N THI CNG CHUYN MN V ATLGVHD: Th.S PHM MINH GIANGMHP: 093110NHM: 01

I. TRNH T V BIN PHP THI CNG CHUNG CHO TON B CNG TRNH1. Trnh t thi cng cng trnh: Khi tin hnh thi cng cng trnh bn nn theo cc trnh t sau: Bc 1: Chun b cng trng, dn dp cc chng ngi vt trong khu vc xy dng. Tin hnh no vt khu nc trc bn bng tu ht hoc gu ngom n ng cao v mi dc thit k. mi dc no vt 1 : 3. Sau khi kt thc no vt phi c o c kim tra nghim thu trc khi lm bc tip theo. Bc 2 : ng cc. Trc khi ng cc i tr phi tin hnh ng th cc. Thit b ng cc t trn s lan, c th dng sn o nh v cc hoc dng tu ng cc. Khi ng cc phi dng 2 my kinh v theo di. Cc cc phi kim tra nghim thu trc khi ng. Bc 3 : Sau khi ng cc, lin kt cc u cc li vi nhau bng h ai cc. Bc 4 : Lp dng vn khun, lp t ct thp tin hnh b tng dm ngang, dm dc. S dng cn cu v trm trn trn s lan 300T b tng thng qua h thng phu hoc s dng my bm b tng trn b v bm b tng thng phm. Bc 5 : Khi cng b tng d cu dn v bn chn t t n cng thit k, tin hnh thi cng kt cu m khu vc cu dn. Bc 6 : Lp dng ct pha, lp t ct thp bn mt cu v tin hnh b tng mt cu cu chnh v cu dn. Bc 7 : Lp t bch neo, m ta tu, g chn xe. Hon thin, bn giao a cng trnh vo s dng.

2. Bin php thi cnga. H thng cc Bc 1: nh v ba ng cc Bc 2: Thit lp b khung dn hng, sn o Bc 3: Kim tra li v tr ca cc Bc 4: ng cc th nht Bc 5: Hn cc on tip theo Bc 6: Cu ba v ng tip on mi Bc 7: Kim tra chi Bc 8: Rt ba Bc 9: X l u cc, ghp lng thp lien kt vi dm

b. Lp dng vn khun, b tr c nh ct thp b tng dm ngang dm dc Gm cc bc sau: Bc 1: Chun b sn thao tc Bc 2: Lp t sn thao tc Bc 3: Lp t h dm Bc 4: Lp t h vn khun y Bc 5: Lp t vn khun y Bc 6: Lp t ct thp lp y Bc 7: Lp t ct thp cc lp bn trn Bc 8: Lp vn khun thnh Bc 9: Lp t cc h cng nghc. b tng v lp t cc cu kin trong bn Gm cc bc sau: Bc 1: b tng Bc 2: Bo dng b tng Bc 3: Tho d vn khun Bc 4: Lp t cu kin c sn Bc 5: Lp t cc ph kin (bch neo,bu-lng neo m va) Bc 6: b tng hon thin v bo dng Bc 7: Bo dng b tng Bc 8: lp t cc ph kin b tng cn li ( ray cn trc, dy in)

PHN III: XY DNG LI O C KHNG CH LP H TA A PHNG PHC V THI CNG

I. CHN MC C BN Cn c vo bnh khu vc xy dng ta chn 2 mc c bn sau: N(1169448.623 ; 612216.449) M(1169318.623 ; 612166.449)

Ngoi ra trn bnh qui hoch ta xc nh thm 2 im thuc tuyn bn: A(1169445.088 ; 611910.535) - gc ngoi cng bn tri tuyn bnB(1169543.650 ; 611978.986) - gc ngoi cng bn phi tuyn bn

Kim tra li chiu di bn:

AB =

= = 120,000m

II. LP H TRC TA A PHNG XOY (CNG TC NI NGHIP).1. Phng trnh ng thng tuyn bn c dng: (d1): y = ax + b (d1) i qua A v B nn ta c h phng trnh:

phng trnh ng thng tuyn bn (d1) l:

(d1): y = 0.6945x - 200265,4123

2. Phng trnh ng thng OY: Chn h trc to cc vi O lm gc: OY (d2) l ng thng i qua A v vung gc vi tuyn bn : Phng trnh ng thng OY (d2) c dng:(d2): y = ax + b Do (d2) vung gc vi (d1) nn ad1ad2 = -1 Mt khc (d2) i qua A nn: 611910.535 = -1,43991169445.088+ b b = 2295784.3537 Phng trnh ng thng (d2) l: (d2): y = -1,4399x + 2295784,3537

Chn gc to O thuc ng thng (d2) cch im A mt on bng 120(m) v pha b. To gc O(xo ; yo). Do O thuc (d2) nn: Yo = -1.4399Xo + 2295784.3537 (1). di on OA = 120(m)

.

Gii phng trnh bc 2 i vi Xo ta c Xo = 1169376,637 Thay Xo vo phng trnh (1): Yo = -1.43991169376,637+ 2295784.3537 = 612009,097 Chn to im O (1169376,637; 612009,097).

3. Phng trnh ng thng OX Gi OX (d3) l ng thng i qua O v song song vi tuyn bn: Phng trnh ng thng OX c dng: (d3): y = ax + b V (d3) // (d1) ad3= 0.6945. Mt khc : (d3) i qua O nn: 612009,097= 0.6949001169376,637+ b b = -200119,3113 Phng trnh ng thng (d3): (d3): y = 0.6945x - 200119,3113III. XC NH IM O V A KHI BIT MC M V N

1. Xc nh im O: N(1169448.623 ; 612216.449)M(1169318.623 ; 612166.449)O(1169376,637 ; 612009,097).

2. di cc on thng trong li o ca. di on thng MN

b. di on thng OM:

c. di on thng ON

3. Cc gc trong li o ca. Gc MON p dng nh l hm s cosin trong tam gic MON ta c: MN2 = OM2 + ON2 - 2OMONcos(MON).

(2)

Thay : vo phng trnh (2) ta c:

MON = 39,384o = 39o23'3".

b. Gc ONM, OMN p dng nh l hm s sin trong tam gic MON

. Kim tra li kt qu: 39o23'3" + 89o13'53" + 49o49'3" = 180o00'00"

4. Xc nh im H theo trnh t saua. Xc nh im H: Gi im H (XH;YH) thuc d3 (d3//d1). Cch im O mt khong 120(m) v bn phi tuyn bn : YH = 0.6945XH 200265.412 (3). Tnh di on thng OH: O(1169376,637 ; 612009,097).

Gii phng trnh ny ta c XH = 1169425.918 thay vo phng trnh( 3) ta c YH = 0.69451169425.918 200265.412 = 612043.323 Vy to im H l (1169425.918 ; 612043.323).5. Tnh di cc on thng trong li: N(1169448.623 ; 612216.449) M(1169318.623 ; 612166.449) H(1169425.918 ; 612043.323).a. Tnh di on thng MH:

b. Tnh di on thng NH:

6. Tnh cc gc trong hng o ca. Gc MHN p dng nh l hm s cosin trong tam gic MHN ta c:

MN2 = MH2 +NH2 - 2MHNHcosMH

(3) Thay : vo phng trnh (2) ta c:

b. Gc HMN, HNM p dng nh l hm s sin trong tam gic MHN ta c:

.

Kim tra li kt qu:

Vy :

IV. CNG TC NGOI NGHIP1. Xc nh ta im O: S dng phng php giao hi my ( giao hi thun ) t hai my kinh v ti 2 mc M v N chn. nh tm cn bng my. My 1 t ti N ngm v mc M c tia ngm NM, chnh bn v 000000. M ngc chiu kim ng h 1 gc . Kha my. My 2 t ti M ngm v mc N c tia ngm MN, chnh bn v 000000. M thun chiu kim ng h 1 gc . Kha my. Giao ca hai tia ngm ny ta xc nh c gc ta O. Tin hnh b tng (hoc ng c) chn mc , lp bin php bo v.

2. Xc nh ta im H: t my ti N, nh tm cn bng my ngm v M, chnh bn v 00000 M ngc chiu kim ng h 1 gc: . Kho my. t my 2 ti M, nh tm cn bng my ngm v N, chnh bn v 000000. M thun chiu kim ng h 1 gc: . Kho my. Giao ca hai tia ngm ny ta xc nh c im H. Tin hnh b tng (hoc ng c), chn mc , lp bin php bo v.

3. Xc nh h trc to a phng XOY: t my ti O ngm v H ta xc nh c trc OX. t my ti O, nh tm cn bng my ri ngm v H ta c tia ngm OH, chnh bn v 0o0000, m ngc chiu kim ng h 1 gc 900 ta xc nh c trc OY. in hnh chn mc (hoc ng c) b tng , lp bin php bo v.

H TRC TA A PHNG OXY C XC LP

I. LA CHN PHNG N NG CC1. Cng tc trc khi ng cc Trc khi thi cng h thng cc ta cn tin hnh no vt lng bn ti cao trnh thit k. Vi cao trnh thit k l -9.433m. dc mi thit k 1: 3. Dng tu no vt xng cp E50116 dung tch gu 1.25m3, chiu di cn 25m, dng x lan m y 150m3 vn chuyn t mang i .2. Kim tra kh nng cc ng nhau trong qu trnh thi cnga. Gia cc xin v cc thng Tin hnh kim tra trn 1 phn on bn Cc c h n su thit k: -26,2m Chiu di cc : L = 33m nghing ca cc: 1: 6 Gc nghing so vi phng thng ng: = 9.46o trnh cc ng nhau trong qu trnh thi cng, hng cc xin c ng lch 10o trong khng gian

Theo s trn th khong cch gia cc ng trc bn v cc xin ca dm dc ray c xc nh nh sau. Vi cc trng phn on bn: Khong cch theo phng ngang cao trnh 26.2(m)

x = Lcsin(9,46o)sin(10o)

= 33sin(9,46o)sin(10o) = 0,94(m) Khong cch theo phng dc

y = Lcsin(9,46o)cos(10o)

= 33sin(9,46o)cos(10o)= 5,34(m) Ta thy vi x, y tnh ton trn, v ng knh cc l 0,6m khong cch t tim cc gia hng cc ray cn trc v hng cc cnh nhau s khng chm nhau. Nhn thy nu 2 cc xin gn nhau th cc tha mn iu kin khng ng khi thi cng.

