Nghien CLPU anh hirang cua qua trinh xay dipng du'dng ham metro den bien dang mat dat l^hu vu'c thanh pho Ho Chi Minh
Study of influence of building metro constructions on surface settlement in Ho Chi Minh city
Ngay nhan bai: 24/01/2015 Ngay siTa bai: 15/3/2015 Ngay chap nhan d^ng: 25/04/2015 TOMTAT
Liin sut va bien d^ng be mat la van de quan tam hang dau trong qua trinh thi cfing dircmg ham m^tro, d^c biet la trong vimg dat yeu. Bai bao n^y dua ra phuong phap tinh toan biSn dang liin mat dat, xic dinh be rpng vung bien d^ng liin v^ tuang quan giita chifiu sau dat ham v6i bien d^ng liin hi mat khi thi cong duong ham metro, Ap dung cho duong h§m xay dung trong dieu ki^n dia chat khu virc Tp, Ho Chi Minh.
Tir kh6a: ducmg ham metro, liin hi mat, mit mat thi tich.
ABSTRACT
Building shallow underground constructions in weak land makes subsidence. This paper introduces some methods predicting surface settlement, defining settlement area and the relation between depth and settlement when building tunnel, being applied to build tunnel in geology condition of Ho Chi Minh City.
Keywords: metro tunnel, surface settlement, ground loss.
PGS.TS. V5 Phin
Chu nhi^m Bo mon Dia co nen mong Khoa Ky thuat xay dung, Truong Dai hpc Bach Khoa - Dai hpc Quoc Gia Tp.HCM.
Email: vophan54(gyahoo com.
Dien thoai: 0913.86.70.08.
ThS.NCS. Nguyen Quang Khai
Nghien ciru smh, Khoa Dia kJ thuat Xay dung, Vien Khoa hpc Thiiy lpi Mien Nam.
Email: nqkhai83(ggmail.com.
Dien thoai: 0989.88.12 18.
yd Phan, Nguyen Quang Khai
1. Dat van de
Viec xay dUng cac he thong cong trinh du6ng ham giao thong trong long dat la mot trong nhdng giSi phap tdi Uu di sil dung dat do thi cd hi^u qua cao He thong cdng trinh du'dng ham rat cln thiet cho mdt thinh pho hien dai de gi3i quyet nhiing van de biJc xOc hien nay trong dd thi, khdng nhung d^m bcio canh quan con tiet kiem dUOc khong glan tren mat dat, Vdi Uu diem vu'Ot troi khi thi cdng du'dng ham b3ng may TBM fTunnelling Boring Machine) khdng Snh hu'dng d^n giao thdng va cdng trinh tren mat dat, khi xuyen qua song se khdng dnh hu'dng den giao thong thuy. Tuy nhien trong khi xay dung hoac sau mdt thdi gian ton tai cua c^c cong trinh dUdng ham trong Idng dat da gay ra hien tuong be mat dat bi lun lam inh hUdng rat Idn den cac cdng trinh hien hu'u tren mat dat
Khi thi cdng dUcmg ham b^ng phuong phap TBM, dien tich dao dSt luon Idn hon dien tfch mat c^t ngang ham, dii dUOc bOm vii'a lap sau vd ham nhi/ng khong the tranh khdi su phan bo lai ung suat va bien dang trong nen dit nhU 1^ k^t quci tat yeu cua qua trinh xay dUng ham, Bai bao nay dua ra phuong phap tinh toan bien dang lun mat dat, xac djnh be rong vCing bien dang lun va tu'Ong quan giija chieu s3u dat ham vdi bien dang liin be mat khi thi cdng dudng ham metro d khu vUc thanh phd Hd Chi Mmh.
2. Phuong ph^p tinh toan bien dang liln ciJa dat nen do thi cong difimg ham metro
2.1. PhUtmg phdp gidi tich
Mdt vhi tac gia phSt tnen phuong phap gi^i ti'ch, ngo^i suy tir cac cdng thilc ban kinh nghiem va kit hop tat c5 cac yeu td d^ tdng quat hda cdng thiJctinh toan bien dang mat dat:
Verruijt va Booker (1996) trinh bay mdt phuong phap phan tfch cho du'dng ham trong khdng gian nO'a dan hdi ddng nhat, sir dung phuong phap gan diJng theo de nghi ciia Sagaseta {1987).
Cdng thu'c duoc du'a ra bdi Verruijt va Booker la su tong quat cua phuong phap Sagaseta trong do:
- Cdng thu'c tfnh bien dang be mat cho trudng hop dat khdng nen duoc va cd hf s6 Poisson bat ky.
- Bao gdm anh hudng ciia ovalisation (dudng ham md hinh oval) trong thdi gian dai,
Cdng thu'c tinh ciia Verruijt va Booker tinh toan bien dang thing dUngva bien dang ben nhif sau:
I'I '2) [ <l <2 } (1)
Z,(n^-k2f) x{K^-fczi)']
'. "i ^ J V ' i ••? - ' > " ^ '
" ^"2 '2 J f " * ' [ r * '2 J
Trong d d c h f sd mat mat hucmg tam deu; & biin dang mat dat dai han do ovalizalion ciia dudng ham; z< = z-H; b = x+H; r,' - x'-tzi'; ri = jf'+z^; fi va h: B i n kfnh vi chieu sau dat ham; m = l(l-2v);m = v /(I -v); V he sd Poisson.
