Tong Hop Bai Giang

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<ul><li><p> TRC A </p><p>(GEODESY) </p><p>GV: o Hu S </p><p>Khoa Xy dng </p><p>daohuusi@hcmuarc.edu.vn </p></li><li><p> TRC A </p><p>(GEODESY) </p><p>GV: o Hu S </p><p>Khoa Xy dng </p><p>daohuusi@hcmuarc.edu.vn </p><p>xb11arch@googlegroups.com </p><p>Huy 0909559196 </p></li><li><p>NI DUNG CC CHNG MC: </p><p>Chng 1. Tri t v cch biu th mt t Chng 2. Sai s trong o c Chng 3. Dng c v cc phng php o trong trc a </p><p>Chng 4. Li khng ch trc a Chng 5. o v s dng bn a hnh Chng 6. B tr cng trnh Chng 7. Quan trc cng trnh </p><p>Kim tra, bi tp </p><p> Thi cui k </p></li><li><p>TI LIU THAM KHO: </p><p>Trc a i cng Tc gi: Nguyn Tn Lc- NXB: i hc Quc gia Tp.HCM </p><p>Trc a xy dng thc hnh Tc gi: V Thng NXB: Xy dng. </p><p>TCXDVN 309 2004 Cng tc trc a trong xy dng Yu cu chung </p><p>K hiu bn a hnh ca Tng cc a chnh (Nay l B Ti nguyn v Mi Trng), </p><p> Internet </p></li><li><p> Trc a (Geodesy) l mt ngnh khoa hc chuyn </p><p>nghin cu v hnh dng, kch thc v b mt t nhin ca </p><p>Tri t. </p><p> Bn (Map) l hnh nh thu nh ca b mt tri t </p><p>c biu din ln mt phng theo mt quy lut ton hc </p><p>nht nh. </p><p>1. KHI NIM </p></li><li><p> Trc a: - Thut ng trc a hm phn chia t ai </p><p> - Ngnh khoa hc trc a c t lu i, n sinh ra do nhu </p><p>cu ca i sng x hi loi ngi: nh vic i li, qun </p><p>l t ai, giao thng bun bn, thm him, qun s... - Trong qu trnh pht trin, Trc a c phn ra </p><p>lm nhiu phn ngnh chuyn mn hp nh: + Trc a cao cp + Trc a nh + Trc a cng trnh + Bn hc . . . </p><p>2. LCH S PHT TRIN </p></li><li><p> Trc a, bn c vai tr quan trng trong cc ngnh </p><p>kinh t quc dn nh: </p><p> Nng - lm nghip, </p><p> Giao thng vn ti, thy li, </p><p> Quy hoch - Xy dng, </p><p> Quc phng (bn l con mt ca qun i) </p><p> Trc a cn thit trong tt c cc giai on: quy hoch, </p><p>kho st, thit k, thi cng, nghim thu qun l v s dng </p><p>cng trnh. </p><p>3. VAI TR </p></li><li><p> Ngy nay nh cng ngh pht trin m trc a </p><p>pht trin ln tm cao mi: </p><p> - Cng ngh nh vin thm, cho php con ngi c </p><p>th xc nh nhng v tr, thnh lp bn nhng khu </p><p>vc nguy him hoc khu vc khng th tip cn </p><p> - Cng ngh nh v ton cu GPS (NAVigation </p><p>System with Time And Ranging Global Positioning </p><p>System) vic xc nh v tr nhanh chng v cho kt qu </p><p>vi chnh xc cao </p></li><li><p>LCH S GPS: </p><p> n c hnh thnh vo u thp nin 60 </p><p> V tinh u tin c phng vo qu o nm 1973 </p><p> c B Quc phng M vn hnh v khai thc. </p><p> Hin ti c tng cng 30 v tinh ang hot ng </p></li><li><p>CU TRC GPS: </p></li><li><p>S lng v tinh GPS quan st c </p></li><li><p>GV: o Hu S </p><p>Khoa Xy