3. Chn phng tin h cc: Xc nh s b thit b ng cc: Theo sch Thi cng cng trnh Cng-ng Thu ca Thy. H Ngc Luyn v cc ng nghip Trng i Hc Xy Dng th chiu cao ca gi ba c xc nh theo cng thc sau : H = Lcc + h1+ h2 + h3 trong : Lcc : Chiu di ca cc. Tnh vi Lcc = 33m h1 : Chiu cao ca ba, i vi ba K25 c h1 = 4,55m. h2 : Chiu cao phn hnh trnh vt ra khi nh ba, h2 =0,3m. h3 : Chiu cao dng cho puli, mc cu(thng ly t 0,5 n 1m). Chn h3=1,0 m H = 33 + 4,55 + 0,3 + 1,0 = 38,85 (m) i vi trng hp trn ta tnh ton cho trng hp ni cc (lc ny khng li dng mc nc) vi 0,5(m) l khong cc nh ln khi mc nc tin hnh ni cc. Chiu cao gi ba : 40 m i vi trng hp ng on cc u tin, lc ny ta c th li dng mc nc nn chiu cao gi ba s nh hn. Vy vi chiu cao gi ba l 37m la chn hp l. ng cc xin dng 1:6 : ng xin 1 gc 9.46o ng cc xin m 1:6 : ng xin 1 gc 9.46o Ch cc cc v tr xin khe lc khng ng xin

4. Chn cn cu bnh xch : Chn loi cn cu bnh xch phi da vo cc thng s ca cn cu m bo ng c ht cc m chng ta cn ng. Cn c vo ta chn Cn cu bnh xch HITACHI PD6: Chiu di cn : 18m. Sc nng max : 7,5T. Sc nng min : 0,75T Tm vi max : 17m. Tm vi min : 4,3m. Trng lng : 32T. p lc ln t : 0,66(Kg/cm2).

5. Chn tu ng cc : Chn tu ng cc c cc thng s nh sau:

6. Chn ba ng cc :

Chn ba loi Diezel MITSHUBISHI MH25, c thng s nh sau: Trng lng tt c ca ba : 19.93T Trng lng va p ca ba : 7.2T Chiu cao ba : 4.55m Chiu rng ba : 0.768m Chiu di ba : 1.0m Nng lng xung kch ln nht: Ett = 21 (T.m)Tnh ton v kim tra iu kin lm vic ca ba PHN V

7. ng cc : Cng tc nh v v ng cc ng trong qu trnh h cc:a. nh v cc ng : Trong qu trnh ng cc, m bo cc ng ng v tr ta dng phng php giao hi tin phng vung gc, im khng ch ly theo bng toa cc theo h trc XOY, v tr cc chnh l giao im ca 2 my kinh v t trn tuyn ngm nh trc. Thao tc ngm: S dng 2 my kinh v, my 1 di chuyn trn sn cng tc, my 2 di chuyn trn trc OX Hng ngm 1: My 1 di chuyn trn sn cng tc sau khi nh v c v tr cc cn ng trn sn cng tc, quay my v mc O chnh bn v 0 quay my 90o ngc chiu kim ng h kha my. Hng ngm 2: My 2 di chuyn trn trc OX sau khi nh v c v tr cc cn ng, quay my v mc O chnh bn v 0 quay my 90o thun chiu kim ng h kha my. Giao ca 2 hng ngm ny l v tr cc cn ng .

b. Cng tc nh v v ng cc xin : i vi cc xin, xoay, cng tc nh v c thc hin nh sau: ng cc bng tu ng cc. Di chuyn tu ng cc n v tr ng cc c xc nh trc, tu c di chuyn bng h thng ti, neo trn tu. Xoay gi ba n xin thit k ca cc. m bo cc ng ng xin thit k ngi ta phi dng thc tam gic vung, c hanh cnh gc vung theo t l xin c cc. Khi p cnh huyn vo mt xin ca cc m dy di trng vi cnh ng ca gc vung l c.

iu chnh v tr cc xin theo ng ta thit k ta thc hin nh sau: Tia ngm ca my kinh v nhn vo mt nghing ca cc phi m bo sao cho dy ng ca mng ch thp phi trng vi ng tim cc. Tia ngm nhn vo pha mt ng ca cc phi c li li mt on x = h.tg. Trong h l cao ca tia ngm hay cao thit k u cc; l gc nghing ca cc.

Xoay tu ng cc m bo cc c xoay trn mt bng theo ng gc xoay thit k (15o). Trnh t c thc hin nh sau: C nh neo trc m bo v tr cc nh v khng b thay i khi tu xoay. Ni neo sau v neo hng tri (hoc phi) ty theo gc xoay trn mt bng, ng thi thu neo phi (hoc tri) tu ng cc xoay ui cho ti khi trc dc ca tu ng hp vi trc dc bn mt gc bng 15o theo thit k. My kinh v s ngm vo v tr ng cc, a my kinh v v s 0, quay sang tri (hoc phi) 15o kha my. Tu ng cc xoay sao cho tim cc pha mt nghing trng vi dy ng ca mng ch thp l c.c. Cc quy nh trong thi cng Trong qu trnh thi cng phi tun th theo cc quy nh v thi cng v nghim thu cng trnh do B Giao Thng Vn Ti v B Xy Dng ban hnh: Cc quy nh v cu kin c sn Cc quy nh v cng tc ng cc Cc quy nh v thp xy dng v ng hn Cc quy nh v sai s cho php khi lp t vn khun b tng ti ch Cc quy nh v nghim thu cng tc b tng (trong phn ct liu phi t tiu chun, ct sch, hm lng ht bn khng c vt qu gii hn cho php).

8. Cng tc th cc : s lng v v tr th cca. S lng cc th: Theo tiu chun TCXD205-1998 s lng cc th l 1% tng s cc ca cng trnh v khng c nh hn 5 cc. Vi tng s cc ca cu chnh l 256 cc. Ta chn s cc th l 6 cc chia u cho cc phn on ca cu chnh v cu dn.b. V tr th cc: c xc nh trn mt bng b tr cc do bn thit k ch nh S lng cc th c chia u cho 4 phn on .c. Cng tc ng cc th: Tin hnh ng cc ti v tr th cc theo yu cu c chn. Tin hnh ng cc n su thit k (n cao trnh -25.214m), Ngng mt thi gian tin hnh th ti (theo phng php th tnh) ti trng th ly bng ti trng tnh ton ca cng trnh sau tin hnh theo di ln ca cc, T xc nh c sc chu ti ca cc, so vi sc chu ti thit k, nu tha tin hnh ng cc i tr .

9. Chn s ng cc Chn phng n ng cc theo s hnh thang (th hin trn hnh v) Mc nc thi cng ng cc: MNTK tu vo tnh hung c th m ta c th chn mc nc khc nhau cho ph hp vi tnh hnh thc t ca con nc khu vc. S ng cc theo phng ngang . Khong cch OH = 60(m)

10. H cc bng phng php ng :

Cc s dng l cc BTCT ng sut trc nn cc c c ti nh my v vn chuyn bng x lan 300(T), chuyn cc t trn b xung x lan dng cn trc nhng phi m bo n nh mi dc mp b. Trc khi lp cc vo gi ba th phi t cc sao cho gi ba chia cc thnh 2 phn bng nhau. Mc dy cp treo cc ca gi ba vo mc cu pha u cc, mc dy cp treo ba ca gi ba vo mc cu pha mi cc. Tip tc ko cc t t ln bng 2 dy cu ca gi n cao 1 2m tin hnh ko t t cp treo ba mi cc a cc v v tr thng ng ng thi rt x lan ch cc ra. Tin hnh p cc vo thanh dn ca gi ba, c nh cc bng ai m cc. Khi cc vo ng v tr, nh ti cho cc t t xung t. Cc t ln xung khi ht ln p ba ln u cc ln ht. Trong qu trnh ng phi tin hnh ng cc t t nhng nht u cn ng chm cc xung t t khng b lch, sau tng dn s nht ng cc ln. Ko ba ln cao nhiu hay t ph thuc vo loi t ti v tr thi cng. Khi ng yu cu ng tim ca ba ca cc ang ng phi trng nhau. Do ta phi ng cc ni nn sau khi ng xong on cc th nht ta tin hnh cu phn cc cn li ln gi t phn cc cn li vo v tr sao cho 2 tim cc phi trng nhau. Sau ta tin hnh ni cc. Do cc s dng l cc BTCT ST nn ta s dng bin php ni cc bng cnh bt bu lng vi cc l c tra sn. Trong qu trnh h cc phi lun kim tra v tr, cao cc bng hai my kinh v giao hi vung gc,ngm vo tim ca cc iu chnh n ng cao thit k. Trong qu trnh ng cc nu c xut hin cc hin tng bt thng (Cc b tt nhanh chng mt cc. Cc khng th ng xung c na mc d cha n c su thit k) ta phi cho dng ngay cng tc ng cc li v bo cho bn thit k h c bin php x l kp thi. Phi c h s ng cc v ghi nht k ng cc thun tin vic kim tra v x l k thut. Ch i vi cc xin phi kim tra xin . nh v cc xin ngay trong gi ba Cc xin dng 1 : 6 Cc xin m 1 : 6 Sau khi ng cc xong tin hnh neo ging tm thi cc cc bng cc thanh thp ging hnh . Cc h ging tm c g b khi cc cc u c lp x kp chnh chun b cho cng tc thi cng phn b tng.

11. Cng tc ni cc Sau khi tin hnh a phn cn li ca on cc ln gi ba (Tim cc phi trng khp vi nhau). Ta tin hnh ni coc: Hai u cc ni c chun b sn cc mt bch c tra sn cc l bt bu lng. bo v khu vc c ni bng thp khi s xm thc ca mi trng ta phi tin hnh x l mi ni bng cch dng cc ming vi b tm nha ng bc kn xung quanh khu vc mi ni mt lp dy khong 30(mm) sau m bo ta nn trt thm mt lp Ximng (H du) m c xung quanh khu vc mi ni. Sau ta tip tc ng cc.Thi gian x l mi ni khong 1 ting.

