PHN I

Thit k mn hc Nn v Mng B mn a k thut

Mc lc PHN IBo co kho st a cht cng trnhI. Cu trc a cht v c im cc lp t3II. Nhn xt v kin ngh.4PHN IIThit k k thutI. La chn kch thc cng trnh61.1. La chn kch thc v cao b cc61.2. Chn kch thc cc v cao mi cc7II. Lp cc t hp ti trng Thit k72.1. Trng lng bn thn tr..72.1.1. Tnh chiu cao thn tr72.1.2. Th tch ton phn (khng k b cc)82.1.2. Th tch phn tr ngp nc (khng k b cc)82.2. Lp cc t hp ti trng thit k vi MNTN82.2.1. T hp ti trng theo phng dc cu TTGHSD102.2.2. T hp ti trng theo phng dc cu TTGHC10 iii. Xc nh sc chu ti dc trc ca cc..103.1. Sc khng nn dc trc theo vt liu PR11 B tr ct thp trong cc 11 Sc khng nn dc trc theo vt liu PR... 113.2. Sc khng nn dc trc theo t nn QR113.2.1. Sc khng thn cc Qs...113.2.2. Sc khng mi cc Qp..143.3. Sc khng dc trc ca cc n15iV. chn s lng cc v b tr cc trong mng154.1. Tnh s lng cc..154.2. B tr cc trong mng..154.2.1. B tr cc trn mt bng154.2.2. Tnh th tch b.164.3. T hp ti trng tc dng ln y b164.3.1. T hp hp trng TTGHSD164.3.2. T hp hp trng TTGHC16

V. kim ton theo Trng thi gii hn cng I175.1. Kim ton sc khng dc trc ca cc n175.1.1. Tnh ni lc tc dng u cc175.1.2. Kim ton sc khng dc trc ca cc n175.2. Kim ton sc khng dc trc ca nhm cc.18 Vi t dnh 21 Xc nh Qg1... 22 Xc nh Qg2... 22VI. kim ton theo trng thi gii hn s dng 236.1. Xc nh ln n nh.. 236.2. Kim ton chuyn v ngang ca nh cc30VII. cng ct thp cho cc v b cc.317.1. Tnh v b tr ct thp dc cho cc317.1.1. Tnh m men theo s cu cc v treo cc317.1.2. Tnh v b tr ct thp dc cho cc327.2. B tr ct thp ai cho cc..357.3. Chi tit ct thp cng mi cc..367.4. Li ct thp u cc.367.5. Vnh ai thp u cc...367.6. Ct thp mc cu..36vIII. mi ni thi cng cc37PHN IiiBn v

PHN I

BO CO KHO ST A CHT CNG TRNHCu trc a cht khu vc xy dng.M t s b cu to a cht khu vc: Ti l khoan BH1, khoan xung cao l - 34m, gp 3 lp t nh sau: Lp 1: Lp 1 l lp bn st, c mu xm, xm en, ln hu c. Chiu dy ca lp xc nh c BH1 l 5.30 m, cao mt lp l 0.00m, cao y l -5.30 m. Lp t c m W = 59.1%, bo ha Sr = 98.4%. Lp t trng thi chy, c st IL = 1.14 Lp 2: Lp 2 l lp st mu xm vng, trng thi do cng, phn b di lp 1. Chiu dy ca lp l 15.40m, cao mt lp l -5.30m, cao y l -20.70m. Lp t c m W = 29.7%, bo ha Sr = 98.8%. Lp t trng thi chy, c st IL = 0.33 Lp 3: Lp th 3 gp BH1 l lp st, mu xm vng, xm xanh, nu loang l, trng thi na cng, phn b di lp 2. Chiu dy ca lp l 13.3 m, cao mt lp l -20.7 m, cao y lp l -34.00. Lp t c m W = 21.5%, bo ha Sr = 97.2%. Lp t trng thi chy, c st IL = 0.14

1. Nhn xt v kin nghTheo ti liu kho st a cht cng trnh, phm vi nghin cu v qui m cng trnh d kin xy dng, em xin c mt s nhn xt v kin ngh sau: Nhn xt:+ iu kin a cht cng trnh trong phm vi kho st nhn chung l kh phc tp, c nhiu lp t phn b v thay i kh phc tp.+ Lp t s 1 l lp t yu do ch s xuyn tiu chun v sc chu ti nh, lp 2, 3 c tr s SPT v sc chu ti kh cao. (Lp 2: IL = 0.33; SPT > 15; Lp 3: IL = 0.14, SPT cao)+ Lp t s 1 d b ln st khi xy dng tr cu ti y. Kin ngh+ Vi cc c im a cht cng trnh ti y, nn s dng gii php mng cc ma st bng BTCT cho cng trnh cu v ly lp t s 3 lm tng ta cc.+ Nn cho cc ngp su vo lp t s 3 tn dng kh nng chu ma st ca cc.