Lo va Rowe (1982) va Rowe et al (1983) da gidi thieu yeu t d khoang hd giiy ra mat mat the tfch cd quan he cUcmg dp va bien dang u'ng xiJT trang thai dan hdi va d§o, la khoSng trdng vat ly giCra du'dng kinh 16 dao va vd ham.
KhoSng trdng n&y duoc di^u chinh bdi Lee et al (1992) n h u sau-
G = G. + ujD*+ia (3) Trong d d Gf. khoSng h d vat ly (Gf=2A + 5): A: chieu day dudi may
dho; 6: khoSng hd bSt budc de ISp dat vo h a m ; USD' : bien dang dan hoi d4o tuong duong tai mat guong dao.
Trong d d k, h f sd sUc khang cSt ciia dat {k = 0,7 -^ 0,9 ddi ven dat set Cling d i n dSt sit mim; k = 1 ddi vdi dSt set yeu); &,: dat xam nhap tai g u o n g dtio.
B , = i ^ (5) Trong dd fl: h f sd c h u y i n vj khdng thU nguyen; R: ban kfnh dUdng
h S m ; f : Modun Young
Po = Ko' P^' + P„-Pi (6) Trong dd Ka': hi s6 Sp luc c6 hieu cua dat tai be mat gUOng d trang
thSi nghl; P „ ' : iing sueit cd hieu t h i n g dilng tai bien ham; P«r; ap luc n u d c l 6 r 6 n g tai b i i n hSm;Pi:SplUccSn b S n g m a t g U o n g d a o ; £ o . g i a tri tiiy thudc vho tay n g h l va cdng nghe thi cdng ham.
Lo et al. (1990) dUa ra bieu thilc xSc djnh chuyen vi tren mat phang d S n h d i d l o c i i a bien h i m UinhUsau'
Gia tr] Min {0,6Gp; 1/3U,) duoc chgn lam gia trj ciia (u'(Lee et al, 1992).
Gia tri ciia a bao gdm ca miit mat hUdng tSm do bSnh c^t.
- Tn/dng hop khdng cd banh cSt:
(0 = 0)'
-TrUdng hop banh cat m d r d n g goc 180°:
ea = a'+ do ddy bdnh edt.
- TrUdng hOp banh c3t p h i i het d u d n g tron:
fi) = ft»V 2xdd ddy bdnh cdt.
Loganathan va Poulos (1998) sifa d6i huong phSp cua Veruijt vS Booker bang each ket hop d i l u kien b i l n thUc te khdi chuyen djch, nhu the h i f n trong hinh 2.1. Mdt hlnh bau due da dugc gidi t h i f u tren dinh dudng ham vi mat mat the tfch xSy ra d cSc giai doan khSc nhau trong qua trinh dao ham.
DUa tren khoang h d hinh bau due hlnh thdnh xung quanh dudng ham, ngufli ta uflc tinh r i n g k h o i n g 75% chuyen ddng mSt d^t dpc xiy ra. Hinh 3 cho thay khu vUc anh hUdng cua khdi chuyen djch thSng difng. Trong dat cat, gdc gidi han, p dUoc djnh nghia la {45 ° + (p/2), trong do tp = goc ma sat trong cOa d i t cat.
Doi vfli dat set mem den cUng, P c6 the dUOc g i l dinh IS 45° dUa tren quan sat ciia Cording va Hansmire (1975), Nghia la, nd dUi^c gil djnh rang dat c h u y i n djch xay ra chO yeu trong gdc (45° + <p/2) giiia mat d i t va duflng h i m . Lfflc tfnh r i n g do Ifln ciia c h u y i n djch ngang IS khoang mdt nifa ciia chuyen ddng t h i n g difng tr&n dinh dUdng him (gay ra 75 % ciia sU chuyen ddng mat dat vao vdng trdn t r l n cOa khoang each hinh oval xung quanh d u d n g ham).
Kinh 1. Cac yeu to cua bien dang be mat vh dudng bien cua khoi chuyen dich Trong do R: ban kinh duflng h i m ; E„: mcxJun Young khong thoat nudc; Cl, : sijfc khang c i t khdng thoat nUflc cOa d i t ; v^ : he so Poisson khdng thoSt nUdc; W; he sd dn ^ n h .
Hinh 2 Bien dang theo phuong thJng diing va phuong ngang khi dao ham ,, ,-.= ""I'-'i .J '•»'•' i
-««=
+(z-H)' x^H2*H^ {x^+(z + H)^)^
[ [(Hcotgp+fi)= H^ JJ
Trong do Uz^o: c h u y i n vi t h i n g dUng tai be mat d i t ; Uy chuyen v|
t h i n g dUng tai do sau r, U/. chuyen vi ngang; ft: d u d n g kinh d u d n g hSm;
z: do sau tinh toan tinh tif b l mat dat; H' d d sau dat h i m ; i^ h f sd Poisson; f^: mat mat the tfch t n j n g binh, x: khoSng cSch ngang Knh til t i m dudng h i m ; fi =(45'+ (p/2}: gde gidl han v i i n g c h u y i n dich cua d i t .