12. X l u cc Sau khi ng cc n cao trnh thit k, do cc s dng l cc BTCT ST nn ta khng th p u cc m phi lm lng thp lin kt phn u cc vi h thng dm Trong trng hp nu cao trnh nh ca cc cc sau khi ng cao hn cao trnh thit k th tin hnh ct u cc n ng cao thit k nhng phi c s ng ca n v thit k. S dng my ct chuyn dng thc hin, m bo to mt phng u cc.

PHN V: TNH TON CHN BA NG CC V XC NH CHI TNH TON CC TH

Vic tnh ton v kim tra iu kin thc hin theo 2 tiu chun sau: TCXD 9394 : 2012 TCXD 88:1982

I. KIM TRA BA NG CC Theo tiu chun TCXD 9394 : 2012. Kim tra ba ng cc theo cc trng hp sau: iu kin 1: Nng lng cn thit ti thiu ca nht ba p Emin c xc nh theo cng thc:Echn Emin = 1.75aP trong : Ptt l sc chu ti ca cc: a h s bng 25(kG.m/T) E l kh nng chu ti ca cc, quy nh trong thit k tnh bng tn (T) Ptt = 198,53(T) Emin = 1.75aP = 1.750.025198.53 = 8.69(T) < E = 21(T) Tha mn iu kin 2: Loi ba c chn vi nng lng nht p phi tha mn iu kin:

trong Kmax : H s thch dng, tra bng trang 91 sch K thut thi cng cng trnh cng ng thy vi cc BTCT ng bng ba diezel n ng Kmax = 5,0 q : Trng lng cc (gm c trng lng m v m u cc): q = 0.408(T/m): q = qcc + 0.5 = 330.408 + 0.5 = 13.964(T) Q: Trng lng ton b ba : Q = 19.93(T)

Tha mn

iu kin 3: V chi thit k ca cc 0.2cm e 2cm chi thit k c tnh theo cng thc :

trong Q : trng lng ton phn ca ba, Q = 19.93T (q + q1): trng lng ca cc, m cc v cc mq + q1 = 13.946T P : kh nng chu ti ca cc theo t nn, P = 198.53T n : h s tra theo Bng 5, loi ba Cc BTCT c thp: n = 150(T/m2) m : h s an ton, i vi ba ng m = 1 k : h s an ton v t k = 1.4 F : din tch tit din ngang cc D600, F = 0,283m2 H: ri ca qu ba vi ba, H = : h s ty thuc vo vt liu va p, i vi ng cc BTCT bng m: 2 = 0.2

Kim tra iu kin 0.2cm e = 0.7cm 2cm Vy s dng ba MH32 cho thi cng.

PHN VI : TNH TON H THNG KHUNG SN O, H ,VN KHUN PHC V CHO THI CNG DM BN

A. BIN PHP K THUT THI CNG Vn khun l kt cu tm nhm nh hnh btng theo thit k v gi btng c nh trong sut thi gian v ninh kt. Cng tc thit k vn khun l xc nh c kch thc vt liu (vn mt, vn thnh, np ng, bulng..) v c ly, kt cu vn khun c th trin khai gia cng v lp dng. V th vn khun phi m bo yu cu: ng hnh dng, kch thc v v tr cc b phn cng trnh theo thit k. Vng chc, n nh, khng c bin dng qu ln khi chu ti. Mt vn khun phi bng phng, trn nhn, kn khng va btng chy khi m. Dng lp, tho d d dng, vn khun phi c s dng nhiu ln. Cng tc vn khun phi to iu kin thun li cho cc cng tc khc nh lp dng ct thp, san m btng. Bo m khi tho g t ng chm nht n vt liu v khng rung chuyn, khi gy cho btng trng thi ng sut qu mc. Trnh t thi cng vn khun bao gm vic lp dng vn khun sau va btng trong phm vi ngn cch ca vn khun, n khi btng t cng theo quy nh mi c tho d. Cng tc thit k vn khun l xc nh c kch thc vt liu (vn mt, vn thnh, np ng, bulng..) v c ly, kt cu vn khun c th trin khai gia cng v lp dng. Trong thc t cc loi cp pha v gio c ch to c th s dng li c nhiu ln v c th dng cho nhiu hng mc cu kin khc nhau, c quy nh trong c tnh lm vic ca chng. V th khi tnh ton ta ch cn xc nh kch thc vt liu cho dm ln nht v c nhp di nht (dm dc di ray 1.01.4(m); nhp di nht ca dm ngang l 5m ).Cn cc dm khc th s dng vt liu tng t ng vn khun, tuy nhin phi ch k kch thm cc thanh sn m bo ng cao thit k ca y dm

I. THIT K VN KHUN Y DM NGANG1. Ti trng tc dng ln vn khun y: Chn vn khun c b rng 30cm. Khi lng ring ca g (ta chn g nhm IV) chn = 0.6T/m3 Trng lng b tng: = 2.5T/m3 Khi lng ca ct thp: = 0.1T/m3 Xem cng tc b tng dm gm 2 giai on: Giai on 1: Tin hnh ti chiu cao dm tr i phn bn v khong d tr 5(cm) Giai on 2: Tip tc phn dm giao vi phn bn l 40(cm)a. Tnh ti Ti trng do b tng: pbt = qbthnvt trong : qbt : khi lng th tch b tng (kg/m3), qbt = 2500 (kG/m3) h : chiu dy lp b tng (m) h = 140 45 = 95 (cm) = 0.95 (m) nvt : H s vt ti, tra bng A.3 trang 35 Tiu chun TCVN 44531995 nvt = 1.2 pbt = 25000.951.2 = 2850 (kg/m2)b. Ti trng do ct thp: pct = qctnvttrong : qct : Khi lng ring ct thp, theo mc A.1.1.ctrang 33Tiu chun TCVN44531995, khi lng thp ly theo thit k, trng hp khng c khi lng c th th ly qct = 189(kg/m3) nvt : H s vt ti, tra bng A.3trang 35Tiu chun TCVN44531995 nvt = 1,2 pct = 1891.2 = 227.22(kg/m2)c. Hot ti Ti trng do ngi v dng c thi cng: Theo mc A.1.1.d)_trang 33_TCVN 4453:1995, ti trng do ngi v dng c thi cng khi tnh cp pha sn th ly 250(kg/m2). H s vt ti c tra bng A.3_trang 35_TCVN 4453:1995 l 1.3. Ti trng do chn ng khi b tng vo cp pha. Tra bng A.2trang 34TCVN 4453:1995, bng my v ng vi voi hoc trc tip bng ng ng t my b tng th ly 200(kg/m2). H s vt ti c tra bng A.3trang 35TCVN 4453:1995 l 1.3. Ti trng do chn ng khi m b tng. Theo mc A.1.1.e)_trang 33_TCVN 4453:1995, ti trng do m rung ly bng 200(kg/m2). H s vt ti c tra bng A.3_trang 35_TCVN 4453:1995 l 1.3. Ti trng do hot ti tc dng ln vn khun y l: pht = (250 + 200 + 200)1.3 = 845 (kg/m2) Vy tng ti trng do tnh ti v hot ti tc dng ln vn khun y l: p = ptt + pht = 2850 + 227.22 + 845 = 3922.22(kg/m2) Chn vn khun y c b rng l b = 30cm Tng ti trng phn b trn 1m di vn khun y l:P = 0.33922.22 = 1568.89(kg/m)

2. Tnh chiu dy vn khun y. D kin vn khun t trn cc sn ngang cch nhau 60cm. Do vy khi tnh ton vn khun y xem vn khun y nh cc dm n gin c chiu di nhp l 60cm. Momen ln nht trong dm :

Momen chng un cn thit:

Vi : ng sut un cho php ca g, = 120(kG/cm2)

Vy b dy ca vn khun thnh l :

Chn b dy vn khun y l 3.5cm Chn kch thc vn khun y: bt = 303.5(cm)

3. Kim tra vng vn khun y: vng ca vn c kim tra theo iu kin: fmax [f] Trong : [f] : vng cho php ca cu kin, theo mc A.3trang 35Tiu chun TCVN 44531995, i vi coffa ca b mt l ra ngoi ca kt cu:

fmax: vng tnh ton (cm)

q : ti trng phn b trn 1m di vn khun (kg/cm), q = 1568.89kG/m =15.6889kG/cm l: chiu di tnh ton vn khun (cm), l = 60cm E : Mun n hi ca g (kg/cm2), E = 1,2106 (kg/cm2) I : Mmen qun tnh ca cu kin:

< [f ] = 0.15 Vy iu kin bin dng c m bo. Kch thc vn khun y chn l hp l c: bh = 303.5(cm)

II. THIT K VN KHUN THNH1. Ti trng tc dng ln vn khun thnh p lc ngang ca hn hp b tng mi . p lc ca va b tng mi , ph thuc vo chiu cao lp b tng gy p lc ngang v bin php m. Tra bng 8.1_trang 109_Gio trnh K thut thi cng 1 P = Hnvttrong : H : chiu cao b tng dm (m), H = 0.95m : trng lng ring ca b tng, = 2500kg/m3, nvt: h s vt ti l nvt= 1.2. H s vt ti do p lc ngang c tra bng A.3_trang 35_TCVN4453:1995l 1.2 P = Hnvt = 25000.951.2 = 2850 (kG/m2). Ti trng do chn ng khi b tng: Tra bng A.2_trang 34_TCVN 4453:1995, bng my v ng vi voi hoc trc tip bng ng ng t my b tng th ly 200 (kg/m2). H s vt ti c tra bng A.3_trang 35_TCVN 4453:1995 l 1.3. Ti trng do chn ng khi m b tng. Theo mc A.1.1.etrang 33TCVN 4453:1995, ti trng do m rung ly bng 200(kg/m2). H s vt ti c tra bng A.3trang 35TCVN 4453:1995 l 1.3. Vy tng ti trng tc dng ln vn khun thnh l:p = 2850 + (200 + 200)1.3 = 3370 (kG/m2)Chn vn khun thnh c b rng l b = 40cmTng ti trng phn b trn 1m di vn khun thnh l:p' = 0.33370 = 1348 (kG/m)

2. Tnh chiu dy vn khun thnh: D kin vn khun thnh t trn cc thanh np ng cch nhau 60cm. Do vy khi tnh ton, xem vn khun thnh nh cc dm n gin c 2 gi l 2 thanh np ng, chiu di nhp l 60cm.