PHN II

THIT K K THUT

1. La chn kch thc cng trnh v b tr cc trong mng1.1. La chn kch thc v cao b mng, mi cc.1.1.1. Cao nh tr (CT).V tr xy dng tr cu xa b v phi m bo thng thuyn v s thay i mc nc gia MNCN v MNTN l tng i cao. Xt c iu kin m quan trn sng, ta chn cc gi tr cao nh sau:

Cao nh tr CT chn nh sau: Trong : + MNCN: Mc nc cao nht, MNCN = 3,7 m+ MNTT: Mc nc thng thuyn+ : Chiu cao thng thuyn. y theo s liu cho th sng khng thng thuynTa c : CT = 3,7 + 1 0,3 = 4,4 m. Vy: CT = + 4,4 m 1.1.2. Cao nh b (CB). CB MNTN 0,5 m MNTN = 1,7 m CB 1,7 - 0,5 = 1,2 m Vy Chn cao nh b l: CB = + 1m.1.1.3. Cao y b. Cao y b = CB - Hb

Trong : Hb l chiu dy b mng (Hb =). Chn Hb = 2 m. Cao y b = 1,0 2,0 = - 1,0 m.

Hnh 2: Tng hp cc thng s thit kVy chn cc thng s thit k nh sau: Cao nh tr: CT = + 4,4 mCao nh b: CB = + 1,0 mCao y b l: CAB = - 1,0 mB dy b mng: Hb = 2 m.Chiu dy m tr: CDMT = 0,8+0,6 = 1,4m 1.1.4. Chn kch thc v cao mi cc. Theo tnh cht ca cng trnh l cu c ti trng truyn xung mng l ln, a cht c lp t chu lc nm cch mt t 15.50m v khng phi l tng gc, nn chn gii php mng l mng cc ma st BTCT Chn cc b tng ct thp c sn, cc c kch thc l 0,45x0,45m; c ng vo lp s 3 l lp st trng thi na cng. Ngoi ra mi cc c t vo trong lp t chu lc ti thiu l 5d. Vy, chn cao mi cc l 24,00m Nh vy cc c ng vo trong lp t 3 c chiu su l 13,3m Chiu di ca cc (Lc) c xc nh nh sau:Lc = CB - Hb - CMCLc = 1.0 - 2.0 - (- 24.00) = 23.00 m. Trong :CB= 1.0 m: Cao nh bHb= 2.0 m: Chiu dy b mngCMC= - 23.0 m: Cao mi cc Kim tra: => Tho mn yu cu v mnh. Tng chiu di c cc s l: Lcd = Lc + 1m = 23 + 1m = 24 m. Cc c t hp t 3 t cc vi tng chiu di c cc l: 24 m = 3x8m. Nh vy hai t thn cc chiu di l 8m v t mi c chiu di 8m. Cc t cc s c ni vi nhau bng hn trong qu trnh thi cng ng cc.2. Lp t hp ti trng tc ti nh b vi MNTN2.1. Tnh ton th tch tr2.1.1. Tnh chiu cao thn trChiu cao thn tr Htr:Htr = CT - CB - CDMT.Htr = 4,4 1,0 1,4 = 2m. Trong : Cao nh tr: CT = + 4,4 mCao nh b: CB = + 1,0 mChiu dy m tr: CDMT = 0,8 + 0,6 = 1,4m.2.1.2. Th tch ton phn (khng k b cc).

Hnh 3: Phn chia tnh th tch tr

Th tch tr ton phn Vtr:

Vtr = V1 + V2 + V3 = == 10,88 + 6,63 + 10,182 = 27,692 m3.2.1.2. Th tch phn tr ngp nc (khng k b cc).Th tch tr ton phn Vtn : Vtn = Str x (MNTN - CB)

= Trong :MNTN = +1,7 m: Mc nc thp nht.CB = +1,0 m: Cao nh b.Str: Din tch mt ct ngang thn tr, m2.2.2. Lp cc t hp ti trng thit k vi MNTN Tin hnh Tnh cc ti trng: thng ng. lc ngang v mmen i vi mt ct nh b ng vi mt ct t nhin. bi cho ta Ti trng TTGHSD ta phi tip tc tnh TTGHC

Bng 1: T hp ti trng thit k vi MNTN

Ti trngn vTTGHSD

- Tnh ti thng ngkN6200

- Hot ti thng ngkN4500

- Hot ti nm ngangkN130

- Hot ti mmenKN.m800

H s ti trng: Hot ti: n = 1,75 Tnh ti: n = 1,25 bt = 24,50 (kN/m3): Trng lng ring ca b tng.n= 9,81 (kN/m3): Trng lng ring ca nc