B i n q 1. Conq thUc xSc dinh t h a m sd be rdnq Tin tic qid
Peck (1969)
Atkinson &
Potts (1979)
*t s
Mair(1993)
Attewell (1977)
C l o u g h &
Schmidt (1981)
Cdng thijrc t i n h 1 l = f . ^ l " n=0,8-i-1,0 R U R J
( - 0,25(Zo + R) ddi vfli dat c i t rfli.
/•=0.25(Zg + R) ddi vdi dat cat chat va dat s i t q u i eo ket 1 = 0,43Zo + 11 ddi vdi dat cd k i t ,
i = 0,28Zo-0,l ddi vfli d i t khdnq cd k^t.
i = 0.5Zi,
a=l vdn =1
R U B J o = J v d n = 0,8
i Ghi chi^
Dua tren sd lieu quan t r i e thUcte.
Dua t r ^ n s d lieu quan t r i e t h U c t e v a k i t quS thf nghiem m d hinh.
DUa t r f n sfl l i f u quan t r i e thuc te d u f l n g h a m tai Anh.
DUa tren sd lieu quan t r i e thuc t e v a t h l n q h i l m l y t a m DUa tren sd lieu quan t r i e thUc te d u f l n g h a m tai Anh DUa tren sd lieu q u a n t r S c t h U c t e duflng ham tai My
(tan 3)"' J S ['_H_'|(ianp)''"
URJ
(12)
Trong d d * : b l rflng viing bien dang liln be mat.
2.2. Phuang phdp tinh todn theo cdc cdng thUc bdn kinh nghiim Schmidt-Peck da tdng h o p s d l i e u t U 2 0 d u S n ham t r U d c d d va t h i y r i n g d u d n g cong liin x l p xl theo 1 dUdng cong'
s-s^
(13)Hinh 3. Mo hmh Gaussian tfnh liin be mat khi thi cdng ham cua O'Reilly va New (1982) V6i d u d n g h i m dang tron xac djnh S™.theo edng thufc:
v/2^ VLD^
= 0.785,(T.ZO+PS). (Herzog,1985) 0 5 }
Trong d o Vi: phan tram t h i tich mat m i t so vdi dien tfch gUong d i o , D: duflng kfnh thitc qui doi ciia ham khi dao; a trong lUOng neng trung binh ciia cae Idp d i t tinh toan, Zo: chieu s l u eiia t i m ham so vdi mat d i t . Pi tdng tai trong c h i t them; E: m d d u n dan hoi trung binh ciia c l e Idp d i t tfnh toan.
3. A p d u n g t i n h t o l n lun b l m a t k h i xay d u n g d U ^ g h a m m i t r o & k h u vUc T h a n h p h d H d Chi M i n h
Xay dung dUflng ham cd dUdng kinh D = 7,8m, bSng phUdng phap TBM, trong dieu kien dia chat thu J van nhU sau
Bang 2. Thdng so d I u vao cho cac Idp dl't tai tuyen metro sd 1 d khu c Q 1 , TP.HCM
NhO'ng phUOng trinh n l y eho phep tfnh toan nhanh chdng ciia b i l n dang m a t dat va y ^ u c l u Uflc tinh g i l trj ciia h f sd Poisson (w) cua d i t . H I sd Poisson gian tiep t h ^ hien nhung dac diem eiia he sd ap lUc dat b i n (ko) gia tri eiia d i t . CSc g i l tri ciia ( M values duoc udc tfnh tU cac mdi quan h f duoc t h i h i l n trong phUOng trinh:
Mdi quan h i giu'a i/R vS H/2R theo phuong phSp phan tich dUOc t h i h i f n trong phuong t r i n h :
".tZ'^
\ 1 M . u i l i . a . ! , C .
1)1111)1 iniiip kho n i i i i p i m i i ! ! liiio lioa I k so i l m i i Jinia
M n d u n V o i r a E
S:"",'i
llVM'Poi'.M'El K.,„.,,
-T"
i ' ^
;;
r 1 L-Jl A
MC Dm 111 I'll
1 S l c - i 1 S k - '
L . T B
,s,;,„
|'^l•H:l•nlJl) l o p D M t \ l !;us
^A ':-l—^
^ , ^ — i A 11 V. 0 >
:ni 1
1 ^(•f'' IIMKIII
L o p t ( C i l e h j l )
MC OraiiifJ
19 r.
