Xác định vị trí chuyển ngang của tường vây trong hố đào sâu

Xac djnh chuyen vj ngang cua tu'ang vay ho dao sau Ngay nhan bai: 4/12/2013 Ngay sCra bai: 12/12/2013 Ngay chap nhan dang: 25/12/2013 T6M TAT: Noi dung cua bai bao la phan tich chuyfa vi ngang cua tvldng vay ho dao sau sti dung philong phap phan ttl hiiu han va dam tren nen dan hoi. Ket qua phan tich chuyen vi ngang cua tiidng diigc kiem chiJng vdi so lieu quan trac hien trildng de danh gia 6n dinh cua ho dao. Ket qua chuyen vi ngang ciia tiidng phan tich bang phan tii hfiu han gan sat vdi sd lieu quan trac hien trildng vdi dp sai so khoang 8%. Tuy nhien, chuyen vi nhan dtlgc tfl philong phap dSm tren nen dan hpi cho ket qua ldn hdn ban so vdi phan thil hflu han khoang til 1,88 - 2,47 lan. ABSTRACT This paper is aimed at analysing the horizontal displacement of diaphragm vfall in a deep excavation, using the Finite Element method (FEM) and beam on elastic foundation method (BEF). The analysed results are compared to the measurements to evaluate the stability of deep excavation. The results of horizontal displacement of the diaphragm wall from FEM are equivalent to the monitoring data with the difference of 8%. However, the horizontal displacement results from BEF analysis are higher from 1.88 to 2.47 times than that of FEM results. Keywords: Deep excavation, diaphgram wall, displacement, Finite Element method (FEM), beam on elastic foundation method (BEF). PGS.TS. Iran Xuan Tho Khoa Ky Thuat Xay Diing, Trilclng Dai hpc Bach khoa TP. HCM 268 Ly Thiidng Kiet, Q. 10, TP. HCM Email: txtho@hcmut.edu.vn DT: 0939.369.777 KS. DoAn Van Toan Khoa Ky Thuat Xay DUng, Tnidng Dai hoc Kien triic TP. HCM 196 Pasteur, Q.3, TR HCM Email: doanvantoanraihcmuarc.edu.vn DT: 0973.392.357 Tran Xuan Tho, Doan Van Toan I.Datvande Dfldi didu kidn dao dat thdng thfldng, mdt Iflpng dat ben trpng hd d i o dflpc dd bd, tap i p Iflc dat khdng ein bang t i c dung ldn tfldng. Ap Iflc dat khdng can bang se l i m p h i t sinh b i l n dang cfla tfldng va be mat dat. N l n dat, d i l u kidn mflc nudc n g i m , hinh dang hd d i o , qui trinh thi edng, phuong phap thi cdng, loai tfldng c h i n gifl va n h i l u yeu td khae lien quan tdi chuyen vj cua tudng. O l dam b i o dn djnh cfla hd d i o , c i n x i c djnh chuyen vj cfla tudng cie giai doan thi cong dao dat. Hidn cd nhieu phuong p h i p d l p h i n tieh tudng vay hd dao siu. Hai phuong phap phan tfl hflu han (FEM) va dam trdn n l n dan hdi (BEF) thfldng dflpc sfldung. FEIVl l i mdt phflong p h i p tflong thieh Si md phdng dng suit - b i l n dang eua dat. Khi lUa chpn g i i i p h i p ddn g i i n hon thi BEF trd t h i n h mdt md hinh dugc sfl dung. O l danh g i i k i t q u i p h i n tich dfl d o i n chuyin vj ngang eua tudng v i y thi can t h i l t p h i i t i l n hanh quan t r i e chuyen vj ngang eua tudng tien h i n h thi edng hd d i o . Tudng v i y hd d i o siu edng trinh Hud Tower, H i Ndi dupe nghidn cflu trpng b i i bap niy. 2. Phuong