2.2.1. T hp ti trng theo phng dc TTSD. Ti trng thng ng tiu chun dc cu:

( kN Ti trng ngang tiu chun dc cu:

Mmen tiu chun dc cu:

(CT CB)

=1242 (kN.m)2.2.2. T hp ti trng theo phng dc cu TTGHC. Ti trng thng ng tnh ton dc cu

16438 (kN) Ti trng ngang tnh ton dc cu:

= 1,75x = 1,75x130 =227,5 kN. Mmen tnh ton dc cu:

(CT CB)

=2173,5 kN.m

Bng 2: Tng hp ti trng tc dng theo phng dc cu vi MNTNTi trngn vTTGHSDTTGHC

Ti trng thng ngkN11343,516438

Ti trng ngangkN130227,5

MmenkN.m12422173,5

3. Xc nh sc khng nn dc trc ca cc n3.1. Sc khng nn dc trc theo vt liu. Chn vt liu + Cc b tng ct thp + Tit din ca cc hnh vung: 0,45m x 0,45m + B tng c = 28MPa + Thp ASTM A615, c = 420 MPa B tr ct thp trong cc + Ct ch : Chn 8#22, b tr xuyn sut chiu di cc. + Ct ai : Chn thp 8 Hnh 4. Mt ct ngang cc BTCT

Sc khng nn dc trc theo vt liu PRDng ct ai thng, ta c: PR = xPn = x 0.8x{0.85xx(Ag Ast) + fyxAst}Trong : : H s sc khng ca b tng, = 0,75: Cng nn quy nh ca b tng tui 28 ngy (MPa) : Gii hn chy ti thiu quy nh ca thanh ct thp (MPa).Ag : Din tch mt ct nguyn ca cc, Ag = 450x450 = 202500mm2Ast: Din tch ct thp, Ast = 8x387=3096mm2Vy: PR = 0.75x0.8x{0.85x28x(2025000 3096) + 420x3096}

= 3925422,78 N 3925,23KN.3.2. Sc khng nn dc trc theo t nn QRSc khng nn dc trc theo t nn c xc nh nh sau: QR = Vi: ; Trong : Qp: Sc khng mi cc (MPa) qp: Sc khng n v mi cc (MPa) Qs: Sc khng thn cc (MPa) qs: Sc khng n v thn cc (MPa) Ap: Din tch mi cc ( mm2 ) As: Din tch b mt thn cc ( mm2 ) : H s sc khng i vi sc khng mi cc. : H s sc khng i vi sc khng thn cc. trong t st vi ta c: trong t st vi ta c: 3.2.1. Sc khng thn cc QsDo thn cc ngm trong 3 lp t, u l lp t st nn ta tnh Qs phng theo phng php . Theo phng php : Sc khng n v thn cc qs nh sau: Trong : Su: Cng khng ct khng thot nc trung bnh (Mpa), Su = Cuu : H s kt dnh ph thuc vo Su v t s Db/D v h s dnh c tra bng theo tiu chun thit k cu 22TCN 272-05. Hnh 10.7.3.3.2a-1 Db l chiu su cc trong lp t chu lc, D: ng knh ccng thi ta cng tham kho cng thc xc nh ca API nh sau :- Nu Su 25 Kpa - Nu 25 Kpa < Su < 75 Kpa - Nu Su 75 Kpa Lp 1:Ta c: Su= 15,7 kN/m= 15,7 kPa = 0,0157 MPa.

m hx: Chiu su xi, hx = 2,2 m.Tra s 3 ta c:

=> Do : =1Tham kho cng thc xc nh ca APISu= 15,7 kN/m 25 Kpa Lp 2:Ta c: Su = 34,7 kN/m= 34,7 kPa = 0.0347MPa. S dng phng php tra biu : Ta thy cu to a cht gn ging s 2 do ta s s dng s 2:Vi chiu su Db tnh t nh lp 2 hay:

=> Db >20D. Do : =0,83S dng cng thc ca API vi Su= 34,7 kPa ta c:

= 0,903 Lp 3:Ta c: Su = 48.9 kN/m= 48.9 kPa = 0.0489 Mpa. Ta coi lp t 2 v 3 lm vic nh nhau, tc l coi nh ng nht (Chng u l lp t chu lc) Nh vy hlm vic cng tng t nh s 2, vi Db l chiu su tnh t nh lp 2S dng phng php tra biu : Ta thy cu to a cht gn ging s 2 do ta s s dng s 2:

Vi chiu su Db tnh t nh lp 2 vi (m)

Tra s 2, vi chiu su Db tnh t nh lp 2 v (m)

>20 Do : = 0.760

S dng cng thc ca API vi Su= 48.9 kPa ta c:

= 0.761

Bng 3: Sc khng thn cc Qs cc lp tTn lp sulp t(m)Chiu dylp t Sau xi: L (mm)Cng khng ct: Su(N/mm2)H skt dnh

qs

(N/mm2)Qs=

(N)

Lp 15,3031000,01571,000,015787606

Lp 220,70154000,03470,830,028801798363,72

Lp 334,00130000,04890,760,037164869637,6

Sc khng thn cc nh sau:

QS= 87606 + 798363,72 + 869637,6 = 1755607,32 (N)

3.2.2. Sc khng mi cc QpSc khngn v mi cc trong t st bo ha qp xc nh nh sau: qp = 9.SuTrong : Su: Cng khng ct khng thot nc trung bnh (Mpa), Su = CuuMi cc t ti lp 3 c: Su = 48,9 kN/m= 0,0489 Mpa=> Qp = Ap qp = 4502 x 9 x 0,0489 = 89120,25 NVy Sc khng nn dc trc theo t nn: QR = = 0,56 (1755607,32 + 89120,25) = 1038087 N = 1038,087 kN

3.3. Sc khng dc trc ca cc n : =min(3627,68; 1038,087) = 1038,087 kN.

4. Xc nh s lng cc v b tr cc4.1. Xc nh s lng cc Trong : N: Ti trng thng ng TTGHC (kN), N=16438kN Ptt: Sc khng dc trc ca cc n (kN), Ptt= 1038,087 kN

Thay s: . Chn n = 24 cc.4.2. B tr cc trong mng4.2.1. B tr cc trn mt bngTiu chun 22TCN 272 05 quy nh: Khong cch t mt bn ca bt k cc no ti mp gn nht ca mng philn hn 225mm. Khong cch tim n tim cc cc khng c nh hn 750mm hoc 2,5 ln ng knh hay b rng cc, chn gi tr no ln hn.Vi n = 24 cc c b tr theo dng li vung trn mt bng v c b tr thng ng trn mt ng, vi cc thng s :+ S hng cc theo phng dc cu l 4. Khong cch tim cc hng cc theo phng dc cu l 1200 mm. + S hng cc theo phng ngang cu l 6. Khong cch tim cc hng cc theo phng ngang cu l 1200 mm.+ Khong cch t tim cc ngoi cng n mp b theo c hai phng dc cu v ngang cu l 500 mm.

Hnh 5. Mt bng cc

4.2.2. Tnh th tch b. Vi 24 cc b tr nh hnh v, ta c cc kch b l: 4600mm x 7000mm.Trong : a = (4600 - 1200) : 2 = 1700 mm. b = (7000 - 4500) : 2 =1250 mm. Chiu dy b: 2000 mm Th tch b l: Vb = 7000x4600x2000 = 64,4x109 mm3 = 64,4 m3.

4.3. T hp ti trng tc dng ln y b

Hnh 6. T hp ti trng tc dng ln nh bTi trngn vTTGHSDTTGHC

Ti trng thng ngkN11343,516438

Ti trng ngangkN130227,5

MmenkN.m12422173,5

4.3.1. Trng thi gii hn s dng

Ti trng thng ng: = 11343,5+ (24,5 9,81) x 64,4 = 12289,5 kN. Ti trng ngang: 130 kN. Mmen =1242 + 130x2 = 1502 kN.m4.3.2. Trng thi gii hn cng Ti trng thng ng: = 16438+ (1,25x24,5 9,81) x 64,4 = 17778,5 kN Ti trng ngang:

227,5 kN. Mmen = 2173,5+ 227,5 x 2 = 2628,5 kN.m

Bng 4: T hp ti trng tc dng ln y bTi trngn vTTGHSDTTGHC

Ti trng thng ngkN12162,6217778,5

Ti trng ngangkN130227,5

MmenkN.m15022628,5

5. Kim ton theo trng thi gii hn cng I

5.1. Kim ton sc khng dc trc cc n

5.1.1. Tnh ni lc tc dng ln u ccCch 1: Tnh theo mng cc b caoLp bng Excel tnh ni lc tc dng ln u cc, ch y ti trng dc cu, kt qu nh sau:Bng tnh ni lc dc trc ln ccCcXnsinncosnLNnFnvuwNn