«'
0 '
^^-
0 1 FJini V]
k \ 111' L N j l l 111 dii\
mclii>
k N III-
3.1. Xdc dinh phgm vi dnh tiudng vimg bien dgng liin va tuang quan giifa chieu sdu dgt hdm vd biin dgng lun be mat khi thi cong duimg hdm metro
Vdi sd lieu dia chat n h u b l n g tren, s i i d u n g ehUong trinh Plaxis tinh toSn chuyen vi liin be mat, ndi lUc phat sinh trong ham va dat nen ilng vdi c l e c h i l u sau ehdn ham khSc nhau dao ddng tir 10 -§• 40m. Od co ngdt duoc tinh bang % la tl sd ciia phan dien tich g i l m so vfli d i f n tich t i l t dien ngang ban dau va lay tl sd nay la 2%. Tren CO s6 n h i i n g nghien ciiu ve iing xU eiia ham trong dat va pham vi I n h huflng khi t h i cdng h i m , Idp dat phii tdi t h i l u t r l n ndc ham doc t u y i n tU 1.5D-2D, D la dudng kfnh vfl h i m .
Odi vdi tuyen metro sd 1 ed duflng ki'nh ham D = 7.8m nen y l u cau b l day Idp dat phu tdi t h i l u tU 11.7 -=• 15.6m. Vi v l y c h i l u sau dat h i m (tfnh t U t i m ham) nhfl n h i t t u 1 5 . 6 - 1 9 . S m .
Trong d f l S: bfen dang liin be mat; 5™.' b i l n dang lun Idn nhat t r l n d u f l n g t i m h i m , x k h o i n g cSch tU true h i m d i n d i l m t i n h liin theo phuong ngang; i: khoSng c i c h tCi true ham d i n d i l m udn ciia dutrng b i l n dang lun.
H'inh4 LifffiphantiihQuhancijab^itoan
Trong do: 0 : Tim dUdng ham, toa do (0,0) A- Oiem n i m tren be m i t phfa tren dinh ham. 6: Oiem n i m tai dinh phfa t r l n v 6 ham, phia ngoai v6 ham, toa do (0,-3.9). C: Biim n i m tai mep ngoai v f l h a m , ngang t a m duflng ham, toa dd (3,9,0). D- Oiem nam tai day v 6 ham, toa do (0,3.9).
1 0 9
BSng 3. BSng tdng hop k i t q u i pham vl anh hudng liin theo chieu sSu d i t ham
Chieu s l u (m) H = 10 H = 12 H = 15 H = 18 H = 20 H = 25 H = 30 H = 35 H = 40
B l rflng dUdng cong lun theo phuong ngang ham
(m) 33.1 31.05 26.73 23.84 22.5 21.37 20.98 20.13 19.72
B^ rdng dUdng cong lun theo phuong dgc h i m
(m) 41.08 3912 33,74 28 94 27,04 26 05 25,84 25,42 25 03 Bang 4 BSn
Chini ( m l
g tdng hop ket qua ehuyen ciia ham theo chieu s3u dat ham C h u v e n v i U , (ram)
A H ' l O - 0 < 0 J H - i ; 0 ^ 0 - H = 13 H = 1 4 H = 1S H = I 6 H = P H - 1 3 H - 1 9 H - 2 0 H - 2 2 H - 2 J H - 3 0 H - 3 S H - 4 0
B -0 049 O O ' J 0 2J1 0 111 0 IAS 0 6 1 1 -O0J4
•0 031 - 0 0 1 7 -0 011 -0 0 1 ! -0 007 -0 021
•0.004 0 127 0 1 2 ' 0 062 0 043 0 0 3 i -0 103 -0 16S -0 115 -0 0S9 -0 04S -0 023 c ' - 4 4 1
n 0 116
Chiiven \ A -74 0 1 ! 61 601 0 2 3 1 -53010 6 < 6 B 9 i 0 013 -49 505 67 021 0 1 - 6 , - 4 6 779 TO 131 73 021 74 035 79 519 83 691
56 316 32 156 23 167
0 139 0 104 -0 157 -0 475 -0 67S -0 466 -0 5B9 -0 923 -0 334
-39 277 -36 213 -34 177 -27 185 -26 722 -24 892 -21.834 -19 425 -17 831 B -125 B17 -114 TSS -111256 -108 459 -105 921 -103 407 -101 016 -98 743 -96 578 -95 478 -91 l O l -S9 235 -84 367
•81.932 -76 243 c -17 507
-9 892 -8.102 -7 126 -6 975 -3 152 -1.092 -0 013 1 113 1602 1 733 2 654 3 376 3S54 4 122 D
68.389 75 262 8 0 J 0 9 85 721 87 289 92.447 95.120 97.154 98.123 99.118 101.977 106 626 99 723 7S099 49 500
(nmi) -125 817 -117 753 -114 755 -111256 -108.459 -103.407 -101.016 -98 743 -96 578 -95 478 -91 101 -89 235 -84 367 -81.932 -7S 243
Hinh S M6 hinh bai toan ham doi theo phuong ng^ng 3.2. Liin b4 mat khi xay dung hdm ddi
Bi giSi quyet b i i toan tren, gia sir mdt duflng ham dfli dUOc xay dung d c h i l u s l u dat ham hgp ly vdi dia chat khu virc TP. Ho Chi Minh la 15 -^ 20m, chon c h i l u s l u dat h i m la 20m. Md hinh bai toSn trong Plaxis b i n g each xay dung 2 duflng ham ddi song song theo 2 phuong ngang va dUng vfli c i c khoSng eSch t i m ham khae nhau. Bai t o l n ciing xet den vile mat mSt t h i tich (contraction) khi xhy dung tUng dudng ham va lay t i sd nay la 2% (trudng hdp x l y dUng dUdng ham b i n g may d i o t d hop TBM c l n b i n g ap lUc dat b i n g viia set bentonite).