phap nghien cflu Phflong phap phan tfl hflu han thdng qua phan m i m Plaxis dupe sfl dung d l phan tich. DUa v i p dae diem dja tang va eac d i e trUng co ly eua c i c Idp dat, md hinh Mphr - Cpulomb (MC) dugc ap dung mo phdng tinh toan. Phuong phap dam tren n l n d i n hdi thdng qua chuang trinh VEX dugc sfl dung md phdng p h i n tich dua tren g i i tri he sd nen theo phuong ngang eua nen dat. Xac djnh he sd nen theo phuang ngang dua trdn phuong trinh cfla Ou (1997). Oe cac cdng cu p h i n tieh dupe sfl dung an t p i n thi can dflgc kiem chflng b i n g cich ddi chieu vdi ket q u i quan t r i e hidn trfldng. Tien h i n h quan t r i e chuyin vj ngang eho tudng v i y hd dao q u i trinh thi edng dao dat bang cic t h i l t bj Inclinometer (Hinh 2). 3. Mo t i cong trinh va mo phdng tinh toan 3.1 Mo ti eong trinh Cdng trinh HudTower cd t i n g ham, sfldung phflong phap thi cdng Top-Down vdi giai doan d i o dat. Hd dap rpng 40m v i s i u n h i t 12,0m. Hd dap dupc chan gid b i n g tudng v i y ed b l day 800mm vdi dp s i u eua tudng 25m, giang H300x300x10x15 vdi khoing c i c h giang l i 5,0m v i k i t hgp vdi san tang ham l i m giang chdng cho thi edng dao dat. Sau thi edng xong tfldng v i y DW800 va epe khpan nhdi va kingpost thi t i l n h i n h thi edng dao dat tang ham. Mat cat ngang hd dao dflgc md t i Hinh 1. 3.2 Bgc diem dia chdt eong trinh Ciu tao dja c h i t va chi t i l u eo ly cfla eac Idp d i t : 01.2014BniniflHl S£T PHU D£OM£M-D£0 CUNG DAOQJITUM 1-3000) y„i=19.8kN/m' SANBI 9' =17°13' 0A0 0i(TLJlll2|-5n0) C =19,5kN/m' SANB2 s. = 50kN/m' N = 8.12 OAOOSTLANa(-9000) DA0D)(TU(N4{-1ZD00) SET CLING r,.i = 20.4kN;m' f' =17°13' C =42.5kN;m' Su=iaokN;m' N = 30 - 40 CAT PHA, TRANG THAl CHAT rs,i = . k N ; m ' •p' =29°19' c' = . k N / m ' N = 30-45 eao dp l i n lucrt la ±0,0; -3,5m va -7,0m san day 200mm, be tdng m i c M350 (B25) co modul d i n hdl la E„ = 3,0xl0'kN, dp cflng dpc true EA = 6,0x106 kN. 3.5Biediemthanheh6ngH300x300x10x15 He chdng thep hinh H300x300x10x1521 tai cao dp -2,0m, sfl dung thep ed mac SS400 hay (CT34) cd modul d i n hdi E = 2.1xl0'kN/m^ dp cflng dpc true EA = 4,914x10' kN, budc chdng L^ = 5,0m. 3.6 Quan trie Men truing h i # » t i t * ""» .^. « V - i. it i'. 'i .1 < li" ji t Quan t r i e chuyin vj ngang eua tfldng viy Hinh 4. Mo hinh phan tich ho dao Plaxis theo tflng giai doan d i o dat va thi cdng t i n g ham. Trflde be tdng tfldng, c i e thiet bj C h u in 11 u u g (nun) « D etxa oo Inclinometer dflgc d i t eac dng thep de chuyen vj ngang cfla tudng theo chu vi tfldng vay nhfl Hinh 2. Dfla trdn nguyen t i e lie trgng lugng ludn ludn tri tinh chat thang dflng eua diy • / i,-', dgi, thdng qua viec lay gdc kep gifla dfldng 1 true d m i y vdi dudng t h i n g dflng cfla day dgi eon lac de tinh chuyen vj ngang cfla doi tflgng p h i i do. d i u tren lie ed djnh mpt l\ la ddng nhip, la ddng nhi'p dau tren ed djnh, UorUlllnl i I .'1/1 dau dfldi dfla v i o d i y lac, may nghieng EUDdillln? i .' EUodilliil} bj n g h i i n g , day lac dfldi t i c ddng cfla trgng lfle E»olllln4 lie tri t h i n g dflng nen ep vao l i ddng lam chp la ddng bj eong, nhd vao p h i l n bien Hinh 5. Ket qu3 chuyen vj ngang cOa tilJng cac giai doan dang didn trd d i n trdn l i ddng dfla tin hieu dao dat (bang VEX) didn, may thu trdn mat dat se thu n h i n tin hieu Omffo v| BfiBg (u) didn trd v i tinh trj udn cong cfla la ddng, tfle la cd the b i l t dflgc gdc nghieng cua m i y n g h i i n g , t f l tinh dflge chuyen vj cua doi tflgng p h i i do. 3.7 Mo phdng tinh todn Q u i trinh thi cdng hd d i o s i u dflge mo phdng bao gdm c i c giai doan sau: Giai doan :Thi cdng tudng vay day 800mm, sau 25m. Giai doan 2: O i o dat lan xudng cao dd -3,0m. Hinh 6. Ket qua chuyen vj ngang ciia tudng cac giai doan Giai doan 3: Lap giang chdng dao dat (bang Plaxis) H300x300x10x15 tai eao dp -2,0m. = 0,35. Giai doan 4: Oao dat lan xudng cao - Ldp 2: Set mau nau vang, trang t h i i cflng, -5,0m. day 18m, y^^ = 20,1 kN/m=, c' = 42,3 kN/m^ cp' = Giai doan 5: Thi cdng s i n h i m Bl tai cao 21 »26', sdc chong eat khdng t h o i t nudc S^ = 180 -3,5m. kN/m^ k = 8.64E-^ m/ngay-dim, E , = 2800N Giai doan 6: T h i o chdng H300x300x10x15 (SPT) = 89600 kN/m^ v = 0,35. va thi cdng s i n tret day 200mm. - Ldp 3: Ldp eat pha, mau nau v i n g , trang Giai doan 7: Oao dat lan xudng cao t h i i chit, b l day rat Idn, y^^^ = 20kN/m^ e' = -9,0m. mim\ cp' = 29°19; k = 0,864m/ngiy-dem, E,^, Giai dpan 8: Thi cdng s i n ham B2 tai cap dd 2500N (SPT) = 80000 kN/m^ v = 0,3. -7,0m. 3.3 Bic diem tudng vdy BW800 Giai dpan 9: Gap dat l i n xuong eao Tudng v i y cd chilu s i u t f l mat dat t i i nhidn -12,0m, rdi thi edng eae d i i mdng be. L=25m, tudng day 800mm. Bd tdng dirng mac Hinh Md hinh phan tich hd d i o bang M350(B25) ed modul dan hdi E, = 3,0x10'kN/ chuong trinh VEX va md hinh p h i n tieh ho dao m^ dp cdng ehdng nen EA = 2,4x10' kN/m, dp Plaxis dflgc md ta Hinh 4. cflng ehdng udn El = 1,28x10' kN/mVm, He sd 4. Ket q u i p h i n tich Poisson v = 0,2. trmh VEX) 3.4 Bic diem sin tret vi hdm B1, B2 San tret, ham (Bl) va s i n ham (82) cd Kit q u i p h i n tich c h u y i n vj ngang eua mmm^^Eame- //Vm Hinh I.Mat cat ngang ho dio / / ' '', Hinh 2. Mat bing bo tri thiet bj quan trac 5000 ! i ; ! i i ! • — ; ; ; I ; ; : ; i ; ; : . . . i \ '• '. '. i ! • ' • . ' , . ' • ! ' '. ,1 ! i ' ^ i : ; ; ;; [2]: i • ; f j - • : • . . : ' , : ' , • . • ' . • • . • . ; . ; [11 : : ; ; • I : \ : : ' p • • 50.00 k - • ; - ; : : : : : — ; — • : [2] — ; ^ f : ^ ^f • - - ; " - i - - - ! - - - i - - - v - ^f •: ; : \ '. ; : : \ ^ ^ ; ; : ; :•.•.'