chuong 5.PDF

1 8 0 THt NGHTcM 0Ar HreN TRUdNG vA UNG DUNG TRoNG PHAN T[cH NEN MONG.. Da sd ld thf nghi€m trong hd khoan sin, trit hai loai Pencel v Tu khoan.. CHUAN BI THIET BI 5.2.2.L Lim b6o hoi hg

CHUONG 5 THf NGHIEM NEN NGANG PMT I I Y

CHUONG 5

T H I N G H i t r M N E N N G A N G P M T

s 1 G t O t T H r F U

Thf nghi€m PMT (PressureMeter Test) ra ddi trr-r6c thi nghi€m DMT, c6 nguyen lli vd c6c ket quA, c6c fng dung tudng tu thi nghidm DMT, tuy nhi€n phfc tap hcrn rar nhi6u so v6i DMT C6 vi\i didm kh6c biet vd nguy€n ly dLroc thd hien tr€n bang 5.1.

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Dat dudc nen ngang bdi

c h u y d n v i c i a m d n g th e p

C h u y e n v i l a c o d i n h : 0 ;

1 , 1 v a 0 m m

Ddt dudc n6n ngang b6i chuydn vi c0a v6 ciic la thep xep vong quanh 6ng PMT (b6n trong co mang cao su cufng, la thep c6 nhiem vu b6o v6

C h u y d n v i d u d c x a c d i n h q u a l u o n g n U 6 c b o m v d o T u y n n i e n , fL r o n O

I

n u 6 c c o s u m a t m a t d o s r J g i a n n d c 0 a h o p d i d u k h i d n , 6 n g P M T , c A p j d5n nlr6c, v.v Do do, qqelfrnn cf'udn noa rdt rm ]

5 1 2 L | C H s 0 C ( J n T H f N G H t f i m n r U r

Ti nhlrng nam 1930, Kogler dI bit diu thu nghiCm v6i thiet bi tLrcrng tu nhrr PMT Tuy nhi6n, den tdn n[m 1957, PMT m6i thuc su chinh thfic ra ddi qua luAn irn Thac s! cfra Louis Menard, tidn h)nh tai Dai hoc Illinois (My), vh thiet bi ba buong cfra 6ng duoc dit tdn ld Menard PMT Sau d6, Menard tr6 vd qu0 huong Ph6p, vi Phrip

ld nudc mh PMT duoc tien hinh nhiOu nhat.

PMT le thi nghi€rn hi€n trulng c6 nhidu version ("ddi") khdc nhau nhift:

o Menard PMT loai E, th( nghiOm "kidm sorit iip luc";

Menard PMT loai GC, thi nghiOrn "ki€m soilt :hp luc";

TEXAM PMT, thi nghidm ci loai "ki€irn sodt dp lrrc", hodc cir loai "kidm soiit thd tich";

P c r r c e l P M T , rh i n g h i d m " k i e m s o i i t t h 0 tf c l r " :

B a n g 5 7 N g u y 6 n lf t h i n g h i e m

i 6 n n d l a k h i

1 8 0 THt NGHTcM 0Ar HreN TRUdNG vA UNG DUNG TRoNG PHAN T[cH NEN MONG

Thf nghi0m tu khoan PMT (Cambridge cira Anh, PAFSOR cira Phrip);

Vi nhidu ddi kh6c.

C6c ddi ndy c6 su ldm vi6c khdc nhau Da sd ld thf nghi€m trong hd khoan sin, trit hai loai Pencel v) Tu khoan.

5.2 Nor DUNG THi NGHIf;U nUr

PMT la thi nghi€m rdt phrlc tap (ri€ng phdn chudn bi vd chudn ho6 thi€t

bi, ndu n€u ddy dtr phii mdt 30 + 40 trang gidy) PMT khdng phd bidn l6m <r

nhidu nudc, k6m uu viOt hon hin so v6i DMT Do d6, trong phdn ndy, chfng

tdi chi trinh bhy vdn tit hai loai PMT: Pencel vd TEXAM.

