chuong 6.PDF

192 THf NGHIEM oAT HICN TRUdNG VA IJNG DUNG TRONG PHAN TICH NEN M6NG.. 194 THf NGHTeM DAr HtgN TRUoNG vA IJNG DUNG TRoNG PHAN TfcH NEN MoNGdC bi ph6 hoai khi c6 tii trong d6ng... 1 9 6 T

CHUONG 6 CAC THINGHIEM KHAC 1 9 1

Thuy Di€n vi ngdy nay v5n rdt th6ng dung 6 chAu Au Ta c6m v)o rrong ddt s6t motc6nh chfr thAp bang th6p, sau d6, quay ciinh chti thAp quanh truc cira n6 vh do m6menxo6n Ta tinh duoc rirrg sudt tidp t, tir d6 c6 sLlc khiing cat khong tho:it nuric S,, (tuc lIc") cira ddt s6t (rp,, = 0)

trong d6 o'n - irng sudt birn thAn theo phuong ngang (vi cdnh chLi thdp cirt

O ' h = K o 0 ' u n

Do ta khdng biet Ko n€n cfrng kh6 xirc dinh chinh x6c q

tru trdn

6.1.2 THtEiT B! vA cAcH THf NGHTEM

Hi0n nay c6 kh6 nhitiu loai thidt bi cit ciinh kh6c nhau Dudi dAy, chfng roi rrinhbly hai loai chinh:

6 hinh 6.1) Loai n)y chi thi nghi0m dugc o dd sAu

Al cdnh c6t xudng dAt;

Chinh vbng doc kdt qui vd 0;

o Quay tay quay dd c6t dat Luc dinh

khdng tho6t nudc S" s€ duoc hidn thi tr€n

hidn thi tr6n ddng hd

2)Loai ghi dd thi l€n giay v€ (cdn goi ld cit

c6nh co hoc, MVST - Mechanical Vane Shear

Test - minh hoa 6 hinh 6.2) Trinh tu thi nghiOm

nhu sau:

An c6nh c6t xudng ddt;

Liip gidy vE hinh trdn vdo bhn v€ (hinh

6.2b) Vbng trbn n6t minh ngoii cirng

Model H-60 Hinh 6.1

trdn, th) kim tr0n bin vd cflng quay vd v6 l€n dudng dAm n6t o h)nh 6.2c;

o Quay tay quay vdi tdc do 1 vbng/gidy Do h€ thdng b6nh rlng chuydn ddi, cdnciinh cit chi quay v6i toc do 60/phul;

Hinh 6.2 Thi nghi6m MVST a) Crinh c5t; O) Cidy v6 hinh trdn; c) Circh tinh T qu6 ngin, thi r thudng bdng 0, do d6, khOng cdn do g6c 1 50 nhu hinh v6

192 THf NGHIEM oAT HICN TRUdNG VA IJNG DUNG TRONG PHAN TICH NEN M6NG

An ci{nh c6t xudng dAt;

Chinh vdng doc kdt qui vd 0;

o Quay tay quay dd c6t ddt Luc dinh

khdng thodt nudc S, s€ duoc hidn thi tren

hidn thi tr€n ddng hd

2)Loai ghi dd thi l6n giay v€ (cbn goi lb cit

ciinh co hoc, MVST - Mechanical Vane Shear

Test - minh hoa 6 hinh 6.2) Trinh tu thi nghiOm

trbn, th'i kim tr6n bdn vE cfrng quay vh vd l€n dudng dAm n6t o hinh 6.2c;

ciinh cdt chi quly v6i toc dd 60/phl1t:

Hinh 6.2 Thi nghi€m MVST a) Crinh c5t; n) Cidy v6 hinh tron; c) Crlch tinh T qu6 ngin, thi r thudng bing 0, do d6, khOng cdn do g6c 150 nhu hinh v6.

