tinh toan coc xm dat

7/22/2019 Tinh Toan Coc XM Dat

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Slide 1

TNH TON NN GIA CBNG CC XI MNGT

TS. Trn Minh Thun

B mn Kthut xy dng


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Slide 2

NI DUNG CHUYN

GII THIU GIA C NN BNG PP XI MNG HA GII THIU V CC XI MNGT

CNG NGH THI CNG CC XI MNGT

TH NGHIM TRONG PHNG V HIN TRNG

TIU CHUN THIT K CC XI MNGT CA VN

L THUYT TNH TON CC XI MNGT

BI TP


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Slide 3

Ti liu tham kho:

TCXD VN 385:2006, Gia cnn t yu bng tr t xi mng.

Gii thi u kt qu ng dng cng nghkhoan pht cao p (jet grouting)chng thm cho mt scng trnh thuli. Nguyn Quc Dng,Nguyn Quc Huy, Nguyn Qu Anh, Vin khoa hc thuli.

Dn mrngng Quang Trung Ci Cui, Q. Ci Rng, Tp Cn Th,Cng ty Tvn v Kho st thit kxy dn g B Quc phng, thng12/2009.

Cement deep mixing applied to soft clay in Mekong delta, Suzuki, K; Usui,H; Sasai, T; Kojima, A; Nozu, M; Nguyen, H. T.

The Application of Various Deep Mixing Methods for Excavation SupportSystems, Kenneth B. Andromalos, P.E., Eric W. Bahner, P.E.

Lime Cement Dry Soil Mixing, Keller Ground Engineering, Pty Ltd,Australia, New Zealand, Pacific Islands, Indonesia

Quality Assessment and Quality Control of Deep Soil Mixing Constructionfor Stabilizing Expansive Subsoils, Raja Sekhar Madhyannapu, Anand J.Puppala, Soheil Nazarian, Deren Yuan.


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Slide 4

GII THIU GIA C NN BNGPP XI MNG HA

Cc kiu cng ngh khoan pht ximng chng thm v gia cnn:


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Slide 5

CC KIU KHOAN PHT XI MNG

Khoan ph t truyn thng: Khoan pht truyn thng (cn c gi l khoan

pht cn tbt) c thc hin theo s hnh 2.Mc tiu ca phng php l s dng p lc phtp va xi mng (hoc ximng st) lp y ccl rng trong cc k rng ca nn nt n. Gny, cnhng ci tin pht va cho cng trnh

t (p t, thn , ... ). Phng php ny s dng kh phbin trong khoanpht nn nt n, quy trnh thi cng v kim tra kh hon chnh. Tuy nhin. v i t ct mn hoc tbn yu, mc nc ngm cao hoc nc c p thkhng kim sot c dng va s i theo hngno.


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Slide 6

CC KIU KHOAN PHT XI MNG

Khoan ph t kiu p tKhoan pht kiu p t l bin php s dng va pht cplc, p va chim ch ca t.

Khoan ph t thm thuKhoan pht thm thu l b in php p va (thng l ho chthoc ximng cc mn) v i p lc nh va t i vo cc lrng. Do vt liu s dng c gi thnh cao nn phng phpny t p dng.

Khoan ph t cao p (Jet grouting)Cng ngh trn xi mng v i t ti ch- d i su to r a cc XiMng t c gi l cng ngh trn su (Deep Mixing-DM).Hin nay phbin hai cng ngh thi cng cc XM l: Cngngh trn kh (Dry Mixing) v Cng ngh trn t (Wet Mixing).


