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Bi tp ln C Hc t GVHD : Nguyn SHng

SVTH: NGUYN VNG THNH LC MSSV: 12149261 Trang 1

BI TP LN C HC T s 24

I/ SLIU :

1. Cng trnhTi trng tnh ton chn cng trnh ti ct mt t :

No= 73.3[T] Mo= 11.1[Tm]

1. Nn t :

s

S liu a cht ca cc lpMNN(t

mtt) (m)

Ti trng tnhton chn ct

(ct mt t )Lp 1 Lp 2 Lp 3

Shiu

Dy(m)

Shiu

Dy(m)

Shiu

No(T)Mo

(Tm)

24 78 3 49 4 66 4.6 73.3 11.1

2. Cc lp ta. Lp t s1

Shiu

Thnh phn ht (%) tng ng vi cc c ht

Ht siHt ct

Ht biHtstTh To Va Nh Mn

ng knh c ht (mm)

>10 10-5 5-2 2-11-0.5

0.5-0.25

0.25-0.1

0.1-0.05

0.05-0.01

0.01-0.002

0.70Ct nh e < 0.60 0.60 e 0.75 e > 0.75

Ct bi e < 0.60 0.60 e 0.8 e > 0.80

maxmax min

e eD

e e

D 1/3 : t ct ri 1/3 D 2/3 : t ct cht va

2/3 D 1 : t ct cht Phn loi t ri theo cp khiPhn loi t theo quy phm Vit Nam TCVN 9362: 2012

S th t Tn t Cn c phn loit ri Hm lng c ht

1 Tng ln Ct ht c d > 200mm chim trn 50%2 Dm cui Ct ht c d > 10mm chim trn 50%3 Si sn Ct ht c d > 2mm chim trn 50%

4 Ct sn Ct ht c d > 2mm chim trn 25%5 Ct th Ct ht c d> 0.5mm chim trn 50%6 Ct va Ct ht c d > 0.25mm chim trn 50%7 Ct nh Ct ht c d > 0.1mm chim trn 75%8 Ct bi Ct ht c d > 0.1mm chim t hn 75%

Tiu chun phn loi t dnh


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Tiu chun nh gi trng thi ca t dnhTn t v trng thi ca n st B

ctRn B < 0Do 1 B 0Chy B > 1

st v st

Rn B < 0

Na rn 0.25 B 0

Do 0.5 B 0.25

Do mm 0.75 B 0.5Do chy 1 B 0.75

Chy B > 1

Bng phn loi cht ca ct theo th nghim SPTTr s Ntheo SPT

chttng i

Trng thica ct

Gc

o

qc(kG/cm2)

0 -4 0.2 Rt ri 30 204 -10 0.2 - 0.4 Ri 30 -35 20 -40

10 - 30 0.4 - 0.6 Cht va 35 - 40 40 - 12030 -50 0.6 - 0.8 Cht 40 - 45 120 - 200

50 0.8 Rt cht 45 200

Ttrng ht no

Ht st : = 2.6 n 2.67 Ht st : = 2.65 n 2.74

b. Xc nh tn v trng thi t Lp t s1

Shiu

Thnh phn ht (%) tng ng vi cc c ht

Ht siHt ct

Ht biHtstTh To Va Nh Mn

Tn t Ch s do Lng cha nhm ht st (%)t st A >17 Ln hn 30

st 17 A>7 30 10

ct 7 A> 1 10 3


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ng knh c ht (mm)

>10 10-5 5-2 2-11-0.5

0.5-0.25

0.25-0.1

0.1-0.05

0.05-0.01

0.01-0.002

0.5 > 0.25 > 0.1 > 0.05 > 0.01 > 0.002 < 0.002Hm lngc ht (%) 3.5 5.5 30 61 70 78 82

+ Cc ht c ng knh d > 0.1 mm chim 30% 0.1 : 30%


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Lp t s2

Shiu

mt nhinW %

Giihn

nhoWnh %

Giihndo

Wd %

Dungtrng t

nhin(T/m3)

Ttrng

ht

Gc mast trong

()

Lc dnh cKg/cm2

49 25.9 29.7 25.4 1.88 2.67 19o45 0.22

+ Chsdo A = Wnh - W d = 29.7-25.4= 4.3 (%)

Theo tiu chun phn loi t dnh, 1%


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Lp t s3

S

hiu

mt

nhinW %

Giihn

nhoWnh %

Giihn

doWd %

Dungtrng t

nhin T/m3

Ttrng

ht

Gc mast

trong ()

