C HC TGV: ThS. NGUYN ANH TUN

NI DUNG MN HCChng 1: BN CHT VT L CA T Chng 2: PHN B NG SUT TRONG T Chng 3: CC NH LUT C HC V TNH TON LN CHO NN Chng 4: N NH V SC CHU TI CA NN Chng 5: P LC T TRN TNG CHN

TI LIU THAM KHO1. C Hc t, NXB Gio Dc 2. Bi Tp C Hc t, NXB Gio Dc 3. C Hc t, Chu Ngc n, NXB HQG 4. C Hc t, Whitlow, NXB Gio Dc

CHNG 1

BN CHT VT L CA T

I.1 Qu trnh to thnh t:t c hnh thnh trn b mt tri t do s ph hoi v lm thay i thnh phn ca gc do tc dng vt l v ho hc qu trnh ph hoi ny gi l phong ha. 1.1.1 Phong ha vt l: b ph hy v bin i do cc tc nhn vt l nh nhit , gi b v vn thnh cc ht c kch thc khng u nhau nhng thnh phn khong vt v ha hc t b thay i. 1.1.2 Phong ha ha hc: b ph hy v bin do cc tc nhn ha hc nh nc, O2 v CO2 trong khng kh. Phong ha ha hc gy ra s bin i thnh phn ha hc ca cc loi khong vt cu to nn , do hnh thnh cc khong vt th sinh bn vng hn trong t nhin, cu to v tnh cht khc vi gc ban u.

I.2 Cc loi trm tch v c im ca n1.2.1 Tn tch: Sau khi b phong ha, t nm nguyn ti ch, cc ht ca n u c gc cnh v thnh phn ha hc khng thay i so vi gc. 1.2.2 Sn tch: Sn phm phong ha b nc ma, tuyt cun t trn ni cao xung lng chng hoc chn dc ri lng ng . 1.2.3 Trm tch: Cc sn phm phong ha s c nc, gi cun i nn c c im ht trn, cnh v thnh phn ha hc c s thay i ln so vi gc.

I.3 Cc pha to thnh t v tc ng ln nhau gia chngt l loi vt th ri, phn tn, khng lin tc nh cc vt liu khc. trng thi t nhin t l mt h thng phc tp bao gm cc ht khong vt b c kch thc khc nhau hp thnh. Cc ht ny to thnh khung kt cu c nhiu l rng, trong cha nc v kh. C th xem t gm 3 th (3 pha) to thnh: - Pha rn: Ht t - Pha lng: Nc trong t - Pha kh: Kh trong t

I.3.1 Pha rn:Chim phn ln th tch ca t v nh hng n tnh cht c l ca t, gm cc ht khong vt (ht t) c kch thc t vi cm n vi phn 100 hay vi phn 1000 mm. Tnh cht ca ht t ph thuc vo: Thnh phn khong Thnh phn ht _ Thnh phn khong: gm cc ht nguyn sinh v th sinh Nguyn sinh: Mica, thch anh, fenfat Th sinh: khong vt st, mica trng, thch cao

_ Thnh phn ht: Kch thc: Tn ht t c phn theo tng nhm ty thuc vo kch thc ca n.TN HT T ln Ht cui Ht si Ht ct KCH THC HT D (mm)

Ht bi Ht st

>100 100 10 10 2 2 0.1 0.1 0.005 19 kN/m3 = 17 19 kN/m3 < 17 kN/m3 = 14 16 kN/m3

n v: kN/m3; G/cm3; T/m3

TRNG LNG RiNG NO NC (BO HA)L trng lng ca mt n v th tch t trng thi no nc (bo ha - cc l rng cha y nc)

sat

Qs + w' Q = V

n v: kN/m3; G/cm3; T/m3

TRNG LNG RiNG Y NIL trng lng ring ca t nm di mc nc ngm c xt n lc y Archimde.

Qs Qw Qs Vs . w '= = V V

c s dng trong tnh ton nn mng khi phn t ang xt nm di MNN Khi mu t bo ho hon ton:

' = sat w ; w 10kN / m

3

TRNG LNG RiNG KHL trng lng ca mt n v th tch t trng thi hon ton kh

Qs 3 d = 16( kN m) / VTrng lng ring kh ca t c s dng trong vic kim tra cht ca nn ng, nn san lp n v: kN/m3; G/cm3; T/m3

TRNG LNG RiNG HTL trng lng ca mt n v th tch t trng thi hon ton cht kh

Qs s = 29) kN m (25 / Vsn v: kN/m3; G/cm3; T/m3

3

T TRNG HTL t s gia trng lng ring ht v trng lng ring nc Ct Ct pha bi St t hu c

s Gs = w

Gs = 2,65 2,67 Gs = 2,67 2,70 Gs = 2,70 2,80 Gs < 2,0

M ( CHA NC)L t s gia trng lng nc trong l rng Qw v trng lng ht Qs

Qw W = x 100% Qst cng yu th c m cng ln. n v: %

BO HA ( NO NC)L t s gia th tch nc trong l rng Vw v th tch l rng Vv n v: %

Sr 50% : t t m 50% < Sr 85% : t hi m Sr > 85% : t bo ha.