H i n h 5 1 B u d n g P M T ( d a n g g i A n n 6 )

5.2.1 CAC THANH PHAN CON THIET B!

Ciic thlnh phdn cira hai loai thi nghiem tren duoc t6m tit trong bAng 5.2.

Thidt bi gia luc vd xuyen (thuong dirng chung

v6i CPT)

Hop tlidu khidn 6p luc-thd tich (hinh 5.2)

P M T o d n v 6 i m 0 i x u v € n

t

I

1

u l ,

1 , '

F I

t r S kf

fl,i

I

t

- f f

Y',

t"'

Bdng 5.2 C6c thinh phdn cria thiet bi

r Thiet bi khoan 16, thidt bi got tia 16 khoan

r HOp didu khidn: pittong, d6ng hd, tay quay ( h i n h 5 3 )

P M T (h i n h 5 1

Hinh 5.2 Pencel

CHUONG 5 THf NGHIEM NEN NGANG PMT

)

5.2.2 CHUAN BI THIET BI

5.2.2.L Lim b6o hoi hgp didu khidn

Dd bidt duoc luong dung dich bom vdo, hop didu khidn cdn phii du-o c bdo hod holn todn, qu6 trinh nhy duo c trinh bdy trong bing 5.3.

Bdng 5.3 Qu5 trinh bio hoir hQp didu khidn

5.2.2.2 Ldm b6o hoi ddng h6 ap luc (kh6ng cdn v6i Pencel)

l DAy den cim vdo ciing l:

2 Chinh van 8 vd "Ch?y v6i ddng hd 6" Ddy pittOng ddn khi ddng hd chi 96crn3, dim bAo dd khOng thdy bong b6ng ra kh6i ddu d1y den;

3 Th6o dAy den;

4 Chinh van 9 vd "ddng hd 6" Ddy pittong ddn khi ddng hd chi 192 cm3;

5 Chinh van 8 vd 9 vd "ddng hd 7" Ddy pittdng ddn khi ddng hd chi 288 cm3;

6 Chinh van 8 vd "Chay vdi ddng hd 3", van 9 vd "Chay" C6m day den vdo cdng 3 Ddy pittong ddn khi ddng hd chi380 cm3;

7 Chinh van 8 vd "Fill" K6o (hrit) pittong quay lai 0 cm3 Chd 1 phrit;

8 Lap lai bu6c 6 vd 7 6 phdn 5.2.2.1 dd 6p bong b6ng khf ra;

9 Kidm tra dO b6o hoi nhu phdn 5.2.2.4.

1 8 1

1 Chinh d6ng hd ap lrrc vd 0

2 D6y ngin: mot ddu cdm vdo cdng 1

("Fill-bleed"), ddu kia c5m vdo binh nu6c (binh

n g o d i )

3 Chinh van 3 vd "Fill-Bleed", d6ng van s6 4

4 Ddy pitt6ng (dd ep khi ra ngodi) ddn khi ct6ng

hd thd tich chi 138 cm3

5 K6o pittdng (hr.it) (60 vdng/phrlt) ddn khi

ddng h6 vd 0 cm3 ad nut nu6c tir binh nu6c

viro

Ddy pittong dd ep nhirng bong b6ng

ngodi, d6n khi d6ng hd chi 100 cm3

L5p lai bu6c 5 dd hUt nu6c

1 Chinh ddng hd ap luc sd 6 vd 7 vd 0

2 DAy ngSn (mdu trSng): m6t ddu cdm vdo cdng

4 vd 5, ddu kia c6m vdo binh nrr6c (binh

n g o d i )

3 Chinh van 8 vd "Fill" van 9 vd "Test"

4 Ddy pittong(quay tay quay nh6 dd ep khi ra

n g o d i ) d d n k h i d d n g h d t h d t i c h c h i 1 7 3 2 c m 3

5 K6o pitt6ng (h0t) (45 vdng/phrit) ddn khi d6ng hd vd 0 cm3 ad trut nu6c tar binh nu6c vio

6 N g h i 6 n g h 6 p d i 6 u k h i d n k h o 6 n g 1 5 0 D d y pitt6ng dd ep nhlng bong b6ng khi ra ngodi, ddn khi d6ng h6 chi 192 cm3

7 Od hop di6u khidn thSng lai Ldp lai bu6c 5 dd h[t nut6c Sau do, doi 30 oiav

182 THf NGHIEM OAT UIEH TRUdNG VA UNG DUNG TRONG PHAN TICH NEru U6ruC

5 2 2 3 L i m b 5 o h o i b u d n g P M T

Tuong tu nhu trOn, qud trinh bfro hoir budng PMT duoc trinh bhy trong birng 5.4.