Chn chiu rng vn khun thnh l b = 40cm. Mmen ln nht trong dm:

Mmen khng un cn thit:

trong : [u]:ng sut cho php ca g (kg/m2), [u] = 120 (kg/cm2)

Chiu di vn khun tnh ton Chn kch thc vn khun thnh l b h = 403 (cm)

3. Kim tra iu kin vng ca vn khun thnh: vng ca vn c kim tra theo iu kin: fmax [f] = 0.15 Trong : [f] : vng cho php ca cu kin, theo mc A.3trang 35Tiu chun TCVN 44531995, i vi coffa ca b mt l ra ngoi ca kt cu:

fmax: vng tnh ton (cm)

q : ti trng phn b trn 1m di vn khun (kg/cm), q = 1348 kG/m =13.58 kG/cm l: chiu di tnh ton vn khun (cm), l = 60cm E : Mun n hi ca g (kg/cm2), E = 1,2106 (kg/cm2) I : Mmen qun tnh ca cu kin:

< [f ] = 0.15 Vy iu kin bin dng c m bo. Kch thc vn khun y chn l hp l c: bh = 403 (cm)

III. THANH NP NG1. Ti trng tc dng ln thanh np ng Cc thanh np ng c t cch nhau 60cm, chiu cao np ng l 95cm. Khi b tng phn np ng chu ti trng bng vi chiu cao b tng h = 95cm. Khi tnh ton ta xem np ng l dm n c nhp l 75m, phn consol l 20cm, c 2 gi l thanh gi chn v thanh chng xin. Ti trng tc dng ln thanh np ng bao gm cc ti trng tc dng ln vn khun thnh nh tnh ton phn thit k vn khun thnh v ti trng do bn thn ca vn khun thnh tc dng ln thanh np ng. Ti trng tc dng ln vn khun thnh ri ln thanh np ng nh tnh l p = 2850 (kg/m2):q1 = pl = 28500,75 = 2137,5(kg/m) Ti trng do bn thn vn khun thnh:q2 = hlnvttrong : h : chiu cao ca vn khun thnh (m), h = 4cm = 0.04 m l : chiu di nhp ln nht (m), l = 0.75m :Khi lng ring ca g, chn g lm cp pha theo mc A.1.1trang 33 trang 35Tiu chun TCVN 4453:1995, chn g nhm VI c khi lng ring l = 600(kG/m3). nvt : h s vt ti, tra bng A.3trang 35Tiu chun TCVN 44531995, nvt = 1,1 q2 = 0.040.756001.1 = 19.8(kG/m) Vy tng ti trng tc dng ln thanh np ng l:q = q1+ q2 = 2137.5 + 19.8 = 2157.3 (kg/m)

2. Chiu dy thanh np ng:

1 : Van khuon thanh 2: Sn ngang 3: Thanh nep ng 4: Thanh chong xien 5: G chong trt

Tnh phn lc ti gi A, B: MA = 0 RB 0.75 - q0.950.950.5 = 0 RB = 1297.98(kG) RA = 751.46(kG)

Momen chng un cn thit:

: ng sut un cho php ca g , =120 kG/m2

Chn chiu rng thanh np ng: b = 7 (cm). Vy chiu dy cn thit l:

Chn h = 9(cm). Kch thc np ng hp l bh= 79(cm).

3. Kim tra iu kin vng ca thanh np ng: vng ca vn c kim tra theo iu kin:fmax [f] = 0,15cm trong : Q : Ti trng phn b trn 1m di thanh np (kg/cm), q = 2157.3kG/m l : Chiu di tnh ton vn khun (cm), l = 75cm E : Mun n hi ca g (kg/cm2), E = 1,2106 kg/cm2 I : Mmen qun tnh ca cu kin:

Vy iu kin bin dng c m bo. Kch thc thanh np ng chn l hp l c: bh = 79(cm)

IV. THANH CHNG XIN Thanh chng xin c xin 1 gc 450 so vi phng ngang. Khi lm vic, thanh chu nn bng chnh ti trng c gi tr bng phn lc gi ca thanh np ng ln phng ngang.

Lc dc trong thanh chng xin:N = RBcos450 = 1297.98cos450 = 917.81(kG) Tit din ca thanh chng xin:

trong : [Rn]: Cng chu nn cho php ca g, [Rn] = 11,5kG/cm2 Chn tit din thanh chng xin c kch thc bh = 810 (cm) Cng chu nn ca thanh chng xin tit din chn trn l:

< Rn = 11.5(kG/cm2)Vy kch thc thanh chng xin chn l hp l c: bh = 810(cm)

V. THANH SN NGANGss1. Ti trng tc dng ln thanh sn ngang Xem sn ngang nh dm n k ln hai gi ta l hai sn dc t cch nhau 60cm.Ti trng tc dng ln thanh sn ngang bao gm cc ti trng tc dng ln vn khun y nh tnh ton phn thit k vn khun y, ti trng do bn thn ca vn khun y tc dng ln thanh sn ngang di dng phn b u (q) t gia hai gi v chu ti trng tp trung (P) hai u mt tha do thanh chng xin ca vn thnh truyn xung. Ti trng tc dng ln vn khun y ri ln thanh sn ngang nh tnh l p = 3922.22(kG/m2)q1 = pl = 3922.220,6 = 2353.33(kG/m) Ti trng do bn thn vn khun y:q2 = hlnvt trong : h: chiu cao ca vn khun y (m), h = 4cm = 0.04 m l: chiu di nhp ln nht (m), l = 0.6m : Khi lng ring ca g, chn g lm cp pha theo mc A.1.1trang 33trang 35Tiu chun TCVN 4453:1995, chn g nhm VI c khi lng ring l = 600(kg/m3). nvt: H s vt ti, tra bng A.3trang 35Tiu chun TCVN 4453:1995. Chn nvt = 1.1 q2 = 0.040.66001.1 = 15.84 (kG/m) Vy tng ti trng tc dng ln thanh sn ngang di dng ti phn b l: q = q1 + q2 = 2369.17(kG/m)+) Ti trng tp trung do thanh chng xin ca vn thnh truyn xung: P = Nsin450 = 917.81sin450 = 648.99(kG)

RA = RB = (2369.17 + 0.5648.99) = 1346.83(kG) Mmax = P0.6 = 648.990.6 = 389.39(kG.cm) Momen chng un cn thit

Vi [R] : cng tnh ton cho php ca thp, [R] = 2100 kG/cm2 Tra theo s tay kt cu cng trnh, ta c: Chn thp hnh I10 lm sn ngang vn khun vi cc thng s sau :+ h = 100 mm + t = 7.2 mm+ Wx = 39.7cm3+ b = 55 mm + R = 7.0 mm+ Jx = 198cm4+ d = 4.5 mm+ F = 12cm2+ g = 9.46 kG/m

2. Kim tra vng thanh sn ngang :

vng cho php ca cu kin :

vng tnh ton ca cu kin :

E : moun n hi ca thp, E = 2.1106 (kG/cm2)

= 0,204 cm < [f] = 0,867 (cm) Vy iu kin bin dng c m bo.

II. THANH SN DC

Sn dc chu ti trng tp trung do sn ngang truyn xung, c gi tr bng chnh phn lc ca sn ngang ti v tr gi k, ph hp vi s tnh ton ta qui v ti trng phn b, coi sn dc nh dm n chu lc phn b u k trn 2 gi ta l 2 s kp. Ti trng phn b trn 1 m di sn dc do ti trng tc dng ln sn dc l cc phn lc ca sn ngang ti v tr gi k. Vi s phn lc gi k > 5 v khong cch gia cc phn lc ny 60(cm) nn khi lp ct pha dm ch lp mt bn thnh t xong ct thpmi tin hnh lp nt thnh cn li vo gia vn khun y v vn khun thnh khngnn lin kt bng inh. V nu lin kt bng inh th s gy kh khn khi tho vn khun. Vn khun s dng li phi co sch s lp ximng dnh trn vn. d dang tho vn khun khi btng cng th trc khi btng nn ltgiy hoc bi cht chng dnh cho vn khun. Cc loi hn hp chng dnh; Hn hp: nigron + x phng git +nc. Hn hp: tn + x phng git + nc. Hn hp: tn + xi mng + nc Hn hp: Parafin + du ha Tm thnh dm dc chnh (dm dc di ray cn trc). Vn khun y.

Thao tc lp t vn khun: Bt c nh sn dc sn ngang. Lp vn khun y. ng np v c nh khun thnh. t ct thp. ng thnh vn khun cn li. ng cc thanh np ng v cc thanh chng xin. Kim tra lin kht ni cc khe ca vn khun. Tho vn khun: Tho vn khun phi cn c vo cng t c ca btng v s chnh lch nhit gia trong v ngoi khi btng, lng ph gia c s dng trong khi tin hnh btng. Phi tho nhng b phn vn khun khng chu lc trc ri n cc b phn vn khun chu lc.