Vw S r = x 100% Vv

H S RNG & RNGH s rng l t s gia th tch phn rng Vv v th tch phn ht Vs rng l t s gia th tch phn rng Vv v th tch mu t V

Vv e= Vs

Vv n= V

I.4.2 Cc cng thc tnh i: Gs w (1 + 0,01 w) e= 1

s e= 1 dn e= 100 n

e n= (%) 1+ e

0,01w Gs Sr = (%) e

d s = 1 0,01 n

d = 1+ 0,01 w(Gs 1) w '= 1+ e

I.4.2 Cc ch tiu trng thi I.4.2.1 Cc ch tiu trng thi ca t dnh (st, st pha ct, ct pha st)Ty theo m m t ht mn c th nhng trng thi khc nhau. Ta c th biu din cc trng thi ca t theo quan h W VThe tch V o m tnhie W a n

Gii hn co: Wco Gii hn do: Wd = Wp Gii hn nho: Wnh = WLT.tha i nha o

T.tha i ra n

T.tha i n ra a n

T.tha i de o

Wco

Wp

WL

o m a W%

Xc nh ch s do Phn loi t dnh

Ip = A = WL - WpIpCt pha 7 St pha 17 St

Xc nh st Phn loi trng thi ca d

W WP IL = B = IP

Xc nh trng thi ca t da vo st TN T V TRNG THICt pha Rn Do Nho St pha, st Rn Na rn Do cng Do mm Do nho Nho

ST ILIL < 0 0 IL 1 IL > 1 IL < 0 0 IL 0.25 0.25 < IL 0.5 0. 5 < IL 0.75 0. 75 < IL 1 IL > 1

_ Dung khoang 100 g at a c say kho, Phng php xc nh gii hn nho nc nghien nho cho qua ray No.40. Tron at vi dng va ucu Casagrande : chm nhao tren knh phang (hoac trong chen s) va u at toi thieu trong khoang thi gian la 2 gi. _ Cho at vao khoang 2/3 a khum, tranh tao bot kh trong at, e mot khoang trong phan tren cho tiep xuc vi moc treo chng 1/3 ng knh a, am bao o day cua lp at khong nho hn 10 mm. _ Dung dao cat ranh chia at ra lam 2 phan theo phng vuong goc vi truc quay. _ Quay eu can quay vi van toc khoang 2 vong/sec, em so lan ri N cho en khi at trong a khep lai mot oan dai 12,7mm (1/2 inch). _ Lay khoang 10g 20g at vung xung quanh ranh khep e xac nh o am (can mau at em say kho can mau at kho xac nh c o am). _ Tang hoac giam o am cua mau at va thc hien lai th nghiem nh tren khoang 3 lan

Tret at vao chom cau

Dung dao cat ranh vach 1 ng

at khep lai sau khi quay

2mm

45 40 35 30 25 20 15 10 5 0 1 10

m W (%)

WL

25S ln ri N

100

nh gii han nhao, e kho cho gan en gii han deo (cam nam khong dnh tay nhng van con tnh deo). _ Dung 4 au ngon tay e lan at tren knh m cho en khi tren than cac day at co xuat hien cac vet nt ma khoang cach gia cac vet nt khoang10mm. Neu vi ng knh o, que at van cha nt th em ve no thanh hon va tiep tuc lan en chng nao at c ket qua nh tren. Neu tren day at co D>3mm ma a xuat hien vet nt th ta them nc vao, xe lai. Lay nhng day at at c ieu kien nh tren em xac nh o am. o am nay

Phng php xc nh gii hn do: dng _ Lay phan at chm cu Casagrande d th nghiem xac

I.4.2.2 Cc ch tiu trng thi ca t ri (ct, si, t hn ln)

H s rng:LOI T Ct si, th, va Ct nh Ct bt

Vv s e= = Vs dCHT CHT VA

1XP

e < 0.55 0.55 e 0.7 e > 0.7 e < 0.6 0.6 e 0.75 e > 0.75 e < 0.6 0.6 e 0.8 e > 0.8

cht tng i D:

emax e D= emax eminD 0 D < 0,33 0,33 D < 0,67 0,67 D 1,0 Trng thi ca t Xp Cht va Cht

I.5 Tnh m cht ca t: I.5.1 m cht t:m cht t l cho ti trng ng lp i lp li nhiu ln lm cho nn t c c chc nht, sau c th xy dng cng trnh ln trn. Qu trnh m cht lm tng dung trng ca t l do th tch l rng gim, tc l nc v kh s nhanh chng thot ra ngoi. m cht thng c thc hin bng cch c hc nh n ln, m nn hoc rung t. Gim h s rng gim h s thm ca t. Tng bn chng ct, do , tng sc chu ti ca t. Lm gim ln ca cng trnh.

