Công trình ngầm giao thông đô thị

+ Xet den tinh dac biet ciia cac cdng trinh ngam khong cd anh sang tu nhien, thong thoang kern, tach biet vdi mdi trudng ben ngoai, nen dudi dat dugc uu tien bo tri cac cong trinh ma con

LCfl N O I D AU

Trong cong cuoc cdng nghiep hoa va hien dai hoa dat nuac, viec xay dung ha tang ky thuat ddng vai trd rat quan trong Truac het phdi hien dai hod cac do thi ldn.

Hien nay a cac thanh pho ldn n hu Hd N oi, thanh pho Ho Chi Minh thudng xuyen bi ach tac giao thdng, o nhiem moi trudng vd ling ngap vao miia mua Dat dai d do thi lai rat quy vd rat dat.

Tat cd nhitng bat cap do, ddi hdi phdi cap bach gidi quyet viec sit dung khong gian ngam do thi.

Trong cac do thi hien dai se cd nhieu nhd cao tang (tic 12 tang trd len), ddi hdi phdi cd cac tang ham De gidi quyet ach tac giao thdng, cdn phdi

I dm nhieu dudng ngam viun qua cac nut giao ldn De cd bai dd xe, ma xe oto ngay cdng nhieu, phdi xay dung cac gara oto ngam nhieu tang dudi mat dat.

O thanh pho Hd Chi Minh d d cd d u an xay dung tau dien ngam vd dudng bo ngam chui dudi day song Sai Gon qua khu dd thi mdi Thu Thiem Hd Noi cung cdn nghien ci'm phuong an xay dung dudng tau dien ngam Trong tuang lai khong xa, chung ta phdi nghi den viec xay dipig cac to hap cdng trinh ngam a cac thanh pho ldn Dd la chua ke den cac cdng trinh ngam quoc phong, an ninh.

De cung cap nhitng thdng tin cdn thiet cho ban doc, N hd xuat ban Xay dung dd cung cac chuyen gia chon dich cuon sach "Cdng trinh ngam giao thdng dd thi" ciia Giao su Vien s i V.L M akopski, xuat ban nam 1985 tai

M atxcava Cuon sach do TS Nguyen Dice Ngudn dich vd GS.TSKH Nguyen Van Quang hieu dinh.

Chung tdi mong rang cuon sach se cd ich cho ban doc.

Nha xuat ban Xay dung

3

C huw ig I

K H A I N IE M C H U N G VE CAC C O N G T R IN H N G A M

§1 SIT SIT DUNG KHONG GIAN NGAM TRONG CAC DO THI

Loi ich cua viec xay dung cong trinh ngam Khoi luong xay dung nha 6 va cong

trinh cong cong tang, sir lien tuc phat tridn mang luoi giao thong dudng bo, su hinh thanh cac cong trinh va cum cong trinh cong nghiep mdi, cac xi nghiep cong nghiep dang yeu cau do thi danh rieng cho nhung khu dat ldn Nhung khu dat do, dac biet tai nhung khu trung tam do thi, ngay cang khan hiem Trong do, tai cac do thi ldn ngay cang thieu nhung dien tfch dat de xay dung cac bon hoa, cong vien, cac khu vuc di bo, dao choi, san the thao Vi vay, c<in thiet phai tang mat do xay dung, tao lap nhung cot cao do nhan tao mdi, sir dung nhung giai phap khong gian do thi Cac do thi hien tai duoc m d rong theo mat bang va mat dung bang cach khai thac khong gian tren mat dat

va khong gian ngam Phan vung theo chieu dung cho phep phan luong phuong tien giao thong va ngudi di bo, giao thong noi hat va qua canh, tdc do cao va binh thudng Trong

do co the co cac phuong an bo tri tuyen giao thong va dudng bo khac nhau: d muc mat dat, tren mat dat hoac dudi mat dat

Giai quyet hop ly van de giao thong dudng pho cho phep khai thac tong the va tan dung duoc khong gian ngam, nghla la bd trf cong trinh va cac cum cong trinh khac nhau dudi dat phuc vu cac phuong tien giao thong va lap dat cac thiet bj ky thuat: cac ben d6

cd djnh, cac cong ty kinh doanh, cac djch vu cong c o n g

Xay dung cac cong trinh ngam trong do thi can tien hanh mot cach tOng the va co quy hoach sao cho chung cung vdi cac cong trinh mat dat va tren mat dat tao nen hethdng khong gian dong nhat Trudc tien, khong gian ngam phai chiem cac vung trungtam do thi, noi khan hiem dat, cac vung trong noi giao thong tap trung ldn nhat, co tfnh den cot cao do tu nhien cua khu vuc (doi, go cao, mai doc, sudn nui ) sao cho thuan loi nhat cho viec xay dung tuyen dudng ngam

Su dung tong the khong gian ngam han chc duoc nhu cau tang dien tfch cua cac do thj ldn va cho phep giai quyet nhidu van de rong ldn cua xay dung do thj, giao thong van tai, cac bai toan ky thuat va xa hoi

Khi sir dung hieu qua khong gian ngam cho phep:

- Tang cudng cau true quy hoach, kien true cua do thj

- Giai phong nhidu cong trinh co tfnh chat phu tro khoi mat dat

5

- Sir dung da't do thi hop ly cho viec xay dung nha d, tao ra cac cong vien, bdn hoa, san van dong, khu vuc cay xanh, cac vung “khong co oto”

- Tang cudng ve si lh moi trudng dd thi

- Bao ve cac tuong dai kien true

- Bd tri hieu qua cac cum thiet bi ky thuat

- Trong trudng hap can thiet sir dung cdng trinh ngam cho muc dich chien tranh ve quoc

- Giai quyet dugc van de giao thong do:

+ Dam bao dugc su di lai lien tuc va tdc do cao ciia cac phuong tien giao thdng

+ Phan luong tuyen giao thong va tuyen di bo

+ Tao nen dugc cac nut giao thong thuan tien (cac nut chuyen doi, cac nha ga ).+ To chuc tot cac ben dd cua oto

+ Tang cudng chat lugng dich vu van chuyen

+ Xet den tinh dac biet ciia cac cdng trinh ngam khong cd anh sang tu nhien, thong thoang kern, tach biet vdi mdi trudng ben ngoai, nen dudi dat dugc uu tien bo tri cac cong trinh ma con ngudi co mat trong thdi gian ngin: cac cdng trinh giao thdng, bao tang, rap chieu phim, bach hoa

De loai bo cac cam giac d dudi dat, cac phong cd the dugc tao dang kien true my thuat dac biet b in g each tao cho chiing net m in cam, nhe nhang va ben vung De lam dieu dd ngudi ta bd tri luan phien cac phong n gim vdi cac phong ndi tren m at dat, xay dung cac cua so gia, cac san dugc chieu sang, cac 16 tren cac tam trin , chieu sang nhan tao, thong gio va trao doi khong khi

De giam so lugng nhan vien phuc vu trong c ic cdng trinh n gim c in tu dong hoa tat

c i cac qua trinh lien quan den su khai thac chung tdi muc cd the

Xay dung sd lugng ldn cac cdng trinh ngim trong do thi se gap phai nhung kho khan nha't dinh, xuat hien d giai doan khao sat, thiet ke, xay dung va khai thac cdng trinh.Viec lira chon giai phap hgp ly quy hoach hinh khdi cho cac cong trinh n g im va su ket noi chung vdi q u in the kien true cua cac cong trinh lien ke tren mat da't cung phuc tap De ket noi cac nhanh ngim rieng biet vdi nhau va vdi mat dat cung nhu vdi c ic cdng trinh dudi mat da't va tren mat da't c in phii xay dimg cac tuyen giao thong nim ngang, than? dung hoac nghieng (thang may, bang tai cac via he di dong ) Ngoai ra, xay dimg cac cong trinh n gim c in thiet phai xay dung lai mang ludi ky thuat va tang cudng mong cho nha lan can

Trong qua trinh xay dung cdng trinh ngim yeu c iu phai thuc hien khoi lugng dao d it ldn va phai tao nen nhung ket c iu chiu luc khong Id va khong tham nude Tuy nhien, mac du co n h ilu kho khan, nhung chuyen gia xay dimg da vugt qua mot each thanh

cong Kinh nghiem xay dung cong trinh ngam khac nhau trong nhieu do thi cua Lien Xo (cu) va d nuoc ngoai da chung minh dieu do.

Hieu qua kinh te xa hoi cua cong trinh ngam Xay dung cong trinh ngam gan lidn

vdi chi phi dau tu rat ldn Phu thuoc vao dang cong trinh ngam cung nhu dieu kien dia

k y thuat va tinh chat do thi, gia thanh xay dung cong trinh n g lm co the cao hon 1,5 den

2 lan gia xay dung cong trinh tuong tu tren mat dat Khoang cach vd gia co thd giam rat nhieu khi mat do xay dung d do thi cao, cudng do di lai cua cac phuong tien giao thong cao va luong ngudi di bo ldn Khi gia thanh cong trinh tren mat dat tang manh (do phai dich chuyen nha, trang bi sua chua lai cac tuyen giao thong va dudng di bo) co the tiem can den gia thanh cong trinh ngam Gia thanh xay dung cong trinh ngam giam dang ke khi bd tri chung trong to hop chung vdi cac cong trinh tren mat dat, khi dieu kien dia ky tLnuat thuan loi cho phep su dung cac ket cau cong nghiep tien tien, cac phuong phap xay dung nhanh va kinh te cung nhu khi khoi lucmg sua chua mang ky thuat ngam nho Ngoai ra, khoang cach ve gia thanh xay dung cong trinh noi va cong trinh ngam duoc gisim nhieu nhd loi the ve xa hoi va do thi trong viec bd tri cum cong trinh nglm Nhu vay trong cac tinh toan hieu qua khai thac to hop khong gian ngam can danh gia khong nhung hieu qua ky thuat ma con phai tinh den hieu qua kinh te xa hoi (tang cudng didu kiCn song cua con ngudi, giam chi phi thdi gian chung cho ngudi lao dong, trong sach rnOi trudng do thi) kd ca danh gia hieu qua kinh te' cua quy dat dung de xay dung cong trinh nglm

Tuong ung vdi cac dieu kien da xet, hieu qua kinh te' xa hoi xay dung cong trinh

n g lm co the duoc neu ra khi so sanh tat ca cac chi phi cho xay dung va khai thac cong trinh nglm tuong tu nhu cong trinh trdn mat d it Trong do, mOi trudng hop cu the cln tiinh den tinh dac biet cua cdng trinh, vi trf, dac diem quy hoach va xay dung khu vuc cu tlhd cua do thi, dieu kien di lai cua cac phuong tien giao thong va ngudi bo hanh, mure do tlhuan loi cho xay dung va trang thiet bi ky thuat khu vuc Hieu qua kinh te xay dung cong trinh n glm trong cac do thi c ln danh gia khong chi cho tung ccng trinh duoc lira chon ma phai danh gia cho tat ca to hop cong trinh n g lm co cong dung da chuc nang.Gia tri chung cua hieu qua kinh te, xa hoi duoc xac dinh theo ket qua tinh toan, so s.anh hieu qua d lu tu, duoc bieu thi bang ty sd giua loi nhuan bo sung tir thuc hien

c huong trinh xay dung n g lm ddi vdi luong chi phi d lu tu de nhan duoc hieu qua do.Hieu qua kinh te xa hoi bo sung nhan duoc tu xay dung nglm la hieu qua kinh te' xa hioi chung khi xay dung cong trinh nOi A n va cong trinh n g lm A ng Nhu vay, hieu qua so s.anh xay dung n g lm co the nhan duoc tu bieu thuc sau:

Z < A „ S - A J ^ _ AA

> A B

7

CS day: 3 ^ 0 - he s6 tfnh toan cua hieu qua so sanh; V ( A ng - A n ) - hieu qua kinh te xa hoi b6

V- i

n

su n g tir xay dung cac cd n g trinh ngam tir i d en n (nghin d 6ng rup); V ( B ng - Bn ) - ch i phi dau tu bo

i

su ng tir khi xay dung ca c co n g trinh ng£m tir i den n (nghin d6ng rup).

