ Glc tpa dp triJng vdi tam trai d I t C .
+ G6c tpa dp kh6ng triJng vdi tam trai dit.
1.5. Vi§c tfnh chuyen ddi giufa cac he tpa dp nay phai dupe thuc hien theo dung cac c6ng thUc da hudng d i n bdi Cue do dac - ban d6. T6t nhlt la hay sd dung ngay ehfnh cac phIn mIm tfnh toan cua Cue Oo dac Ban d l .
2. He toa do dja tam qudc t l WGS-84 (CXYZ)
2.1. TU nam 1984 ca t h i gidi da thing nhlt thanh lap he tpa dp dja tam quIc t l WGS-84 de xac djnh vj trf kh6ng gian (3D) cua cac diem trong khong gian dua tren co sd la trai d i t thuc nhu sau (hlnh 5).
2.2. G I C C cua he tpa dp trung vdi tam cua trai d i t C.
2.3. True Z cua he tpa d6 trung vdi true quay thang dumg cua trai dit. Hudng len tren bac cue la chilu duong (+).
2.4. True X cua he tpa dp la giao tuyln giufa mat phang xfch dao trai dat vdi mat phang kinh tuyln g l c (Grinuyt, Luan 06n, Anh). Hudng td tam C ra kinh tuyln g l c la chilu dupng (+).
2.5. True Y cua he tpa dp nIm trong mat phIng xicfi dao trai d i t v^ vu6ng gdc vdi true X. Hudng tCr tam C ra phfa d6ng ban c l u la chilu duong (+).
Ba true CX, CY, CZ vuong g6c
vdi nhau tUng d6i mot.
2.6. M6i mot diem A trong kh6ng gian se dupe ha vu6ng gdc xuing ba true CX, CY, CZ tuong Ung cho ba thanh phIn tpa dp kh6ng gian la
(XA. YA, ZA).
Vf du:
XA =-191,904m YA = -39,303m ZA =-111,450m.
2.7. He tpa dp dja tam quIc t l WGS-84 (CXYZ) dupe toan t h i gidi edng nhan va sd dung de djnh vj cho cac diem trong khdng gian k l tUnam 1984.
HinliS
3. He toa do dja tam qudc gia VN-200b (OX'Y'Z'i
3.1. Muln xac djnh dupe vj tri kh6ng gian cua cac diem thupc lanh t h i Vi§t Nam td nam 2000 nha nude ta thanh lap he tpa dp dja tam quIc gia VN-2000 dua tren co sd la mat Elip x6it tron xoay trai d i t quIe gia VN-2000 cu the la (hlnh 6).
3.2. G I C O cua he tpa dp trung vdi tam O cua mat Elip xdit trdn xoay tr^i d i t qudc gia Vn-2000 (kh6ng trung vdi tam trai d i t C).
3.3. True Z cua he tpa dp trijng vdi true be b cua mat Elip xdit tron xoay Trai d i t quIe gia VN-2000 (kh6ng trijng vdi true quay thang dumg cua trai dit). Hudng len tren b l e cue la chilu duong (+).
3.4. True X' cua he tpa dp la giao tuyln giufa mat phang xfch dao O vdi mat phang kinh tuyln 0° cua mat Elip x6it tron xoay Trai d i t quIe gia VN-2000. Hudng td tam O ra kinh tuyln 0° la chilu duong (+).
3.5. True Y' eCia hd tpa dd nIm trong mat phang xfch dao (O) cua mat Elip x6it trdn xoay Trai d i t qudc gia VN-2000 v^ vudng gdc vdi true X'. Hudng tCr tam O ra d6ng ban
c l u la chilu duong (+).
Ba true OX', OY', OZ' vu6ng g6c vdi nhau tilmg d6i m6t.
3.6. M6i mot d i l m A trong kh6ng gian lanh t h i Vi§t Nam se 6uac ha vu6ng gdc xuIng ba true OX", OY', OZ' tuomg umg cho ba th^nh phIn tpa dp la X'A, Y'A, Z'A.