B d n g 5 4 Q u 6 t r i n h b i o h o i b u d n g P M T

3

L:

P e n c e l

1 Ndi bu6ng PMT v6i cing (cap) d6n nu6c Ddt

bu6ng thing drrng Noi d6y (clai 10 m) vdi

c o n g z

2 C h i n h v a n 3 v d 4 v d " C h a y " O d y p i t t O n g 6 p

nu6c vdo budng PMT den khi ddng hd chi

i 30 cnr3

V a n 3 6 " F i l l - B l e e d " , d 6 n g v a n 4 K e o ( h r l t )

pitt6ng Od nut nu6c vdo hOp didu khidn

Lbp lai buoc 2 vdr 3

I n a o o a y K n o r c o n g z

Kiejm tra d6 bao hod nhr-t phAn 5.2.2.4

P e n c e l

1 V a n 3 v d 4 6 " C h a y "

2 Ddy pittong t6i 6p h/c ld 2500 kPa

Qua trinh bao hod ld chudn ndu:

o D6ng h6 thd tich chi < 5,0 cm3

Sau 2 phrLt, 6p h-tc v5n l6n hon

2000 kPa

4

5

6

1" Noi budng PMT v6i ong (cirp) d5n nrrdc Ddt budng hoi nghi6ng d{rng N6i day telecan v6i cdng 'l

C h i n h v a n B v d " C h a y v6i ddng nd 6", van

9 vd "Chay" Ddy pitt6ng 6p nr-rdc vdo bu6ng PMT ddn khi chl c6 nu6c (kh6ng bot) di vdo budng

Od nu6c ch6y kh6i budng ddn khi bu6ng trd lai kich thrj6c ban ddu

T h a o d 6 y T e l e c a n k h 6 i c d n g 1 Van 8 6 "Fill" Keo pitt6ng dd htt nd6c vdo cho tdi khi ddng h6 chi 0 cm3" Cho 1 phut Kidm tra do b6o hod nhu phAn 5.2.2.4

Thiio dav trinq khoi 4 v a 5

1 C h i n h v a n 8 v d " C h a y v6i d6ng hd 6", varr 9 v6

"chav".

Quay tay quay ldn den dp [/c 2500 kPa Ddng hd thd tich chi < 18 cm3 thi b60 hod ld t6t

C h u y d n v a n 8 v d " d d n g hd 7" Quay tidp l6n 10000 kPa Sau 2 phtit, 6p luc (tr6n ddng hd 7) v5n phii l6n

h o n 9 5 0 0 k P a GiAm 6p tr,rc vd 2s0o lea

C h i n h l a i v a n 8 v d " C h a y v 6 i d d n g h d 6 "

5.2.4.4 KiSm tra do b5o hoi

Su brio hot\ cia h6p didu khien vir budng PMT du-o c kiOrn tra nhu trong bing 5.5.

BAng 5.5 Ki6m tra d6 b6o hoi

G i i m 5 p I v 6 0

CHUONG 5 THI NGHIEM NEN NGANG PMT 1 8 3

5 2 3 C H U d N H O A THTET B !