Thai han hoan von cua chi phi dau tu bo sung vao xay dung ngam:

bi ky thuat cho khu vuc ma con quyet dinh mot chu6i cac chi so khac (vi du chi phi di chuyen nha d va mang ky thuat, xoa bo c ic bon hoa va cong vien, tang cudng dich vu giao thdng cho nhan dan va lam trong sach mdi trudng )

Hieu qua tu giai phong dat dai do thi lien quan den xay dimg cdng trinh ngim la rat dang ke Vi du, khi xay dung 1 km dudng dtd ndi 6 lan c in den 4,5-7 hecta dat, con de xay dung 1km n gim nhu vay chi mat 0,1 hecta

Theo tinh loan ciia Vien nghien cuu kinh te xay dung thuoc Bo Xay dung Lien Xo (cu), sir dung to hop khong gian ngim d Matxcova cho phep giai phong hon 5.000 hecta dat dd thi, trong do gia thanh 1 hecta khoang 250.000 rup va thay doi tir 100.000 rup d ngoai vi den 3 trieu rup d trung tam do thi Ro rang trong dieu kien sd huu xa hoi chii nghla dat dai khong phai la hang hoa va gia thanh ciia no chi de so sin h gia tri dat dai sir dung vao muc dich xay dimg

Tfnh den gia thanh xay dimg cong trinh ngim cao, co the cho rin g tot nhat tien hanh chuong trinh sir dung to hop khong gian n g im trong dd thi mot c ic h tir tir

Trong do thur tu xay dung cac cong trinh ngim duoc sip xep theo nhu c iu cua dd thi Ton tai thuc te kha pho bien la dua vao khai thac theo giai doan timg hang muc cong trinh rieng biet n im trong tong the cong trinh ngim

Phan loai cong trinh ngim do thi Nhung cong trinh dugc ggi la n g im neu p h in

chinh ciia chung n im dudi mat dat theo quan difim khai thac Cac cdng trinh ngim trong

do thi hien dai co rat nhieu va nhieu loai va co the dung de lam loi di hoac bao quan cac phuong tien giao thong (dudng h im , gara), lam cac diem sinh hoat cong cong, kinh doanh, rap chieu phim va cac cong trinh co cong dung khac nhu khu giao thong lien hcrp, cac cong trinh quoc phong Cac cong trinh ke tren co the dupe bo tri hoan toan dudi m at dat hoac mot phan dudi mat dat Vf du: phan ngam co the la cac phong rieng biet cua cong trinh noi: gara, nha ga, cang hang khong, cac trung tam thuong mai, nha 6

va nha hanh chinh cao tang

Trong so rat nhidu cong trinh ngam do thi, cong trinh giao thong chiem so lupng kha ldn, chung khac nhau ve mat cong dung, so do quy hoach, vi tri bd tri trong do thi, chieu sau, phuong phap xay dung (hinh 1.1) Ngoai ra, cac cong trinh giao thong n g im co thd khac nhau ve hinh dang va kich thudc mat c it, loai v&t lieu, dac diem ket c iu , dieu kien thong gio, chieu sang

Theo so do mat blng, ngudi ta chia:

- Cac cdng trinh co chieu dai ldn: cac dudng h im (tuynen), chieu dai ldn hon rat nhieu so vdi mat c it thiet dien

- Cac cong trinh co chidu dai han che phu thuoc vao cong dung, cac dudng h im co the la dudng oto, dudng tau dien ngam (metro), dudng tau dien cao tdc, dudng cho cac dang phuong tien giao thong dac biet (dudng tau co nhieu ray, tau tren ray tir trudng hoac tren dem khong khi, cac phuong tien giao thong khi nen ) K i ca cac ldi bo hanh hoac hPn hop danh cho cac phuong tien giao thong khac nhau va ngudi di bo Vf du: theo cac mat c it khac nhau cua mot tuyen ngam co thd oto, tlu dien ngam, tau hoa cua

do thi va ngudi di bo di dupe

Cac cong trinh giao thong ngim co chieu dai gidi han co the’ dung de bao quan cac phuong tien giao thong (cac diem dP oto, gara) de bd trf cac ga tau dien n gim , tau dien tdc d ) cao hoac dudng s it do thi, cac nut giao thong, cac diem giao nhau cua cac tuyen oto ngim , cac phong rieng biet cua cac nha ga hoac cang hang khong, dd tao cac dudng

di bo co cao dp khac nhau va cac to hop giao thong nhidu tin g (hinh 1.2)

Cac cong trinh giao thong ngam (CTGTN) co thd dupe bd tri dudi khu vuc do thi da

co cong trinh xay dung (hinh I.3a-b) va chua co cong trinh xay dung (hinh I.3i-e) Cac cong trinh ngam trong trudng hop thur nhat co thd dupe xay dung cach biet khoi cac toa m a va cong trinh phfa tren cung nhu n im trong khu vuc va ben canh khu vuc co cong trinh

N im trong khu vuc co cong trinh goi la nhung cong trinh n g im ket hop vdi cac tin g nglrr cua toa nha Cdn cac cong trinh ben canh co cong trinh la nhung cong trinh bd tri canh va ket noi vdi chung b ln g nhung ldi di ngim va dudng vuot Ngoai ra con ton tai cong trinh n g im n im trong va canh khu vuc co cong trinh xay dung

9

Hinh 1.1 Phan loai cdng trinh giao thong ngam do thi

Kni bd tri cac cdng trinh ngam tai nhung khu vuc dat trong cua dd thi, ngudi ta thudng bd tri chung dudi tuyen dudng dtd cao tdc n im ngoai tuyen pho hoac dudi tuyen dirdr.g sit, dudi cac bon hoa hoac cac cong vien, cung nhu dudi cac chudng ngai vat tir nhien hoac nhan tao Nhu vay, de di qua cac go, d6i cao chia c it dd thi thanh cac phin kho qua lai giua cac vung rieng biet cua do thi, ngudi ta xay dung nhung dudng ngim giao thong c a gidi va dudng bo dang tuy nen qua nui Trong mot sd trudng hop, dudi nhuTig chudng ngai vat cao nhu vay ngudi ta bd tri cac gara va cac to hop ngim Cac dudng him dd thi thudng hay xuyen qua ca c ic chudng ngai vat cao nhan tao nhu cac go dat dip, dudng oto, dudng sit, cac de dap

Trong n hilu do thi ldn co c ic tuyen va ho nude: song, kenh, hd, cac khu du tru nude De ket ndi giao thong lien tuc thudng xuyen giua c ic bd vdi nhau, ngudi ta khong chi xay dung c iu ma con xay dung ca cac dudng n g im dudi muc nude

Dud cac chudng ngai nude co the bd tri ca cac cong trinh giao thdng khac: ben dd dtd, gara, cac to hop nhieu ting

r 51

g h i

Hinh 1.2 Cac so do cdng trinh ngam do thi;

a dudng ham cho oto; 8 dudng ngam cho ngudi di bo; b gara dtd - diem dd;

i to hop giao thong nhieu tang; d ga tau dien ngam (metro);

1 dudng ham (tuynen); 2 dudng len xudng; 3 bac thang len xudng;

4 ben dd; 5 dudng ray nhidu nhanh; 6 dudng tau dien n g lm

Cat CTGTN co the dugc bo tri tai cac chieu sau khac nhau so vdi mat d it Ngudi ta phan bet cong trinh n g im dat nong, bd tri d do sau H < 10-12m va dat sau, bd tri d do sau H > 10-12m (xem hinh 1.2) Ton tai ca cac cong trinh nua n gim , mai cua chung cao han m i dit

Phi thuoc vao chieu sail dat ngam cua cac cong trinh ngam, tinh dac biet ve c iu true

va dd hi cua chung cung nhu dieu kien dia chat cong trinh, viec xay dung cdng trinh

11

dugc tien hanh bang nhieu phuong phap khac nhau: dao lo thien, ha chim, dao ham mo, mang chan, ep Trong do, d mot so trudng hop cac phuong phap nay duoc sir dung ket hop vdi nhung phuong phap dac biet nhu lam dong cung nhan tao, gia cudng dat b;\ng hoa chat, ha muc nude ngam (xem chuong VII-X).

a

b)

[ f t

Hinh 1.3 Cdng trinh ngam dudi khu vuc d d va khdng co cdng trinh xay dung a tach biet;

5 trong khu vi(c co cong trinh xay dung; b trong va canh khu vifc cd cdng trinh xay dung;

i dudi chudng ngai vat nhan tao; d dudi chudng ngai vat cao tu nhien; e dudi ludi chan nude.

Anh hudng cua cac CTGTN den moi trudng do thi Cac CTGTN dong vai tro huu

ich cho moi trudng do thi vi chung cho phep giai phong dien tfch tren mat dat va chuyen mot phan tuyen giao thong xuong d rdi mat dat Dieu do tao dieu kien tang cudng cau true quy hoach cac vung cua do thi, >lp xep lai dudng bo hanh, giam tai nan giao thong dudng bo va tang cudng an toan giao thong Ngoai ra, cac nhanh cua cong trinh nglm nang cao trang thai ve sinh moi trudng cho khong khf vi mot m at lam giam luong khi thai, tieng on va chan dong, mat khac cac khu dat duoc giai phong co the xay dung cac bon hoa, cong vien, trong cay xanh

Trong nhieu trudng hop, cac CTGTN duoc xay dung chi n h lm muc dich bao ve moi trudng xung quanh khoi bi tac dong co hai cua cac phuong tien giao thong de giu gin tron ven khu dat va quan the kien true cua cac khu vuc do thi

Vi vay, khi bd tri cac tuyen dudng oto g in sat nha d, trudng hoc, benh vien, thu vien, nha hat, ngudi ta chuye’n mot p h in tuyen giao thong vao dudng n g lm co trang bi he thdng thong gio nhan tao va cac phuong tien chdng on, chdng chan dong

Hieu qua cua cac giai phap do da dupe chung minh trong thuc te xay dung cac tuyen duang ngam trong cac do thi ldn d Lien Xo (cu) va cac nude khac Vf du: sau khi xay dung dudng giao thong ngam den Quang trudng Maiacopski d M atxcava do dam dac

m ax cua oxft cac bon tai vung nay giam tdi 4 lan, ham lupng hydroxit cacbon, oxft nito trong khong khf cung giam rat manh Sau khi xay dung cac dudng ngam khac d

M atxcava, lupng khf doc va bui trong khong khf giam khoang 3-4 lan Neu muc dp on tai khoang cach 15m so vdi mep dudng oto co cudng dp chuyen dong cua 10 nghin oto quy udc trong ngay dam dac nhat den 80-95 dexiben thi sau khi xay dung tuyen duong ngam, muc do on giam xuong con 55-65 ddxiben

Dac diem va muc do anh hudng cua cac CTGTN len trang thai moi trudng do thi chu you dupe xac dinh qua cong nang chfnh cua quy hoach khong gian, so do cau tao, dp sau dat ngam, su co mat trong do thiet bi khai thac nay hay thiet bi khai thac khac Vf du: Dudng ngam oto va dudng ngam bp hanh dat nong dupe bd tri tai cac nut co cudng do giao thong cao tiep giap hoac co nhanh noi vdi tuyen chfnh dam bao phan chia luong oto

va dong ngudi di bo, loai bo dupe ach tac oto trudc den tin hieu va d muc do nhat dinh lam trong sach moi trudng xung quanh Tuy nhien can biet rang, xay dung tuyen oto chfnh ngan va cac dudng giao thong luon dat nong thi khong phai luc nao cung hop ly theo quan diem an toan moi trudng do thi vi didu do lam tfnh chat doc tuyen kem di Tiep do su thay doi lien tiep doc len xudng tren nhung doan dudng vong chuyen doi lam tang lupng khf thai tu dong ca oto va tao them tieng on giao thong TCr do co the thay rang tot hem het la xay dung cac tuyen ngam dai han va dat sau trung vdi cac doan dudng noi va cach biet vdi dong giao thong cudng do cao

Xay dung cac tuyen ngam nhu vay dac biet hieu qua tai nhung vung trung tam co mat

dp xdy dung cao, noi khong co cac phuong tien binh thudng bao ve tranh khf thai va tieng on nhu cay xanh, rao ngan tieng on, cac ranh dao va cac khoi dap De giam lupng khf thai :fin giam do doc doc doan dudng vao cua dudng ngam tdi 30-35 % o

Cac diem bd trf ben dP oto, cac gara, cac to hop ngam can dupe sap xep sao cho dam bao sir thuan tien cua nhan dan theo quan diem dd tiep can phuong tien giao thong Trong khi do, cac CTGTN lai phai cach mot khoang nao do vdi cac cong trinh nha d sao cho tieng on va chan dong khong truydn tdi cac toa nha Trong mot sd trudng hop, cac cdng trinh ngam can phai tach khoi cac toa nha noi lan can bang cac buc tudng bao ve hoac cac hao chua day dung djch set, cac rao bao ve bang coc cu

Ket ciu cua cac CTGTN ngoai do ben va on dinh lau dai, can phai bao dam cach am

va chong chan dong Tieng on ldn trong cac cong trinh ngam xuat hien chu yeu do be mat trong cua vo khu am kem Vi vay can phai dung bien phap dac biet hoan thien mat trong va tao dang kien true cach am (xem chuong XII - §37) Cac cong trinh phu sat dudng ngam: cac buong thong gio, cac hd ga chuyen tiep, cac ga phu keo ha tau cung