1-3.000.001.0023.000.200.030.000.00646.31

2-1.800.001.0023.000.200.030.000.00681.10

3-0.600.001.0023.000.200.030.000.00715.88

40.600.001.0023.000.200.030.000.00750.67

51.800.001.0023.000.200.030.000.00785.45

63.000.001.0023.000.200.030.000.00820.24

7-3.000.001.0023.000.200.030.000.00646.31

8-1.800.001.0023.000.200.030.000.00681.10

9-0.600.001.0023.000.200.030.000.00715.88

100.600.001.0023.000.200.030.000.00750.67

111.800.001.0023.000.200.030.000.00785.45

123.000.001.0023.000.200.030.000.00820.24

13-3.000.001.0023.000.200.030.000.00646.31

14-1.800.001.0023.000.200.030.000.00681.10

15-0.600.001.0023.000.200.030.000.00715.88

160.600.001.0023.000.200.030.000.00750.67

171.800.001.0023.000.200.030.000.00785.45

183.000.001.0023.000.200.030.000.00820.24

19-3.000.001.0023.000.200.030.000.00646.31

20-1.800.001.0023.000.200.030.000.00681.10

21-0.600.001.0023.000.200.030.000.00715.88

220.600.001.0023.000.200.030.000.00750.67

231.800.001.0023.000.200.030.000.00785.45

243.000.001.0023.000.200.030.000.00820.24

Ni lc cc ln nht Nmax= 820,24 kN.Cch 2: Tnh theo chng trnh FB-PierKhai bo cc thng s, chy chng trnh, c kt qu nh sau:********************************************* ***** Final Maximums for all load cases ***** ***** PIER # 1 ***** *********************************************

Result Type Value Load Comb. Pile *** Maximum pile forces *** Max shear in 2 direction 0.1412E+02 KN 1 0 12 Max shear in 3 direction -0.2245E-01 KN 1 0 4 Max moment about 2 axis -0.5299E-01 KN-M 1 0 4 Max moment about 3 axis -0.2435E+02 KN-M 1 0 12 Max axial force -0.7736E+03 KN 1 0 13 Max torsional force -0.1036E-03 KN-M 1 0 21 Max demand/capacity ratio 0.1764E+00 1 0 13 *** Maximum soil forces *** Max axial soil force 0.6025E+02 KN 1 0 13 Max lateral in X direction 0.7697E+01 KN 1 0 12 Max lateral in Y direction 0.1108E-01 KN 1 0 4 Max torsional soil force -0.6523E-04 KN-M 1 0 21

Do : Nmax = 773,6 KN, vy ly gi tr ln hn l Nmax = 820,4 KN kim ton.

Hnh 7. Biu ni lc cc trong Fb-pier

5.1.2. Kim ton sc khng dc trc cc nCng thc kim ton sc khng dc trc cc n:Nmax + N PttTrong :Ptt: Sc khng tnh ton chu nn ca cc nNmax: Ni lc tc dng ln nht ln mt cc, Nmax =820,4 KNN: Trng lng bn thn ccTa c: N = 0.45 x 0.45 x 23 x 24.5= 114,11 KNKim ton: Nmax + N = 820,4 + 114,11 = 934,5 kN Ptt= 1038,087 kN => t5.2. Kim ton sc khng dc trc ca nhm cc Cng thc kim ton sc khng dc trc ca nhm cc:Trong :VC: Tng lc gy nn nhm cc nhn h s. VC = 16438 (kN)QR: Sc khng dc trc tnh ton ca nhm cc Cc h s sc khng ca nhm cc. Ta c: Qg: Sc khng dc trc danh nh ca nhm cc, c xc nh nh sau Vi t dnh

Qg = min{ xTng sc khng dc trc ca cc cc n; sc khng tr tng ng}= min{Qg1; Qg2}Ta c: Cao mt t sau xi l: - 2.2 m Cao y b l : -1 mDo vy sau khi xi l, y b khng tip xc cht ch vi t, t trn b mt l mm yu, khi kh nng chu ti ring r ca tng cc phi c nhn vi h s hu hiu, ly nh sau:

= 0,65 vi khong cch tim n tim bng 2,5 ln ng knh

= 1,00 vi khong cch tim n tim bng 6 ln ng knhM khong cch tim n tim bng ln ng knh cc do ta ni suy h :

Xc nh Qg1Nh xc nh trn, sc khng thn cc danh nh: Qs = 1755607N = 1755,607 kN Sc khng mi cc danh nh: Qp = 89,12 kN Vy, tng sc khng tnh ton dc trc ca nhm cc trong t st:

Qg1 = n x (Qs + Qp) x = 28 x (1755,607 + 89,12) x 0,653 = 33729 kN

Xc nh Qg2Sc khng ca ph hoi khi c xc theo cng thc:Qg2 =

Hnh 8. Quy i kch thc nhm ccTrong :X : Chiu rng ca nhm cc X = 3.1200 + 450 = 4050 mm = 4,05 mY : Chiu di ca nhm cc Y = 5.1200 + 450 = 6450 mm = 6,45 mNC : H s ph thuc t s Z/X Z : Chiu su ca khi t di b cc, Z = (-2.2) (- 24) = 21,8m

Ta c:

Do : : Cng chu ct khng thot nc trung bnh dc theo chiu su ca cc

Su : Cng chu ct khng thot nc ti y mng(Mpa). Su = 0,0489 Mpa => Qg2 = (2x4050+2x7650)x21800x0,5932 + 4050x7650x8,29x0,0489 = 32342170 N = 32342,17 kNVy, Qg= min{Qg1; Qg2} = min {33729; 32342,17 } kN = 32342,17 kN