Lc dnh c

Kg/cm2

66 26,9 45.3 31.5 1.93 2.69 20o10 0.33

Kt qu th nghimnn p e-p vi p lc nnp (Kpa)

Kt quxuyn tnh

qc(MPa)

Kt quxuyn tiu

chunN50 100 200 400

0.741 0.723 0.707 0.694 5.65 25

+ Chsdo

A = Wnh - W d = 45.3-31.5=13.8(%)

Theo tiu chun phn loi t dnh7% 0.7 t xp

Kt lun : t st pha ( st) trng thi rn ( cng )


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c. Nhn xt t nn :t nn gm 3 lp t:

- Lp 1: t ct bi trng thi cht va,

- Lp 2: Ct pha trng thi do xp

- Lp 3: t st pha ( st) trng thi rn ( cng )

d. Chn chiu su t mng

Qua kt quphn loi t v trng thi ca 3 lp t trn, mng thit kl mngnng , ta thy lp t 1 l t ct bi trng thi cht va c chiu dy l 3 m l t tt ,nn ta chn chiu su mng ln l 1.6m nm trong lp t tt.

HNH TRA CHT


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2. Xc nh kch thc y mng (bxl ) theo iu kin ptp[p] Vi tc= 31o 10

Ta ni suy c cc gi trA,B,D nh sau :

Trstiu chun gc

ma st trong tc A B D

30 1.15 5.59 7.95

1.26 6.03 8.3032 1.34 6.35 8.55

Chn b = 1.8 m Chiu su chn mng l hm= 1.6 (m) Theo TCXD 9362-2012 ,cho php tnh ton trsp lc tiu chun ca nn t

khi vng bin dng do pht sinh n su bng brng mng b. Biu thc tnh ton theo tiu chun TCXD 9362-2012Rtc=

1 2. ].[

tc

m m Ab Bh D c

k

Trong Rtcl cng tiu chun ca t nn - m1,m2l hsiu kin lm vic ca t nn v cng trnh, chn m1= 1.2, m2= 1- ktc: hstin cy cc chtiu c l ca t( ktc= 1 nu th nghim

thc hin trn nguyn dng, ktc= 1,1 nu th nghim ly theo thngk). Ta chn ktc = 1

- A,B,D l cc hsphthuc vo trsgc ni ma st trong tc Cng tiu chun

Rtc= m1[(Ab + Bh)1+ D.c]

= 1.2[( 1.26x1.8+6.03x1.6)x1.84 + 8.3x0]= 26.31(T/m2)

Vi b = 1.8, chn =l/b= 1.16, ta kim tra cc iu kin Kim tra vi iu kin [1+e 1+2e)


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Vi e = MN

M = M0= 11.1 Tm=111 KNm

e =M

N = 0.13

1+ e = 1.114 , 1+2e = 1.13

Vy 1.13


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+ Rtc= 263.1(KN/m2)

Vy pmax= 30.982( T/m2) 1.2Rtc= 31.591 ( T/m2)

Kim tra iu kinpmin> 0 Pmin= N/FM/W = (853.96/3.78111/1.323)= 142.02KN/m2 >0

iu kin vkinh t0%


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ng sut gy ln ti tm y mng KN/m2 ng sut gy ln ca cc im nm trn trc O c tnh vi ng sut gy ln

y mng phn bu bng

p= ptb-1.hm= 225.9218.4 x 1.6= 19.648 (T/m2)

Bng tinh ng sut gy lnTa chia chiu cao nn t thnh cc lp nh, mi lp c chiu cao tha mn

0.25b hi 0.4b 0.45 hi 0.72chn hi=0.45m

lp t 1dy 3.0m,chiu su chn mng l 1.6m ,cn li 1.4m .ta chia

thnh 3 lp nhc chiu dy l 2 lp 0.45 v 1 lp 0.5m

lp th2, chiu dy l 4m, ta chia thnh 8 lp nh, mi lp dy 0.5 m

.