IV. TNH TON AI KP CC

Xem x kp chu ton b ti trng t trn sn dc truyn xung di dng ti tp trung, chnh l phn lc ca sn dc v sn ngang trn n. thun li trong vic thi cng v m bo tnh ng b, ta tnh vi s kp chu ti ln nht ri b tr cho cc v tr s kp khc. Xt ti v tr va dm cn trc 100x140cm v dm ngang 100x140cm s chu ti trng ln nht v th ta tin hnh tnh ton vi s kp ti y. Tng ti tc dng ln x kp :

trong : Rd = 5.5(T) - Phn lc ca dm dc tc dng ln x kp. Rn = 1.35(T) - Phn lc ca dm ngang tc dng ln x kp.=> P = (5.5 + 1.35) x 2 = 13.7(T)1. Tnh bu-lng Chn bulng 30a. Lc xit cht ca bulng : Pb = RkblAthbl trong : Rkbl : Cng chu ct tnh ton ca vt liu bulng bng 70% cng chu ko tnh ton ; Rkbl = 0,7Rbc Tra Bng 2.9 gio trnh Kt cu thp vi bulng t thp 30 Ta c Rbc = 12000(Kg/cm2) Rkbl = 0,7Rbc = 0,712000 = 8400(kG/cm2) Athbl : Din tch thc tit din thn bulng Tra Bng 2.10 gio trnh Kt cu thp c Athbl = 5,6(cm2)

Pb = 84005,6 = 47040(kG)b. Kh nng chu trt ca bulng: Nbl = Pbmf trong : m: H s iu kin lm vic, m = 0,85 f: H s ma st b tng - thp, f = 0,45

Nbl = Pbmf = 470400,850,45 = 17992,8 (kG)c. Tnh s bulng cn thit:

Vy chn s bu lng l n = 2 bulng d. Tnh chiu cao ai kp cc: Chn bn thp dy = 10mm, cao h = 20cm. iu kin bn ca bn thp (chu nn phng ngang)

trong : Nbl = 2N2bl = 217992,8 = 35985.6(kG) F = Dh = 3,143020 =1884 cm2

iu kin nn phng ng :

trong N = 20646(kG) F = D = 3.14301 = 94.2 cm2

Vy bn thp = 1(cm), h = 20(cm) chn l hp l. V. GIA CNG CT THP1. Un ct thp: Thp loi trn trn 2 u c un mc tng lc dnh vi b tng. Un ct ai, ct ch nh trong thit k

2. Ct ct thp: Ct ct thp m bo ng thit k. Dng thc thp kim tra chiu di ct ct thp.

3. Hn ct thp: m bo ng quy nh v k thut v hn ct thp Khng c thanh p: Chiu di ng hn 1 pha : l 10d Chiu di ng hn 2 pha : l 5d C thanh p: Chiu di ng hn 1 pha : l 8d Chiu di ng hn 2 pha : l 4d

4. Ni buc ct thp: i vi ct thp chu ko khi ni phi c un mc cu u ct thp. on ni khng nh hn 40 d. i vi ct thp chu nn khng cn un mc cu. Chiu di on ni khng nh hn 25 d Mi mi ni phi but t nht 3 cho

VI. CNG TC B-TNG Chn mc nc thi cng b tng l MNTTK : +0,92m. Cc thit b phc v cho cng tc b tng bao gm: X lan 200T phc v thi cng. m di 50, 380CV, 1.5KW. My pht in 100 KVA. My hn 24 KW. My bm btng USB-5B, cng sut 15 m3/h. Cng tc trn b tng c thc hin ngay trn x lan. Trnh t b tng c thc hin t pha trong b ra. Dng h thng ng phu vi voi. ng knh ng ln hn t ( 2,5 3 ) ln ng knh ca ht ct liu. Khong cch t ming ng n mt hn hp b tng khng ln hn 1,5m. Gc gia ng vi voi v phng thng ng khng ln hn 300 B tng phi ri tp trung gia vn khun khng chm v bm vo ct thp. Ch tin hnh b tng khi kim tra ln cui cng tc vn khun v lp t ct thp.

Cng tc m b tng: S dng m di v m mt i vi m di: Bc di chuyn khi m khng ln hn 1,5 ln bn knh tc dng ca my m. cm su b phn cng tc ca my m phi bo m xuyn vo lp b tng trc 5 10 cm. Khng c t trc tip my m ln hoc cho chy m chm vo ct thp khi my ang hot ng. Thi gian m ti mt v tr t 20 40 s Khi m gc th khong cch b phn cng tc ca my m n m vn khun khng ln hn 5 10 cm i vi my m mt: Bc di chuyn phi m bo ph ln vt m trc t (10 22) cm. Thi gian m ti mt v tr: (30 60)s Khi m nn tin hnh hai bn vn khun thnh i vo gia khi chn ng nc ximng tp trung vo gia. Tho vn khun: Thi gian tho vn khun phi cn c vo cng t c ca b tng v chnh lch nhit gia trong v ngai khi b tng quyt nh. Trnh tho vn khun khi c lung kh lnh. Khi nhit b mt qu thp 110 140 th sau khi tho vn khun phi c lp vt liu gi nhit b mt b tng. Trnh t tho vn khun: tho nhng b phn vn khun khng chu lc trc ri mi tip n cc b phnvn khun chu lc.

VII. BO DNG B-TNG CT THP Thi gian bo dng ti thiu ( ngy m ): Ma kh : 6 Ma ma : 1

VIII. TRNH T THI CNG NG CC Cc c vn chuyn bng x lan n v tr ng. Mc cp gi ba vo mc cu ca cc cu cc. nh v cc vo ng tim thit k, c nh cc bng ai m. Tin hnh ng cc theo quy trnh: th ri t do, p ba khng n, n ba ng cc n cao thit k. Mt s yu cu cn thit: Chiu cao ba nhiu hay t ph thuc vo loi t ca tng cng trnh v phi iu chnh cho ph hp vi gi tr do n v thit k tnh ton. Trong qu trnh h cc phi lun kim tra v tr v cao cc. Cc xin: phi kim tra thm xin. u tin ng cc thng ng trc trnh va chm cc nhiu. Cn lp quyn nht k ng cc tin li cho vic kim tra v x l k thut

III.1.1. ng cc bng h sn o ba treo.* Thit b thi cng.- Trang thit b phc v cng tc ng cc bng sn o bao gm:+ Cn trc cu cc, treo ba.+ S lan ch cn trc v cc.+ Ba treo.+ Gi ba.+ H thng dm thp lp dng sn o.+ My kinh v, my thy bnh v my ton c in t.+ My hn tay.* Trnh t thi cng.Bc 1: Xc nh v tr khung sn o: Da vo ta cc ng tin hnh xc nh ta tng ng ca cc cc khung sn o.V tr cc cc khung nh v s c xc nh bng phng php giao hi gc, gip cho cng tc nh v c d dng v c chnh xc cao hn.Bc 2: Tin hnh lp dng h sn o. Dng s lan ch cn cu, cu lp cc cc ca khung nh v, lin kt gia cc mi ni l lin kt hn.Bc 3: Xc nh v tr tim cc ng trn khung sn o: Da vo ta cc ta d dng xc nh c v tr cc tim cc trn khung nh v. Tuy nhin i vi cc xin, cng tc nh v cc s phc tp hn, da vo vch du tim cc, xin thit k ca cc kt hp vi dy ri, my thy bnh xc nh chnh xc v tr t cc ta lng cc m bo xin ca cc.Bc 4: Lp dng cc: S dng cn cu, cu cc t s lan ch cc vo v tr cc c xc nh trn khung nh v. ng thi s dng my kinh v kim tra li ta trc khi h cc.Bc 5: ng cc: Ba treo c lp vo cn cu, s lan tin vo v tr ng cc, s lan c c nh bng h ti cp v h neo. a ba treo vo gi ba, tin hnh cn chnh sao cho hng chuyn ng ca ba ng trng vi tim cc. ng thi tin hnh kim tra ta cc, xin cc ln cui trc khi ng.Khi h on u cc n cao dng cc nh, dng h thng thp hnh trn khung nh v c nh on u cc, tin hnh hn ni on cc th hai, kim tra nghip thu mi hn cc, ta cc. Khi mi kim tra nghim thu u t, tin hnh ng cc n cao thit k.* Cc im lu .- Trong sut qu trnh ng cc phi b tr 02 my kinh v, 01my thy bnh t trn b, thng xuyn theo di ta , cao u cc. Khi pht hin s sai lch cn dng ng c phng n iu chnh kp thi.- Qu trnh ng cc nu gp s c nh: v u cc, cc sai lch ta vt gii hn cho php hay u cc cha t cao thit k m chi nh hn chi thit k... cn dng ng cc, thng bo ngay cho bn thit k.- Mi cc ng cn lp mt vn bn nghip thu, vn bn ny bao gm cc ni dung sau:+ Nu c im ca cc: loi cc, kch thc...+ Nu c im ca ba: Loi ba, nng lng xung kch.+ Kt qu ng: Ta thc th, cao thc t.+ Nhng ngi c trch nhim k: K thut, gim st, ngi c my kinh v...* u, nhc im ca phng n ng cc bng sn o.- u im:+ Thit b thi cng n gin, d dng tho lp.+ C th thi cng ti nhng ch c mc nc thi cng thp, tu ng cc khng th vo c.+ D dng lp trnh t thi cng, trnh t ng cc.- Nhc im:+ Thi gian thi cng ko di, nh hng n tin thi cng.+ Tng chi ph xy dng.+ Kh khn trong vic cn chnh ta , hng ng ca cc, chnh xc khng cao.III.1.2. ng cc bng tu ng cc.* Thit b thi cng.- Trang thit b phc v cng tc ng cc bng sn o bao gm:+ Tu ng cc+ S lan ch cc.+ Ba ng cc.+ My kinh v, my thy bnh v nh v GPS.+ My hn tay.* Trnh t thi cng.Bc 1: Xc nh v tr ng cc: Dng h my nh v GPS xc nh ta cc cn ng.Bc 2: Cu lp cc vo gi ba: Tu ng cc tin hnh cu cc t x lan ch cc ri lp dng cc vo gi ba theo s sau:

Hnh 1: Cu lp cc vo gi ba.Bc 3: ng cc: Tu ng cc di chuyn vo v tr ng cc bng h ti cp ko tu. C nh v tr tu bng neo. a gi ba cc vo v tr ng, ng thi s dng my kinh v kim tra li ta trc khi h cc.Khi h on u cc n cao dng cc nh, c nh on u cc. Tin hnh cu lp on cc th hai vo gi ba, hn ni on cc th hai, kim tra nghip thu mi hn cc, ta cc. Khi mi kim tra nghim thu u t, tin hnh ng cc n cao thit k.* Cc im lu . Xem phn thi cng ng cc bng sn o.* u nhc im ca phng n ng cc bng tu ng cc.- u im:+ Tu ng cc di chuyn linh hot, cng tc chun b ng cc n gin.+ ng cc nhanh hn dn n tin thi cng nhanh.+ Cn chnh hng cc, xin ca cc d dng, chnh xc cao.- Nhc im:+ Ch ng c nhng ni c su nc ln, khng th ng nhng hng cc st mp b.+ S lng tu ng cc cn hn ch, huy ng kh khn, tn km.