dng </p><p>Chng 1: </p><p>TRI T V CCH BIU TH </p><p>MT T </p></li><li><p>NI DUNG CHNG 1 </p><p> Hnh dng - kch thc tri t v cch biu th </p><p>mt t </p><p> Cc h ta - cao </p><p> Khi nim v bn </p><p> Phn mnh v nh s hiu bn </p></li><li><p>1.1 HNH DNG V KCH THC </p><p>TRI T 1.1.1 Hnh dng </p><p> B mt tri t c din tch S 510,2 triu km2. Trong </p><p>: i dng chim 71% </p><p> Lc a chim 29% </p><p> L mt g gh, li lm; ch cao nht +8882m (nh </p><p>Hymalaya), ch thp nht -11032m (h Marian Thi </p><p>Bnh Dng, gn Philippines) </p><p> u th k 20 (Listinger c), a ra khi nim </p><p>mt Geoid v dng mt ny biu th b mt tri t </p><p> Mt Geoid : l mt nc bin trung bnh yn tnh, ko </p><p>di xuyn sut qua cc lc a hi o to thnh mt mt </p><p>cong khp kn (Mt Geoid cn c gi l mt thy </p><p>chun lc a, hay mt nc gc tri t) </p></li><li><p>Hnh nh tri t chp t v tinh </p></li><li><p> Mt Geoid c dng lm mt quy chiu ca h thng </p><p>cao </p><p> Mt Geoid c c tnh: </p><p> + Mt Geoid khng phi l mt ton hc </p><p> + Ti mi im trn mt Geoid u vung gc vi </p><p>phng ca ng dy di ti im . </p></li><li><p> 1.1.2 Kch thc. </p><p> Do mt Geoid khng phi l mt ton hc, nn khi </p><p>tnh ton - biu din kch thc Tri t chng ta phi </p><p>dng b mt khc gn trng vi Geoid v phi l mt </p><p>ton hc, l mt Ellipsoid tri t (Gi tt l </p><p>Ellipsoid), cn tho mn: </p><p> - Tm Ellipsoid trng vi tm Geoid </p><p> - Mt phng xch o Ellipsoid trng vi mt phng </p><p>xch o Geoid </p><p> - Th tch Ellipsoid tri t = th tch Geoid </p><p> - Tng bnh phng chnh cao t mt Ellipsoid ti </p><p>mt Geoid l nh nht ([h2] =min) </p></li><li><p>c im ca Ellipsoid: </p><p> - Ellipsoid l mt mt biu din c bng phng </p><p>trnh ton hc v hu ht mi tnh ton Trc a thc </p><p>hin trn mt ny (gi l Mt quy chiu) </p><p> - Ti mi im, b mt Ellipsoid lun vung gc vi </p><p>phng php tuyn. </p></li><li><p>c trng cho Ellipsoid </p><p> + Bn trc ln (bn knh ln): a </p><p> + Bn trc nh (bn knh nh): b </p><p> + dt a</p><p>ba </p><p>2 2 2</p><p>2 2 2</p><p>Ph.trnh:</p><p>1.X Y Z</p><p>a a b </p><p>Geoid </p><p>Ellipsoid </p><p>O </p><p>b a </p></li><li><p>Tc gi </p><p>(Ellipsoid) </p><p>Quc </p><p>gia </p><p>Nm Bn trc ln a (m) </p><p>Bn trc nh b (m) </p><p> dt </p><p>Delambre Php 1800 6.375.653 6.356.564 1:334,0 </p><p>Everest Anh 1830 6.377.276 6.356.075 1:300,8 </p><p>Bessel c 1841 6.377.397 6.356.079 1:299,2 </p><p>Clark Anh 1980 6.378.249 6.356.515 1:293,5 </p><p>Krasovski Nga 1940 6.378.388 6.356.863 1:298,3 </p><p>WGS84 M 1984 6.378.137 6.356.752,3 1:298,257 </p><p>Mt s Ellipsoid tri t </p></li><li><p>1.2.1 Khi nim </p><p> Trong trc a, </p><p>tin cho vic thit k </p><p>k thut, ngi ta </p><p>tm cch biu din b </p><p>mt tri t ln mt </p><p>phng. Phng php </p><p>ny cho php chng </p><p>ta thu nh b mt tri </p><p>t vi chnh xc </p><p>cn thit. </p><p>1.2 CCH BIU TH MT T </p></li><li><p> V b mt tri t l b mt t nhin v cng phc </p><p>tp, v vy biu din ln mt phng ta phi chiu b </p><p>mt tri t ln mt Ellipsoid hoc mt cu ri thu nh </p><p>mt cu tri t theo t l mong mun. Bng php chiu </p><p>xuyn tm ngi ta tip tc chiu hnh cu tri t ln </p><p>mt tr, mt nn, theo cc phng php khc nhau. </p><p>Sau ct mt tr, mt nn, theo mt ng sinh c </p><p>chn trc v tri ra mt phng. </p><p> Phng php chiu ny lm cho b mt qu t b </p><p>bin dng. S bin dng ph thuc vo im chiu v cc </p><p>im trn mt t cng nh phng php chiu. </p></li><li><p>1.2.2 nh v cc im trn mt t </p><p> V tr khng gian cc im trn mt t c xc nh </p><p>bng 2 yu t: </p><p> 1. To a l (, ) hoc to vung gc phng (x, y) trn mt quy chiu Ellipsoid </p><p> 2. cao ca im so vi mt Geoid </p><p> xc nh v tr cc im A,B,C trong khng gian ta </p><p>chiu chng xung mt Geoid theo phng dy di ta </p><p>c cc im a, b, c. </p></li><li><p> Trong trng hp biu din b mt tri t trong mt </p><p>phm vi khng ln, vi yu cu chnh xc khng cao </p><p>chng ta coi b mt tri t c chiu trc tip ln mt </p><p>phng </p><p>B</p><p>A</p><p>C</p><p>c</p><p>b</p><p>a</p><p>P</p></li><li><p>1.3 H TO A L Trong ton hc cng nh trong trc a, xc nh to </p><p>ca mt im, chng ta cn xc nh quan h gia im </p><p>vi mt h trc c chn lm gc. </p><p> P </p><p>P1 </p><p>O M </p><p>M </p><p>Q Q1 </p></li><li><p> xc nh to a l ca mt im trn b mt </p><p>tri t, Gi s phng php tuyn trng vi phng dy </p><p>di v mt Geoid trng vi mt Ellipsoid trn xoay ca </p><p>tri t. </p><p> Cc yu t c chn lm gc trong h to a l </p><p>nh sau: </p><p>- Tm O ca tri t c chn lm gc to </p><p>- Hai mt phng gc l mt phng kinh tuyn gc v mt </p><p>phng xch o </p><p> T hnh v: </p><p>- P, P1: l cc Bc v cc Nam ca tri t </p><p>- PP1: trc xoay ca tri t </p><p>- Q, Q1: l cc Ty v cc ng ca tri t </p><p>- G (Greenwich): V tr i thin vn Greenwich ngoi </p><p>Lun n </p></li><li><p> hiu r h to a l, chng ta c mt s khi </p><p>nim sau: </p><p>- Mt phng kinh tuyn l mt phng i qua trc xoay PP1 </p><p>ca tri t </p><p>- Mt phng v tuyn l mt phng vung gc vi trc xoay </p><p>PP1 </p><p>- ng kinh tuyn l giao tuyn ca mt phng kinh tuyn </p><p>vi mt cu tri t </p><p>- ng v tuyn l giao tuyn ca mt phng v tuyn vi </p><p>mt cu tri t </p><p>- Mt phng kinh tuyn gc l mt phng kinh tuyn i qua </p><p>G (Mt phng kinh tuyn gc chia tri t ra lm hai na </p><p>ng bn cu v Nam bn cu) </p><p>- Mt phng xch o l mt phng v tuyn i qua tm O </p><p>ca tri t </p></li><li><p>To a l ca im M(M ,M) </p><p>M (v ): l gc hp bi mt phng xch o v ng </p><p>dy di qua M </p><p>M (kinh ): l gc hp bi mt phng kinh tuyn gc v </p><p>mt phng kinh tuyn i qua im M </p><p>Trn xch o =0, trn kinh tuyn gc =0 </p><p>Thng quy c: </p><p>M t xch o ln gi l v Bc (00 900) </p><p> M t xch o xung gi l gi l v Nam (00 900) </p><p>M t kinh tuyn gc G sang ng gi l kinh ng (00 </p><p> 1800) </p><p>M t kinh tuyn gc G sang Ty gi l kinh Ty (00 </p><p>1800) </p></li><li><p>1.4 H TO VUNG GC KHNG GIAN </p><p>OXYZ (H T. A TM) </p></li><li><p> H ta vung gc khng gian: l h thng gm </p><p>im gc to v 3 trc to X, Y, Z xc nh </p><p>trong khng gian Euclide 3 chiu: h quy chiu ny </p><p>c s dng trong o c v tinh v nhng bi ton </p><p>trc a ton cu. </p></li><li><p>1.5 H TO VUNG GC PHNG Trong trc a h to vung gc phng ngc vi h </p><p>to vung gc cc; trc X theo phng ng, trc </p><p>Y theo phng ngang </p><p> Qua nhiu thi k khc nhau th c nhng h to cng </p><p>khc nhau (ngay c Vit nam cng nh th gii) </p><p>y </p><p>x </p><p>O </p></li><li><p> th hin mt khu vc trn b mt tri t ln mt </p><p>phng ngi ta phi s dng cc php bn . Thng qua </p><p>cc php chiu bn nh ngha cc h ta vung gc trc a </p><p>Cc li chiu bn thng dng: </p><p>- Hnh tr ngang, </p><p>- Hnh tr ng, </p><p>- Hnh nn, </p><p>- Phng v, </p></li><li><p>1.5.1 Php chiu Gauss, H to vung gc phng </p><p>Gauss Kruger </p><p> Php chiu ny s dng Ellipsoid Krasovski vi cc </p><p>thng s </p><p> a= 6.378.245 m , b= 6.356.863 m, = 1/298,3 </p><p> Php chiu Gauss l php chiu hnh tr ngang ng gc. </p><p> Trong php chiu ny tri t c chia thnh 60 mi </p><p>chiu 60 v c nh s tng ng t 1 60 bt u t </p><p>kinh tuyn gc Greenwich (00) sang ng vng qua Ty </p><p>ri tr v knh tuyn gc. </p></li><li><p> Mi mi chiu c gii hn bi kinh tuyn ty - bn </p><p>tri v kinh tuyn ng - bn phi (2 kinh tuyn bin). V </p><p>kinh tuyn gia ca mi chiu c gi l kinh tuyn </p><p>trc, i xng vi 2 kinh tuyn bin. </p><p> T=60(n-1), G=6</p><p>0.n-30, P=60 .n </p><p>Vi n l s th t ca mi chiu </p></li><li><p>GP'</p><p>O</p><p>P</p><p> Sau khi chia ra tng mi chiu v xc nh kinh tuyn </p><p>trc ca mi mi chng ta cho qu cu tri t tip xc </p><p>vi mt trong ca mt hnh tr ngang theo ng kinh </p><p>tuyn trc. </p><p> Ly tm chiu O l tm tri t ln lt chiu cc mi ln </p><p>mt tr tng mi mt, sau va xoay va tnh tin hnh </p><p>cu n mi s 2 tng ng vi on chn cung trn xch </p><p>o </p></li><li><p> v tip tc cho n ht </p><p>Sau ct mt tr theo hai ng sinh KK ri tri ra mt </p><p>phng ta c nh hnh sau </p><p>kmR</p><p>L 84,666180</p><p>6..0</p><p>0</p><p>x</p><p>y</p><p>K</p><p>K'</p></li><li><p>c im ca mi mi chiu: </p><p>- Bo ton v gc </p><p>- Xch o c chiu thnh ng thng v lm trc Y </p><p>- Kinh tuyn trc (gia) c chiu thnh on thng