5 2 3 1 H i Q u c h i n h 6 p t u c :

Dat budng PMT thang dring trong khOng khf, muc dich ld do 6p

khdng lai dd cfng cira bin than budng pMT (hinh 5.4) Sau d6 thao t6c

5 6

luc cdn c6 dd tiep theo bing

BAng 5.6

1 Van 3 vd van 4 6 "Chqy"

2 V6i 16 thep mdi, bdm vd hut budng pMT 5 tdn,

m6i t6n 90 cm3

3 Bom 90 cm3, tdc d6 1 vdng/9 gi6y Ghi lai 6p

luc m6i khi thd tich tdnq 5 cm3

1 Van 8 6 "Cnay v6i d6ng hd 6,', van 9 d

"chav"

2 Bom 1200 cm3, tdc d6 1 vdng/2 gi6y Cho

30 gi6y, sau do ghi lai 6p ltrc m6i khi thd tich tdng 60 cm3

3 G i 6 m 6p tuc v d 0.

4 Ve dudng cgng D d hinh 5.4 5.2.3.2 Hi6u chinh ttrdtictr

Dat budng PMT trong mOr 6ng th6p diy (ducrng kinh cfia dng

dudng kfnh budng) Mqc dfch ld do su mdt m6t thd rich do su ci

khidn, dAy d6n nudc vi budng pMT.

TEXAM voi

;i nhinh hon ' , : r hdp didu

Van 8 6 "Chay v6i ddng hd 6", van

9 6 "Chay" Doc so doc ddng hd thd tich khi 6p tr/c td 0 kpa

Bom ddn 500 kPa Chd 30 gi6y rdi ghi lai thd tich m6i khi ap tuc tdng

50 kPa L5p tay quay t6n Bom tidp ddn 2500 kPa Cho 30 giey rdi ghi lai thd tich m6i khi 5p tr/c ting 50

k P a Gi6m rip vd 0 VO dlrong cong A 6

h i n h 5 5 Chuydn dudng A v6 duong C (di qua gdc toa do)

1 V a n 3 v a v a n 4 6 "Chav,'

2 Bom d6n 2000 kPa, toc d6 1 vdng/9 gi6y Ghi tai ap

luc m6i khi thd tfch tdng 5 cm3

3 Giim rip vd O VC dlrong cong A 6 hinh 5.S

4 Thao budng PMT, ddu d6y d5n s6 tu dlroc d6ng kin

Bom ddn 2500 kPa (do il6, chi c6 st/ gi6n n6 c0a ddy

d6n vd cria h6p didu khidn) Ghi tai 6p trrc m6i khi thd

tich tdng 1 cm3

5 Gi6m 5p vd 0 V6 drldng cong B 6 hinh 5.5

6 Dua vio A vd B v6

184 THINGHI€M oAT HIEH TRUdNG VA ITNG DUNG TRONG PHAN TICH NEN MONG

I g

Thd tich Hinh 5.4 Oudng hi6u chinh 6p lr,rc

Th6 tich Hinh 5.5 Duong hi6u chinh ttrd tictr

C6ch vE duong C (Pencel):

Xdc dinh didm E 0n didm bit ddu cfra doan tuydn tinh) tr0n dudng A;

K6o dei AE, cit truc hodnh tai K; V€ dudng EF nam ngang;

Ldy KH bang FG; VE bang tay doan EH;

Chuydn dudng cong AEH vd gdc toa do duoc dulng C.

5 2 4 T I E N H A N H T H f N G H I E M

l-t K

BAng 5.8

Xuy6n PMT b5ng h6 gia h-rc

V a n 3 v d v a n 4 6 " C h e y "

Bom 90 cm3, m6i cdp 5 cm3,

t6c do quay 6 + 7 vdng/phtit

Chd 30 gi6y, ghi lai 5p lr-rc

t Khoan ho, c5t tia frd Ha bu6ng PMT xuong hd Van 8 6 "Chay v6i ddng hd 6", van 9 6 "Chay"

2

"Kidm soat thd tich" "Ki6m soat 6p hlc"

3 Bom 1200 cm3, m6i cdp

60 cm3, tdc d6 quay

12 vdng/ph0t Cho 30 gi5y, ghi lai 6p h/c

3 U6c dodrn 6p hlc gi6i h?n p,- Bom 10 cdp,

m 6 i c d p 0 , 1 p , g h i l a i thd tich dd duy tri cdp 6p lrJc d6 tai thoi didm