3.2.1. Bdi todn hSm ddt ndm ngang
Tren co sd nhUng nghien cuU ve ifng xil ciia ham trong dat va pham VI anh hudng khi thi cong ham, ngUdi ta da riit ra k i t luan: k h o i n g each ngang tdi thieu giOa cle true ciia ham ddi tir 2D •§- 3D, vdi D la duflng kinh h i m .
Odi vfli t u y i n m I t r o sd 1 cd duflng ta'nh h i m D= 7.8m n l n y l u clu k h o i n g each ngang tdi thieu glu^ c i c true eiia ham ddi t i l 15.6 -i- 23,4m, Bai toan dUoc mfl hinh trong Plaxis nhU sau:
HinhG Tmong chuyen vitrong nln dat
Gili bai toan vfli 2 dUflng h i m xay dUng cilng c h i l u s l u ehdn him, khoSng eSch t i m h i m c i c h nhau t i f l 0 ^ 50m, thfli gian xay dung 2 ham each nhau la 3 t h i n g . K i t quS t d n g hop t r o n g b i n g sau: •
B i n g 5. B i n g t d n g hgp ket q u i chuyen vj liin cOa ham dfli KhoSng
each B (m) 11 12 15 20 25 30 40 50
Liin ciia 2 ham doi n i m nqanq U, (mm)
16,164 16,735 21,651 18,306 11,071 6.514
•1,464 S I (mm)
-1.309 -1.334 -1.348 -2.189 -0.967 -0.189 -1.214
U, (mm) -97.276 -97.184 -97.532 -97.336 -97.436 -96.75 -96.263
S»{mm)
•51.388 -47.111 -41.957
•36.782 -32.337 -28.495 -23.814 Trong dfl:
- Uu U,: ehuyen dich ngang va t h i n g d i h i g tai dinh ham, - Su S,: chuyen dich ngang va chuyen vj lun Idn nhat t r l n b l mat.
Luulic uial kuulial (uim)
Hinh 7 Bieu do quan he khoSng each 2 ham ngang - chuyen vi liin bi mat Vfli k h o i n g each giUa 2 h i m B£ 11 m thi nen dat glUa 2 h i m bj p h i hoai. Khi thi cdng ham thi vUng b i l n dang d i o cua n l n x u l t h i l n tai cSc vi trf xung quanh ben hdng h i m . Khi 2 d u d n g h i m x l y dung q u i g i n nhau thi cle diem d i o giao thoa nhau g l y nen mat dn djnh trUOt trong nen. Khi khoSng eSch 2 duflng ham Ba 12m, vimg bien dang d i o eiia 2 duflng ham each xa nhau khflng gay mat dn djnh t r u o t t r o n g n l n . So dd elc diem e h l y d i o trong nen quanh d u d n g h i m efl dang n h u sau:
3.22 Bdi todn hdm ddi theo phucmg dUng
T r l n eo sfl nhUng nghifin eiJfu v l ijfng x i l ciia ham trong d i t vS pham vi I n h huflng khi thi cdng h i m , ngudi ta da rut ra k i t l u i n : k h o i n g c i c h
t h i n g aCfng toi thi^u gifla c l e t n j c ciia ham ddi > 2D, vfli D la duflng duflng ham c i c h xa nhau khdng gay mat o n d m h trUot trong nen. So do kfnh h i m , cac d i l m e h l y d^o trong nen quanh dudng ham co dang n h u sau-
Odi vfli t u y i n m I t r o sd 1 cfl dUdng kinh ham D= 7,am n l n y l u cau k h o i n g cSch ngang tdi t h i l u giCfa cSc true ciia h i m ddi 2 15.6m.
O O
Hinh 8. Ck diem chjy d^o trong nen hhi khoing each 2 hSm B-12m
Hlnh 9. Trucing diuyin vi trong nen dat Ijmhc m.ithiniilinlliiini'
Hinh 10. Bieu do quan he khoang each 2 ham diing - chuyen vj lun be mat G i l i bai t o l n vfli duflng ham t h f l hai xay dflng eiing t i m theo phuong X, khoSng c i c h dat h i m thU nhat IS 20m, thay ddi chieu sau chfln h i m thU 2 s l u dan vdi khoSngclch vdi tim h i m 1 t i i 10-^ 30m. K i t q u i tinh toan n h f l sau:
Trong do,
- U<i, U,i, U<2, Uyi: chuyin dieh ngang va t h i n g duTig tai dinh h i m 1,2.