v </p><p>chn lm trc X; X Y </p><p>- Kinh tuyn trc khng b bin dng sau khi chiu </p><p>- Cc kinh tuyn v v tuyn khc b thay i sau khi chiu </p><p>- Cng xa kinh tuyn trc bin dng cng ln </p><p> to Y lun dng ngi ta di kinh tuyn trc v </p><p>pha Ty 500km, X dng di X v Nam 10000km </p><p> Vit Nam h to Gauss c thnh lp nm 1972 </p><p>gi l h to HN72, chn Ellipsoid quy chiu Kraxosky </p><p>gc t ti i thin vn Punkv (Lin X c) truyn to </p><p> ti Vit Nam thng qua h to quc gia Trung Quc. </p></li><li><p>1.5.2 Php chiu v h to vung gc phng UTM </p><p>(Universal Transverse Mercator) </p><p>500 km</p><p>x</p><p>xch ao</p><p>cat tuyen</p><p>kinh tuyen truc</p><p>y</p></li><li><p> Php chiu UTM s dng Ellipsoid WGS 84 </p><p> Thng s Ellipsoid WGS 84 </p><p> Bn trc ln a = 6.378.137 m </p><p> Bn trc nh b = 6.356.752,3 m </p><p> dt cc = 1 / 298,257 </p><p> Php chiu UTM cng l php chiu hnh tr ngang </p><p>ng gc nhng mt tr khng tip xc vi mt Ellipsoid </p><p>ti kinh tuyn trc m ct mt Ellipsoid ti 2 ct tuyn </p><p>cch kinh tuyn trc 180km </p></li><li><p>c im ca mi mi chiu. </p><p>- Bo ton v gc (ng dng) </p><p>- Xch o thnh ng thng ngang kinh tuyn trc </p><p>- Hai ct tuyn h s bin dng m = 1 (khng bin dng) </p><p>- Kinh tuyn trc m = 0,9996 </p><p> Vng trong ct tuyn m &lt; 1 (bin dng m) </p><p> Vng ngoi ct tuyn m &gt; 1 (bin dng dng) </p><p> K t ngy 12/08/2000 Vit Nam s dng thng nht </p><p>trn phm vi ton quc h to vung gc UTM gi l </p><p>VN2000, chn Ellipsoid quy chiu WGS 84, im gc to </p><p> l im gc ca li GPS cp 0 ti H Ni. </p></li><li><p>1.5.3 H ta c lp (t do) </p><p>Y </p><p>X </p><p>O </p></li><li><p>1.6 H CAO Mt Geoid c chn lm mt quy chiu cho cao. </p><p> cao ca mt im l khong cch tnh theo phng </p><p>dy di t im ti mt Geoid </p><p>A </p><p>B </p><p>H </p><p>H </p><p>g g </p><p>A </p><p>B </p><p>Mat thuy chuan gia nh </p><p>Geoid (mat thuy chuan goc) </p><p>Ellipsoid trai at </p></li><li><p>- Nu mt chun gc (l mt Geoid), ta c cao tuyt i </p><p>- Nu mt thy chun l mt gi nh ta c cao gi nh </p><p>- Khong cch t mt im ti mt Ellipsoid theo phng php </p><p>tuyn gi l cao trc a </p><p>- Hiu s cao gia 2 im (chnh cao) l khong cch theo </p><p>phng dy di gia 2 mt thy chun i qua 2 im . </p><p> Trong trc a khng o c cao trc tip m ch o </p><p>c chnh cao gia cc im. </p><p> Trc 1975, Bc Vit Nam mt thy chun gc c chn i </p><p>qua trm Nghim triu Hn du Sn Hi Phng. </p><p>Nam Vit Nam chn mt thy chun gc Mi Nai H Tin </p><p> Sau 1975, Vit Nam mt thy chun gc c chn i qua </p><p>trm Nghim triu Hn du Sn Hi Phng </p><p>HH.Dau = HM.Nai + 0,167 m </p><p>T 2001, thng nht trn lnh th VN ch s dng cao HD </p></li><li><p>CC H TA C TI VIT NAM </p><p> Thi Php thuc: Ellipsoid Clark (Anh), im gc ti H </p><p>ni, php chiu Bonne v h thng im to ph trm </p><p>ng dng; lm c s cho lp bn 1/100.000 v </p><p>1/200.000 khu vc ng Dng. </p><p> Min Nam VN t 1954-1975: h Indian 54 vi Ellipsoid </p><p>Everest (Anh), im gc ti n , php chiu UTM v </p><p>h thng im to ph trm Nam Vit Nam, h cao </p><p>Mi Nai, H Tin; </p><p> Min Bc t 1959 bt u xy dng h thng li Trc a </p><p>v h quy chiu v kt thc nm 1972 =&gt; h HN-72 vi </p><p>Ellipsoid Krasovski , im gc ti Punkovo chuyn v VN </p><p>ti i thin vn Lng HN (thng qua im Ng Lnh </p><p>Trung Quc), php chiu Gauss- Kruger, h cao Hn </p><p>du, Hi phng </p></li><li><p> Quan h gia cao Hn du v cao Mi nai </p><p>HH = HM + 0,167 m </p><p> T 1992-1994: nh v li Ellipsoid Krasovski ph hp </p><p>Vit Nam. </p><p> T 1996-2000: Xy dng h VN-2000 vI Ellipsoid </p><p>WGS-84 c nh v ph hp vi lnh th Vit nam, </p><p>im gc to N00 t ti Vin nghin cu a </p><p>chnh, ng Hong Quc Vit, H ni; php chiu </p><p>UTM, h cao Hn du - Hi phng. </p><p> H Quy chiu WGS 84 </p></li><li><p>1.7 KHI NIM BN . </p><p>1.7.1 nh ngha bn Bn l hnh v thu nh trn giy cc hnh chiu bng </p><p>ca nhng phn b mt tri t, c k n s bin dng </p><p>do nh hng ca cong tri t, theo mt quy lut ton </p><p>hc no . </p><p> Bn l biu hin thu nh ca b mt tri t ln mt phng theo mt quy lut ton hc xc nh, th hin bng </p><p>cc k hiu quy c c bit; trn trng thi, s phn </p><p>b v mi quan h gia cc hin tng t nhin, kinh t, </p><p>vn ha, x hi c chn lc v khi qut ha ph hp </p><p>vi mc ch s dng c th ca bn </p></li><li><p>1.7.2 Phn loi bn : </p><p>a. Phn loi theo mc ch: Ph thng, chuyn ngnh </p><p>b. Phn loi theo ni dung </p><p>* Bn a l chung: Bn a hnh, Bn a hnh </p><p>khi qut, Bn Khi qut. </p><p>* Bn a l chuyn (gi tt l bn chuyn ): </p><p>Cng nghip, Nng nghip, Du lch, a cht, Thy vn, </p><p>Kh hu, Th nhng, Thc vt, ng vt </p><p>c. Phn loi theo t l </p><p> Bn t l ln, trung bnh, nh </p><p>d. Phn loi theo phm vi din tch </p><p> Ton cu, i dng, lc a, chu lc, quc gia, tnh, </p><p>huyn, x </p></li><li><p>1.7.3 T l bn a) nh ngha: </p><p> T l bn l t s gia chiu di ca mt on thng </p><p>trn bn vi chiu di nm ngang tng ng ca n </p><p>ngoi thc a (thc t). </p><p> T l bn k hiu 1:M hoc </p><p> T l bn l mt phn s c t s l n v, cn mu </p><p>s thng l nhng s trn trm, trn nghn,.. </p><p>b) Phn loi bn a hnh theo t l </p><p> - T l ln: </p><p> - T l trung bnh: </p><p> - T l nh: </p><p>;5000</p><p>1;</p><p>2000</p><p>1;</p><p>1000</p><p>1;</p><p>500</p><p>1 </p><p>;000.50</p><p>1;</p><p>000.25</p><p>1;</p><p>000.10</p><p>1</p><p>1.000.000</p><p>1;</p><p>500.000</p><p>1;</p><p>250.000</p><p>1;</p><p>100.000</p><p>1</p><p>tt</p><p>bd</p><p>SM</p><p>1 