Sc khng dc trc ca nhm cc:

QR = kN=> QR = 21022,41 > VC = 16438 (kN)

6. Kim ton mng theo TTGHSD6.1. Xc nh ln n nh6.1.1. Xc nh ng sut c hiu do trng lng bn thn cc lp t theo chiu su, tnh n trng tm ca lp t tnh ln.Vi mc ch tnh ton ln ca nhm cc, ti trng c gi nh tc ng ln mng tng ng t ti 2/3 su chn cc vo lp t chu lc (2Db/3) .Ti trng phn b theo ng 2:1 theo mng tng ng nh hnh v.

Hnh 9. M hnh quy i sang mng tng ng

Db l tnh t lp t chu lc, theo ti liu kho st a cht lp 1 l lp xu, ch c lp 2, 3 l lp tt, lp chu lc su bt u t lp 2 (lp ch lc) (tc l t lp tt) l: -5,3 mNh vy y Db= - 5,3 (-24) = 18,7 m 2Db/3 = 12,47 m. Nh vy mng tng ng nm trong lp 2, cch y lp 2 l: (15,40 12,47) = 2,93 m Lp t tnh ln bn di mng tng ng, c chiu dy nh hnh v.

Hnh 10. Phn chia cc lp tnh ln

ng sut c hiu do trng lng bn thn cc lp t theo chiu su c xc nh nh sau: = Trong : : ng sut tng

: p lc nc l rng ng vi MNTN = 2 mhw : l su so vi MNTN. hw= Zi + 2

Bng 5: ng sut c hiu cc im do trng lng bn thnimTrng lng th tch

suZi(m)= Zi+1-Zi(m)

ng sut (KN/m2)

ng sut tngp lc nc l rngng sut c hiu

=

A16.300019,6219,620

B16.35.305.3086,39106,0171,61334,397

C18.817.7712.47234,44340,45193,944146,502

D18.819.2351.46527,542367,99208,315159,673

E18.820.71.46527,542395,53222,687172,843

E119,321,7119,3414,83232,497182,333

E219,322,7119,3434,13242,307191,823

E319,323,7119,3453,43252,117201,313

E419,324,7119,3472,73261,927210,803

E519,325,7119,3492,03271,737220,293

E619,326,7119,3511,33281,547229,783

F19,327,350,6512,55523,88287,9235235,952

E719,327,70,356,76530,63291,357239,273

E819,328,7119,3549,93301,167248,763

E919,329,7119,3569,23310,977258,253

E1019,330,7119,3588,53320,787267,743

E1119,331,7119,3607,83330,597277,233

E1219,332,7119,3627,13340,407286,723

E1319,333,7119,3646,43350,217296,213

E1419,334,7119,3665,73360,027305,703

Vy, ng sut c hiu ti gia cc lp t tnh ln l: Lp t th 1: = 159,673 kN/m2Lp t th 2: = 235,952 kN/m2

6.1.2. Xc nh ng sut gia tng do ti trng trng thi gii hn s dng gy ra tng ng sut c hiu ti gia lp t do ti trng trng thi s dng gy ra c xc nh theo cng thc sau :

Ta c :

=>

Hnh 11. Minh ha quy i vng din tch im tnh ng sut c hiu

Trong : : tng ng sut c hiu ti gia lp t do ti trng ngoi gy ra V: Ti trng thng ng theo trng thi gii hn s dng, V = 12162,62KN Bg: Chiu rng trn mt bng ca nhm cc. (=X) Lg: Chiu di trn mt bng ca nhm cc. (=Y) Zi : Khong cch t v tr 2Db/3 n trng tm lp t cn tnh lnTa c bng tnh nh sau :

Bng 6: ng sut c hiu cc im do ti trng TTGHSDim tnh lnBg (m)Lg (m)Zi (m) (Mng tng ng) (kN/m2)T l:

C4.057.650,00294,89

D4.057.651,47181,575,28

E4.057.652,93123,620,84

E14.057.653,9398,800,62

E24.057.654,9380,820,47

E34.057.655,9367,370,37

E44.057.656,9357,040,30

E54.057.657,9348,930,24

E64.057.658,9342,430,20

F4.057.659,5838,890,18

E74.057.659,9337,160,16

E84.057.6510,9332,810,14

E94.057.6511,9329,190,12

E104.057.6512,9326,140,11

E114.057.6513,9323,540,09

E124.057.6514,9321,310,08

E134.057.6515,9319,390,07

E144.057.6516,9317,710,06

6.1.3. Chiu su tnh ln ( Hc )Quy nh: Chiu su Hc ca tng t chu nn tnh t y mng n su m ng sut ph thm bng 0.1 ng sut do trng lng bn thn ca t