- Su Sy: ehuydn dich ngang v l c h u y i n vj lim Ifln nhat tren be mat, Vdi k h o i n g c i c h gifla 2 h i m H< 10m thi nen d i t giCla 2 ham bj pha hoai. Khi thi cdng h i m thi vung bien dang d i o cua n l n x u l t h i f n tai c i c vi tri xung quanh bin hong h i m . Khi 2 duflng ham xay dUng qua gan nhau thi c l e diem d i o giao thoa nhau g l y n l n m i t dn dinh trugt trong n l n . Khi khoSng e l c h 2 dUflng h i m H> 1 Om, viing b i l n dang d i o cua 2
Hinhll Cacdiemch^ydeotrong nen tuang ling H=12m¥aH=1Sm B i n q 6. B i n g tdng hop ket q u i c h u v i n vi lun eua h i m ddi Khoing
cachH (m)
10 12 15 20 25 30
Lun eiia 2 h i m ddi thang difng U.I
(mm) -0.127 0,209 0,133 0 207 -1,471 0.176
U,i (mm) 0.095 0.021 -0.477 0.106 -1.471 0.428
S, (mm) -1,298 -1.297 -1.306 -1.303 -1.379 -1.325
Uy, (mm) -154632 -148,147 -148 009 -141,674 -130,016 -128.71
Uy!
(mm) -66.261 -82.980 -110.651 -133,849 -130,151 -124.657
SJ- (mm) -69 543 -67,199 -66,712 -66 015 -59,152 -58,6 3.3. Phdn tich kA qud nghiin ciili
3.3,? TU bdng 3 rdt ra mgt so nhdn xet nhu sau:
Bi rdng dUflng cong li^n 2i g i l m theo e h i l u sau dat h i m nhung viing I n h hfldng liin do thi cdng h i m g l y ra dfli vfli n l n d i t lai tang khi chieu sau dat ham tang. Vdi chieu sau d i t h i m t f l 10 -r 15m thi dfldng cong liin ed dd ddc Idn hay ndi khac di la dUdng cong cd vung Idm sau.
K h i c h i l u s l u d a t h i m >15m thi dudng cong lun m d rdng d i n n l n cfl do doc t h o l i hon. 8 1 rdng duflng cong lUn dat g i l t n Ifln n h i t bang 33.1 m khi h i m dat sau 10m.
Sd sanh viing bien dang lun theo 2 phuong ta thay b l rdng dudng cong lun theo phUOng dgc ham luon ludn ldn hon b l rdng duflng cong lun theo phuong ngang h a m d e S e d d sau d l t h a m k h i c nhau.
23 2 Tiibdng 4 rdtra mdt sdnhdn xet nhusau:
Tai diem D I I diem day vfl ham, cd chuyen vi theo phuong ngang gan nhU bang 0 vl day la bai toSn ddi xflng. Chuyen vl theo phflong dflng eiia d i l m D deu ed giS tri dUong, nghia la diem D e h u y i n vi ndi len. Tai H= 10m, U_Dy= 68 389mm C h i l u sau dat h i m cang Ifln thi chuyen vi dflng d i l m D cang t3ng, tuy nhien den ehieu sau H= 25m t r f l di thi giSm xudng. Ly do cang xudng sSu thi dia chat Idp dat ben dudi tdt hon v l I p lUc n l n cila eae ldp d i t phia tren vd h i m c i n g tang.
Tai diem C la d i l m trin vfl ham 6 vi tri cao ngang t i m ham, vfl h i m bj b i l n dang theo phuong ngang ehii yeu do sfl chenh lech ap luc dia t i n g phia t r l n va dufli vd ham l i m cho ham bi bien dang thanh hlnh ovan. Diem C lufln cd chuyen vi hudng ra xa tam duflng ham, Chuyen vi theo phuang ngang eiia d i l m C t i n g dan theo sU tang d d sau ehdn ham. Khi c h i l u s l u chfln h i m >22m thi d i l m C cd chuyen vj theo phuong ngang giSm dan, NgUOC lai c h u y i n vi dflng ciia diem C ft thay doi theo ehieu s l u dht ham va cd g i l tri nhfl khdng d i n g k l , Khi chieu sau ehdn ham >19m thi d i l m C b i t dau cd chuyen vi d u o n g , tflc I I trdi len nhung it thay ddi khi chieu sau dat ham tang len. Oieu n l y cd the ly
111
g i l i do khi ehdn s l u , phfa t r l n h i m hinh thanh nen vdm Sp lUc va do e h l n h ap lUc dja tang t i e dung len h i m h l u n h u khdng thay ddi.
Tai diem B la diem tren dinh vd ham eung co bien dang theo phuong ngang g i n b i n g 0 do la bai t o l n ddi xflng. Cdn c h u y i n vi theo phflOng d i i n g g i l m rd r f t theo c h i l u sau dat h i m . Tuy n h i l n khi c h i l u sau chfln ham Ifln hOn 20m thi do lun giam nhanh hon khi c h i l u sau dat ham t i n g .