13

can duoc bao ve each am Cac bien phap bao ve cho phep loai tru hoac giam duoc tieng

on truydn len pho

De tranh truydn chan dong khi xe co chuydn dong trong dudng n g lm len cac ngoi nha va cong trinh lan can, cac ket cau ngam can co kha nang triet chan dong cao Dieu nay co the’ dat duoc Vf du: tang chieu day ket cau, do cung va trong luong cua chung se lam giam manh tan so dao dong rieng cua ket cau

Khi tao su thong gio nhan tao cho cac dudng ngam oto, cln phai co bien phap ngan ngira khf thai tu oto ra cac vung lan can De lam duoc didu do cln phai lam cac phin loc dac biet

de tai sinh khong khf Vdi muc tieu bao toan cac nguon nuoc do thi khoi su nhidm ban, cln phai so bo lam sach nguon nuoc thai tu cac cong trinh nglm khoi xang dlu, mo

Cac CTGTN la mot bo phan quan trong cua mot to hop cong trinh x ly dung, c ln phai phu hop voi xu the' hien dai trong llnh vuc tong hoa khong gian kien true Chung cln duoc ke't ndi chat che vdi viec xay dirng va quy hoach dd thi, c ln duoc ke't hop nhuln nhuydn vdi quang canh xung quanh, giam toi thieu sir kho cung canh quan dd thi, c ln co

q u in the khong gian dep bieu thi duoc sir don gian va ro rang cua hinh dang Yeu c ln tinh nhuln nhuydn trudc tien ddi vdi p h in san va mat dung cua dudng n g lm giao thdng

co gidi, doi vdi ldi vao, ldi ra va cac gian phong ndi cua dudng h im bo hanh, cac doan len xuong cua cac ben d6 oto, gara, nha thdng gid va kiot, nghla la doi vdi cac bo phan cua cong trinh n glm true tiep lien he vdi kien true dd thi va la ddi tuong nhin thay Nhu vay, khi thiet ke' cac CTGTN ngoai tfnh toan can nhlc ve kinh te va ky thuat, c ln phai tfnh den yeu c lu th lm my va moi trudng sinh thai, hudng tdi viec bao toan va cai thien moi trudng lan can cua do thi

§2 XAY DUNG CONG TRINH GIAO THONG NGAM () CAC DO THI LIEN XO (CU)

VA Cl CAC NUOC KHAC

d Matxeova, Leningrat, Kiep va cac do thi ldn khac cua Lien Xo (cu) da va dang xay dung rat nhieu cdng trinh nglm : d Jdng oto, dudng di bo, cac dudng h im cua mang

ky thuat, cac ben dd oto va gara, cac dudng nglm va ga tau dien ngam

Xay dung giao thdng nglm trong cac dd thi d Lien Xo (cu) duoc biet den tir khi cd chfnh quydn Xo Viet Vao nam 1931 quyet dinh xay dung d Matxccrva dudng tau dien nglm d lu tien gom 13 ga va nam 1935 da duoc dua vao khai thac Nam 1982 trdn cac tuyen dudng tau dien n glm dai 200km da co 115 ga

Vao cuoi nhung nam 50 da phe duyet va quyet dinh xay dung cac tuyen dudng nglm cho oto va ngudi di bo tai nhung quang trudng va cac nut giao thong cd cudng do di lai cao trong dd thi Matxeova Dudng nglm oto d lu tien da duoc x ly dung d Matxccrva tai dai lo Kutudd'p, nhung dudng him di bo d lu tien duoc xay dung tai dai lo Cac Mac Vao nam 1961 d Matxeova da khai thac 7 tuyen giao thong co gidi n g lm va khoang 20 tuyen nglm danh cho bo hanh Ngay nay, trong do thi hien cd 17 tuyen oto n g lm vdi tong

chieu dai hem 7 km cho 2, 4 va 6 lan xe chuyen dong vdi chieu dai 200-500m va tren

250 tuyen di bo vdi khau do 3 -12m va dai den 150-200m

Viec xay dung dudng ngam oto 8 lan dai 1km theo tuyen dudng vong dudi nnanh dudng sat M itkob dang duoc hoan thien Vira qua, dudng ngam bo hanh 2 tang dau tien trong do thi tai vi tri cat qua dai lo Novicop vdi dudng vong Xadop da duoc dua vao khai thac Dudng ngam chinh dudi dudng vong Xadop dai hon 100m, rong 7,5m va 2 dudng ham song song dudi dai lo Novicop dai 42m tao nen he thdng dudng bo rat thuan tien, ket noi tat ca cac do thi lan can vao mot nut (xem hinh 1.4) Tuyen di be nam d tang tren cua dudng ngam, con phia dudi duoc bd trf nhieu mang ky thuat cong trinh

A - A

Hinh 1.4 So do dudng ngam bd hanh o giao diem cua dai Id Ndvokirop voi ducmg vong Sadop

Nhung nam gan day d M atxcova da xay dung hang loat ben d6 oto va gara ngam Gara ldn nhat la gara 7 tang chira 2500 oto tai dai lo Hoa Binh, gara 3 tang tai pho Nhegdanop nam dudi toa thi chfnh 6 tang, tren pho M iclukho -Malka, tai nut Khamutop dudi toa nha C3B, dudi tO hop khach san"Kosmos", "Xalut", "Irmaildp", gara nua ngam nirc noi tu dong tren pho Kiep Trong do thi M atxcova co tren 30 nghin km mang ludi

ky thuat ngam

Nhidu khoi luong xay dung ngam duoc thuc hien d vimg phfa Bac Trertano, d day

17% khoi luong nha duoc bd trf ngam Trong cac phong ngam co tat ca cac thiet bi ky thuat, cac gara cho 3500 oto, cac didm dich vu cong cong

Tuyen ngam chfnh la tuyen ngam khai thac giao thong dai gan 1km cho 3 dong chiydn dong, tir do theo cac tuyen ngam phu co the tdi cac cum nha d, gara va trung tam thujng mai Dieu do cho phep giai phong gan 20 hecta dat va sir dung chung dd tao cac boi hoa, cong vien va xay dung cac san the thao

Duai dai lo Kalenhin ngudi ta xay dung 4 dudng n g im bo hanh dudi cac ngoi nha cao tin g Dudng ngim van tai hang hoa dai 800m de’ phuc vu cac phong kho n g im cua trung tam thuong mai Cac cdng trinh n g im khac nhau dugc xay dung dudi to hgp khach san

Izmailop, dudi cac toa nha lang Olimpic

Trong tong mat bing phat trien do thi, so dd “To chuc va su dung khong gian n g im cua M atxcova” da dugc hoan thien, no xac dinh khdi lugng xay dung n g im rat ldn trong tuong lai Thu tu va cdng suat cac cum ngim , gidi han phan vung theo mat b in g va mat dung, hieu q u i kinh te xay dung cac cong trinh giao thdng n g im cac loai va cac cong trinh ngim da dugc neu ro

Mang ludi tau dien ngim d Matxcova cung dugc tiep tuc phat trien trong tuong lai Trong nhung nam cua ke hoach 5 nam lin thu 11 da co ke hoach dua vao hoat dong gin 30km dudng mdi vdi 17 ga Cac dudng ngim oto va bo hanh de phan nhanh chuyen dong d cac do sau khac nhau se dugc tiep tuc xay dung Cac dudng ngim giao thong dugc len ke hoach xay dung tai cac quang trudng Boxtanhia, Ximangolen, Lermantop, Zubop, Tagan, Preobrazen, nha ga Riz, doc pho Begop theo dudng vong B Cac dudng ngam van tai hang hoa den quang trudng Komxamon, Davucop va Izmailop dang dugc du kien xay dung Trong tuong lai da cd ke hoach xay dung cac dudng ngim chfnh va lien ket cac vung ngoai

vi vdi trung tam dd thj Trong do kha nang xay dimg tuyen oto ngim “Bic Nam” va “Ddng Tay” de ket ndi tuyen dudng sit hudng Kiep vdi Gocop Pavelex vdi Xverlop cung dugc xem xet Tuyen dudng ngim dai tiep can vdi dudng vong Xadop cd the dugc xay dung bing cach ket hgp dudng ngim hien cd vdi viec xay dung mdi

Cac dudng ngam di bo ldn se dugc xay dung dudi quang trudng Lenin canh nha ga Pavelex, tai cac quang trudng Tagan, Komxamon va Kalantrep trong khoang 1981 den

1990 d Matxcova du kien xay dung tong cong 150 dudng ngam di bo, mot sd dudng ngim

se dugc trang bi cac hanh lang di dong Rat nhieu ben dd ngim va cac gara ngim dudi cac toa nha thi chfnh, cac quang trudng ldn, trong cac khu dan cu da dugc du kien xay dung Vf du: cac gara ngim dudi nha trung tam thuong mai quoc te va tai cac quang trudng Xverlop, Xmolen dang dugc du kien xay dung Tai Iaxenhep se dugc xay dung cac gara cho 400-500 oto co 1 va 2 ting ngim Da cd thiet ke dinh hinh cho cac gara ngim chua 25, 50, 70 va 100 oto, ke ca gara 1 0 -1 5 ting tu dong va co gidi iiira ngim , nua ndi

Giai doan phat trien tiep theo cua chuong trinh sir dung va chiem llnh khong gian ngam Matxcova la lien ket tung cong trinh ngim rieng biet b in g cach tao nen nhung to hgp da nang lien he vdi nhau bing he thdng tuyen giao thdng n g im Trong thanh phin cac to hgp n g im se bao gom cac tuyen giao thong co gidi va bo hanh, cac ben d6 dtd va gara, cac ga tau dien ngim , cung nhu cac cum thiet bi cong trinh, c ic co sd thuong mai,

c ic rap chieu bong Viec su dung to hgp khong gian n g im da dugc quy hoach tai cac quang trudng Kalkhoz, Tagan, Kurxc, tai dai lo Novokirop, pho Dmitrops, tai cac vung mdi cua Matxcova (Tropareko, Vrekhovo, Borixovo ) to hgp n g im 3 tin g da dugc thiet

ke tai quang trudng Kalkhoz (hinh 1.5)

Hinh 1.5 M at cat (a), vd mat bdng (b) cua to hop ngam nhieu tang

tai quang trucmg Kalkhoz Matxeova (do dn).

1 via he di ddng; 2 tien sanh cua ga tau dien ngSm; 3 dudng n g lm bd hanh;

4 gara 4 tang ngam; 5 ca c diem thuang mai; 6 dudng ngSm g ia o thdng c o gidi;

7 san chieu sang hd; 8 dudng h^m - cau thang m ay; 9 ga tau dien n g lm ;

10 gara 1 nhanh n g fa i; 11 bach hoa; 12 gian trung bay.

T in g ngam dau tien la khu danh cho ngudi di bo co dien tfch 13400 m 2 gom co cac cua hang bach hoa, caphe, kiot Tren cac tin g thu 2 va 3 duoc bo trf cac ben dd cho

360 den 544 oto Se co mot dudng nglm giao thong co gidi duoc x ly dung tiep can vdi

to hop de xe ra vao theo hudng dudng vong Xadop Dudng van dong hudng tim cua oto thuc hien tren mat dat Trong tang dudi cua to hop bd trf ga tau dien n glm Dudi quang trudng Xem enop du kien bd trf cac phong thuang mai, ben dd oto, khu di bo de’ ket ndi vdi cac diem dd cua phuong tien giao thong cdng cong, ga tau dien nglm Dudi khu virc

ga Belarux du kien xay dung td hop nglm , trong dd cd 2 ga tau dien ng lm , cac tin g di

bo, cac ben dd oto, 2 dudng nglm giao thdng co gidi, cac phong cua nha ga Tren dai

Id Ndvdkirop du kien xay dung to hop nglm gom 5 ben dd oto nglm cho 4500-5000 xe,cac tuyen n g lm danh cho giao thdng co gidi va ngudi di bo Mot to hop nglm ldn duoc

du kien xay dung tai giao 10 cua dai lo Hoa Binh vdi pho Vien han lam Korolex 6 day

DAI HOC QUOC GIA HA NO!