Vf du: X'A = -1.626.924,018m Y'A = 5.729.423,469m
Z'A = 2.274.274,990m.
3.7. He tpa dp dja tam quIc gia VN-2000 dupe nha nude ta c6ng nh§n va sCr dung de djnh vj cho cac dilm thupc lanh d l Viet Nam k l tCr nam 2000.
3.8. Nhan xet
He tpa dp dja t§rTi quIc t l WGS- 84 vUa dupe tjnh tiln di mot doan, lai vCra dupe quay di mot goc trong kh6ng gian de trd thanh he tpa d6 dja tam qudc gia VN-2000. NghTa 1^
hai he tpa dp nay hoan to^n kh^c nhau.
Hi nil 6
4. He toa dd trac dja qudc t l WGS-84 (LBH)'
4.1. Di xac djnh vj tri khong gian cua cac diem tr6n mat dit tu nhien cua toan t h i gidi, tis nam 1984 ngudi ta thanh lap he tpa d6 trie dja quIc t l WGS-84 dua tren CO sd la (hlnh 3):
a. Mat Elip xoit tron xoay trdi dit quIc t l WGS-84.
b. Mat phang xfch dao chda t&m C cua trai dit.
c. Mat phang xfch dao chura tam C cua tr^i d i t .
4.2. D i l m A thupc mat d i t tU nhi§n dupe ha vu6ng gdc xuIng mat Elip xdit tron xoay Trai d i t quIc t l WGS-84 la AQ. Ba y l u td de x^c djnh vj trf khdng gian cua diem A1^:
H = AAQ la dp cao trie dja qudc NGUdl XAY DUNG SO THANG 7 & 8 • 2 0 1 4
MAT THUY CHUAN QUY UCiC TRONG XAY
D U N G . . . te WGS-84.B 1^ dp vT trie dia quIc t l WGS- 84.
L la dp kinh trie dia quIc t l WGS-84.
4.3. D6 cao trie dja quIe t l WGS-84 cua mot d i i m (H) la khoang each theo phuong phap tuyln td diem l y d i n mat Elip xooit tron xoay trai d i t quIc t l WGS-84.
4.4. Dp vT trie dja quIc t l WGS- 84 cua mot diem (B) la goc nhpn hpp bdi phap tuyln AAQ vdi mat phang xfch dao trai dit, co gia trj tU 0° d i n 90°, tuong Ung gpi la d6 vT ble (+) hay dp vT nam (-).
4.5. Dp kinh trie dja quIc t l WGS-84 cua mot diem (L) la gdc phang cua nhj di§n tao bdi mat phang kinh tuyln g l c chUa tam trai d i t vdi mat phang kinh tuyln ddng thdi chUa ca Ap v^ tam trai dit, co gia tri tCr 0° den ±180°, tuong umg goi la dd kinh d6ng (+) hay dp kinh tay (-).
Vfdu:BA = 21°00'00".N
L A = 1 0 5 ° 0 0 ' 0 0 " . E
HA =2,123m.
5. He toa do trie dja qudc gia VN-200b (B'L'H')
ifmli?
5.1. De xac djnh vj tri khong gian cua cac diem tren mat d i t tu nhien thupc lanh tho Viet Nam, tCr nam 2000 Nha nude ta da thanh lap he tpa dp trac dja qudc gia VN- 2000 dua tr§n cac co sd (hlnh 8).
a. Mat Elip xoit tron xoay trai d i t quIe gia VN-2000.
b. Mat phang xfch dao chufa t§m O cua mat Elip xooit trdn xoay trai d i t qudc gia VN-2000 (khong chUa
tam trai d i t C). ^ c. Mat phang kinh tuy§n O chUa
tam O eua mat Elip xoit trdn xoay
trai d i t quIc gia VN-2000 (khdng chufa tam trai d i t C).
5.2. Diem A thupc mat d i t tu nhien tren lanh tho Viet Nam ha vu6ng goc xuinq mat Elip x6it trdn xoay tr^i d i t quIc gia VN-2000 la A'Q. Ba y l u t l de djnh vj diem A trong khong gian la:
A' = AA'o la dp cao trie dja quIc gia VN - 2000.