30 vd 60 qi6v

4 Ndu c6 dd t6i ta qiim 6o trr trl vd ohi lai sd li6u nhrl 6 brr6c 3

CHUONG 5 THI NGHIEM NEN NGANG PMT 1 8 5

5 2 5 C H U A N H O A S O D O C

I COng rip luc ghi duoc o mrc 5.2.4 vdi chidu cao c6t nudc dp (tr) binh nuclc den mit

dat);

Sau d6, vO durrng cong E nhu d h)nh 5.6a;

Thd tich hieu chinh = thd tich do duoc (tr phdn 5.2.4) trU thd tich o durrng cong C (phdn 5.2.3.2) V€ lai duoc duoc cong F (hinh -5.6a);

Ap luc hi6u chinh = 6p lqc rr bu6c I tril di iip luc 6 dudng cong D (phdn 5.2.3.1).

VE lai duoc dudng cong G (hinh 5.6b);

p,, hay p'u ggi ld rip luc "ddu", tai didm bat ddu doan tuyen tinh Vdi thi nghi€m Pencel, th) khOng x6c dinh dugc p,,* vi doan cong trudc doan tuyen tinh kh6ng tdn tai (do d6, kh6ng biet doan tuyen t(nh bit ddu tir dAu);

Cdn vdi TEXAM, p,,, cbn c5 thd dutvc x6c dinh bang c6ch vO bidu dd tii bien;

p, li 6p luc "til bidn", tai didm kdt thric doan tuydn tinh V6i TEXAM, ta cung c6 thd ding c6ch ve bidu dd tir bidn dd xric dinh p,;

p'-ld rip luc tdi han:

Trong Pencel, 6p luc pr- tudng rlng vdi thd tich giln nd ld 100 cmr ;

Trong TEXAM, ilp luc pL tuorlg rmg vdi th€ t(ch v mI vr - Vo = vo * v (= L tren hinh 5.6b);

v,, ld thd tfch "ddu", x6c dinh o budc 5;

v ld thd tfch cira budng PMT c, trang thdi tu nhi6n.

2

a

J

4

5

6

7

- V

( b )

vf

( a )

Thd tich

Hinh 5.6 Hi6u chinh duong quan h6 dp h,rc - ttrd tictr

vlThd tich

1 8 6 Tdf NGHIEM OAT HIEN TRUdNG VA UNG DUNG TRONG PHAN TICH NEN MONG

5.3 uoc rlruH cAc cni lEu co Ly DUA rREN xdr ouA pMT

5.3.1 DU BAO MODUN BIEN DANG CtN OAr DUA TREN KET OUA PMr

Ti doan tuyen tinh tr6n duimg cong pMT, ta c:6:

( s l )

Trong phuong tr)nh tr€n, vdi dat cdt, Ern, ctruo c coi lh m6dun bidn dang thoiit nudc (E'); cdn v6i ddt sdt, E,,n, duoc coi ld mOdun dhn h6i kh6ng tho6t nu6c (E")

Ban ciAu, nhidu nhi nghi€n ctiu cho rang p, tuong ducmg v6i 6p luc titin co ket p'.,

do d6, h0 sd qui{ co ket crja dat s6t lI:

Tuy nhi€n, tu thf nghi€rn PMT tu khoan, ngudi ta cho rarrg cong thfc sau n€n duo.c dDng (Kulhawy v) Mayne, 1990):

OCR = 0,45 pr l a'u

po (hay pun,) duo.c coi lI 6p lLrc ngang dia tjnh, do d6 h0 sd

s i t l d :

trong d6

t/ P.r - tl.,

N n = ,

-o u,-,

p n - u' - iip luc ngang hi6u qui;

u , , - ip lqc rruoc lo r6ng:

6',,, - dp lqtc dring hi0u c1uri.