• 0 0 0 4 2 1 i

17

se xay dung ben oto ngam nhieu chO, tuyen ngim giao thong co gidi va he thdng tuyen

bo hanh de lien ket cac nut chuyen doi cua ga tau dien n g im va dudng sit

Mang ludi cong trinh n g im d Leningrat se duoc m d rong Ngay nay do dai cua cac tuyen tau dien ngam Leningrat khoang 75km gom 43 ga Den nam 1990 mang ludi tuyen tau dien ngam phat trien tdi 130 km Trong do thi duoc xay dung 5 dudng ngim giao thong co gidi va tren 30 tuyen di bo ngam G in day da hoan thanh viec xay dung dudng ngam giao thong dau tien n im dudi muc nude tijf cac don nguyen duoc ha chim dai g in 1km de ket noi Leningrat vdi dao Kanonhep

Trong tuong lai viec m d rong xay dung n g im dang duoc du kien “So do tong the’ to chuc quy hoach va sir dung khong gian n g im ” dang duoc soan thao Viec dua vao khai thac chung se cho phep giai phong tdi 4.000 hecta dat Trong dd thi chia ra 5 vung vdi muc do su dung khdng gian n g im khac nhau Cac dudng giao th o rg co gidi n g im doc tuyen dudng cao tdc cung nhu cac dudng n g im ket hop vdi cac tuyen pho chm h dang duoc du kien xay dung Trong do, tuyen giao thong n g im tai doc bd phai g in ciu Bolsekhchim, tai quang trudng Chien T h in g , tai diem giao nhau cua dai lo M atxcova \di pho Kraxnoputinop, cung nhu 2 dudng n g im dudi song Nheva va cac nhanh cua no dang duoc len ke hoach x ly dung Hai tuyen ngam dudi nude vdi 6 lan xe dang dir kien xay dung d vi trf giao nhau cua dap vdi cac tuyen dudng thuy tai vinh Phin theo ke hoach bao ve Leningrat chong nude tran Ho so thiet ke xay dung dudng cao tdc xuyen tam vdi

50 doan ngim , trong do mot sd doan co chieu dai rat ldn dang duoc khoi thao

He thdng cac dudng n gim bo hanh, cac ben oto va gara n g im , cac to hop nhidu tin g

ng im cung dang duoc du kien xay dung M ot trong nhung to hop ngim bao gom cac ga tau dien n gim , dudng h im bo hanh, cac cdng trinh nua n g im va noi cdng dung khac nhau dang duoc tao ra tai giao tuyen giua dai lo Nhepski, pho Xadop va pho Brot Dudi quang trudng Muzextva tuyen giao thong n g im va he thdng tuyen n gim bo hanh ke ca gara ngim 650 xe dang duoc du kien xay dung Cac to hop n g im nhieu tin g duoc quy hoach xay dung tai vung san Goxchim va tai quang trudng Vaxtanhia

Hang loat cong trinh ngim da duoc x ly dung d Kiep T u nam 1961 da dua vao khai thac mang ludi dudng tau dien n g im dai 34km vdi 25 ga Vira qua, lin d iu tien d Lien

Xo (cu) dudng tau dien cao tdc dai 9,25km vdi 12 ga va 5 nhanh giao thong duoc xay dung Hon 40 dudng n g im di bo da duoc xay dung d Kiep Dudng n gim di bo ldn nhat tren pho Kresachic co hanh lang ra den cac diem d6 cua cac phuong tien giao thong cong cong va ket noi vdi ga tau dien ngim Trong dudng n g im bd trf 4 quan ca phe, cac diem kinh doanh, bach hoa (hinh 1.6)

Da co thiet ke dudng n gim giao thong co gidi tai quang trudng Lvop, tai giao diem cua pho Kraxnokazax vdi dudng sit Cac dudng ngim bo hanh mdi dang duoc xay dung Dudng n gim bo hanh dai 400m, rong 12m vdi cac via he di dong de noi dudng ngim hien co dudi quang trudng mang ten Doan thanh nien cong san Lenin vdi c iu treo bo

hanh qua song Dnhep dang duoc kien nghi xay dung Tai quang trudng Lexiukrain dang duoc du kien xay dung to hop giao thong ngam, bao gdm ga tau dien ngam, dudng ngam giao thdng dat nong va sau, ga tau dien cao tdc He thdng dudng ngam bo hanh ket ndi vdi gara, diem dd ngam 3 tin g vdi 900 oto dang duoc quy hoach Cac to hop ngam tuong tu dang duoc xem xet xay dung tai khu vuc cac pho Kraxnoarm en Gocki, Bozenko Tai quang trudng Bexapok dang duoc du kien x ly dung nhanh giao thdng vdi

3 cap cao do va ben dd n g lm 4 tin g cho 2000 oto Ben oto n g lm 3 va 4 tin g rat ldn vdi sue chua 6000 oto d vung quang trudng Bogda, Xm enhin, Kalinhin va Lvop dang duoc thiet ke Do an thiet ke tuyen dudng cao tdc hudng tam vdi mot sd nhanh n g lm dai khoang 2-3km d trung tam dd thi dang duoc thuc hien

Tai Tbilixi mang ludi tau dien n g lm dai 19km vdi 16 ga da duoc x ly dung va dang duoc xem xet md rong them Trong dd thi, dudng n g lm giao thong co gidi dang h im lo dai 2km doc bd song Kura, mot sd gara n g lm va dudng n g lm bo hanh dang duoc

k h aith ac

Tai Erevan mot dudng tau dien n g lm d lu tien dai 11,5km vdi 9 ga, mot dudng nglm giao thdng co gidi va m ot sd dudng n g lm bo hanh dang duoc khai thac Mot chuong trinh x ly dung nglm rat ldn dang duoc du kien, theo dd tram d lu m ay tlu dien nglm , cac diem dd xe ca, cac ben oto va gara, rap chieu phim, cac co sd thuang mai, tram thiet

bi ky thuat dang duoc xem xet Su ket ndi trung tam dd thi vdi cac vung ngoai vi se duoc thuc hien theo hai dudng n g lm hudng tam vdi tong chieu dai g in 10km, cat nhau tai viing quang trudng Lenin Td hop n glm rlt ldn duoc thiet ke dudi khu vuc ga dudng sit C) day bd tri cac phong ciia nha ga oto, cac ben dd oto tren 1000 chd, cac dudng nglm bo hanh cd cac via he di dong Cac to hap tuong tu du kidn x ly dung ca dudi quang trudng Lenin va d viing Norzeitun tai Erevan Nhd sir dung td hop khdng gian nglm se giai phong duoc 1200 hecta dat

H inh 1.6 Mat bdng dudng ngam di bp qua dudng a Kiep

19

Xay dimg cac CTGTN dang dugc tien hanh d nhieu do thi khac nhau thuoc Lien Xo (cu) Ngoai nhung do thi neu tren, cac tuyen tau dien ngim dang duoc khai thac d Bacu, Tasken, Kharcop Trong ke hoach 5 nam lin thu 11 du kien hoan thanh xay dung duong tiu dien n gim d M inxk, Gorky, Novoxibirxk Cac dudng tau dien n g im d Kybusep, Xverlop, Dnheprapetropxk se duoc xay dung tiep Cac do an thiet ke dudng tau dien

A

ngam dang duoc tien hanh cho c ic vung Riga, Omxk, Almata, Trerbinxk, Rostapnadonu

va Permi Cac tuyen tau dien cao tdc co nhung dudng ngim duoc quy hoach xay dung d Lvop, Tallin, Vongagrat, Xaratop, Roge, Oxkol, Trerepov Cac tuyen giao thdng co gidi

n g im dang duoc xay dung d Bacu tai giao diem c ic pho Ruxtan va Nhephchedabutkov (L=50m), d Vongagrat tai dai lo M etalugop (L=150m), d Xim pherdpon tai tuyen Ximpherdpon Evapatoria (L=420m) Bon dudng n g im giao thdng co gidi dir kien xay dung d trung tam Kharcop D a cd ke hoach xay dung cac tuyen giao thong d D anhep va

Viec xay dung cac CTGTN d c ic do thi Lien Xo (cu) dugc tien hanh theo ke hoach

va mang tinh tong the’ phu hgp vdi cac thanh tuu dat dugc trong llnh vuc dd, cd xet den cac ygu c iu v6 bao ve va lanh manh hoa mdi trudng dd thi

Nhieu cdng trinh ngim khac nhau da dugc xay dimg, dang xay dimg va dang dugc thiet ke d thu dd va d nhung dd thi ldn cua c ic nude XHCN

C ic tuyen tau dien n g im dang dugc khai thac va dang dugc xay dung d Beclin, Budapet, Phraha, Vacxava va Xophia Cd rit nhi6u cdng trinh n g im d Budapet Mot dudng h im giao thong co gidi rit ldn da dugc xay dung tai quang trudng Blakhaluiza Tai quang trudng Kalvina dang xay dung mot to hgp giao thdng ngim 4 tin g , tiep ndi vdi no la tuyen tau dien ngam “Bic - N am ” va tuyen dudng sit Trong tin g thur nhat cd khu vuc phan ludng bo hanh vdi nhung ldi len mat dat Cao do mat dat dugc sir dung de lam ldi thoat cho oto, con c iu can lam ldi di lai cho oto buyt tdc hanh To hop n g im 2 tin g dugc xay dung tai quang trudng Baros Dang co du kien xay dung 2 dudng ngim

7 ,

giao thong co gidi dudi Dunai O Phraha, vao nam 1980 da dua vao khai thac 1 dudng

n gim giao thdng co gidi 4 lan xe, chieu dai 344m bd tri dgc bd song L.Xvaboda Ngay nay, dgc tuyen dudng giao thong nhiSu lan xe, tai giao diem vdi cdng vien ldn nhat Xtormoka dang xay dimg 1 dudng n g im giao thong co gidi dai 1,7km Tai trung tam Brachislava da x£y dimg he thdng gom 3 tuyen ngim giao thdng co gidi (hinh 1.7) D6

an thiet ke 2 tuyen dudng tau dien cao tdc dai 70km, trong dd 20 km n im trong dudng

n gim dang dugc thuc hien Tai pho Dim itrop d Plopdiva dang dugc d6 nghi xay dimg dudng n gim giao thdng co gidi 4 lan dudng dai 250m Mot dudng n g im bo hanh r it ldn

dang phong (50 x 60m), trang bi 8 thang bo va 5 cau thang may cho loi xuong cung vdi cac diem dich vu thuong mai duoc xay dung tai quang trudng Vaxlap d Phraha Co nhidu dudng ngam di bo da duoc xay dung d Xophia C) Vacsava dang xay dung tuyen dudng cao tdc mdi co nhieu doan di trong dudng ngam va cat qua Vixla.

Mot sd luong ldn cac CTGTN da duoc xay dung d cac do thi Tay Au, Bac My va d Nhat Trong hon 70 do thi ldn tren the gidi hien dang khai thac va xSy dung cac dudng

x

tau dien ngam O London va Chicago ngoai tuyen tau dien ngam chd khach, cac tuyen tau dien ngam chd hang hoa dang duoc khai thac de chuyen chd hang hoa buu phaim Nhieu do an tau dien ngam chd hang hoa dang duoc tien hanh d Beclin, Vien, Pari Tai Brucxen, Xtockhom va Gocheboc cac dudng tau dien ngam cao tdc da duoc xay dung, trong tuong lai co the duoc trang bi lai de chuyen sang tau dien ngam Dudng ngam giao thdng co gidi va bo hanh, cac ben d6 va gara ngam, cac to hop ngam, cac dudng ngam dudi nude da duoc xay dung d Pari, London, Miukhen, Newyork, M orial, Tokyo, Oxac

va d nhieu do thi khac

Hinh 1.7 So do cac tuyen giao thdng ngam d trung tam Brachislava

O ’ari mang ludi tau dien ngam dang hoat dong co tong chieu dai gan 290km vdi 420

ga, trrng do bao gom tuyen tdc hanh “Dong - Tay” dai 46,5km, tuyen tdc hanh mdi

“ Bac N am ” dang duoc xem xet xay dung Trong do thi hang chuc tuyen ngam giao thdng co gidi da duoc xay dung vdi tong chieu dai gan 15km va rat nhieu dudng ngam

bo haih dat nong Tong sue chua cua tat ca cac ben xe va gara d Pari khoang 100 nghin

xe oti Khong gian ngam cung duoc sir dung rong rai khi xay dung nha d, cac toa nha thi chnh va cac nha cong cong Tai quang trudng Quoc phong, mot to hop giao thong

21

ldn dang dirge xay dirng, trong do bao gdm mot doan dudng tau dien ngam tdc hanh, 2 nhanh giao thdng co gidi n g lm , gara nhieu tin g sue chua 10.000 oto va tren cao la dudng di bo (hinh 1.8) Phia tren la td hop cdng trinh n g lm cd 1 nhdm nha cao tang, tua tren ban san bo hanh ldn vdi dien tfch 70 hecta Ban san hoi cao hon mat dat dd cho oto

cd thd thoat len duoc

Hinh 1.8 To hop giao thdng ngam tai quang trudng quoc phong d Pari.

I gara ngam; 2 dudng dich vu; 3 via he di ddng; 4 ca o dd tuydn bo hanh;

5 tuyd'n dudng 6 t6 ngam; 6 tuyS'n tau dien ngam tdc hanh; 7 ga 6 t6 buyt;

8 dudng 6t6 sd 14 dfin Pari; 9 dudng 6 to sd 13 tir Pari ra; 10 dudng 6 t6 sd 14 tir Pari ra;

I I dudng 6 t6 sd 192 den Pari; 12 dudng 6 t6 sd 192 tir Pari ra; 13 dudng ngdm d ich vu;

14 dudng ot6 sd 13 den Pari.