Qua bng 6 ta thy Hc = Zi (E11) = 13,93 m6.1.4. Xc nh ln n nh

- Xc nh OCR hay t l: :

: p lc tin c kt ( ly t th nghim nn c kt ). (kN/m2)

: ng sut c hiu ti gia lp t do trng lng bn thn t gy ra. (kN/m2)

Bng 7: Tnh ton t s c kt OCR

Lp t tnh ln

OCR=

Gia lp tnh ln th 1(D)227.0159.6731.42

Gia lp tnh ln th 2(F)356.0235.9521.51

V OCR c 2 lp tnh ln u ln hn 1, nn ta s dng cng thc tnh ln i vi trng hp t qu c kt ban u:

Trong : Sci: ln c kt.Hc: Chiu cao ca lp t chu nn. Hc = 13.93 me0: T s rng ti ng sut thng ng hu hiu ban u Lp t tnh ln th 1 (Lp 2): e0=0.903 Lp t tnh ln th 2 (Lp 3): e0 =0.698: ng sut hu hiu thng ng cui cng ti im gia lp t ang xt: ng sut c hiu tng thm ti gia lp t do ti trng ngoi gy ra=

Gia lp tnh ln th 1:

Gia lp tnh ln th 2: Cc: Ch s nn p c xc nh t th nghim Lp tnh ln th 1: Cc=0,31 Lp tnh ln th 2: Cc=0,22Ccr: Ch s nn p li (ch s n), c xc nh t th nghim Lp tnh ln th 1: Cr=0,043 Lp tnh ln th 2: Cr=0,028

Hnh 12: ng cong nn c kt in hnh i vi t nn qu c kt-Quan h bin dng thng ng vi ng sut thng ng hu hiu EPRI (1983)

Lp t th 1: i vi t c kt cao ban u (do mt t b ln t trc do c cng trnh )ADCT:

Lp t th 2:

Vy ln ca mng l : Sc = 0,0218+0,01358 = 0,03538 (m) =3,538 (cm)

6.2. Kim ton chuyn v ngang ca nh cc S dng phn mn tnh ton nn mng FB-PIER ta tnh c chuyn v theo cc phng dc cu (X), phng ngang cu (Y), phng thng ng (Z) ti v tr u mi cc nh sau :

********************************************** ***** Final Maximums for all load cases ***** **********************************************

Result Type Value Load Comb. Pile *** Maximum pile head displacements *** Max displacement in axial 0.2308E-02 M 1 0 13 Max displacement in x 0.2682E-04 M 1 0 14 Max displacement in y 0.3101E-07 M 1 0 25Chuyn v ngang ln nht ti nh cc l: Theo phng ngang cu: x= 0,2682.10-4 m = 0,02682 mm 38mm Theo phng dc cu: y = 0,3101.10-7 m = 0,3101.10-4 mm 38mmVy m bo yu cu v chuyn v ngang

7. cng ct thp cho cc v b cc7.1. Tnh v b tr ct thp dc cho ccTng chiu di cc dng tnh ton v b tr ct thp l chiu di c cc :L = 24 (m). c chia thnh 3 t, mi t c chiu di Ld = 8 m. Ta i tnh ton v b tr cho tng t cc.7.1.1. Tnh m men theo s cu cc v treo ccM men ln nht dng b tr ct thpMtt = max(Mmax(1) ; Mmax(2))Trong :Mmax(1): Mmen trong cc theo s cu ccMmax(2): Mmen trong cc theo s treo cc Tnh mmen cho t cc c chiu di Ld = 8 m Tnh m men ln nht trong cc theo s cu ccCc mc cu t cch u cc mt on :1,6 m8x2.0L2.0dTrng lng bn thn cc c xem nh ti trng phn b u trn c chiu di on ccq1 = gbt.A = 24,5 x 0,452 = 4,96 (kN/m)Di tc dng ca trng lng bn thn ta c biu m men nh sau :

1,64,81,67.946.356.35Hnh 13. Tnh ton cc theo s cu ccTa c mt ct c gi tr m men ln nht l : Mmax(1)= 7,94 kN.m Tnh m men ln nht trong cc theo s treo cc:Mc c t cch u cc mt on:0,294Ld = 0,294 x 10 = 2,94(m)Di tc dng ca trng lng bn thn ta c biu m men nh sau :

5.6482.35213.7212.92Hnh 14. Tnh ton cc theo s treo cc

Ta c mt ct c gi tr m men ln nht l : Mmax(2)= 13,72 KN.mVy m men ln nht dng b tr ct thp l :Mtt = max(Mmax(1) ; Mmax(2) ) = max(7,94; 13,72) = 13,72 kN.m7.1.2. Tnh v b tr ct thp dc cho ccTa chn ct thp dc ch chu lc l thp ASTM A615MGm 822 c fy = 420 MPa c b tr trn mt ct ngang ca cc nh hnh v :