S</p></li><li><p>c. chnh xc (sai s) ca t l bn </p><p> t = 0,1xM (mm) </p><p> M: Mu s t l bn </p><p> t: sai s c bn quy ra thc t </p><p>1.7.4 Thc t l c gi tr chiu di on thng ngoi thc a tng </p><p>ng biu din trn bn mt t l no c nhanh </p><p>chng v d dng, ngi ta dng thc t l: </p><p>C hai loi thc t l: </p><p> + Thc t l thng </p><p> + Thc t l xin (cho chnh xc cao hn) </p></li><li><p>1.7.5 Biu din a vt trn bn . - K hiu theo t l </p><p>- K hiu phi t l </p><p>- K hiu na t l </p><p>- K hiu ch gii </p><p>1.7.6 Biu din a hnh trn bn . - Phi cnh, t bng (t s dng) </p><p>- Ghi cao v ng bnh (phng php ph bin) </p><p>1.7.7 Bn s. D liu c lu tr di dng file v hin th trn cc </p><p>thit b in t. </p><p>u im: </p><p> chnh xc, lu tr, cp nht x l thng tin, tt hn </p><p>hn so vi bn giy </p></li><li><p>1.8 CHIA MNH V NH S HIU BN . </p><p> Bn a hnh ni ring cng nh cc loi bn khc </p><p>c biu din nhiu loi t l khc nhau. </p><p> Mc ch ca chia mnh v nh s hiu tin cho qun </p><p>l v s dng bn . </p><p> S hiu bn cn gi l danh php bn (hay </p><p>phin hiu bn ). </p><p> Trn th gii v Vit nam tng tn ti nhiu kiu t </p><p>danh php bn khc nhau. </p><p> Lu : mi loi bn c cc quy nh v t l v cch </p><p>chia mnh nh s hiu khc nhau </p></li><li><p> Di y trnh by cch chia mnh v phin hiu </p><p>(danh php) bn a hnh theo kiu hin nay ang </p><p>c s dng Vit Nam </p><p> T bn a hnh c bn c t l 1:1.000.000, trn </p><p>c s t bn ny tin hnh chia mnh v nh s hiu </p><p>cho cc t bn t l ln hn (theo s chia mnh </p><p>trang tip sau) </p><p> T bn t l 1:1.000.000 c hnh thnh theo </p><p>php chiu hnh nn, c dng hnh thang (l giao ca </p><p>hng v ct) nh sau: </p><p> - Theo v tuyn t xch o v hai cc Bc, Nam ta </p><p>chia ra cc di 40 v t tn bng cc ch ci Latin: </p><p>A,B,C, . . . (b ch ci I v O) </p><p> - Theo kinh tuyn chia tri t ra cc mi 60 (nh </p><p>vy c 60 mi) v nh s t 1 60. </p></li><li><p> nh s th t t Ty sang ng (bt u t kinh tuyn </p><p>1800) </p><p> Mi s 1 nm gia kinh tuyn 1800 v 1740T </p><p> Mi s 2 nm gia kinh tuyn 1740T v 1680T </p><p> Nu kinh tuyn nh s lin tc t 0 3600, th mi 1? mi 2? </p><p>Ch : Mi bn khc mi chiu. S th t mi chiu </p><p>c nh s bt u t kinh tuyn gc Greenwich (00) </p><p>v ng sang Ty. Cn mi bn c nh s t </p><p>kinh tuyn 1800 v Ty sang ng. Nh vy s hiu </p><p>mi chiu v s th t ct ca t bn 1:1.000.000 lch </p><p>nhau 30 n v. </p><p>V d: = 1050 ng, tc mi chiu th 18 ct ca t bn 1:1.000.000 l 18 + 30 = 48. </p></li><li><p>1.8.1. Phin hiu bn a hnh t l 1:1.000.000 </p><p> giao nhau gia hng v ct ni trn s c biu din </p><p>thnh 1 t bn t l 1:1.000.000 </p><p> Tn ca t bn ny ghp t k hiu Hng s hiu </p><p>Ct </p><p> S...</p></li></ul>