Lrru y: N6u doan cdn

CHUONG 6 CAC TH[ NGHIEM KHAC 02

cdn quay mh ciinh cirt kh6ng quay Nhu vAy, luc do duoc (tuong duong doan r

cfra ciinh cit;

Ndu coi ting suat cat tren hai mit (driy vir clinh) cua hlnh tru dit bi cit l):

d i r t ( n h < l r r o c " f ' = 1 2 5 i a ' - r ' ) , r , ' i 1 < k r d d t i n h d u o c S , , , b i t t g c t i n g t h ( L c 6 ' l :

f r - r l l r

rl o'

; | ? - ;,o-d)r(tancr + t:rn ft +2)

194 THf NGHTeM DAr HtgN TRUoNG vA IJNG DUNG TRoNG PHAN TfcH NEN MoNG

dC bi ph6 hoai khi c6 tii trong d6ng

Bjerum cho ring, cdn phii hi6u chinh sfc kh6ng cit S, nhu sau:

trong d6, u phq thudc vdo chi s6 d6o cua dat dinh nhu & hinh 6.3

r Th6ng thudng, clvsr! 3,22 + 3,54;

Tidn hi\nh ngi6n crlu rr0n ddt sdt Thuy didn, Hanbo cho rdng:

I

< o

I I

+

-l." s

222 crusr

Lf- i

CHUONG 6 CAC THI NGHIEM KHAC

trong d6

LL (hay wr, hay w.n) - gi6i han chiy;

Neu don giin, ta c6 thd ldy crur = 0,9

Thf nghi€m cit c6nh c6 dd tin cay tuong ddi tdt Cdc sai s6t c6 thd c6 do thi

6.4 minh hoa thiet bi mfri xuy€n bdc

1 9 6 THINGHTEM oAr nrqru TRUdNG vA IJNG DUNG TRoNc PHAN TfcH N€N MONG

6.3 THi NGHTfiM cAr rRoNG H6 rown

Thf nghi0m c6t trong h0 Iowa (Iowa Borehole Shear Test) lh thf nghi€m duy nhAt

Flinh 6.5 minh hoa thidt bi c6t trong hd, gdm hai c6nh c6 khia rdnh Trinh tu thf

tit mfri khfa rdnh l6n thhnh hd khoan nhd 6p luc khi n6n Nhu vAy, dung cu sE tu

o Quay tay quay dd tr4c dung ring sudt c6t t ttr mfri c6 khia rlnh l€n ddt o thdnh

hd khoan Trong qui{ trinh quay nhu vAy, dung cu sE di chuydn dung dung l€n

6.4 CAC THi NGHIEM DIA VAr IY

hi€n tuong vat li nhu su truydn di€n, su truydn s6ng 6nh s6ng, s6ng Am thanh, v.v Nhirng thi nghidm dia vAt lf th6ng dung li: thi nghi€m phin xa dia chan, thi nghiOm

vAt lj x6c dinh duoc bd ddy c6c lop ddt 6 hdu nhu todn b6 mat ddt Day chinh ld m

kh6c

thOm c6c ln phdm ctra US Army Corp tai website sau:

PHAN PHU LUC 197

Ndu ta c6 l"*, (i = I + N) ld dey ci{c sd 1i6u

Gi6 tri trung binh:

D0 l€ch chudn:

H€ sd thay ddi(Coefficient of variation):

PHU LUC 1 VAI KHAI NIEM THONG KE

ToM rAr vE cAc THI NGHIEna nIEru TRUoNG

ta thdy, thi nghi€m DMT vI ECPT c6 d6 tin cAy cao rrhat

Bdng P2 T6m tit rru, nhuoc didm cria c6c thi nghi6m hi6n truong

+ Xuy6n qua moi dat

+ Ldy dugc mau ddt

+ DU b5o stlc chiu t6i

( c o c , m 6 n g n 6 n g ) , 9,

su

+ Chinh x6c + N h a n h + D{ bdro loai (tdn) ddt + DU b5o srlc chiu t6i (coc m6ng nong), <p, S"

+ Chinh xac + R6 tidn + D o n g i 6 n + D\r b6o loai (t6n) ddt + DU b6o mOdun E, dd ltrn + it xeo dong ddt

+ Thi nqhidm tinh

+ DLr b5o m6dun E, do

+ Thi nqhi6m b6n tinh

+ M6i, chua biSt ddn d Vi6t

N a m

+ CUc kyphfc tap+ [t rlrng

d u n gKhdnq ldv duoc m5u ddt

1 9 8 THI NGHIEM DAT HIEN TRUdNG VA UNG DUNG TRONG PHAN TICH NEN M6NG

PHU LUC 3

TOM TAT CEC DAC TRUNG VA UNG DUNG

Ghi chil: Tuy thudt' dO t:hrit vd dp lttc l|n mdu dAi, en c6 thd l6n hon g,, tt 0 d|it

thiet ke' Do d6 voi cdc loai cdt chdt, ta cd thd tril bot ili vdi iI6 khi ufuc tinh g6c qtheo tdi liAu ndv