Dng hsKo tnh ng sut gy ln ,ta c bng:

im su

z

su tmt t

(m)l/b 2.z/b

(T/m2

)K0 bt(T/m

2) gl=K0xp

0 0 1.6 1.16 0.000

1.84

1.000 2.944 19.6481 0.45 2.05 1.16 0.500 0.931 3.772 18.2882 0.9 2.5 1.16 1.000 0.733 4.600 14.4103 1.4 3 1.16 1.556 0.513 5.520 10.0764 1.9 3.5 1.16 2.111

1.88

0.347 6.460 6.8205 2.4 4 1.16 2.667 0.246 7.400 4.8356 2.9 4.5 1.16 3.222 0.179 8.340 3.5207 3 4.6 1.16 3.333 0.171 8.528 3.351

8 3.4 5 1.16 3.778

0.934

0.137 8.902 2.6969 3.9 5.5 1.16 4.333 0.107 9.369 2.10310 4.4 6 1.16 4.889 0.086 9.836 1.69411 4.9 6.5 1.16 5.444 0.071 10.303 1.39212 5.4 7 1.16 6.000 0.058 10.770 1.144


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c. Biu ng sut gy ln :

4. Dbo ln n nh ti tm mng i vi t thng, mng c xem l tt ln su z khi:0.2

z z

gl btp p

Do ta tnh ln n lp phn tth10 l tt ln0.2*9.836=1.1.967>1.694

Tlp phn tth1 n lp phn tth3, ln c tnh bng :1i

i i

osi

S hE

Trong , =0.8, Eosi = .pc, v lp 1 l lp t ct bi c qc=

6.3(MPa) >2.0(MPa) => chn = 2.5=> Eosi = 2.5x630=1575 (T/m2)

Ta sdng phng php cng ln cho lp t c th nghim p-e : Cng thc tnh ln: tlp phn tth4 n lp th10 :

1 2

1 1 11

n n

i i

i i

i i i

e eS S h

e

Trong :e1i l hsrng ca t ti im gia lp ang xt, ng ving sut do trng lng bn thn.e2i l hsrng ca t ti im gia lp ang xt, ng vi ng sut dotrng lng bn thn v ti trng ngoi.

Cc hse1i , e2i c tnh da trn biu nn p e-p lp 2 v lp 3


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Dng phng php ni suy tnh e1i v e2i ta c:

p1i (T/m ) e1i P2i(T/m ) e2i5.99 0.752 14.43 0.727

6.93 0.748 12.75 0.7307.87 0.744 12.05 0.7318.43 0.742 11.87 0.7328.72 0.74 11.74 0.7329.13 0.739 11.53 0.7329.60 0.737 11.50 0.732

Bng tnh ln :

Kt qu th nghim nn ln e-p vi p lc nn p (kPa)p1 e1 p2 e250 0.756 50 0.741

100 0.735 100 0.723

200 0.717 200 0.707

400 0.701 400 0.694


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Lpphn

t

Chiudylp

phn

t

su z1i(m)(tnh ty

mngn

ylp

phnt)

ng sutdo trnglng

bn thnti y

lp phnt Z0i(T/m2)

ngsuttngthm

ti ylp

phn ti=

K0i.pgl(T/m2)

ngsuttngthm

ti tmlp

phn t1i

(T/m2)

ngsut dotrnglngbn

thn titm

lpphn t

p1i(T/m2)

ngsuttng

ti tmlp

phn tp

2i

=p1i +1i

(T/m2)

H srnge1i

(tng

ngp1i)

H srnge2i

(tng

ngp2i)

ln si(m)

0 2.944 19.648 01 0.45 0.45 3.772 18.288 18.97 3.36 22.32 0.00432 0.45 0.9 4.600 14.41 16.35 4.18 20.54 0.00373 0.5 1.4 5.52 10.076 12.24 5.06 17.3 0.00314 0.5 1.9 6.46 6.82 8.45 5.99 14.43 0.752 0.727 0.00715 0.5 2.4 7.4 4.835 5.83 6.93 12.75 0.748 0.730 0.0051

6 0.5 2.9 8.34 3.520 4.18 7.87 12.05 0.744 0.731 0.00377 0.1 3 8.528 3.351 3.43 8.43 11.87 0.742 0.732 0.00068 0.4 3.4 8.902 2.696 3.02 8.72 11.74 0.740 0.732 0.00189 0.5 3.9 9.369 2.103 2.4 9.13 11.53 0.739 0.732 0.00210 0.5 4.4 9.836 1.694 1.89 9.60 11.50 0.737 0.732 0.0014

0.0328Vy tng ln tng cng ti tm mng l: S= 0.0328 (m)=3.28(cm) < Sgh = 8(cm) => tha mn iu kin nn ln ca mng n

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