I.5.2 Dng c xc nh max trong Phng Th nghim:C khun

Chy m

Thn khun khun

Ci m Proctor tiu chun

I.5.3 Mi quan h W, Trng lng ring kh (g/cm)S=0.8 S=1

max

max k

ng cong m cht

ng bao hoa

W optH s m cht k k =

m W %

d ( site ) d . max (lab )

I.6 Phn loi t: I.6.1 t dnh ch s do Ip:CH S DO IP IP > 17 7 IP 17 IP < 7 TN T St St pha Ct pha

I.6.2 t bn ch s do Ip , W, st IL:Bn st Bn st Bn ct IL > 1 IL > 1 IL > 1 WL > W e > 1.5 WL > W e > 1.1 WL > W e > 0.9 IP > 17 7 IP 17 IP < 7

I.6.1 t ri:TN T -t hn ln dm, cui Si, sn -t ct Ct si Ct th Ct va Ct nh Ct bt PHN PHI HT TNH BNG % KL ht ln trn 10mm trn 50% KL ht ln trn 2mm trn 50%

KL ht ln trn 2mm trn 25% KL ht ln trn 0.5mm trn 50% KL ht ln trn 0.25mm trn 50% KL ht ln trn 0.1mm trn 75% KL ht ln trn 0.1mm di 75%

I.6.4 Phn loi t theo ton do ca Casagrande:Ch s do IP60 50 40 30 20 10 0 10t bi ML v t hu c rt do OL

t st rt do CHIP = 0,73(WL-20)

t st t do CL

t hu c rt do MH

CL-ML

t hu c rt do OH

20

30

40

50

60

70

80

90

100

Gii hn chy wL

I.3 BI TPI.3.1. Cho khi lng th tch t nhin mt mu t l = 1860 kg/m3 , khi lng th tch ht l s = 2650 kg/m3 , v m W = 15%. Hy tnh: a. H s rng e b. rng n (%) c. bo ha Sr I.3.2. Mt mu t st cng trng thi t nhin cn nng 129.1g v c th tch l 5604cm3. Khi lng th tch ht l s = 2650 kg/m3. Hy tnh: a. m b. H s rng e c . bo ha Sr

I.3.3. Cho mt mu t st, trng thi do cng, bo ha hon ton, c chiu cao 4 cm v ng knh d = 6.4cm, cn nng 235G. Khi lng t sau khi sy kh cn nng 200G. T trng ht Gs = 2.68. Ly trng lng ring ca nc l w = 10kN/m3. Xc nh cc c trung sau ca mu t trn: a.Trng lng ring t nhin (kN/m3) b.H s m W% c.H s rng e d.Trng lng ring kh d (kN/m3)

I.3.4. Mt mu t trng thi t nhin c ng knh 6.3cm v chiu cao10.2cm, cn nng 590g. Ly 14.64G t trn em sy kh hon ton, em cn li c 12.2G. Gii hn nho WL = 25.0%, gii hn do Wp = 15.0%. T trng ht Gs = 2.67. Ly trng lng ring ca nc l w = 10kN/m3. Xc nh cc c trng sau ca mu t trn: a.H s rng e trng thi t nhin ca mu t. (0.7) b. bo ha Sr (71.58%) c. rng n (%) (41.52%) d.Trng lng ring y ni (kN/m3) (8.59) e. Xc nh tn v trng thi ca t theo TCVN, ASTM f. Cn thm vo mu t mt lng nc bao nhiu (ml) mu t bo ha hon ton? (35.05) g. Xc nh trng lng ring bo ha khi Sr= 1(19.73)

I.3.5. Cho mt mu t c ng knh 7cm, cao

5cm. khi em cn c trng lng 365g. sau khi sy kh, mu t cn nng 300g. em mu t lm th nghim nho do ta c gii hn nho l 27% v gii hn do l 13%. Th nghim t trng ht ta c 2.66. Hy xc nh: a.Trng lng ring t nhin ca mu t. (18.98) b. m (21.67%) c. Trng lng ring kh ca mu t. (15.6) d. H s rng e (0.705) e. rng n (%) (41.35%) g. bo ha Sr (81.72%) f. Tn t (st pha) g. Trng thi ca t theo TCVN, ASTM) (B=0.62)