Ke hoach tiep tuc chiem ITnh khdng gian n glm d Pari da duoc du kien Tai vi tri clio danh tieng da thiet ke trung tam thuong mai 4 tin g “Forum ” dat d do sau 14m so vdi mat dat Trong thanh p h in td hop dd cd ga tau dien n glm , ben xe oto n g lm cho 1650 chd, ben dd cua cac phuong tien giao thdng cdng cong

Dd an thiet ke xay dung tuyen oto nglm tong chidu dai 130km da hoan thien Dudng nglm 2 ting thiet dien hinh trdn dudng kfnh 15m hoac hinh elip chieu cao 15m va chieu rong 12m di vao long dat 15-100m va se cd cac ldi len mat dat dang dudng lan vdi do doc 10% Toan bo cd 270 dudng lan thang va dang xoln dd thoat duoc 100 nghin Oto trong 1 gid De ket ndi vdi mat dat du kien lam thang may va bang chuyen Tren tuyen nglm du kien xay dirng 40 ben xe cd tong sue chua 58 nghin oto Dang luu y la dd an cua kien true

su ngudi Phap Meimon ve viec xay dung d Pari mot td hop n glm dudi long song Xen Tren dien tfch 3 nghin hecta va tai chieu sau toi 60m thap hon day song, du kien bd tri cac pho nglm , cua hang bach hoa, kho chua, quan ca phe, rap chieu phim, cac phong the thao, ben

xe oto vdi 500 nghin chd, cac be chua nude uong, nhien lieu, cho, phong trung bay

Trong nhiSu cong trinh ngim khac nhau cua London co mang ludi ducmg tiu dien

ngam tong chieu dai 417,5km vdi 247 ga O London nhieu dudng ngam bo hanh va giao

thdng co gidi ldn, cac ben xe va gara ngam da duoc xay dung Vf du dudi cang hang

khong Khitroy mot dudng ngim van tai co gidi dudng kfnh 10m va he thdng dudng

n g im bo hanh tdng chieu dai 1,3km vdi via he di dong de ket ndi 3 nha ga cua canghang khong vdi ga dudng sit n gim da duoc xay dimg Do cd kho khan xuat hien trong

su phat trien mang ludi giao thong d London, mot dd an thiet ke' he thdng cac tuyen

dudng dtd n g im dat d do sau 20-30m so vdi mat dat da duoc hoan thien Sau tuyen

dudng n g im chfnh vdi tdng chieu dai 300km giao nhau se di dudi p h in trung tam dd thi

va se cd ldi vao va ldi ra d xung quanh no Cur 800m theo chi6u dai tuyen n g im duoc bd

tri 1 khoang quay xe de co di6u kien thay doi hudng chuyen dong, con qua 4,8km bd tri

ldi vao va ldi ra trung gian de len mat dat Tai nhung chd dd se xay dung cac ben xe

n g im vdi sue chua 250 nghin dtd, duoc trang bi thang m iy va bang tai de van chuyen

hanh khach va hang hoa (hinh 1.9) Cac tuyen oto ngim dugc thiet ke theo dang h im 2

tang, dudng kfnh 18m, cho phep 3 luong xe di theo mdi hudng O phan tren va phan

dudi cua thiet dien dudng ngim se dugc xay dung cac nhanh danh cho tau chay tren ray

treo va cac nhanh di bo cd trang bi via he di dong

Cac to hgp n g im , c ic dudng n g im giao thdng va bo hanh, c ic ben xe ngam va gara

tuong tu dang dugc khai thac v i xay dung d Bern, Xiuric, Stockhom, Bruxen

Birmingem, Milan, M adrit, M iukhen va a cac do thi chau Au khac

H inh 1.9 M at cdt ngang dudng true ngam Luan Don tai vi tri ben dd oto (do an)

1 duong n g im bo hanh co via he di dong; 2 p h in ducmg ray; 3 cac kenh cho m ang ky thu&t;

4 ben d6 oto buyt; 5 dudng vao va ra co b en d 6 ot6; 6 ben d6 6t6 6 tin g ;

7 thang m ay; 8 V i tri thay ddi hirong ch u yen d ong cua 6t6; 9 dudng true n g im

23

Trong cac do thi ldn cua My, khi m d rong mang lirdi giao thong dong thdi vdi cac dirdng tau dien ngam ngudi ta xay dung cac dudng giao thong co gidi ngam va dudi nude, cac ben oto va gara ngam, cac to hop ngam nhieu tang 6 New York ben canh mang ludi tau dien ngam phat trien (dai 384,9km, 484 ga), mot sd dudng ngam ldn dudi nude, cac gara va cac to hop ngam da duoc xay dung 6 p h in trung tam do thi xay dung mot trung tam ngam 5 tang, 2 tang trong do dung cho ngudi di bo, d day bd trf cac diem kinh doanh, nha hang, phong hoa nhac, 3 tang dudi nude su dung de d6 oto, de bd trf cac doan dudng noi va cac thiet bi ky thuat Trung tam thuong mai ngam cung da duoc xay dung dudi nhom nha cao tang, 2 trong sd cac toa nha dd cao khoang 400m Tat ca cac nha duoc lien ket vdi nhau bang cac tang ngam, trong dd co gara, ben d6 oto, ga tau dien ngam, cac dudng ngam bo hanh, trung tam thuong mai, rap hat M ot do an thiet ke to hop giao thong ngam ldn tai cang hang khong Los A ngeles da duoc hoan thien C) day tren 5 tang ngam duoc bd trf ben xe oto, dudng bo hanh co via he di dong, cac cum thuong mai va dich vu Tdi cac to hop se co cac dudng ngam giao thong co gidi ket nci.

Hinh 1.10 To hop ngam 5 tang d Tokyo

Nhtfng nam gan day su chie'm llnh khong gian ngam d cac do thi cua Nhat Ban duoc tien hanh theo ke' hoach rong ldn Su can thiet khong gian ngam la do mat do dan sd cao, khong du dat trong, do o nhiem moi trudng xung quanh lam that thoat hang nam tdi 20

ty USD Ngoai cac tuyen tau dien ngam duoc khai thac d Tokyo (186km, 180 ga) trong

A

cac do thi Oxaca, Xappopo, Nagoie, Yokogama, K obe da xay dung g in 130 ben oto ngam vdi sue chua 30 nghin oto, m ot sd luong ldn cac dudng ngam giao thong co gidi

Chutmg II KHAO SAT KY THUAT PHUC VU THIET KE VA XAY DUNG • • • •

CAC CONG TRINH NGAM

§3 KHAO SAT VA NGHIEN CUU DIA CHAT CONG TRINH

Vai tro d|a ky thuat trong xay dung De thiet ke cac cong trinh ngam do thi can co

cac so lieu ban dau bieu thi dieu kien cua moi truong se xay dung cong trinh Do la cac dieu kien dia hinh, dac di6m quy hoach va xay dung khu vuc do thi, su bo tri cac cong trinh nhan tao (ngim , noi) va cac m ang luoi ky thuat, dac diem dia chat cua nen dat, su phan bo va che do nude n gim , cac thdng sd ve khf hau Lam ro cac dieu kien do la bai toan cua khao sat ky thuat cong trinh - mot trong nhung giai doan chung cua day chuyen

“khao sat - thiet ke - xay dung”

Dira tren ket qua k h io s it ky thuat cdng trinh, ngudi ta xac dinh duoc kha nang ky thuat xay dung cong trinh ngim , lira chon duoc phuong an tdi uu, cac g iii phap quy hoach khong gian va ket c iu , tfnh duoc cac tai trong len ket c iu cdng trinh, chinh xac hoa so do ti'nh toan va lap duoc khdi luong xay dung Sd lieu khao sat cong trinh cung duoc sir dung de du tinh su thay doi k h i d! cua mdi trudng do thi xung quanh trong mdi quan he vdi qua trinh xay dung va khai thac cdng trinh ngim

Khao sat dia chat cong trinh duoc tien hanh theo chuong trinh da thdng n hit trong tat ca cic giai doan thiet ke va xay dung cdng trinh ngim , con cac dang cdng tac rieng biet - d giai doan khai thac Khao sit dia chit con;’ trinh trong dieu kien dd thi (tai nhung vung it duoc nghien cuu) lien quan tdi mot sd kho k lan khi thuc hien do sir co mat cua cac cdng trinh xay dung, sir di lai nhon nhip cua cac phuong tien giao thdng va ngudi di bo

Tuy nhien, xay dung d vung da cd cdng trinh ndi hoac n gim theo b in dd hoac theo mat b in g vi tri cu the, cdng tac khao s it dia c h it cdng trinh se don gian hon, giim duoc khdi luong va gia thanh

Khao s it de thiet ke va xay dung cac cdng trinh ngim bao gom nghien cuu, khao sat dia chat cdng trinh va cac cong tac trie dia cong trinh Noi dung, phuong p h ip va ky thuat tien hanh duoc xac dinh theo dieu kien cu the cua tung cdng trinh n g im De co co

sd thiet ke va xay dung cac cong trinh n g im dd thi, c in phai biet dieu kien dia c h it cdng trinh Du doan khong chinh xac trang thai dia chat cdng trinh cd the phuc tap hoa cong tac xay dung n gim , d in den keo dai thdi gian va tang gia thanh xay dung Ngoai ra, sir sai sot trong danh gia didu kien dia chat cd the anh hudng xau den mdi trudng do thi26

xung quanh, nghia la, co the d in den pha hoai do on dinh khoi dat, lun be mat dat, bien dang cac ngoi nha va cong trinh lan can.

Dia chat cong trinh trong xay dung ngam dong vai tro dac biet quan trong, no tao nen tmh dac biet cua cong trinh n gim tir cac hudng duoc dat bao phii Moi trudng dat la ngn cua cdng trinh ngam, no tao nen tai trong chfnh len ket cau chiu luc ciia cong trinh.Khi xay dung cong trinh n g im c in xet day dii to hop cac thong sd dia chat cong trinh mot cach tong the va xac dinh trang thai dia chat cu the Trong cac thong sd do c in luu y:

- Tinh chat ciia dat va didu kien tao thanh

- Che do va tfnh chat hoa ly ciia nude ngim

- Dac diem xuat hien qua trinh dia vat ly va dia chat cong trinh

- Che do va tfnh chat khf ngim

Tfnh chat ciia dat quyet dinh cong nghe xay lip, phuong phap dao va d ip dat, loai gia

cd tam thdi Dac diem tfnh chat ciia dat c in thiet khi xac dinh gia tri tai trong len ket cau

n g im , khi lua chon so do tfnh toan cong trinh ngim , khi xac dinh cac thong sd gia cd tam thofi

Tu> nhien, hieu biet tfnh chat ciia dat vln chua dii de thiet ke cac cdng trinh ngim Mot loai dai cung tfnh chat nhu nhau co the co the nim khac nhau tren tuyen cong trinh ngim.Thong thudng cac cong trinh ngim duoc cd g ln g bd trf trong mot ldp dat on dinh va khong bi nude cuon trdi, boi vi bd trf chung tai ch6 tiep xuc giua hai loai ldp d it k h lc nhau se xuat hien tai trong khong d6u tac dung len cong trinh do truot ldp no len ldp kia (dac bi;t khi ton tai cac thau kfnh set giua cac ldp) va do dong chay ciia nude ngim Trang thai dia chat khong the duoc nhan thirc d iy dii neu thieu sir hieu biet dieu kien thuy van: Chieu slu nude, che do va tfnh chat hoa ly ciia nude ngim Ro rang, khi dao dat ngam se lam pha vd trang thai c in blng cua nude ngim , lam tang tdc do loc va hoat tfnh hoa ly ciia nude

Qua trinh dao sau vao khoi dat chira nude se co dong nude ngim chay vao hd dao, do do cin co Dien phap dac biet de hut nude, ha muc nude, gia cudng hoa hoc hoac dong bang dat Nude trong dat tao nen ap luc thuy tinh tac dung len cong trinh, lam cho cdng trinh ngim noi len va pha vd sir on dinh ciia khoi dat do giam do cung va bien loang dat rdi