Hnh 15. B tr ct thp dc cho cc

Ta i tnh duyt li mt ct bt li nht trong trng hp bt li nht l mt ct c m men ln nht trong trng hp treo cc: +) Cc c chiu di Ld= 8 m th Mtt = 13,72 KN.m

Kim tra b tng c b nt hay khng trong qu trnh cu v treo cc +) Cng chu ko khi un ca b tng l : 0,8.fr = 0.8x3,334 = 2,667 (MPa)ng sut ko ti th ngoi cng ca mt ct nguyn :+) Cc c chiu di Ld= 8 m:

(Mpa)Vy: Cc khng b nt khi cu v treo cc Tnh duyt kh nng chu lcNhn xt : Do ct thp c b tr i xng, mt khc ta bit b tng c cng chu ko nh hn nhiu so vi cng chu nn v vy trc trung ha lch v pha trn trc i xng. Gi thit tt c cc ct thp u chy do Phng trnh cn bng ni lc theo phng trc dm :Trong :As1v As2 : Din tch ct thp chu ko (mm2): Din tch ct thp chu nn (mm2): Cng chu nn ca b tng (Mpa), = 30 (Mpa)fy : Cng chy ca ct thp, fy = 420 (Mpa)a : Chiu cao vng nn tng ngd : ng knh cc, d = 450 (mm)E : M un n hi ca ct thp, Chiu cao vng nn tng ng c xc nh theo cng thc :

Do fc =28 MPa V tr ca trc trung ha c xc nh : Kim tra s chy do ca ct thp chu ko v chu nn theo iu kin :Trong :ds1 v ds2 : Khong cch t trng tm ca ct thp chu ko n th b tng chu nn ngoi cng: Khong cch t trng tm ca ct thp chu nn n th b tng chu nn ngoi cngTa c :Vy tt c cc ct thp u chy Gi thit l ng M men khng un danh nh l :

= 238.86x106 N.mm = 238.86 KN.m M men khng un tnh ton l :

Mr = .Mn = 0,9x238,86 =214.98 (kN.m) > Mtt = 13,72 (kN.m) t Kim tra hm lng ct thp ti a v hm lng ct thp ti thiu => t => => tKt lun: Ct thp c chn v b tr nh trn l m bo kh nng chu lc

7.2. B tr ct thp ai cho ccDo cc ch yu chu nn, chu ct nh nn khng cn duyt v cng ca ct thp ai. V vy ct thp ai c b tr theo yu cu v cu to. u mi cc ta b tr vi bc ct ai l 50 mm trn mt chiu di l: 750 mm. Tip theo ta b tr vi bc ct thp ai l 100 mm trn mt chiu di l: 1100mm on cn li ca mi on cc (phn gia on cc) b tr vi bc ct ai l : 150 mm

7.3. Chi tit ct thp cng mi ccCt thp mi cc c ng knh 40, vi chiu di 100 mmon nh ra khi mi cc l 50 mm

7.4. Li ct thp u cc u cc b tr mt s li ct thp u cc c ng knh 6 mm ,vi mt li a = 5050mm. Li c b tr nhm m bo cho b tng cc khng b ph hoi do chu ng sut cc b trong qu trnh ng cc.

7.5. Vnh ai thp u cc

u cc c bc bng mt vnh ai thp bng thp bn c chiu dy =10mm nhm mc ch bo v b tng u cc khng b hng khi ng cc v ngoi ra cn c tc dng hn ni cc t cc trong khi thi cng vi nhau.

7.6. Ct thp mc cuCt thp mc cu c chn c ng knh 22. Do ct thp b tr trong cc rt tha v vy ta c th s dng lun ct thp mc cu lm mc treo khi ta khng cn phi lm mc th 3 to iu kin thun li cho vic thi cng v cc trong biKhong cch t u mi on cc n mi mc neo l a = 1.6 m = 1600 mm

8. Tnh mi ni thi cng ccTa s dng mi ni hn ni cc on cc li vi nhau. Mi ni phi m bo cng mi ni tng ng hoc ln hn cng cc ti tit din c mi ni. ni cc t cc li vi nhau ta s dng 4 thp gc L-10010012 tp vo 4 gc ca cc ri s dng ng hn lin kt hai u cc (i vi cc c, vung ta thng s dng mi ni hn; i vi cc trn, ng ta thng s dng mi ni bu lng). Ngoi ra tng thm an ton cho mi ni ta s dng thm 4 thp bn 500x100x10mm c tp vo khong gia hai thp gc tng chiu di hn ni.

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- 20 -Trn Ngc Trang a k thut CTGT- k48