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Slide 7

Phn loi chung cc thit b trn su

Phng php trn

Trn su

Quay mt trc

Trn kh Trn t

Mt cn/Nhiu cn &mt cnh/nhiu cnh

Gung xonlin khi

Gung xontho ri

Mt cn,mt cnh/nhiu cnh

Nhiu cn &nhiu cnh

Trn t hp

Quay mt trc+ thy lc

Quay mt trc+ tnh tintheo tuyn

Quay trongmt phng +tnh tin theotuyn

Ch tnh tintheo tuyn

Trn kh Trn t

Mt cn, cnh& phun tia pcao

Cnh ct,xch/cam hocbnh lp

Mt cn, cnh .Gia c khi ln

My o


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Slide 8

ng dng trn su

Tm thi

Tng sc chu ti trng ngang cho ccNgn chn nng y hon nh mi dcTng chnn nh thnh ho

Vnh cu

Trn t lin

sngng b, ng st

M cuTng chnNn nh v cng trnhn nh mi dcGim chn ng

Trn bino nhn toTng chnNgn nc


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Slide 9

Bng 1-Thng s thi cng

Trn kh Trn tS hiu tr, thi gian thi cng S hiu tr, thi gian thi cngp lc kh nn p lc bm (kh nn nu c)Hnh dng u trn Hnh dng u trnBiu thi gian/ su (vn tc xuynxung, rt ln)

Biu thi gian/ su (vn tc xuynxung, rt ln)

Tc quay(vng/pht, khi xuyn xung

v rt ln

Tc quay(vng/pht, khi xuyn xung

v rt lnChng loi xi mng v thnh phn Chng loi va xi mng v thnh phn

T l nc/ximngKhi lng xi mng theo mt chiu su (khixuyn xung v rt ln)

Khi lng va xi mng theo mt chiu su(khi xuyn xung v rt ln)

Sai s thi cng(phng ng,ng knh,v tr)

Sai s thi cng(phng ng,ng knh,v tr)

Cao y v nh Cao y v nh


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Slide 10

GII THIU V CC XI MNG T

Cc ximng t l hn hp giat nguyn trng ni gia c vximng c phun xung nnt bng thit b khoan phun.

Mi khoan c khoan su

xung lm ti t n khi t su lp t cn gia c th xoayngc li v dch chuyn ln.

Trong qu trnh dch chuyn ln,xi mng c phun vo nn t(bng p lc kh nn i vi hnhp kh hoc bng bm va

i vi hn hp dng va t).

Khoan cc xi mngt gia c nn

t yu ti Sn bay Cn Th

Cc xi mng t (hay cn gi l ct xi mng t,tr xi mng t) -(Deep soil mixing columns, soilmixing pile)


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Slide 11

Nguyn l hot ng

Bc 1:t my khoan phun ti v trtim ct u tin bt u khoanxung

Bc 2: My khoan bt u khoanxung v tr d kin ct (cha bmva)

Bc 3: My khoan xung suhn v bt u tin trnh va khoan

va bm va Bc 4: Sau khi khoan-bm va-trn u n su thit k, choquay ngc chiu mi khoan rtln.

Bc 5 : Kt thc chu trnh thi cngmt ct ximng t.

( Ngun: Dn Khu bit thcao cp Sunrise )


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Slide 12

Phm vi ng dng

Cc xi mng t l mt trong nhng gii php x l nn t yu:

Khi xy dng cc cng trnh c ti trng ln trn nn t yu cnphi c cc bin php x l t nn bn di mng cng trnh,nht l nhng khu vc c tng t yu kh dy (nh vng NhB, Bnh Chnh, Thanh a thnh ph H Ch Minh v mt stnh ng bng sng Cu Long)

Cc xi mng tc p dng rng ri trong vic x l mng vnn t yu cho cc cng trnh xy dng, giao thng, thu li, snbay, bn cngnh: lm tng ho chng thm cho p, sa cha thm mang cng v y cng, gia ct xung quanh ng hm, n nh tng chn, chng trt t cho mi dc,

gia c nn ng, m cu dn...


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Slide 13

u im ca cc xi mng t

Thi cng nhanh, k thut thi cng khng phc tp, khng c yu t ri ro

cao. Tit kim thi gian thi cng n hn 50% do khng phi chc ccv t cng (V d ti d n Sunrise). Tc thi cng cc rtnhanh.

Rt thch hp cho cng tc x l nn, x l mng cho cc cng trnh cc khu vc nn t yu nh bi bi, ven sng, ven bin.