Bdng P3 Tuong quan gi[ra c6c dic trung co li

Su: srlc kh6ng c5t khong thorit

ntl6c Su/o'uo ! (0,23 t 0,04) OCR0'8 (.22) lrung

PHAN PHU LUC 1 9 9

do srlc khdng q vi f, doddt tic dung lOn xuy0n

Bdng P4 G5c rirrg dung trr thi nghi6m CpTThi nghi6m xuy6n c6n (xuy6n tinh) - Cone penetration Test

o tra hinh 2.28: a = 3 + 11 v6i c6t cd kdt thuong

a tra hinh 2.29: tt = 5 + 20 v6i c6t rdt qud cd kdt

cr tra b6ng 2.6; a =1,5 + 2 (gop ydu td tU bidn) S6t: a tra b6ng 2.6 (SQp ydu td trl bidn)

S6t: M =8,25 (q, - o")

(Mayne) (Mayne) ( B a l d i ) (Jamiolkowski) (Sanglerat) (Sanglerat) (Mavne)

( 2 5 )

( 2 7 )

t : E = a q " ; tr a h i n h 2 3 0 , 2 3 1

200 THINGHIEM DAT HIEN TRUONG VA IJNG DUNG TRoNG PHAN TICH NEN MONG

a , = 0 , 5 q " o ' 6 1 1 (b a r )

^ = 30.1 o'*-0,08e-l,0aor

( l m a i v ) T o n o u c h i ) ( J a m i o l k o w s k i )

( 2 8 )

Q 9 \Trang

c 6 t : N ^ = N = 1 , 2 5 o ^ , " 2.26)

Tand, Funegard vd Briaud: s6t

Q,, = R, (Q" .o - o"^) + o.,^; Ru tra hinh 2.46 dJa tr6n R" = D- / B

PHAN PHU LUC z v l

3, Trr sd hi6u dr.tong cong vd q", tra hinh 2.49 tim f,

Theo DeRuiter vd Beringen

khdrng ben f,: tt-fong trJ Schmertmann, lay c = 0,0025 + 0,0033

kh6ng m0i 9o = trung binh q" tr6n hinh 2.52vit phurong trinh (2.38),

202 THf NGHIEM DAT HIEN TRUdNG VA IJNG DUNG TRONG PHAN TICFi ruEII IVIoIIC

D G i b b s & H o l t z h i n h 3 4 thSo

t r Ohya et al 1982 9 , 0 9 N o 6 6 ( 3 1 0 ) rdt thdp

( 5 + 1 5 ) N ^ o ( 3 9 ) t h a oE., sr!t Ohva et al 1982 ( 5 + 6 0 J N 0 ' 6 3 ; t r u n g b i n h l d 1 9 , 3 N 0 , 6 3 8 1 1 rdt thdp

Hara 1974 0 , 2 9 N 0 7 2 , b a r ( 3 1 S truno

I h i n h 3 i 3 _ Burland vd Burbridge; S =f" t [ (p" - 0,667o'") B0,7 l" , mm

q : D a n g J /

g o : b i n g 3 8 _ c h i 6 u s a u n g a m d 0 : b

Jttorg_qle-n QlIffl lang 2.5, bins 3.10 vd hinh 3.i9.