Khi thiet ke va x ly dung cac cong trinh ngim c in tfnh den trang thai dong hoc cua khu vu; do thi co anh hudng nhieu den dieu kien dia chat cdng trinh xay dung Trang thai dong hoc duoc bieu thi blng kha nang xuat hien va tang cudng do cac hien tuong va qua trir.h dia vat ly khong thuan loi: truot Id, cac dong chay, su xoi Id cu va mdi, su pha hoai kien tao, dong dat, cac dong tham ngoai nhung hien tuong dia vat ly, c in luu y den cac qua trinh va cac hien tuong dia chat cong trinh g in vdi x ly dung cong trinh noi

va cong trinh ngam lan can

va bo hanh C) Tokyo hau nhu tat ca cac toa nha m ai deu co 8 tin g n g im m a rong ket ndi vdi xung quanh qua cac pho tiep giap Cac to hap n gim dang dugc tao lap, cac pho

xa, quang trudng tham chi' ca vung lanh tho n g im To hgp n g im 5 tin g ldn d ii 735m rong 44,4m da dugc xay dung dudi nha ga dudng s it Tokyo (hinh 1.10) Ke't ndi vdi to hgp co cac tuyen dudng sit va dudng tau dien n g im T in g n g im d iu tien dung cho ngudi di bo co c iu thang len m at dat T in g n g im thu 2 - cum ky thuat - bao gom cac thiet bi dieu tiet khong khf, cac thiet bi may moc kiem soat Tren tin g n g im thu 3 bd tri

q u iy ban ve, cac diem tra cuu, quan ca phe, nha hang, cac phong chd T in g n gim thu 4

la phong phan phoi va ket ndi 16 c iu thang m iy vdi c ic tin g k h ic Tren tin g n g im thu 5

bd tri san dudng s it va 4 n h in h dudng ra vao cho tau Hang ngay cd tdi 200 nghin ngudi lui tdi to hgp ngim

To hgp n g im 3 tin g dang dugc khai thac dudi quang trudng Iaexu Tren tin g ngim

d iu tien bd tri trung tam thuong mai, tin g thu 2 la ben xe dtd, con tin g thur 3 - tuyen

n g im ndi to hgp vdi cac dudng did cao tdc 6 vung X indiuco da xay dung mot khu vuc

n g im rong 250 nghin m2 cho ngudi di bo Tren mat dat cho phep dtd di lai Tren tin g

n g im thu 2 dugc bd tri ben d6 cho 500 oto, d day cd dudng n g im dai 300m di qua, d in den trung tam giao dich cua thanh pho Khong gian md dang elfp kfch thudc 60 x 50m dam bao thdng thoang va anh sin £ cho cac phong ngam CJ Tokyo da x&y dimg 5 pho

n g im dai 640m dat sau 8m cach m at dat Trong khong gian n g im bd tri cac bach hoi, quan ca phe, rap chieu phim Tat ca cac phong dugc trang bi quat gid nhan tao va he thdng dieu hoa khong khf Trong chi tiet kien true cua cac phong, cac hoa van, tranh anh dugc su dung rong rai cung phong canh cong vien do thi, cac cua sd gia, cac Id anh sang, den treo va cac thu thuat khac de tranh cam giac dudi long d it Trong tuong lai d Tokyo se quy hoach cong trinh tuyen dtd n g im 12 luong cho xe tdc do cao Trong do d6

i n xi\y dung dudng vong n g im quanh dd thi dang dugc h o in thien

25

Trudc tien, c in xet den cac qua trinh va cac hien tuong gay nen su thay doi trang thai ung suat cua khoi dat dudi tac dung cua tai trong dong va tinh do xay dung dudng, nha, cac cong trinh nhan tao, cac hd dao, cac tuyen dao ngim , cung nhu cac qua trinh va hien tuong thudng gap trong cac do thi lien quan den viec tang hoac giam muc nude ngim Muc nude n g im trong dat nang cao do ap luc nude be mat hoac ap luc nude ngim , nude thoat tir cac nguon va nude trong da't, nude chay do tir cac tuyen ong d in nude v v co thd gay nen su d iy noi thuy tinh ciia da't, lam ngap cong trinh ngim , thay doi do sau dong ket, lam truong no da't v.v Giam do cao muc nude trong ndn da't nhd khai thac cac nguon nude mat, xay dung cac he thdng gieng nude, thuc hien viec ha muc nude ngam de tang trong lire, lam cho khoi da't bi ep lun, nen bien dang do thoat nude Tat ca cac dieu do cuoi cung, lam cho da't chat hoac dan no, tao nen cac mat nghieng va mai doc khong on dinh cung vdi su bien dang va truot ciia khoi dat va mat da't, pha hoai do 6n dinh nen nha.

Neu cong trinh ngam dat d vung da't chua khf, c in co cac bien p h ip dac biet de ngan ngira kha nang chay va no, cung nhu loai trir tac dong ciia khf len con ngudi va len vat lieu cong trinh, cac ldp dp lat De lam duoc dieu do, trudc tien c in xac dinh loai khf

n gim , vi tri thoat ra va khoi luong kha di

Khi thiet ke cac cong trinh ngim , c in hieu biet ca didu kien khi hau ciia vung do thi

do No co thd anh hudng true tiep den viec lira chon he thong va cac chi sd thong gio

nh in tao ciia dudng n gim , su chieu sang ldi ra vao ciia xe va ngudi di bo, he thdng thoat nude, cac phuong phap cap nhiet cho tung doan ducmg n g im giao thdng va cac ldi xudng ciia dudng n gim bo hanh

Cac phuong phap va cac giai doan khao sat dia chat cong trinh Noi dung va khoi

luong cong tac khao sat dia chat cong trinh duoc xac dinh chii yeu dua vao dang cong trinh ngim , kfch thudc ciia no tren mat blng va chidu sau chon ngim , cung nhu mire do da duoc nghien cuu ciia viing do thi do Cong tac khao sat duoc tien hanh theo mot so giai doan, phu thuoc vao dang cong trinh ngam va mi c do phuc tap ciia dieu kien dia chat, trong do tai inoi giai doan, ngudi ta tien hanh cac phin viec chuln bi ngoai hien trudng va trong phong Muc

do chi tiet ciia cong tac khao sat duoc xac dinh theo giai doan thiet ke cong trinh ngim (giai doan lap du an kha thi, thiet ke ky thuat, thiet ke thi cong)

Nhung giai doan chinh ciia cong tac khao sat dia chat cong trinh la:

- Dieu tra dia diem

- Do ve dia diem theo ty le ldn

- Tham do dia ky thuat

Khi tien hanh dieu tra dia chat dia diem cong trinh, ngudi ta sir dung cac tai lieu luu tru hien co: ban do, cac tai lieu trie dia hang khong, cac mat c it dia chat, cac so lieu nghien cuu trong phong co duoc khi xay dung cac cong trinh ngim lin can Cac dieu kien dia chat cdng

trinh dirge danh gia bing cach sir dung cac yeu to tu nhien khac nhau: khf hau, dia hinh, cac didu kien thanh tao dia chat, cac hien tugng dia vat ly v.v , lam ro cac chi tieu, tfnh chat cua dat, chieu day ciia timg ldp dat, dieu kien the nlm ciia chung cung nhu cao do muc nude nglm, danh gia dac diem, tfnh chat va dong chay ciia nude nglm Ngoai ra, ngudi ta con nghien cuu tat ca bien dang ciia cac cdng trinh nglm va ndi, nlm lan can vung xay dung, cac qua trinh xay ra lien quan den dia chat cdng trinh.

Theo tai lieu dieu tra, ngudi ta lap cac ket luan, the hien su tiep can d lu tien den cac dieu kien dja chat cdng trinh ciia viing x ly dung Dieu dd cho phep kha nang thiet ke cac phuong an cdng trinh va lira chgn cac phuong an kha di

Giai doan tiep theo ciia cdng tac khao sat dia chat cdng trinh - do ve dia diem theo ty

le ldn dugc tien hanh vdi muc dfch danh gia chung dieu kien dia chat cdng trinh ciia khu virc va lua chon phuong an hgp ly cho cong trinh ng lm Thdng thudng do ve binh dd chi tiet theo ty le ldn chi dugc thuc hien d cac viing mdi cua dd thi, d cac viing xay dung cd, cdng tac do ve dia hinh dugc tien hanh vdi khoi lugng gidi han de chfnh xac hoa mot sd

sd lieu cd san khong xac dinh dugc khi didu tra Cong tac do ve dia diem bao gom nghien cuu dia hinh, cau tao dia chat ciia nen dat, tuoi va ngudn goc ciia dat, dau hieu phan loai chung, dac diem thanh tao, cac qua trinh dia vat ly

Do ve dia chat cdng trinh dugc thuc hien theo ty le 1:10000 ddi vdi cac didu kien don gian va 1:5000 doi vdi didu kien phirc tap, chii yeu b in g cac phuong phap tren mat dat, khdng sir dung trie dia hang khdng va quan sat tren khdng Trong nhidu trudng hgp, dong thdi vdi viec tien hanh do ve binh dd, ngudi ta td chuc quan sat cd dinh trang thai ciia dat va che' do nude nglm Quan sat cd dinh dugc tiep tuc trong giai doan xay dung

va doi khi ca trong giai doan khai thac cdng trinh nglm Ket qua do ve dia hinh ty le ldn, ngudi ta nhan dugc cac so lieu c ln thiet va d ly du de lua chgn phuong an cuoi cung cho cdng ‘rinh nglm

Theo phuong an lira chgn, ngudi ta tien hanh khao sat chi tiet dia chat cdng trinh - Tham dd dia ky thuat Muc tieu chinh ciia cdng tac tham dd - nhan dugc dac tfnh dinh lugng sir dung khi xac dinh tai trgng ldn ke't ca'u cdng trinh n glm , khi lira chgn so dd tfnh toan cong trinh, cac phuong phap dao da't, cac thdng so dn dinh tam thdi v.v cung nhu du doan tfnh dong hgc ciia su phat trien cac qua trinh dia vat ly, cac trang thai ung suat - bien dang ciia khoi dat, cac che' do nhiet va nude nglm

Chuong trinh tham dd dugc dat ra cd xet den cac sd lieu da cd tir ke't qua dieu tra va

do ve binh dd ty le ldn Trong dd, ngudi ta xac dinh cac gidi han hinh c lu tac dung tuong hd ciia cdng trinh n g lm dd vdi mdi trudng dia chat, nghla la khoi lugng dat ma trong gidi han dd, cd the’ vi ly do nao dd thay doi didu kien d giai doan x ly dung hoac khai thac cdng trinh nglm Binh dien cdng tac tham dd dugc xac dinh bing dang va dac diem ket ca'u ciia cong trinh nglm , muc do phirc tap va muc do nghien cuu tinh hinh dia

ch it, ^hucmg tien chfnh cua cdng tac tham dd dia ky thuat la khoan Id (hinh II 1) Cac vi

29

tri va sd lugng 16 khoan dirge xac dinh b in g cac didu kien cu the cua cdng trinh xay dung cd tfnh den mang ky thuat ngam Ddi vdi cac cdng trinh ngam keo dai (cac dudng

h im giao thdng va bo hanh, c ic gara dang tuyen), c ic Id khoan duoc bd tri doc true,

c ic h nhau 150 -4- 200m (cho giai doan lap luan chung kinh te ky thuat), hoac 30-h50m (cho giai doan thiet ke ky thuat), cung nhu theo phuong vuong goc vdi true cua chung.Khi khao sat theo tuyen cdng trinh n g im cd kfch thudc gidi han trong mat b in g d cao

do ldi di bo va gara dang phong ngan, cac to hop giao thong v v , cac 16 khoan duoc bd tri theo chu vi tudng va theo true cot cua ket cau, trong dd khoang cach giua cac Id khoan cd the thay doi tu 200 den 20m Chieu sau 16 khoan thudng sau hon day cdng trinh n gim 8-nlOm hoac khoan sau vao ldp ben nude 2n-3m Ld khoan dudng kfnh 75^-300mm duoc khoan vao dat khong on dinh b in g phuong phap xoay dap theo cdng nghe guong tin g vong (vao dat set va dat hoang tho) hoac guong tin g lien tuc vdi cac vong vuot trudc (trong dat c it va dat hdn ldn) Viec lay m iu dat duoc tien hanh theo ldp0,5m Trong dat set cung, nua d i, d i, cac Id duoc khoan b in g phuong p h ip xoay (dang cot) co phun nude hoac dung dich set ket hop lay m iu nguyen dang, ngudi ta con su dung cac phuong phap guong x o in rung, c ip va dap de khoan Id Trong qua trinh tham

dd dia ky thuat, ngudi ta khoan 16 khoan dia chat - de lay m iu d it va m iu nude - de nghien cuu che do nude ngim D it tu Id khoan duoc lay theo dang ldi khoan trong da, dat set chat hoac bot khoan trong cat, trong d it hdn ldn va chuyen ve phong thi nghiem

de nghien cun va thu nghiem Doi khi tfnh chat bien dang cua dat duoc xac dinh true tiep trong Id khoan b in g c ic h ha vao dd thiet bi chuyen dung - thiet bi do ap luc va do chuyen vi Cac thdng so dja chat thuy van trong cac 16 khoan dia chat thuy van duoc nghien cun b in g each hut thur nude rot vao hd hoac Id khoan

Ngoai cac Id khoan tham dd tam thdi, ngudi ta con khoan cac Id khoan dia chit va dja chit thuy van tac dung lau dai de tien hanh quan sat cd djnh Thdi gian g in day, ngoai cac Id khoan tham do dung eon cd cic Id khoan nim ngang duoc sir dung Chung duoc khoan tu cac gieng lo dung, tir cac hd dao n g i n, tu cac nhanh dudng h im v.v N giy nay ngudi ta tao ra c ic m iy khoan nim ngang ket hop lay m iu, cho phep khoan Id dudng kfnh 45^-120mm tdi chieu sau den 500m va ldn hon, vdi tdc do tdi lOOm/ngay dem

Ld khoan ngang thay the Id khoan dung tao kha nang giam khdi luong khoan rit nhieu va tang do chfnh xac cho du doan cac dieu kien dia c h it cdng trinh

De quan sat c iu tao khdi dat b in g m it, liy m iu tung ldp d it, xac dinh dac tfnh do ben va bien dang, ngoii khoan lay m iu , ngudi ta con dao hd tham dd: gieng, ho dao, cac gieng ld durng, cac nhanh dudng h im (hinh II 1) Tai nhung noi khong the thuc hien duoc d iy du khdi luong khoan tham do hoac viec m d nhung hd dao phu, do mot nguyen nhan nao dd (mat do xay dung cao, mang ludi ky thuat n g im day dac, cudng do giao thdng tren pho ldn) khong the thuc hien duoc hoac khong kinh te, thi cong tac khoan duoc sir dung ket hop vdi phuong phap tham dd dia vat ly Phuong phap nay dua tren

viec nghien curu cau tao khoi dat, tmh chat ldp dat va che do nude ngam mot each gian tiep Trong do, ngudi ta do cac dac tfnh vat ly khac nhau cua dat (dien trd khang, tdc do truyen song hoac song sieu am, do truyen nhiet v.v ), tren co sd do co the ly giai cac dac tinh dia chat cong trinh: do chat, do ben, do r6ng v v

/ / / S'S • * .