Thi cngc trong iu kin mt bng cht hp, mt bng ngp sutrong nc. Kh nng x l nn t yu su (c thn 50m).

Thch hp vi cc loi t yu (t ct th cho n bn yu). Nu a chtnn l ct rt ph hp v tin cy cao.

Nhiu trng hp a li hiu qu kinh t r rt so vi cc gii phpx l cc ng. (nu s dng phng php cc b tng p hoc cckhoan nhi th r t tn km do tng t yu bn trn dy. Vi 1 trnghp p dng vi lp t dy 30m, th khi s dng phng php cc-t xi mng tit kim cho mi mng xi l khong 600 triu ng. (NgunWikia)


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Slide 14

Tiu chun thit k

Ti Vit Nam, tiu chun thit k - thi cngnghim thu cc xi mng t l TCXDVN 385 :2006 "Phng php gia c nn t yu bngtrt xi mng" do Vin Khoa hc Cng nghXy dng - B Xy dng bin son, V Khoahc Cng ngh Xy dng ngh, B Xydng ban hnh theo Quyt nh s38/2006/Q-BXD ngy 27 thng 12 nm 2006


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Slide 15

Quy nh v vicg iac nn bngcc xi mng t (TCXDVN 385:2006)

Thit k, thi cng gia c nn t yu bng trt xi mng cntun theo quy trnh sau: Kho st a cht cng trnh, th nghim xc nh hm lng xi

mng thch hp trong phng th nghim; Thit k s b nn gia c theo iu kin ti trng tc dng ca

kt cu bn trn (cn c vo kt qu th nghim mu trong phngv kinh nghim tch ly);

Thi cng tr th bng thit b d kin s dng;

Tin hnh cc th nghim kim tra ( xuyn cnh, xuyn tnh, nntnh, ly mu...); So snh vi cc kt qu th nghim trong phng, nh gi li cc

ch tiu cn thit ; iu chnh thit k ( hm lng cht gia c, chiu di hoc

khong cch gia cc tr); Thi cng i tr theo cng ngh t yu cu v tin hnh kim

tra cht lng phc v nghim thu.


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Slide 16

Cc kiu b tr cc xi mng t

Hnh v d b tr cc trn kh: 1 Di; 2 Nhm, 3 Li tam gic, 4 Li vung


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Slide 17

Hnh v d b tr cc trng nhau theo khi

Hnh v d b tr cc trn t trn mt t:1 Kiu tng, 2 Kiu k , 3 Kiu khi,4 Kiu din


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Slide 18

Hnh v d b trcc trn t trn

bin:1 Kiu khi ,2 Kiu tng,3 Kiu k ,4 Kiu ct,5 Ct tip xc,6 Tng tip xc,7 K tip xc,8 Khi tip xc

Hnh v d b tr cctrng nhau trn t,

th t thi cng


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Slide 19

Cng ngh thi cng

Hin nay th gii c hai cng nghc p dng ph

bin l cng ngh ca Chu u v cng ngh ca Nht.

Hin nay Vit Nam ph bin hai cng ngh thi cngcc xi mng t l: Cng ngh trn kh (Dry Jet Mixing)v Cng ngh trn t (Wet Mixing hay cn gi l Jet-grouting)l cng ngh ca Nht Bn.

Trn kh l qu trnh phun trn xi mng kh vi t choc khng c cht ph gia. Dnh cho t tht v st c

m cao (>50%).

-Trn t l qu trnh bm trn va xi mng vi t choc khng c cht ph gia.

Mi phng php trn (kh hoc t) c thit b giychuyn thi cng k thut, thi cng phun (bm) trn khcnhau.

Ct XMc o ln


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Slide 23


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Slide 24

Cng ngh trn kh

a)Thit bkhoan su vo trongtn su thit k, xi mngc phun rat lphun pha trn dao trn t. b)Thit bquay nhanh hn khi rt ln trn

xi mngu vit. c)Ph ti b cc v nn tr c trong khi dng h cct cng nhanh trong tun u. d)C th cht ti sau khi c ccdng h 3-4 tun (cct 90% cng).