Tai d i l m A la diem tr^n b l mat ciing ed bien dang theo phUOng ngang g i n b i n g 0 do la bai t o l n dfli xflng. Chuyin vi theo phflong dflng ciia d i l m A deu ed gia t n I m . Vdi c h l l u sau dat h i m cang tang thi giS trj c h u y i n vj dflng tai A eang giSm, Tai H= 10m, U_Ay= 74.011 m m Tuy nhi^n d i n e h i l u s l u H= 20m t r d di thi giSm ft dan di, Ly do cang xudng s l u thi dja chat ldp dat ben dfldi tflt hon. Tai H= 40m, U_Ay=
17,831mm,
Tif p h i n tich 6 tren, chieu sau dat ham h c ^ ly trong khoing 15 T 20m so vdi m i t d i t . Tai khoSng chieu sau nay, chuyen vi cila ham tuOng ddi nhfl t f l 5 - Scm vS bien dang lun b l mat t f l 2 -^ 4em coi n h f l l n h huflng khdng dang k l d i n cSc edng trinh tr^n mat dat Khi ham dat sau han 40m thi b i l n dang lOn b l m i t nhfl vi thay ddi khflng dang k l < 2em, tuy nhign IUc n l y c l n phSi xem xet tang c h l l u day vo ham ldn hon khi h i m d i t slu,
3.3.3. TU b i n g 5 riit ra mot sd n h i n xet nhU sau:
Chuyen vi theo phuOng ngang i U , ciia 2 h i m dao ddng t f l -1.646 - 21.651mm, nhfl vay Snh hfldng do chuyen vj ngang la nhfl khdng dang ke.
Chuyin vi theo phUcJng diing AU, tai vi tri dinh cua mdi ham g i n nhfl I I khdng ddi khi khoSng each giiia 2 ham thay ddi va gan b i n g gia tri i U y khi thi cdng h i m don la -95.478mm, NhU vay chuyen vi theo phuong dflng AUy tai vi trf dinh ham h l u nhu khdng phu thudc vao k h o i n g eSch dat 2 ham,
Chuyin vi liin Idn n h l t t a i b l m a t d l t g i l m d i n t f l g i l trj-51.388mm flng vdi khoSng elch B= 12m den -23.814mm flng vdi B= 50m v l gia tri n l y gan b i n g vdi giS tn lun khi x l y dflng ham dem vdi cimg dfl sau dat ham, Vay khi 8? SOm, xem nhfl viec xay dflng 2 duflng ham lan can khdng Snh huflng den nhau.
Qua phSn tich d tren, khoang elch giUa 2 h i m hop ly n i m trong k h o i n g 20 •;• SOm, liie nay viec thi eflng dfldng ham thU 2 I n h huflng khflng dSng k l den dfldng h i m thU n h i t . Tuy n h i l n , d nhflng vi tri gidi han v l dja hinh hay qui hoach thi khoang each B cd t h i nhd hon nhUng khdng nhd hon 12m.
3.3.4. TU b i n g 6 rut ra mdt sd nhan xet n h f l sau:
Chuyin vi theo phuong ngang AU. cua 2 ham dao ddng quanh gia tri 0, nghia I I khi xSy dflng h i m ddi thi Snh huflng do chuyen vl ngang I I r l t nhd.
Chuyen vj theo phuong dflng AU, tai vi tri dinh ciia h i m 1 g i l m khi khoSng each giila 2 ham tang nhflng vdi ham 2 thi nguoc lai giam khi khoSng c i c h giCfa 2 h i m tang.
Chuyen vj lUn Ifln nhat tai b l mat d i t g i l m khi khoSng eSch gifla 2 ham t i n g . G i l m dan tU g i l tri -69.543mm flng vdi khoSng each H=10m den -58.6mm ifng vfli H= 30m, Nhfl v l y khi thay ddi H thi liin be mat g i l m khdng dSng k l .
Khi k h o i n g each h gifla 2 ham >10m, vung bien dang deo eiia 2 duflng h i m khflng giao thoa vdi nhau. Do dd d l khdng bi m i t dn dinh trflgt trong n l n thi khoang each ham H nen Ifln hon 10m. Tuy nhien, vifc x l y dflng duflng h i m eang sau thi c i n g tdn kem do ap lUc l l n dudng ham thif 2 ldn hOn thi vo ham phai day hon, phai xay dflng cac g i l n g dflng s l u hdn, nha ga dat s l u hon K i l n nghi k h o i n g elch diing H giCfa tim 2 duflng h i m n l n n i m trong k h o i n g 10 - 15m la hgp ly e l v l ky t h u l t v l kinh te
4 . K^t l u i n v ^ kien n g h i 4.1. K^t ludn
4.1.1. G i l trj Ifln b l mat dat Ic^ nhat khi thi edng duflng ham bang mSy khoan d i o t d hop TBM ifng vdi viing dia c h i t yeu khu vUe TP. Hd Chi Minh IS 125.817mm ung vdi e h i l u sau dat h i m la 10m, ddng thdi
gia tri nay giSm dan theo c h l l u s l u dat ham. Vfli dflflng ham efl dfldng kfnh 7 8m trong d i l u k i l n dia c h i t TP, Hd Chi Mmh thi 6 e h i l u s l u 40m giS tri liin b I m S t d i t Ifln n h i t la 17.831mm cd t h i coi n h u Snh huflng khdng dSng ke d i n eSe cflng trinh t r l n be m a t