PHAN PHU LUC 203

Nguy€n lyi: irp luc lric mdng th6p khdng chuy€n vi l)r po;

iip luc lfc mlng th6p chuy€n vi ra ngoli

l , l m m ( d o k h i n 6 n d a y r a ) ld p , ;6p luc lfc ming th6p tro lai vi tri ddu l) p

( 4 1 4 )

( 4 1 5 )

k " = 0 , 5 ( B + 0 , 3 ) 2 5 l - x q o ' u n

2 B 7 , 5 m r n K 0

204 THf NGHIEM OAT HIEN TRUdNG VA UNG DUNG TRONG PHAN ThH NEN M6NG

s e t q i d ( S , , / o ' , , ^ > 0 , 8 ) : K n = 0 , 6 8 K n o 5 a

( 4 1 B )( 4 1 e )G.20),

O C R s e t

s e t q i d ( S , , / o

u o < 0 , 5 ) : O C R = 0 , 3 K D 1 ' 1 / ' , ^ > 0 , 8 ) : O C R = 2 , 7 K n l ' 1 1

( 4 2 1 ) (4.22\

f , , )

PHAN PHU LUC 205

P H U L U C 4

(doan congZY vdYZ 6 hinh P.l) tr mdt cap lon hon p (rip luc ti€n co ket) u6c dodnban ddu

Ta cdn thuc hi€n ciic budc hiOu chinh sau:

Budc l: Xdc dinh dp luc ti6n co kit p, (Casagrande):

o V6 doan PR ld phAn gi6c cira g6c TPQ;

nghi€m O;

tidn cd ket (rnrg sudt co kdt trudc) p (hay o'n)

Budc 2: Xdy dung dudng cong @ (Schmertmann):

phdn td ddt dang x6t tai hi0n trudng; e,, ll h€ sd r6ng ban dAu tai hi4n ftudng;

Budc 3: Chinh xdc thdm cdc thong so (Schmertmann):

206 THINGHIEM DAT HIEN TRUdNG VA U'IG DUNG TRONG PHAN TICH NEN MONG

doan sV khdc di) Dudng cong c6 dang doi xfng qua p niry cdn goi lr duimg

PHAN PHU LUC

P H U L U C 5

THi NGHtEtvt ttEtt riruH coc

n6n tinh coc di duoc tr)nh biy chi tiet trong nhidu girio tr'inh Do d6, & day, chring t6i

log-1og Ndu tren dd thi c<i hai doan gAn thing 16 rdng nhu hinh v6, thi giao cria hai doantudng rrng v6i sfc chiu tiii huy ddng Pn,,

Trong vi du tren hinh P.2, Pro= 190 tan, taid6, A = 8,5 mm

thang 16 r)ng nhu hinh P.2, do d6, kh6 xdc dinh Pno

t s I

-t _ _

I I

\

I I

t s I

I I

Hinh P.2 Phudng phip DeBeer

208 THf NGHIEM DAT HIEN TRUONG VA I]NG DUNG TRONG PHAN TICH NEN MONG

o F lI tiet dien coc (mr), E li m6dun cl)n hdi cira coc (kN/mr), t, lh chidu cl)i coc( m n 1 ) ;

PHAN PHU LUC

Phan ttch mt di4'm ciia phuong phdp Davisson:

Ta x6t vi du trdn hinh P.3, ngodi ra ta cbn biet coc d)ri 30 m, tiet di6n 0,40 x 0,40

= 0,16 m' Than coc dit vlo ddt tot M[i coc dit vdo lop dat cdt, thf nghi€m SPTcho

Itin (dn dinh tai cdp tii ndy) ld 8 mm O;

Theo cdch tinh phd bii'n o nudc ta hiin nay:

Srlc chiu tii cuc han lh tii trong n6n tinh m) tai d6 do lf n bang { [Sl

[S] = 40 + 80 mm (do hin cho ph6p cia cong trinh);

Nhu c6ch t(nh 6 vi du ndy thi Q" = 150 tdn (vi 8 mm = € [Sl);

chuydn vi, holc chuydn vi rdt it Do d6, 150 tan n)ry hdu nhu chi bao gdm srlc kh6ng

Nhu vAy, chuydn vi o mfri coc (ddu du6i cfra coc) li 23 - 10,5 = 72,5 mm Dudi

209

2 1 0 THf NGHIEM DAT HIEN TRUONG VA IING DUNG TRONG PHAN T[cH NEN MONG

PHAN PHU LUC 2 1 1

\ ^

TAt LIEU THAM KI"IACI

1 G SANGLERAT, M PETIT-MAIRL, F RARDOT, I'.SAVASTA AMAP'SOISstatic penetration in dense sandy gravel, sandstone and hard claystone

2 P.K ROBERTSON Soil classification using the cone penelration test

3 JEAN-LOUIS RIAUND, JEROME MIRAN The cone penetration test Federal