.(NgunKELLERGroundEngineering)

a) b) c) d)


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Slide 28

Cng ngh trn t (Jet-grouting)

Phng php ny da vo nguyn l ct nham thch bng dng ncp lc. Khi thi cng, tr c ht dng my khoan a ng bm c vi phun

bng hp kim vo t i su phi gia c(nc + XM) v i p lc khong20 MPa t vi bm phun x ph v tng t.

V i lc xung kch ca dng phun v lc li tm, trng lc... s trn lndung dch va, ri s c sp xp li theo mt t l c qui lut gia tv va theo khi lng ht. Sau khi va cng li s thnh ct XM.

Hin nay trn th gii pht trin ba cng ngh Jet-grouting: u tin lcng ngh S, tip theo l cng ngh T, v gn y l cng ngh D:

+ Cng nghn pha S: Cng nghn pha to ra cc cc xi mng t c ng knhva v nh 0,4 - 0,8m. Cng ngh ny ch yu dng thi cng nn t p, cc...+ Cng ngh hai pha D: Cng ngh hai pha to ra cc cc xi mng t c ng knh t0,8 -1,2m. Cng ngh ny ch yu dng thi cng cc tng chn, cc v ho chngthm.+ Cng ngh ba pha T: Pht ba pha l phng php thay tht m khng xo trn t.Cng ngh T s dng lm cc cc, cc tng ngn chng thm, c th to ra ctSoilcrete ng knh n 3m.


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Slide 32

Thit b trn t 2 cn

(a) Mixing blades of CI-CMC machine (Ngun Toa Corporation,Tokyo, Japan)


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Slide 33

Thit b trn t 4 cn

(b) CDM-Land 4 machine (Ngun Toa Corporation, Tokyo, Japan)


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Slide 34

Mt ct ngang cc XM viloi my tr n 2 cn v 4 cn


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Slide 35

Thi gian khoan trn hon thnh 1 cc XM vihai loi my tr n 2 cn v 4 cn


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Slide 37

Thit b trn t c 4 cn khoan

DMM Column Overlap Pattern (Deep soil mix retaining wall )


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Slide 38

S cung cp va bm

ca thit b trn t


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Slide 39

Bn v tng chn bng BTCTlin kt vi cc xi mng t


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Slide 41

Cc ng dng ca trn su( Terashi, 1997)

8/ bin. 9/ Ngn nc

1/ng b, n nh/ln. 2/ n nh cao. 3/ M cu.

4/ Thnh ho. 5/ Gim nh hng tcc cng trnh lncn

6/ Chng nng y ho

7/ Chng chuyn dchngang ca mng cc.


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Slide 42

Gia c nn h mng cng

(Ngun Toa Corporation, Tokyo, Japan)


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Slide 44

S tnh ton n nh trtca mi dc c gia c bng cc XM


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Slide 45

Quy trnh th nghim trong phng vCc loi th nghim

thit k cc xi mng t ngoi nhng th nghimkhoan kho st ngoi hin trng nn c mt s thnghim km theo nh sau:

Th nghim xuyn tnh c o p lc nc l rngCPTU

Kt qu phn tch ho nc Th nghim nn c kt

Th nghim hn hp xi mng t ( xc nh hmlng xi mng s dng cho gia c)

Th nghim ct cnh Th nghim trn t ti ch vi xi mng theo tiu chun

ca Thu in


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Slide 48

Cc th nghim hin trng

Sau khi khi thi cng ngoi hin trng cn c mt s th nghimhin trng nh sau:

Th nghim xuyn ct tiu chun, c chia thnh 2 loi: xuynct thun v xuyn ct nghch.

Kt qa th nghim sc khng ct c so snh vi kt qu thnghim trong phng. Gi tr hm lng xi mng c chp thunl gi tr sao cho cng khng ct ca ct tng ng vikt qu phng th nghim.