.: ; I ; ; -•:•---;---•:•---;--- : ; ;: - - - j - - - i - - - r - - - i - - - - - ; ' : : : • ' ; : : • * ' • ; : ;; • ' : ' . ' . Hinh 3. Mo hinh phan tich ho dao VEX - Ldp 1: Set pha, mau xam trang, trang t h i i ddo mem den ddo cflng, d i y 12m, trgng Iflgng r i l n g trdn mflc nudc ngam y^^^^^ = ^6,5kN/m^ trgng Iflgng ridng b i o hda y^^^ = 19,8kN/m3, c' = 19,5 kN/m^ cp'= 17°13', sfle ehdng c i t khdng t h p i t nfldc S„ = 50 kN/m^ he sd tham k = 8.64E"' m/ngay-dem, module bien dang t i l p tuyen E^^, = 2800N (SPT)= 25000 kN/m^ he sd Poisson'v 104IBWn'KnB» 01.2014 ; / ' tudng qua eac giai doan dao dat bang phuong p h i p dam tren nen dan hdi dugc md t i Hinh 5. giai doan dao dat l i n 1, tfldng cd xu hfldng djch chuyen vao bdn hd dao, chuyin vj ngang Idn n h i t d dinh tfldng u_^^^ = 20,76mm. Giai doan dao dat lan 2, chuyen vj efla dinh tfldng g i i m vi d i lap chdng, ehuyin vj ngang Idn n h i t cfla tfldng la u^^^ = 24,3mm d vj tri dp s i u 6,0m sp vdi mat dat tU nhien. Giai dpan dao d i t lan 4, tudng chuyen vj vao bdn hd dap nhieu n h i t va cd xu hfldng bj udn bung, ehuyin vj ngang eua dinh tfldng la 19,8mm, chuyen vj Idn n h i t la u^^^= 41,17mm d vj tri dp s i u 10m sp vdi mat dat t f l nhien. 4.2 Kit qui phdn tieh bing FEM (chuang trinh Plaxis) Ket q u i p h i n tieh chuyen vj ngang eua tudng qua cae giai dpan d i p dat bang phfldng p h i p phan t f l hflu han dflgc md t i Hinh 6. d g i a i doan dao dat lan 1, chuyen vj ngang Idn nhat d dinh tfldng u^^^ = 11,04mm. Giai doan dao d i t l i n 2, chuyin vj cfla dinh tfldng g i i m vl d i lap ehdng, chuyen vj ngang Idn nhat efla tudng l i u^^^ = 13,54 mm d vj tri dp s i u m so vdi mat d i t t f l nhidn. Giai dpan d i o d i t l i n 4, chuyin vj ngang cua dinh tudng l i 12,34 mm, chuyen vj Idn n h i t l i u^^^ = 18,5 mm d vj tri dp siu 10 m so vdi mat dat t u nhien. 4.3 Ket q u i quan t r i e Kit q u i quan trac ehuyin vj ngang efla tudng tai vj tri dng 1-2 dupe md t i Hinh 7. Hinh 7. Ket qua quan trac chuyen vj ngang ciia tirdng cac giai doan dao dat 4.4 Bdnh gid ket qua phdn tich vdi ket qud quan trie hien truing Hinh tdng hgp k i t q u i c h u y i n vj ngang cua tfldng c i c giai doan thi cdng dao dat theo Plaxis, VEX v i k i t q u i quan t r i e hien tudng. Trj sd b i l n dang tinh t o i n eua tfldng vay tinh toan bang Plaxis g i n sat vdi sd lieu quan trie thflc te vdi dp sal khic khoing 8% v l dp Idn. Tuy nhien, cung dua tren k i t q u i sp sanh nay, chp thay c h u y i n vj n h i n Siigc t f l VEX eho k i t q u i Idn hon ban so vdi Plaxis khoing t f l 1,88 + 2,47 lan. Trong sudt qua trinh dao dat, tudng v i y sd p h i t sinh hai xu hfldng ehuyin vj, tdng hai xu hfldng se tao djch chuyen ngang Idn nhat cho ti'-^ J B d la xu huong djch chuyen ngang Ckay^BViBgiag(m) 001 0015 CfaofCB vj ngoiig (m) OUI OOIS —\ H H Hinh 8a. Bao dot tan den -3,0m Hinh 8b. Dao dot Ion 6en -5, Om Cbin*cD v | ngiDg (m) Chuyen v | a g i n g (m) Hmh ic Bao dot lan den -9,0m Hinli Sd Boo dot Idn dm -U,Om Hinh 8. Chuyen vj ngang ciia tucing bang quan trac va tinh toan bang Plaxis, VEX v i o hd dao cfla t o i n tudng (xu hfldng 1) va xu hflong u o n p h a n b u n g cfla tfldng (xu hfldng 2). Trong giai doan d i o d i t ban d i u , xu hfldng l i chu dao, n h i i n cic giai doan sau (khi da bd tri hd ehdng va thi edng eic san tret, s