E n n , , - 2 , O 6 l r , + t " 1u' I P " - P'

L Z _ j V o - V r

s.4 Du BAO O0 lUn cOn MoNG ruoruC

DUA rREN xEr auA pMr

sri dung thf nghiOm PMT, ta c6 thd du b6o d0 hin c[ra m6ng n6ng nhu sau:

S = :-o,1 x0,6"1 2",, -:- , 9E,r [ " 0,6/

trong d6 B - be rdng m6ng, m;

o - he sd tir bidn, ldy theo bAng

n S a n g

( s 3 )

cua dlft

(s.4)

+ c t o ^ , 1 " ^ B m

9 E a F ' L

( 5 5 r

CHUONG 5 THf NGHIEM NEN NGANG PMT 187

tr., l.- h€ sd hi0u chinh hinh ddng, l{y theo bring 5.10-Neu h- < B (chidu sdu ch6n m6ng nh6 hon bti rong m6ng), thi d6 lfn s6 tdng ( l Z - 0 ? h - / B ) li n

Eo lb gi6 tri trung binh cfra E,,r, vDng 8B dudi ddy m6ng Ciich tinh trung binh rat dac bi€r (goi ld harmonic mean) du-o c trinh bly chi tidt bdi Centre d'Etudes Menard.

BAng 5.9 He so tdt bi6n

(.( E-.,, / o, cL E.-,,i p, cr E o / P , G E / n

ou6 cd kdt (OC)

1

> 1 6 1 > 1 4 2 t 3 > 1 2 1 t 2 > 1 0 1 1 3

cd kdt thudnq (Nc) 9 + 1 6 2 1 3 8 + 1 4 1 1 2 7 + 1 2 1 1 3 6 + 1 0 1 1 4

B d n g 5 1 0 H 6 s o h i 6 u c h ? n h h i n h d 6 n g

M 6 n q t r d n M 6 n q v u o n q L l B = 2 L / B = 3 L / B = 5 L I B = 2 0

s.5 D0 rN cAY cOn rHf NGHlEru Prur

S a i s o c u a P M T d u o c t 6 m t a t t r o l l g b i n g 5 1 l T h e o

( I996) thi thi nghi€m PMT loai trong hd khoan c6 COV = 0,1

( S B P M T ) th) c6 COV = 0,15 + 0,2-5 ( x e m phLr l u c I v d 2 )

Kulhawy vr\ T'rautmann + O - 2 - c d n l o a i t t t k h o a n

B A n g 5 1 1 T 6 m t i t n h f n g s a i s d c r l a P M T

Do thi6-t bi

Kich thu6c c0a 6no thdm

M d n o q i a n n d

6 n q d 5 n d u n q d l c h

V 6 i S B P M T : h i n h d 6 n q c & a o n g th d m , m O i c i t , t f r i e t b i k h o a n 1 6

D o t h i

n g h i 6 m

khoan vd cnudn bi 16 tni

T o c d o q i a n n d o n q t h b m

T h d i nqhi tru6c khi doc so doc

1 8 8 THINGHIEM OAT HIEN TRUdNG VA I.JNG DUNG TRoNG PHAN T[cH NEN MONG

l

2

a

J

Thi nghiOm PMT do 6p lqc tU ddt l€n mdng th6p/ cao su ctra dng tham PMT khi ta dDng nudc (hoac chdt l6ng kh6c) ddy mdng thdpl cao su 6p vd phfa dat.

PMT le I thf nghiCm crlc kj' phfc tap, thoi gian chudn bi thi nghi€m rdt ldu.

PMT le thi nghi€m n6n ngang, cho k6t quA lA quan hC "5p lqc - chuyin vi" cfia dat Tir PMT, ta c6 thd udc tinh m6dun bi€n dang cira dAt, du b6o d6 hin cira m6ng

vd du biio sric chiu tii theo phuong ngang.

Cfrng n6n luu 1i rang, cdc quan h0 thuc nghi€m thubng dua trOn dat tucrng ddi ddng nhdt (c6t holc s6t) Vi v4y cdn c{in thAn khi s[t dung PMT dd u6c tinh c6c chi tieu cho nhlrng ddt pha rap (c6t pha, s6t pha), holc ddt phong ho6 kh6c thudng.

4