Th nghim nn ngang Th nghim nn tnh mt ct Th nghim o ct Th nghim cht ti trn mt ct Th nghim cht ti ton phn o ln trn hin trng o p lc nc trong khi g i ac o ln theo su ca tng t ca khi gia c v.v


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Slide 50

Kch thc cnh xuyn


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Slide 52

Mt s kt qu th nghim(Ngun KELLER Ground Engineering)


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Slide 57

Tnh ton cc xi mng t

Bi ton gia ct c 3 tiu chun cn c tha mn:1. Tiu chun cng : C, ca nn c gia c phi

tha mn iu kin sc chu ti di tc dng ca titrng cng trnh.

2. Tiu chun bin dng: M un bin dng tng cann c gia c phi tha mn iu kin ln ca cngtrnh.

3.iu kin thot nc: p lc nc l rng d trong tcn c "gii phng" cng nhanh cng tt.


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Slide 58

L thuyt tnh ton

Hin nay c 3 quan im:1. Xem ct xi mng t v nn t thin

nhin cha gia c cng lm vic ngthi - Nn tng ng.

2. Xem ct xi mng t nh ct n chulc- Tnh ton thit k nh mng cc.

3. Tnh sc chu ti th theo mng cc,tnh bin dng th theo nn tngng.


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Slide 59

L thuyt tnh ton

S dcc quan im trn cha thng nht bi v bnthn vn phc tp, nhng nghin cu v l thuytv thc nghim cn hn ch. Ngoi ra cn c xutcch tnh ton nh sau:+ Tnh sc chu ti ca mt cc nh cc cng.+ Tnh s cc cn thit (Cn c lc tc dng, kh nngchu ti ca t gia cc ct).

+ Ty thuc t l din tch thay th gia ct v t tnh ton tip:- Nu t l ny >20% thi coi khi t+Cc l mt

khi v tnh tan nh mt khi mng quy c.- Ngc li th tnh tan nh mng cc.


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Slide 60

Cng thc thit k theo quan imnn tng ng

Cc xi mng t v t nn chung quanh (chag iac) c xemnh l 1 loi nn tng ng ng nht vi cc tnh cht c l Ct,t, qut, Et c tng ln.

t= ac+(1-a)n : gc ni ma st tngng

Ct= aCc+(1-a)Cn : Lc dnh tngng

Sut= aSuc+(1-a)Sun : Lc khng ct khng thot nc tngng

Et= aEc+(1-a)En : M un n hi tngng

Trong a l t l din tch ca cc xi mng t chim ch trn tnn:

Ac l din tch ca t nn thay th bi cc XM, An l din tch cat nn cng iac.

n

c

A

Aa =


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Slide 61

Kim tra 2 tiu chun

Kim tr abn : theo sc chu ti ca nn tng ng Pgh sc chu ti gii hn ca khi t nn tng ng

Fs h s an ton, ty thuc vo quy m, tnh cht ca cng trnh

Kim tra bin dng ca cng trnh: theo ln ca cng trnh. ln ca nn gm 2 thnh phn:

Ln trong khi t c gia c S1

Ln trong lp t pha di khinn tng ng S2

Kim tra:

Si : ln tng cng ca mng cc XM

Sgh : ln cho php ca cng trnh

s

gh

F

P

P

max

[ ]ghi SS

Ti trng phn b, q

21

S2

21

S1

H


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Slide 62

Kimt rasc chu ti ca lp t yucn c x l

Biu thc tnh ton Rtctheo TCXD 45-70:

m: H s iu kin lm vic m

b : B rng cnh mng nh nht (gi nh) (m)

h: su chn mng d kin (m)

: Trng lng ring trung bnh ca t nm trn y

mng (T/m2) ctc : Lc dnh n v ca t nm di y mng

(T/m2)

tcGc ni ma st tiu chun (o)

A, B, D: H s ph thuc gc ni ma st ca lp tnm di y mng

])[( DcBhAbmRtc ++=


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Slide 63

Kim tra sc chu ti ca lp t yucn c x l

Cng thc tnh Rn

theo TCXD 205-1998:

Rn = 1 ( .d.N+ .h.Nq + C.Nc)

Trong : : Dung trng t nhin ca lp t

Rn : Cng chu ti ca t nn

d : ng knh mng

C : lc dnh ca t nn

h : chiu dy tng t yu

FS - H s an ton (ly FS = 2)

N, Nq , Nc : Thng s sc chu ti ph thuc vo gc ma st trong ca

t nn


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Slide 64

Kim tra cng chu ti ca cc XM

Cng thc tnh sc chu ti ca cc XM theo t nn

Vi (TCXD:205-1998) Qs l sc chu ma st ca thnh cc:

Cv : l lc dnh v ma st trong gia cc v t nnu : l chu vi ccli : chiu d i cc trong lp t th i : trng lng ring ca lp t th i

Qp l sc chu mi ca cc: Qp = Ap.qpvi Ap l din tch mi cc v qp l sc chu ti ca t nn dimi cc:

qp = 1 (.d.N+ .h.Nq + C.Nc) : trng lng ring ca lp t ti mi ccFSs , FSp: l cc h s an ton

+= iiiS lChuQ )tan)sin1((

P

P

S

SaFS

Q

FS

QQ +=


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Slide 65

Kim tra cng chu ti ca cc XM

Hoc tnh theo cng thc:Rc= 2c+ 3h

Vi:Rc: Cng chu ti ca cc

c : cng khng ct ca cc (d kin l17.5 Tn/m2)h: Gi tr ng sut ngang tc dng ln thnhcc (th nghim nn ngang)


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Slide 66

Cng chu ti ca ton khimng c gia c

S dng cng thc tnh Rn theo TCXD 205-1998:

Rn = 1 (.d.N+ .h.Nq + C.Nc)

Trong : - Dung trng t nhin ca lp t

Rn: Cng chu ti ca t nn

d- ng knh mng

C - lc dnh ca t nn

h - chiudy tng t yu cn x l

FS - H s an ton (ly FS = 2)

N, Nq , Nc Thng s sc chu ti ph thuc vo gc ma st trongca t nn


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Slide 67

Tnh ln ca bn thn khi g iac

ln S1

ca bn thn khi gia cc tnh theo cng thc:

Trong :q - ti trng cng trnh truyn ln khi gia c (kN);H - chiu su ca khi gia c (m)a - t s din tch, a = (nAc / BL), n- tng s tr, Ac - din tch titdin tr, B, L - kch thc khi gia c;

Ec- M un n hi ca vt liu tr; C th ly Ec= (50100) Sctrong Sc l sc khng ct ca vt liu tr.En - M un bin dng ca t nn gia cc tr. (C th ly theocng thc thc nghim En = 250qu, vi qu l sc khng ct khngthot nc ca t nn).

Ghi ch: Cc thng s Ec, Sc, En, qu xcnh tkt qu thnghim mu hin trng cho kt quph hp thc t hn.

nctb EaaE

qH

E

qHS

)1(1

+==


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Slide 68

Tnh ln ca t nn di khi gia c

ln S2c tnh theo nguyn l cng ln tng lp(xem ph lc 3 TCXD 45-78). p lc t ph thmtrong t c th tnh theo li gii cho bn khng gianbin dng tuyn tnh (tra bng) hoc phn b gimdn theo chiu su vi dc (2:1) nh hnh C.1.Phm vi vng nh hng ln n chiu su m ti p lc gy ln khng vt qu 10% p lc t tnhin( theo quy nh trong tiu chun thit k nn nh

v cng trnh TCXD 45 - 78).

Ghi ch: thin v an ton, ti trng (q) tc dngln y khi gia c xem nhkhng thayi sut chiucao ca khi.


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Slide 69

Thng s thit k cc XM

ng knh cc XM, d Mng li b tr cc

Mt v hm lng xi mng

Chiu su gia c bng cc XM: H

Dung trng lp t p nn tb Hot ti tc dng ln cng trnh q


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Slide 74

Ht

tinh toan coc xm dat

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