i n ham 1, s i n ham 2) thi xu hudng dugc t h i hidn r i t rd va c h i l m Uu t h i . Vj tri tfldng dat gia trj cue dai (tai vj tri tfldng bj uon bung n h i l u nhat) cd xu hfldng djch ehuyin theo c h i l u s i u d i o dat tfl vj tri khoing 8m d (giai doan dao d i t l i n 3) t i n g len vj tri 10m so vdi dinh tfldng (trong giai doan dao dat l i n 4). Ben canh ehuyin vj ngang eua tudng cung t i n g dan theo cie giai doan dao dat. Theo tieu chuan thiet ke ASTM, chuyin vj ngang cua tudng eho phep khoing [ux] =1,5 inches = 3,81 em, dd ehuyin vj ngang cfla cflc dai thflc te eua tfldng v i y la umax =l,8em, ndn tfldng vay hd dao van d i m b i o d i l u kien dn djnh. 5. Ket l u i n K i t q u i chuyin vj ngang eua tudng tinh t o i n b i n g Plaxis g i n s i t vdi sd lieu quan t r i e hien trfldng vdi sai sd k h o i n g 8%.Tuy n h i i n , chuyen vj nhan dflgc t f l chflong trinh VEX cho k i t q u i Idn hon han so vdi chuong trinh Plaxis k h o i n g t f l 1,88-2,47 l i n . Du rang phflong trinh efla Ou cho ket q u i khdng phu hgp vdi ket q u i quan t r i e du i n , nhidn cic thdng sd cfla Idp d i t set l i cic ydu td i n h hudng tdi phuong trinh. He sd nen theo phuang ngang cd khuynh hfldng tang theo he so Poisson, modul d i n hdi cfla d i t v i sfl t i n g ldn cfldng dat n l n . Trong sfl tuong p h i n , he sd nen theo phuong ngang g i i m xudng vdi sfl t i n g len be rdng hd dao v i t i n g len chilu d i l c i m s i u cua tfldng. O l dflpc hgp ly trpng viec thflc hidn tinh t p i n i p lfle ngang doe theo chieu s i u vung dat bi p h i hoai keo gdm c i b i l n dang cfla tfldng va phu hpp vdi hd d i o thflc, sfl h i l u ehinh i p Iflc ngang phia sau lung tudng bang hai l i n c h i l u s i u m i vung dat bj p h i hoai keo la dupe xac djnh rd phflong phap dam tren nen d i n hdl. TAI LlCU THAM KHAO [1] Ou, Chang-Vu (2006), Deep Excavation theory and practice. First edition, Taylor and Francis/Balkema, Netherlands. [2] Malcolm Puller (1996), Deep Excavation a practical manual, first edition, Thomas Telford, New York. [3] Monitoring of Diaphragm Vtfall Displacement and Assodated Ground Movement, Braced Excavation Adjacent to Historical Building at The Bank of Chao Phraya River. Bangkok, Thailand, 2000. [4] Vesic, A.B. (1961), Beams on Elastic Subgrade and the Winklers's Hypothesis, Proceedings, Fifth Intemational Conference on Soil Mechanics and Foundation Engineering, Paris. 01.20149Dnil[|SX . Hinh 5. Ket qu3 chuyen vj ngang cOa tilJng trong cac giai doan dao dat (bang VEX) Omffo v| BfiBg (u) Hinh 6. Ket qua chuyen vj ngang ciia tudng trong cac giai doan dao. ehuyin vj ngang efla tudng tai vj tri dng 1-2 dupe md ti trong Hinh 7. Ckay^BViBgiag(m) 001 0015 OUI OOIS CfaofCB vj ngoiig (m) Hinh 7. Ket qua quan trac chuyen vj ngang ciia tirdng trong. bao la phan tich chuyfa vi ngang cua tvldng vay trong ho dao sau sti dung philong phap phan ttl hiiu han va dam tren nen dan hoi. Ket qua phan tich chuyen vi ngang cua tiidng diigc kiem