H inh I I.l Khu vuc tham dd tren tuyen dudng ham dang xay difng

1.16 dung; 2 lo nSm ngang; 3 chu tuyen h^m; 4 16 khoan tham do n im ngang;

5 16 khoan tham do dirng; 6 chu tuyen dudng ham nghieng; 7 h 6 dao; 8 nhanh M m

Su dung dien tham ket hop vdi do xa khf dua tren co sd tang luong khf duoc tao ra khi pha vd nguyen to Radi trong khoi dat Ngoai phuong phap do dia ky thuat thuc hien tren mat dat, ngudi ta con dung phuong phap “Carota” kha rong rai - do la to hop cac phuong phap dia vat ly nghien ciru dat bang cach do cac dac tfnh cua chung true tiep trong cac 16 khoan

Ton tai nhidu loai Carota: tu trudng, dien, khf, phat xa, dia chan, sieu am v.v Trong

do ngudi ta ha cac thiet bi chuyen dung vao 16 khoan de do tfnh chat dan dien va tu trudng cua dat, thanh phan hoa hoc cua chung, do phat x a Cac m ay quay truyen hinh nho dua tren co sd song sieu am duoc ha xudng 16 khoan va truyen hinh anh len man hinh dat tren mat dat

U u the co ban ciia phuong phap dia vat ly tham do dia chat cong trinh la d ch6, no co kha nang nghien ciru viing rong ldn ciia nen dat, trong khi do khoan tham do chi cho phep nhan duoc sd lieu timg didm Nhuoc diem ciia cac phuong phap tham do dia vat ly

la kho diSn giai ket qua nhan duoc Do do cac phuong phap dia vat ly nen sir dung ket hop vdi cac phuong phap tham do truyen thdng

De chfnh xac hoa cac dieu kien dia chat tren tuyen cong trinh ngam, ngudi ta sir dung phuong phap xuyen tinh va dong, tien hanh chu yeu d da't rdi, ft am va kho, khi xuyen co kha nang xac dinh sue chiu tai tinh va dong cua da't, lam ro chieu sau ldp da va dat honldn, xac dinh duoc do chat va modun bien dang cua dat cat Khi xuyen tinh, ngudi taddng dau con tieu chuan hinh non hoac mot thanh don vao da't, chieu sau ngap vao dat duoc ghi lai tu dong Con khi xuyen dong, ngudi ta do sire khang cua dat bang cach dung bua co d iu hinh chop non dong vao dat

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Khi tham do dia ky thuat, ngudi ta cung nghien cuu trang thai cac cong trinh xay dung trong vung du kien xay dung mdi Khi ghi chep cac bien dang cua nha, mong cua chung cung nhu ndn dat, cung can xac dinh nguyen nhan cua cac bien dang do va d in h gia hieu qua cac bien phap bao ve.

Tat ca cac so lieu nhan duoc qua dieu tra, do ve ty le ldn va tham dd dia kv thuat duoc xu ly trong phong Trong phong thi nghiem ngudi ta nghien cuu tmh chat cua dat

va nude ngam, phan tfch thanh phan co hoc, hoa hoc, thach hoc, xac dinh cac chi tieu tfnh toan cua tinh chat co ly, tfnh chat hoa ly, tfnh chat nude ngam v v

Trong trudng hop can thiet, de du doan sir tac dong tuong hd cua ket cau ngam vdi dat, ngudi ta nghien cuu thuc nghiem d giai doan khao sat dia chat cdng trinh

§4 KHAO SAT DIA HINH CONG TRINH VA CONG TAC TRAC DIA HAM MO

Khao sat dja hinh cong trinh Xay dung cdng trinh ngam dd thj thuc te khdng the

duoc neu thieu do ve dja hinh Cdng tac trik dja cho phep dua do an thiet ke vao thuc dja, dieu chinh vj tri va cac kfch thudc cua nd Cdng tac trik dja duoc thuc hien tren tat

ca cac giai doan xay dung cdng trinh ngam: trong qua trinh khao sat cdng trinh, thiet ke

va xay dung, ke ca trong qua trinh khai thac Chung bao gom mot td hop do dac va xay dirng dja hinh Phuong phap va ky thuat thuc hien chung duoc xac djnh tuong ung vdi dang cdng trinh ngam, tfnh dac biet cua nd, so dd quy hoach khdng gian, cac bien phap thi cdng cung nhu dieu kien xay dung va quy hoach cua vung dd thj dd

Tien hanh do dac trong dieu kien dd thj kha phuc tap do chidu dai cac canh ludi khdng che dja hinh ngan hon so vdi khu vuc ngoai do thj dSn den sai sd do dac tang Ngoai ra, viec bd trf cac cot moc cua ludi trik; dja, phan thi tren noc nha, phan thi trdn mat dat va ddi khi sir di lai cua cac phuong tien giao thdng va ngudi di bo vdi cudng do cao cung anh hudng den ket qua do dac

Noi dung khao sat dja hinh thuc h,en trudc khi xay dung cdng trinh ngam bao gom:

- Do ve ban do dja hinh

- Tao cac moc khdng che' do cao, mat bang

- Thiet ke' tuyen va dua true cdng trinh vao thuc dja

De xay dirng cac moc trac dja tren mat dat va thiet ke tuye'n cdng trinh ngam can cd ban do dja hinh hoac mat bang khu vuc dd thj tao dung tren co sd do ve ban do dja hinh.Ban do dja hinh duoc thuc hien bang phuong phap trac dja cdng trinh Trong cac vung dd thj cd dja hinh on djnh vdi mat do xay dung khdng cao va khi dien tfch khao sat ldn, ngudi ta su dung trac dja hang khdng Su dung cac phuong phap trac dja hang khdng anh ndi chu tuyen - lien hop, lap duoc cac ban do theo ty le 1:10000, 1:5000 hoac 1: 2000 Trong trudng hop neu vi mot ly do nao dd khdng thuc hien trac dja hang khdng duoc, ngudi ta sir dung binh do, thanh lap ban dd dja diem vdi ty le 1:10000-f 1:1000

Khi khao sat khu dat nho, mat do xay dung cao cung nhu dieu kien thuy van phirc tap, tot nhat sir dung phep do toan dac, ket qua do duoc sir dung lap ban do dia diSm ty

le I :5000h- 1 :1000 Tren nhung khu vuc do thi co dia hinh phuc tap thudng dimg phuong phap chup anh noi va lap ban do ty le 1:10000^-1000 Trong nhi6u trudng hop tren nhung doan co mat do xay dung cao, ngudi ta do dac dia hinh b in g may kinh vi va thuy chuan va lap ban do ty le 1:2000 -M000 Co the ket hop cac phuong phap neu tren de do dia hinh

Trong ket qua do c in cd mat bing cac pho, dudng oto, cac khu d it cd nha dan, cac diem cay xanh cung nhu cac d iu hieu ciia cac da giac va tam giac khong che De lap thiet ke ky thuat xay dimg cong trinh ngim ngudi ta do ve b in d6 ty le 1:2000, 1:1000

va 1:500 va de lap ban ve thi cong do ve ban do ty le 1:500

De thiet ke c in co ban do dia hinh co g in mang ludi cdng trinh va ky thuat hien cd

va dang thiet ke theo ty le 1:500 va 1:200, cac mat c it cua chung (theo khoang cach

20 -r 40m) hoac tai nhung die’m dac biet

Ban dd mang ludi ky thuat n gim duoc tien hanh nhd su dung cac gieng dao cung nhu bing c ic h khai quat De phat hien c ic cap dong luc va cap dien thoai, dudng dng

d in nirdc, dudng dng d in khi, mang ludi cap nhiet v v sir dung thiet bi do cam ung cap

va xac dinh tuyen

Thdi gian g in day, cac ban do dia hinh khu vuc dd thi duoc thuc hien dudi dang goi

la mo hinh sd ciia dia diem Cac sd lieu co ban duoc luu trong may tinh dien tir co the duoc trinh bay rat nhanh theo dang giai tich hoac dang binh dd va duoc sir dung cho cac giai doan khac nhau ciia cdng tac dia hinh Theo md hinh sd cd the xac dinh duoc phuong phap hop ly tien hanh cdng tac do dac dia hinh h im md, danh gia muc do chinh

x ic c^n thiet va do tin cay ciia ket qua do dac dia hinh

Khi thiet ke cong trinh ngim , bd tri tai khu vuc dd thi da duoc auy hoach, ban do dia hinh vi tri doi khi khong thuc hien ma sir dung b in dd cd sin da do khi xay dimg cac cdng '.rinh trudc do Trong ban d6 do c in cd cac cong trinh, cac co sd da duoc dimg len sau kni do dac va tat ca cac su thay doi khac Co mat b in g vi tri, c in tien hanh tao lap cac d em moc trie dia khong che mat b in g va do cao viing xay dung cdng trinh ngim Cac n o c ndi la he thdng cac diem do dac dua tren c ic d iu hieu ciia ludi quoc gia hien tai

Phj thuoc vao dang, kich thudc cdng trinh ngim , trong mat b in g goc ngudi ta xay dung iudi tam giac, da giac tren mat dat, ludi giai tich v v

Khi xay dimg cong trinh ngim dai ngudi ta bd tri ludi tam giac dang he thdng cac tam £iac cd cac canh g in bing nhau (goc khong nho hon 40°) dua vao ludi co bin (hinh II.2) Cu 4 goc tao lap duoc 2 tam giac c in co 2 dudng cheo, bd tri cach deu qua it nhat f) tam giic Dang ludi tam giac duoc xac dinh b in g hinh dang tuyen cong trinh

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ngam Su sap xep rdi rac he tam giac phu thuoc vao chieu dai quy udc cua cdng trinh Ludi tam giac duoc bd tri bang cac thiet bi thdng thudng do dac tren mat dat (may kinh vi) vdi 2 lan lap lai cua ludi tam giac va do kiem tra chieu dai c a sd va goc trong cac tam giac dia hinh ket hop lan luat tmh chieu dai cua cac canh Cac diem moc cua tam giac dugc cd dinh tai dia diem bang cac moc trac dia chac chan, khi bd tri cd xet den cua chinh cua dudng ham, cac doan thang dung, cac hanh lang san, cac ldi vao loi ra vdi muc dich bao dam nhin thay khi dinh hudng dao hao ngam Tat ca cac dau hieu can dat ngoai gidi han khu vuc bien dang kha di cua mat dat do qua trinh xay cdng trinh ngam

dd gay nen

Ky hieu

A - Cac moc tam giac

O - Cac moc ca ban cua da giac

• - Cac moc phu cua da giac

Hinh II.2 So do co so do dac mat bang theo tuyen ham

1 p h in km cua dirdng h im ; 2 ca c san hanh lang; 3 cac 16 dung.