III.2 Thi cng lp dng vn khun.- Vn khun l kt cu tm nhm nh hnh cho cu kin b tng theo thit k, gi n nh cho b tng trong sut thi gian v lin kt. V vy vn khun phi tha mn cc yu cu sau:+ ng hnh dng, kch thc v v tr cacs b phn cng trnh theo thit k.+ Vng chc, n nh v khng b bin dng qu nhiu khi chu ti.+ B mt vn khun phi bng phng, trn nhn, kn nc.+ Lp dng, tho d d dng v ti s dng c nhiu ln.+ Cng tc vn khun phi m bo thun li cho cc cng tc khc nh cng tc st thp, , san m b tng.+ m bo khi tho d vn khun t ng chm t nht n kt cu v khng rung chuyn khng gy cho b tng trng thi ng sut qu mc.III.2.1. Phng n s dng vn khun thp.- y l loi vn khun c ch to trc theo hnh dng v kch thc ca cu kin, sau vn chuyn n v tr lp dng ri lin kt chng li vi nhau, to thnh khun c cu kin. * u im:- Vic lp dng vn khun nhanh chng do vn khun c ch to sn mt phn hoc ton b ty theo c im ca cu kin.- B mt vn khun bng phng, kn kht tt hn vn khun g, do cht lng ca cu kin c m bo bi khng b tht thot nc trong qu trnh b tng.- S ln ti s dng nhiu hn vn khun g, do thch hp vi vic c vi s lng ln cc cu kin c hnh dng v kch thc ging nhau. * Nhc im: - Chi ph ban u cho vic ch to vn khun ln.- Khng thch hp cho nhng cu kin c hnh dng v kch thc khc nhau.- Phi c bin php bo v vn khun sau khi s dng, trnh cc tc ng ca mi trng lm h hi, r st vn khun.- B nh hng bi s dao ng mc nc, gy r st.III.2.2. Phng n s dng vn khun g.- Vn khun g thng khng c ch to sn trc khi lp dng v trong qu trnh vn chuyn n v tr lp dng kh nng vn khun b bin dng cao. Cho nn vn khun gc c ch to ti ch.* u im:- Gi thnh r hn so vi vn khun bng thp.- Cng tc vn chuyn n ni lp dng d dng, trng lng nh nn c th lp dng th cng.- Thch hp cho nhiu loi cu kin c hnh dng v kch thc khc nhau, vic gia cng, ct gt d dng.* Nhc im:- Cng tc lp dng vn khun chm hn vn khun thp.- phng v kn kht ca vn khun km hn so vi vn khun thp, d b tht thot nc khi b tng nu khng c bin php s l.- S ln ti s dng t.III.2.3.Phng n s dng vn khun nha.- y l loi vn khun c ch to trc theo hnh dng v kch thc c sn, sau vn chuyn n v tr lp dng ri lin kt chng li vi nhau, to thnh khun c cu kin. * u im:- Vic lp dng vn khun nhanh chng do vn khun c ch to sn mt phn hoc ton b ty theo c im ca cu kin.- B mt vn khun bng phng, kn kht tt hn vn khun g, do cht lng ca cu kin c m bo bi khng b tht thot nc trong qu trnh b tng.- S ln ti s dng nhiu hn vn khun g, do thch hp vi vic c vi s lng ln cc cu kin c hnh dng v kch thc ging nhau. - Vn khun nha nh, d dng thao tc, t b nh hng bi thi tit v n mn do nc.* Nhc im: - Chi ph vn khun ln.- Khng thch hp cho nhng cu kin c hnh dng v kch thc khc nhau.III.3. Thi cng h thng dm, bn.III.3.1. Thi cng bng phng n lp ghp.a: H thng dm ngang.- Theo phng php ny, dm ngang c ch to sn trong cc cng xng ri c lin kt vi u cc c ng sn ti cng trng. lin kt dm vi u cc th trn thn dm ngang phi sn cc l c kch thc rng hn tit din ngang ca cc theo mi bn t 7,5 n 10cm ( phng trng hp cc b ng lch).- Ti v tr ca l trn thn dm, ngi ta t thm thanh thp C hoc I tng cng cho dm v t ln trn u cc.- Dm ngang c vn chuyn xung cng trng bng x lan, ri dng cn trc ni cu dm vo v tr. Sau khi iu chnh v v tr v cao dm, tin hnh c nh tm thi sau cu lp vn khun, lp t thm ct thp ri d b tng lin kt.b: H thng dm dc.- Dm dc cng c ch to sn ti cng xng ri c chuyn ti cng trng bng x lan.- Dm dc thi cng bng phng php lp ghp, ti v tr lin kt gia dm dc v dm ngang th dm ngang c ch to sn l ch t dm dc. .- Khi cu lp dm dc vo v tr th tin hnh lin kt ct thp ch ca dm ngang vi dm dc, ca dm dc vi dm dc. Lp t vn khun, v sinh mi ni ri tin hnh b tng lin kt mi ni.c: H thng dm bn.- Thi cng bn mt cu bng phng php lp ghp cn phn chia bn mt cu, nh s th t cc v tr, cn c vo vic phn chia, trnh t thi cng theo mt bng c kt hoch thi cng c sn bn mt cu thch hp. - Bn mt cu c ch to sn ti xng thi cng, khi bn t cng th tin hnh vn chuyn ra cng trng ri cu lp vo v tr.- Bn mt cu k trn cc dm ngang v dm dc, tin cho cng tc lp ghp v lin kt ta chia bn mt cu thnh cc tm c chiu di bng khong cch gia hai dm ngang cng thm 5cm v sai s khi ng cc. Nu bn c chiu rng ln th ty vo sc nng ca cn trc m ta chia thnh tng tm c chiu rng thch hp.Trong : e l khong cch gia hai mp ca bn mt, c ly theo iu kin lin kt ca ct thp.- Khi lp t bn mt cu vo v tr, iu chnh cao ri tin hnh lin kt ct thp ch ca bn vi bn v ca bn vi dm.- Trn mt bn, b tr ng thng hi thot nc bng nha PVC.d: u, nhc im ca phng php thi cng lp ghp.* u im.- Do cc cu kin c ch to sn trong nh xng nn c th p dng c cc bin php thi cng tin tin, cht lng c m bo, ci thin iu kin lm vic cho cng nhn.- Nng sut lao ng cao nn gim c gi thnh xy dng.- Thi gian chu nh hng ca cc yu t t nhin nh: thay i mc nc thi cng, ma gi...t nn tc thi cng nhanh.- Khi lng thi cng vn khung t nn gim thi gian v gi thnh xy dng.* Nhc im.- i hi trnh thi cng cao, cc phn cng vic thi cng u phi c chnh xc ln.- Kh khc phc cc sai st trong qu trnh thi cng nh: ng cc hay c ph u cc.- Vic p dng phng php thi cng lp ghp yu cu ngi thit k phi nm vng cc tnh cht chu lc ca tng b phn cng trnh phn chia cng trnh thnh cc b phn kt cu hp l.- i hi cc thit b thi cng nh cu lp, vn chuyn phi c sc chuyn ch, sc nng, tm vi ln.III.3.2. Thi cng bng phng n ti ch.a: H thng dm dc, dm ngang.- Vi dm ngang v dm dc thi cng bng phng php ti ch th c tin hnh thi cng ng thi cng lc.- Cc bc thi cng: + Xc nh cao bt ai p cc, lp th thanh x ngang, x dc v vn khun y, ng thi lin tc kim tra cao mt vn y tin hnh iu chnh.+ Sau khi kim tra xong cao , vng chc ca h thng vn y th tin hnh lp dng ct thp dm.+ Sau khi kim tra ct thp xong th tin hnh lp dng vn khun thnh, lin kt thanh np dc, thanh np ng v thanh chng xin.+ Kim tra, nghim thu vn khun v ct thp tin hnh b tng.- V tr mch ngng: Thng thng dm ngang s c lin tc, v tr mch ngng s nm trn dm dc. Mch ngng c t ti v tr c momen nh nht (M = 0), ti v tr hoc nhp dmb: Thi cng bn sn.- Dng cy chng bng g chng vo vn khun y ca h thng dm cc thanh x dc pha trn. Cc thanh x ny c nhim v vn y ca bn sn. - d dng iu chnh cao v tho d vn khun th chn cc cy chng c nm bng cc nm g.- Tin hnh ri vn khun y bn sn, sau tin hnh tri mt lp bt bng nilon va c tc dng chng dnh va c tc dng m bo kht ca vn khun y trnh tht thot nc khi b tng.- Lm cng tc ct thp bn sn, lm v sinh sch s mt dm b tng , b mt vn khun ri tin hnh b tng.- V bn mt cu c khi lng ln v ph hp vi tin thi cng h thng dm, ta chia bn sn thnh nhiu t . Khi lng mi lt ph thuc vo tin thi cng dm, khi lng b tng bn, nhn lc, thit b, mt bng...c: u, nhc im ca phng php thi cng ti ch.* u im.- m bo tnh ton khi ca cng trnh.- K thut thi cng n gin.- Sa cha nhng sai st trong qu trnh thi cng trc n gin hn.- Khng cn cc thit b cu lp c sc nng ln.* Nhc im.- Mt bng thi cng cht hp do phng tin thi cng v con ngi tp trung ng vo cng mt thi im.- Chi ph xy dng cao.- Phi tnh ton h thng vn khun, gio.- Cu kin c kch thc ln, do khi thi cng b tng phi thit k mch ngng. Cng vic ny cn m bo chnh xc v ti v tr ny cng ca b tng khng ng nht, cho nn nu ta b tr mch ngng ti v tr c ni lc ln th cht lng ca cng trnh khng c m bo.- Cng tc thi cng b tng hon ton ngoi tri do cn c k thut thi cng v bo dng b tng tt.- Chu nhiu s tc ng ca s dao ng mc nc v ca thi tit.- Kh p dng c cc bin php thi cng tin tin, kh ci thin c iu kin lm vic ca cng nhn.III.4. Thi cng no vt.- Ty thuc vo iu kin a hnh, a cht, khi lng no nt v iu kin t m c th la chn phng tin thi cng ( tu cuc, tu ht, tu ngom).- Khi o th o theo dng bc thang, chiu su mi lp khng nh hn 0,5m v ly mi dc t 1:3 n 1:4 m bo n nh cho t khi ng cc. do c mi dc theo thit k ta cn phi dng cc chp tiu theo chiu ngang v theo chiu dc iu chnh tu no vt theo ng tuyn.III.5. Thi cng k b.- K b sau bn c dng tng gc nm trn nn cc. K sau bn c tc dng to thnh mt bc tng chn t, gi n nh cho phn bi pha sau bn. C th c thi cng bng phng php lp ghp, ti ch hoc kt hp c hai phng php trn.- Trong qu trnh thi cng k sau bn cn ch n s nh hng ca mc nc ngm trong t ca bi sau bn.Nhn bn giao tim mc khng ch v mt bng xy dng.- Sau khi c kin ph duyt ca ch u t v ca n v t vn gim st v ngy chnh thc khi cng xy dng cng trnh. n v thi cng s c pha ch u t v t vn thit k bn giao h thng mc khng ch. n v thi cng c trch nhim kim tra, trin khai v bo lu ton b h thng mc c bn giao lm c s thi cng, kim tra v nghim thus au ny.- Trn c s cc mc c giao v mt bng thi cng, n v thi cng phi trin khai dn dp, o c, gii phng mt bng, vn chuyn v di di cc chng ngi vt trong phm vi mt bng thi cng.II.2. C s nh v cng trnh.- nh v cng trnh l xc nh v tr c th ca cng trnh trn thc a. T cc mc chun do ch u t bn giao, n v thi cng c nhim v ly cc mc lm c s xc nh chnh xc v tr cng trnh trn khu t c giao, m bo c chnh xc ta ca cc nh, cc gc ca cng trnh ng nh ta m bn thit k quy nh.- Trn c s cc mc c ch u t bn giao, da vo iu kin c th ca khu t nh: a hnh, a mo, bin gii gip ranh gia khu t v khu nc... ta s tin hnh xy dng h trc ta a phng v h thng cc mc c s, cc li ng truyn... thc hin cng vic nh v c chnh xc v thun tin nht, khng lm nh hng n qu trnh thi cng. Mun nh vy, cc mc c s v h li ng truyn phi c t nhng ni thun tin cho vic o c, ngm my, nhng phi m bo khng b x dch, khng gy vng v cn tr trong khi thi cng. III.4. Cng tc ng cc th.- Mc ch ca vic ng cc th l quyt nh chiu di thit k cui cng ca cc. V vy da vo h s thit k do bn thit k cung cp, lp bin php chi tit v k hoch th cc nh sau:III.4.2. Trnh t th cc.b/ Trnh t th cc.* Xc nh v tr, lp dng khung nh v: Da vo ta cc th xc nh v tr khung nh v, dng phng php giao hi xc nh v tr khung nh v c d dng v chnh xc.- Cao u cc thp hnh khung nh v * Xc nh v tr tim cc trn khung nh v, lp dng cc.- Da vo ta u cc, xc nh v tr cc th trn khung sn o, nh du v tr ca cc.- Dng cu cu KH-150 cu lp cc vo v tr nh sn, cn chnh, kim tra li ta cc ng trc khi h cc.* ng cc: - ng cc giai on 1:+ Sau khi cc c nh v ng ta v trng thi cc, cn b gim st nghim thu th cng tc ng cc c tin hnh. + Th dy cp gi cc cc trt xung pha di. Khi cc chm t, di trng lng bn thn cc, cc tip tc ln xung. Qu trnh ny phi lu th dy cp t t, iu chnh i trng trnh hin tng tt cc v lc x lan do mt trng lng mt u. + Khi cc ht ln, tin hnh p ba vo u cc. Vi trng lng bn thn ba tc dng ln, cc tip tc ln. Trong sut qu trnh ny cn lin tc kim tra ta , xin ca cc m bo cc i ng hng. + Khi cc ht ln, tin hnh n ba ng cc, nhng nht ba u cu ng nh (chiu cao ri ba nh), ng chm m bo cc khng b lch. Tng dn chiu cao ri ba t nng lng xung kch cn thit nh yu cu thit k. Trong sut qu trnh ng, lin tc theo di bng my kinh v, nu c s sai lch cn dng ng c bin php s l.+ Khi on mi cc c h n cao thch hp, dng ng cc, tin hnh cng tc cu lp on ui cc hn ni cc. Cng tc cu lp, nh v on ui cc c tin hnh nh on u cc c trnh by trn. Vic hn ni cc phi tun theo cc quy nh trnh by trong phn nhng quy nh chung, m bo hai on cc ni c trng tim.+ Sau khi hon thnh cng tc hn ni cc, mi ni c kim tra nghip thu ri tin hnh ng tip on ui cc n cao thit k.+ Trong qu trnh ng cc ghi li s lng nht ba v chiu cao ba ri trung bnh cho tng mt cc cm vo t. i vi mt di cc cui cng, ghi li s lng nht ba ri cho tng 10cm cc cm vo t.- ng cc giai on 2:+ Sau khi ng cc th giai on 1, cho cc ngh t 3 n 6 ngy, tin hnh ng cc th giai on 2 theo trnh t sau: (tham kho TCXD 88:1982)+ Th chi phi tin hnh t 3 n 5 nht ba, cao ri ba phi ng u cho tt c cc nht v ly chi trung bnh ln nht tnh ton.+ Khi cn thit phi kim tra chi tip theo sau khi th chi, cho php ng bng 30 nht ba, trong trng hp ny chi trung bnh ca 10 nht ba cui cng c xem l chi ti mi cc khi thi cng xong.- Trong qu trnh ng th cc cn thc hin ghi chp theo ch dn ph lc A TCXD VN 286:2003 (tham kho)