B' la dp vT trie dja quIc gia VN - 2000
L' la dp kinh trie dja quIc gia VN-2000.
5.3. 0 6 cao trie dja quIe gia VN-2000 cua m6t diem H') 1^
khoang each theo phuong phap tuyln ke tU diem l y d i n mat Elip x6it tron xoay trai d i t quIc gia VN- 2000.
5.4.06 vT trie dja quIe gia VN- 2000 cua mot diem (B) la gdc nhpn hpp bdi phap tuyln AAQ vdi mat phang xfch dao chda tam O cua mat Elip xdit trdn xoay trai d i t qudc gia VN-2000, ed gia tn tU 0° d i n 90°, tuong umg gpi la dp vT b l e (+) hay dp vd nam (-).
5.5. 0 6 kinh trie dja quIc gia VN-2000 cua mot diem (L) la goc phang cua nhj dien tao bdi mat phang kinh tuyln 0° chUa tam O va mat phang kinh tuyln chufa AQ va tam O cua mat Elip xooit tron xoay trai d i t qudc gia VN-2000, cd gia trj tu 0° d i n 180°, tuong Ung gpi la dp kinh d6ng (+) hay dp kinh tay (-).
Vf du:
B'A = 2 1 ° 0 1 ' 4 0 " . N L'A = 1 0 5 ° 5 1 ' 0 8 " . E
H'A = -1,230m.
5.6. Nhan xet
He tpa dp trie dja quIe t l WGS- 84 vUa dupe tjnh tiln di mot doan, lai vUa dupe quay di mot gdc trong
khdng gian de trd thanh he tpa dp trie dja quIe gia VN-2000, nghTa la hai he tpa dp nay hoan toan khac nhau.
6. He toa do thien van
Trong he tpa dp thien van, ngudi ta xac djnh tpa dp cua eae diem tren mat d i t so vdi phuong cua day dpi.
0 6 vT thien van cp la goc nhpn hpp bdi phuong cua day dpi tai diem da cho vdi mat phang xfch dao. No CO gia tri td 0° d i n ±90°, tuong Ung gpi la dd vT b l e (N) hay dp vT nam (S).
0 6 kinh thien van la goc phang cua nhj dien tpa bdi mat phang kinh tuyln thien van ehUa diem da cho vdi mat phang kinh tuyln glc. Nd cd gia trj td 0° d i n ±180° tuomg Ung gpi la dp kinh d6ng (E) hay d6ng kinh tay (W).
Vfdu:
Hinh 8
A = 105°00"£
Kinh tuyln thien van la giao tuyln giOa mat Elip x6it vdi mat phang chUa dudng day dpi va dudng song song vdi true quay trai d i t di qua diem da cho.
Nhu da bilt cac tpa dp trie dja va tpa dp thien van co khac nhau mot lupng nhlt djnh, tijy thupc vao su khong trung nhau giOa phuong phap tuyln cua Elip x6it va phuong phap day dpi, tufC la phu thupc vao goc lech cua cac dudng day dpi. Do do, su khac nhau gida cac tpa dp thien van vdi cac tpa dp trie dja trung blnh la td 3" d i n 4" tai cac vijng dac biet co the d i n hang chue giay. Khoang each giufa hai diem d tren mat Elip xdit umg vdi hieu dp vT 1 giay la vao khoang 31 m. Bdi vay tpa dp cua diem da cho thupc hai he thien van va trie dja ed the khac nhau d i n 100m, d nhdng vung dac biet con co the nhilu hem nOa.
He tpa dp thien van va he tpa dp trie dia duoc goi ehung la h§ toa d6 dja ly.a
1^i ligu tham klido:
1. Trie dja edng trinh, chu bien: PS Zakatov NXB "Nhedra" Matscdva -1969.
2. Bio do l<hoa hoc xiy dUng h$ quy chieu va h$ thong diim toa dd qudc gia - long cue Dja chinh H^ No! 2000.