Trong nhidu trudng hgp, de quy hoach cong trinh ndi (dac biet tai nhung vung mat do cdng trinh da xay dung cao) ngudi ta su dung dudng da giac lap tu ludi da giac kin hoac

tu tung budc rieng biet ndi giua cac didm tam giac khdng che Ludi da giac bao gom cac budc da giac chinh cd chieu dai 3-^5 km Cac budc trung gian dai 0,4n-0,8km Ludi chia

co ban cd chieu dai 0,2-rO,3 km va cac budc do 5+ 100m

Lien ket cac diem tam giac tien hanh theo khoang cach ft nhat 3km Dinh cua cac da giac dugc dua ra khoi cac dau hieu cua ludi quoc gia va dugc gia cd chac chan nhu cac dau hieu ludi tam giac Chieu dai cac canh cua da giac va cac goc giua chung dugc xac dinh Trong mot so trudng hgp de tao lap ca sd mat bang tren mat dat, ngudi ta sir dung

td hgp tam giac va da giac

Khi xay dung cong trinh ngim co kich thuoc tren mat b in g khong ldn, ludi co sd tren mat dat duoc thuc hien theo dang ludi giai tfch hinh vuong hoac hinh chii nhat vdi canh

50, 100 hoac 200m, dua tren ludi tam giac khong che C ic diem cua ludi nhu vay duoc

bd tri tren mat d it g in c ic chi tiet cdng trinh ngam tren thuc dia tdi mure cd the Trong

do, dirge su dung he toa do rieng

Trong he toa do do ngudi ta dinh vi vi tri cac d iu hieu va cac goc dinh hudng, cac canh cua ludi hinh chii nhat Ngoai cac dang ludi co sd mat d it neu tren, trong m ot sd trudng hgp rieng biet thudng su dung ludi chia nhd, phuong p h ip c it ludi dia hinh v v Tao lap co sd ludi cao do tren mat d it chu yeu bing phuong p h ip thuy ch u in dia hinh C ic budc thuy ch u in tao ra ludi da g iic kfn cd su lien he vdi cac moc va c ic d iu hieu thuy chuan do thi

Cac moc cao do va mat b in g da xay dimg va g in tren m at d it dugc chuyen sang mat

b ing vi tri Sau dd, chia true chfnh va phu cua cdng trinh n g im tren mat b in g , tfnh toan tit ca cac dac tfnh hinh hgc c in thiet va tien hanh lien ket true vdi cac dau hieu co sd tren mat d it va vdi cac diem dac trung tren m at bing Ngoai ra, c in x ic dinh cac toa do true timg p h in cua cdng trinh ngim : cot, m ong, tudng, mai v v Theo mat b in g nhu vay, ngudi ta dua cac true cdng trinh ngim vao thuc te

Cong tac phan ludi theo true cua cdng trinh ngam de dua vao thuc dia dugc tien hanh tir cic moc tren mat dat ciing vdi viec g in chat cac hudng tuyen va cac diem cao do bing

ky hieu cd dinh hoac tam thdi De chuyen toa do va cac goc dinh hudng tir c ic diem moc tren mat d it xudng c ic ld dung, hd dao nghieng, mat b in g xay dimg v v ngudi ta

bd sung them cac budc don le chieu dai khong ldn hoac c ic da giac khep kfn theo budc ludi da giac tua tren ft nhat 2 d iu hieu cua da giac chfnh

Trrdc khi xay dimg cong trinh n gim c in phai tfnh toan so bo do chfnh xac hgp ly cua phep Jo trie dia theo dgc tuyen cong trinh n g im Do tat ca do dac trie dia dugc thuc hien '6i sai so nao dd d in den su tfch tu sai lech, gia tri nay khong dugc vugt q u i tieu chuir cho phep Tfnh toan so bo do chfnh xac yeu c iu cua phep do, cho kha nang lira chgn ohuong phap trie dia va lira chgn thiet bi, dung cu do dac tuong ling

Ceng tac trie dja ham mo Trong qua trinh xay dimg cdng trinh ngim c in dinh hudng

no tuong ddi vdi moc tren mat dit, tao lap c ic moc do dac ngim va phan chia tat ca c ic chi tiet ket c iu tren mat bing va mat c it cung nhu kiem tra thudng xuyen vi tri c ic diem moc chfnh va cac true da chia ciia cdng trinh Ngoai ra, cin phai thuc hien viec ghi chep qua trinh xay dmg, tfnh toan khdi lugng lam d it va vat lieu dung trong xay dimg cung nhu kiem soat

vi tri cac chi tiet cua cong trinh ngim luong ung vdi do an thiet ke

Su dinh hudng cac cong trinh n g im dugc tien h in h bing nhieu each khac nhau phu thuoc vao phuong phap xay dimg Vf du, khi xay dimg cdng trinh n g im b in g phuong phap iao lo thien va ha gieng, cung nhu khi m d h im n g in va th in g tren mat b in g tu

35

hudng cua chfnh b ln g phuong phap dao kfn, su chuyen hudng va mdc cao do duoc thuc hien b ln g cach true tiep keo dai cac budc di tren mat dat N eu cac phan viec n g im duoc thuc hien bang phuong phap kfn qua cac gieng dung hoac cac ham nghieng thi viec dinh hudng dao c in thuc hien cac thao tac trie dia dac biet va tien hanh qua 1 gieng dung, 2 gieng, 1 gieng va 1 Id khoan, ham dao n im ngang hoac nghieng.

De chuyen goc dinh hudng va toa do cac didm, ngudi ta sir dung cac phuong phap dinh hudng khac nhau, phu thuoc vao dang h im lo phu va chidu slu dat cong trinh ngim Dinh hudng h im lo n g im qua 1 gieng dung phan ldn bang phuong phap tuyen dinh hudng 2 qua doi hoac tam giac lien ket Mac du cd m ot sd diem khac nhau, ca hai phuong phap nay deu dua tren nguyen ly tuong tu nhau ket hop sir dung cac qua doi ha vao gieng dumg

Hinh II.3 Dinh huang dao ham ngam theo phuong phap tuyen dinh hudng qua dpi

a) va chuyen mdc cao do (8, b) qua gieng dung

I m ay kinh v i ; 2 da'u hieu trac dia; 3 tdi; 4 m ay d ong co c ; 5 k y hieu tha'y d u oc ;

6 g ien g dirng; 7 M m dao; 8 qua doi; 9 thung chura d iu md; 10 tai trong;

I I m ay thuy chudn; 12 thudc ngam ; 13 noi gan thudc; 14 thudc thep bang;

15 thi&'t bi do chi6u dai

Trong phuong phap (Mu tien cac qua doi duoc bd trf trong tuyen dinh hudng bang may kinh vi gan theo hudng tuong ung vdi hudng cua ham dao Sau dd ngudi ta bd trf may kinh vi trong tuyen dinh hudng cua cac qua doi dudi dat va theo true dudng M m dao gan nd bang cac dau hieu trac dia md I va II (hinh II.3a).

De chuydn toa do vao ham ngam, ngudi ta do khoang cach giua cac qua dpi, khoang cach tir may kinh vi den qua doi gan nhat tren mat dat cung nhu khoang cach tu mot trong nhung qua doi den dau hieu trac dia ham lo va giua cac dau hieu trong dudng dao ngam.Phuong phap tuyen dinh hudng 2 qua doi can su dung khi guong ham cach gieng dung khdng ldn hon 50m Trong dd sai sd binh phuong trung binh du tfnh nam trong khoang ± 3 0 ” Tang do chfnh xac dinh hudng cd the dat dupe bang cach xet bien do dao dong cua cac qua doi, gia tri cua nd dupe do bang may kinh vi tren thudc do Trong phuong phap cac tam giac lien ket ngay canh qua dpi (khdng phai d trong tuyen dinh hudng) ngudi ta dat 2 may kinh vi: mot tren mat dat, con cai thu 2 trong ham ngam canh gieng dung bang may kinh vi thu nhat ngudi ta do goc giua hudng tdi cac qua dpi va goc lidn kd cung nhu khoang cach giua cac qua dpi va khoang cach til true may kinh vi tdi tung qua dpi Trong tam giac dupe tao thanh nhu vay ngudi ta tfnh dupe gia tri goc sau

dd xac dinh goc dan hudng cho tuyen di qua mat phang tuyen djnh hudng qua dpi Sir do dac va tfnh toan tuong tu dupe thuc hien trong ham dao ngam, nhan goc dan hudng cua mat phang qua dpi lam goc xuat phat Nhd may kinh vi, ngudi ta dua toa do cac ky hieu gan trong ham dao ngam ra va tfnh dupe goc dSn hudng cua tuyen gieng dung Sau dd dua vao ludi da giac ngzim

Cac moc cao do dupe chuyen vao ham dao qua cac gieng dung hoac qua cac Id khoan nhd may thuy chuan lap trdn mat dat va dudi ham dao, nhd thudc bang thep - qua dpi va thudc ngam (hinh II.3S)

Diem cao do cua thudc do (Ho) dat trong ham lo ngam cd the xac dinh tu bieu thirc sau:

Ho = Hi + h | - h2 - [(d) - <\{) + A/ + Am] (II 1)

CJ day: H , - d o cao cua di&n b£ mat thudc ngam ; h^ h2 - s6 d oc trdn thudc tren mat da't va dudi

M m ngam , mm; d ,, d2 - sd d oc tren thudc thep trdn m at da't va trong ham ngam ; A/ - lu on g dieu chinh trdn thudc thep, mm; Am - luong didu chinh do dan dai bang, m m

Trong mot so trudng hop de chuydn cao do qua gieng dung, ngudi ta sir dung thiet bi do chidu dai tu dong J\k-2 dam bao do chfnh xac do dac trong gidi han 1:15.0004-1:25.000 (hinh II.3b)

De’ dinh hudng dao ham ngam, ngoai nhung phuong phap hinh hoc da xet, ngudi ta con sir dung cac phuong phap vat ly: thiet bi hdi chuyen, tir trudng, thau kfnh, ddng anh sang, xung dien tu dong v.v Ban chat va cac phuong phap sir dung chung dupe neu trong cac tai lieu chuydn nganh (Lebedev H.H Chuong trinh dia ky thuat M.Hegpa 1974)

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Phucfng phap thiet bi hoi chuyen dinh hudng duoc dung pho bien nhat, no dua vao thiet bi chuyen dung la may kinh vi hoi chuyen co vat treo thuoc bo phan cam ling vdi bo ep thu cdng hoac tu dong FM- BI, TH- B2 v.v Phan chinh ciia thiet bi dd la con quay M-2, M-3, MF-1 va MB-1 cho phep xac dinh hudng kinh tuyen vdi do chinh xac 35-h45".

Phuong phap dinh hudng hdi chuyen cho kha nang xac dinh goc phuong vi hudng bat

ky true tiep trong ham ngam khong can chuyen goc dan hudng tu m at dat qua gieng dung hoac Id khoan Trong dd do chinh xac dinh hudng khoang 1,5 lan cao hon so vdi phuong phap tam giac lien ket, sai so binh phuong trung binh la ± 8 ”

Sau khi dinh hudng ham ngam, ngudi ta thuc hien toan bo cdng tac do dac ham ld, bao gom tao lap ludi trac dia co sd n glm , phan chia chu tuyen cdng trinh ngam, dam bao

ld ndi di thang tdi h^m dao, lam cac ludi chan doc tuyen, di chuyen cac may moc v v Trong phuong phap kin xay dung cdng trinh nglm , co sd do dac m at bang la da giac ngam, no xac djnh vi tri cua cac diem tru dudi dat trong he toa do m at dat So vdi tren mat dat, nguyen ly do dac ngam co nhieu diem dac biet Trudc tien hinh dang cua la giac ngam la cudng biic va hoan toan duoc xac dinh bang mat bang cua cdng trinh ngam Trong mdi lien he dd, ldi di qua h£m ngam thudng duoc d in bang guong 16 kho, cac budc cua da giac ngam duoc lap dat treo Dieu dd khong cho phep kha nang xac dinh su ket ndi va danh gia do chinh xac cua cdng tac trac dia trudc khi thuc hien

Da giac ngam duoc dat theo budc cd chieu dai khac nhau va ket ndi vdi ludi trac dia tren mat dat qua cua chinh, gieng dung, ld ndi via va cac ham dao phu khac Da giac ngam duoc chia ra cac loai tiep can, lam viec, co ban va cac tien trinh do da giac chinh (hinh II.4)

Z i ' //.' '// /// / " /// /// /// /// / / / /// /// /// ///

7/ //.

A i f " »

p-7/y /77~7,

1 dudng h im ; 2 tuyen cua da gidc;

3 da giac lam viec; 4 da g ia c chfnh;

5 gien g dung; 6 dudng h^m dao;

De chuyen hudng tir ham dao tiep can sang tuyen ngam ngudi ta do da giac tiep can vdi chieu dai budc 10-50m Khi chieu dai cac via

“kho” nhd hon 1km, ngudi ta dat cac budc cua da giac lam viec va da giac cO ban Da giac lam viec duoc bd tri trong dang day chuyen tdi cac tam giac canh 25 * 50m va dung de chia true va cac chi tiet ke't cau

Da giac co ban duoc dat theo cac diem lam viec (cach 1) vdi chieu dai budc 50n-100m, muc dich de kiem tra do chinh xac cua da giac lam viec Khi chieu dai cac doan vuot hon 1km, cac budc da giac chinh duoc bd sung vdi chieu dai 150n-800m theo