III.4.3 Cc im cn lu khi thi cng th cc.- H thng dy neo ca s lan v tu ng cc chu nh hng ca s dao ng mc nc nn trong sut qu trnh ng cn theo di, iu chnh dy neo thng xuyn.- V tt c cc cc th s c a vo s dng trong kt cu cng trnh nh cc cc i tr, v vy cn kim tra nghim thu k lng cht lng cc trc khi ng.- v tr cc th phi chnh xc.- Khi ng cc giai on 1 nu chi ca cc ln hn chi thit k ( eht> etk) m cc t cao trnh thit k hoc cc cha t cao trnh thit k m cc t c chi thit k th dng ng, cho cc ngh t 5 7 ngy ri tin hnh ng cc giai on 2.- Khi ng cc th giai on 2 nu chi ca cc vn ln hn chi thit k ( eht> etk) m cc t cao trnh thit k, th tin hnh ng thm t 1m cc. Cho cc ngh t 5 7 ngy, sau tin hnh ng cc giai on 3. Quy trnh ng tng t nh giai on 2.- Sau khi c kt qu th cc, kt hp kt qu th ng PDA. n v thit k s tnh ton v quyt nh chiu di cc i tr.III.5. Cng tc ng cc i tr.- Sau khi c kin ngh v chiu di cc i tr ca n v thit k, tin hnh t c cc theo ng yu cu k thut.III.5.3. Trnh t ng cc.a. ng cc bng h sn o, ba treo.Bc 1: Xc nh v tr, lp dng khung nh v: Da vo ta cc th xc nh v tr khung nh v, dng phng php giao hi xc nh v tr khung nh v c d dng v chnh xc. - Dng cu KH-150 t trn x lan 600T, cu lp cc thanh thep I lp dng h sn o. ( chi tit h sn o c trnh by trong bn v).Bc 2: Xc nh v tr tim cc trn khung nh v, lp dng cc.- Da vo ta u cc, xc nh v tr cc th trn khung sn o, nh du v tr ca cc.- X lan ch cc 400T c tu ko v h thng ti ko vo v tr tip cc. Dng h ti v neo c nh x lan. - Dng cu cu KH-150 cu lp cc vo v tr nh sn, cn chnh, kim tra li ta cc ng trc khi h cc. Cng tc nh v chi tit c trnh by trong mc nh v cc.Bc 3: ng cc: - Sau khi cc c nh v ng ta v trng thi cc, cn b gim st nghim thu th cng tc ng cc c tin hnh. - Th dy cp gi cc cc trt xung pha di. Khi cc chm t, di trng lng bn thn cc, cc tip tc ln xung. Qu trnh ny phi lu th dy cp t t, iu chnh i trng trnh hin tng tt cc v lc x lan do mt trng lng mt u. - i vi cc ng thng:+ Khi cc ht ln, tin hnh p ba vo u cc, Vi trng lng bn thn ba, cc tip t ln xung. + Khi cc dng hn, tin hnh n ba ng cc, nhng nht ba u cn ng nh ( chiu cao ri ba nh) m bo cc khng xung qu nhanh, kh kim sot hng ng ca cc. Tng dn chiu cao ri ba t nng lng xung kch cn thit nh yu cu thit k. ng cc n cao trnh thit k.