4.1.2. B l rflng duflng cong lun theo phflong ngang h i m dat giS tn Idn nhat b i n g 33.1m khi ham dat s l u 10m. Be rdng duflng cong lOn g i l m theo c h l l u s l u dat ham nhUng v i i n g Snh hudng lun do thi cdng ham g l y ra doi vdi n l n dat lai tang khi e h i l u s l u d i t h i m tang Odng thfli b l rdng dflflng eong lun theo phuong doe h i m lufln ludn Idn han be rflng duflng cong liin theo phucmg ngang ham fl cac dd sSu dat ham khae nhau,
41.3. C h i l u sau dat h i m hop ly trong khoSng 15 - 20m so vdi mat dat, Tai khoSng c h l l u s l u n l y , chuyen vi efla h i m tuong ddi nhd tif 5 -r Scm va bien dang lun be mat tU 2 -^ 4cm coi nhu I n h hfldng khdng dang ke d i n eSe edng trinh t r l n m i t dat, Khi ham dat sau hon 40m thi b i l n dang liin be mSt nhd < 2cm va thay ddi khdng d i n g k l ,
4,1,4, Khi x l y dflng dflflng h i m dfli n i m ngang k h o i n g each gifla 2 ham hop ly n i m trong khoSng 20 -r- SOm, luc nay v i l e thi edng dfldng ham t h f l 2 Snh hflflng khdng d i n g ke den dfldng ham thil nhat, Tuy n h i l n , 6 nhflng vi tri gidi han v l dja hinh hay qui hoach thi khoSng each B cfl the nhd hOn nhung khdng nhd hon 12m,
4.15. E)di vdi ham ddi t h i n g diing d l khong bj mat dn djnh tnjot trong nen thi khoang each 2 ham nen Idn hon 10m. Tuy nhiln, vifc x l y dung duflng ham cSng s l u thi cang tdn kem do l p luc iin dfldng ham thfl 2 Ifln hon thi vfl ham phSi d l y hon, p h l i xSy dflng cac gieng duTig sSu hon, nha ga dat sau hgn. Kiln nghi khoing each dung gifla tim 2 dfldng h i m nen nam trong khoing 10 ^ 15m la hop ly eS ve ky t h u l t v l kinh t l .
4.2. Kien nghj
4.2.1, Tinh t o l n dfldng h i m tren nen dat y l u rat phflc tap, ddi hdi phSi cd sfl k i t hgp giiia phflOng phSp ly t h u y l t va thuc nghi&m de cd nhifng d i n h gia mdt each tUOng ddi flng xfl ciia duflng ham trong n l n d i t Dly ciJng la hfldng nghiln eflu t i l p theo de luan an mang tinh k h i thi v l cfl t h i l p dung trong d l l u kifn khu vflcTP, Hd Chf Mmh v l trcing c l nudc.
4.2.2. Nghien cflu tren day mdi chi difng lai d mflc do ly t h u y l t ddi vdi VLing dia chat khu vflc TP. Hd Chi Minh. VI v l y ket q u i n g h i l n eflu dua ra mang tinh tUong ddi, g i n d u n g . Oe cd ket qua ehfnh x l c hon tic g i l kien nghi t i l n hanh thi nghiem m d hinh ddi vdi mau dat khu vUC TP.
Hd Chf Minh v l t i l n hhnh do dac quan t r i e trong qua trinh thi cdng de ed bien phap xfl ly thich hgp,
4 2.3. Vi tuyen metro sd 1 cfl phan ngam di qua viing d i t y l u ciia khu vflc TP. Hd Chi Mmh ddng t h d i phfa t r l n be mat dat cd nhieu cong trinh quan trong n l n d l han ehe t h i p nhat bien dang liin be mat kiln ngh] diing phuong p h l p khoan bang khien can b i n g ap lUc d i t . Hifn tflgng c i t c h i y vS an mfln b l t d n g la nhflng nguy co c6 k h i nSng x l y ra doi vdi dfldng ham x l y dUng trong khu vUc TP. Hd Chf Mmh c l n phii dUOc chu trong.
TAIUEUTHAMKHAO
1. Cong l y Co phan TVTK GTVT phia Nam, 2007. DUdn Idia thi tuyen m&ro Ben Thdnh - Sudi Tien.
2. Loganathan, N, 1999 Effect of tunnelling adjacent to pile loundaiions Ph.D thesis, The Univ of Sydney, Sydney, Australia.
3 Loganathan, N., and Poulos, H. G.. 1998. Analytical prediction for lunnelling-mduced ground movements in clays. J Geotech, Geoenviron. Eng., 1240 9, ppB46-856
4, Loganathan, N , Poulos, H. 6 , and Stewart, D P., 2000, Centrifuge model testing of lunnelling-mduced ground and pile deformation Geot«hnique, 50 3, pp283-294,
5, Chanaton Suiarak, 2011 Geotedinical aspeds of the Bangkok MRT Blue Line Project. PhD thesis, Griffith University
6, John Anthony Pickhaver, 2006, Numencal Modelling of Building Response to Tunndling, Ph.D.
thesis, Oxford University,
7.Hquyendiic'iiati,2Q06,TBMandliningessenlialinterfaces,Nii thesis,TunnUniversity