- i vi cc ng xin:+ Khi cc ht ln, tin hnh p ba mi (ba K45)vo u cc. Vi trng lng bn thn ba mi cc tip tc ln. Khi cc ht ln, tin hnh ni ba mi ng cc. (Mc ch s dng ba mi l m bo chnh xc xin ca cc nh thit k).Trong sut qu trnh ny cn lin tc kim tra ta , xin ca cc m bo cc i ng hng. + Khi c nh c hng ng chnh xc ca cc, tin hnh lp ba ng cc vo v tr ng. ng cc n cao trnh thit k. Trong sut qu trnh ng, lin tc theo di bng my kinh v, nu c s sai lch cn dng ng c bin php s l.- Khi on mi cc c h n cao thch hp, dng ng cc, tin hnh cng tc cu lp on ui cc hn ni cc. Cng tc cu lp, nh v on ui cc c tin hnh nh on u cc c trnh by trn. Vic hn ni cc phi tun theo cc quy nh trnh by trong phn nhng quy nh chung, m bo hai on cc ni c trng tim.- Sau khi hon thnh cng tc hn ni cc, mi ni c kim tra nghip thu ri tin hnh ng tip on ui cc n cao thit k. Ngim thu, kim tra li ta , cao ca cc ng.- Tin hnh nh v v tr cc tip theo trn khung sn o. Qu trnh ng cc c lp li cho n khi ng xong tt c cc cc trong mt khung sn o. - Di chuyn h khung nh v, dng cu KH-150 tho d, nh cc thp hnh di chuyn qua v tr mi. Qu trnh ng cc c lp li nh trn.- tin trong qu trnh theo di qu trnh h cc, nh du bng vch sn ln thn cc nh sau: 1m cui ca cc nh du bng sn hoc dn giy k ly c chnh xc n cm. 5m cc tip theo c nh du bng sn khong cch gia cc vch l 50cm.b. ng cc bng tu TDC-98.Bc 1: Tip cc t x lan ch cc, lp dng cc vo gi ba. - Cc c ch bng x lan ch cc 400T.- Tu ng cc TDC-98 di chuyn n v tr thch hp cu lp cc, tu c c nh bng h thng neo trn tu. X lan ch cc c tu ko a vo v tr mi tu ng cc v c c nh v tr bng h thng ti v neo trn x lan.- Tu TDC-98 dng h thng nng ca mnh cu cc t x lan. Khi cc c cu ln, x lan ch cc c tu ko a ra khi khu vc thi cng. Tu TDC-98 a cc vo v tr trn gi ba v c nh cc.Bc 2: nh v cc v a tu vo v tr ng.- V tr ng cc c nh v t trc, tu ng cc c tu ko di chuyn vo v tr ng. Qua b m v h thng my kinh v, iu khin tu ng cc vo ng v tr h cc. C nh tu bng neo.- iu khin gi ba cho ng trng thi cc ( xin i vi cc xin hay thng ng i vi cc thng).Bc 3: ng cc. - Sau khi ta v trng thi cc c xc nh, t vn gim st hin trng tin hnh kin tra, nghim thu v cho php h cc th tin hnh h v ng cc.- Th dy cp cu cc cc trt xung pha di. Di trng lng bn thn cc, khi cc chm t cc s tip tc ln. Trong qu trnh ny, cn ch th dy cp t t trnh trng hp cc b tt khi gi ba. - Khi cc ht ln, tin hnh p ba vo u cc. Vi trng lng bn thn ba tc dng ln, cc tip tc ln. Trong sut qu trnh ny cn lin tc kim tra ta , xin ca cc m bo cc i ng hng. - Khi cc ht ln, tin hnh n ba ng cc, nhng nht ba u cu ng nh (chiu cao ri ba nh), ng chm m bo cc khng b lch. Tng dn chiu cao ri ba t nng lng xung kch cn thit nh yu cu thit k. Trong sut qu trnh ng, lin tc theo di bng my kinh v, nu c s sai lch cn dng ng c bin php s l.- Khi on mi cc c h n cao thch hp, dng ng cc, tin hnh cng tc cu lp on ui cc hn ni cc. Cng tc cu lp, nh v on ui cc c tin hnh nh on u cc c trnh by trn. Vic hn ni cc phi tun theo cc quy nh trnh by trong phn nhng quy nh chung, m bo hai on cc ni c trng tim.- Sau khi hon thnh cng tc hn ni cc, mi ni c kim tra nghip thu ri tin hnh ng tip on ui cc n cao thit k. Ngim thu, kim tra li ta , cao ca cc ng.- Di chuyn tu TDC-98 ra v tr tip cc, qu trnh ng cc c lp li nh trn.III.5.4. Cng tc x l mi hn cc.- Cc quy nh khi hn ni cc ng BTDL c trnh by trong mc: nhng quy nh chung.- Trnh t hn ni cc c thc hin nh sau:+ Khi nh v chnh xc hai on cc cn ni, kim tra lch tm gia hai cc, kim tra kht gia hai mt bch thp.+ Cng nhn hn tin hnh hn cc xung quanh mt tip xc gia hai bn bch thp. G x mi hn v kim tra cht lng mi hn.+ Khi hn i u gia hai bn bch xong, tin hnh hn p ming thp tm vng xung quanh bn bch thp ca hai cc. Nhm bo v cho mi hn cc. Hn ni thp tm vo vi bn bch thp.+ Tin hnh g x mi hn v kim tra cht lng mi hn.+ Dng nha ng nng, qut xung quanh mi hai bn bch thp va hn.- Trong sut qu trnh hn ni cc, cn b gim st lun theo di, kim tra cht lng ng hn. Nu pht hin ng hn khng m bo, yu cu x mi hn v thc hin hn ni li. Cc ch c tip tc ng khi mi yu cu v kim tra mi hn cc u t.III.5.5. Cc bin php d phng v nghip thu khi ng cc.- H thng dy neo ca s lan ch cn trc v tu ng cc chu nh hng ca s dao ng mc nc nn trong sut qu trnh ng cn theo di, iu chnh dy neo thng xuyn.- Trong qu trnh ng cc phi lun t hai my kinh v trn b ngm v theo di v tr to cc cng nh nghing ca cc. Nu pht hin sai lch phi ngng ng cc ngay v c bin php x l thch hp i vi tng s c.- C th khi ta u cc sai lch so vi thit k qu gii hn cho php ( tham kho Bng 11 TCXD VN 286:2003) i vi loi cc trn rng c ng knh t 0,5 n 0,8m sai lch cho php ca cc nh sau:+ Cc bin:10cm.+ Cc gia:15cm.- Nu cc b sai lch qu gii hn trn th cn bo cho bn t vn gim st v ch u t c bin php khc phc. C th phi nh cc ng sai ln v ng b vo v tr c, nu khng nh c th phi ng thm cc khc bn cnh, v tr ng cc thm do bn thit k ch nh.- Nu c s c gy, nt cc th bt buc phi b cc b s c v ng b thm cc. - Trong qu trnh ng, nu u cc cn cch xa cao trnh u cc m cc t chi thit k, th ngng ng cc. Cho cc ngh ri tin hnh v li cc cho n cao trnh thit k. Nu cc vn khng xung th bo cho bn t vn gim st c quyt nh ng cc b bn cnh hay ct u cc n cao thit k.- Ghi chp nht k h cc cho tng cc c ng, lp bin bn nghip thu theo mu in sn ( trnh by phn ng cc th).III.6. Bin php x l cc sau khi ng.- Do chiu su nc kh ln, cng thm lp t trn cng l bn st yu. Nn sau khi ng cn m bo n nh cc trc tc ng ca dng chy v do ti trng bn thn cc (i vi cc xin). Cng tc gng u cc c tin hnh nh sau:- Cng tc gng u cc c thc hin ngay sau khi nhc gi ba ra khi u cc (ti thiu 2 cc). - S dng cc ai m cc c kch thc ph hp vi tng loi ng knh cc, bt p vo cc cc ng, lin kt gia hai mt ai m bng cc bulng. ai m cc c gn cao thit k t h dm I ln hai bn tai ca ai m. Lin kt cc dm I bng mi hn, cc dm ch I ny va c tc dng gng gi cc cc li vi nhau, va lm h cho h vn khun dm bn trn. (chi tit ai m cc v h dm I gng u cc s ng trnh by trong phn thit k bin php thi cng vn khun).I. Thi cng x l u cc.I.1. Ct u cc.- Sau bt ai m cc v tian hnh gng u cc li vi nhau. Vi nhng cc khi ng t chi thit k m cao trnh u cc vn cha xung ti cao trnh thit k (sau khi bo li cho n v thit k v c php) th tin hnh ct u cc ti cao trnh u cc thit k.- Cc c nh du bng vch sn ti v tr ct, dng my ct chuyn dng ct cc. ng thi dng cn trc t trn x lan mc gi on cc b, trnh trng hp on cc c ct ri xung gy nguy him v gy gy nhng cc xung quanh.- Sau khi c ct xong, on cc b s c cu lp ln b.I.2. Thi cng b b tng cng m cc v lin kt u cc.* Thi cng m cc.- Tc dng ca m cc l nhm bn v mt bch thp ca cc ng BTCT DUL khi s n mn ca nc.- Vic thi cng phn m cc chu s nh hng ca s dao ng mc nc. V tr thi cng m cc thp nht l hai hnh cc trc bn Vi mc nc thi cng chn vic thi cng b tng m cc cn tranh th mc nc ( trong 1 ca 8 ting th ch thi cng c 4 ting). B tng m cc cn thm ph gia ng cng nhanh nhm m bo cht lng ca b tng m cc.* Thi cng lin kt u cc.- Mc nc thi cng: chn mc nc thi cng l mc nc trung bnh: (ng vi tn xut P = 50% ca ng tn xut mc nc gi).- Vic thi cng b tng lin kt u cc c tin hnh dng thi vi vic b tng m cc. B tng c s dng ph gia ng cng nhanh.

II.Thit k gii php thi cng vn khun.Vn khun l kt cu tm nhm nh hnh b tng theo thit k v gi b tng c nh trong sut thi gian ninh kt. Cng tc thit k vn khun l xc nh c kch thc vt liu ( vn mt, vn thnh, np ng, bu lng), trin khai thi cng lp dng.Trong thc t cc loi cp pha c ch to c th s dng li c nhiu ln v c th dng cho nhiu hng mc cu kin khc nhau, c qui nh trong c tnh lm vic ca chng. V th khi tnh ton ta ch cn xc nh kch thc vt liu cho dm ln nht v c nhp di nht. Cc dm khc th s dng vt liu tng t ng vn khun, tuy nhin phi ch k kch thm cc thanh sn m bo ng cao thit k. Nh trnh by trong phn la chn phng n thi cng, vn khun cho h dm kt hp gia vn khun g v vn khun nha. Vn khun y s dng kt cu vn khun g, vn thnh s dng vn khun nhaII.3. Trnh t thi cng v tho d vn khun.- Yu cu b mt vn khun phi bng phng, cc khe gia cc tm vn khun phi kn kht, khng thot nc.II.3.2. Cng tc lp dng v tho d vn khun.* Lp dng vn khun.- Cng tc lp dng h dm v vn khun c thc hin theo trnh t sau:+ Xc nh v nh du cao bt ai m cc. Yu cu cc ai m phi c bt ng cao nh, cng tc ny quyt nh n chnh xc v ca cc cng tc lp dng vn khun.+ Bt ai m cc, xit bulong ai m.+ Gc v hn ni h dm I vo cc ai m.+ Thi cng vn khun m cc.+ Lp dng ct thp m cc v lin kt cc-dm .+ b tng m cc v lin kt u cc, bo dng b tng.+ Tho d vn khun m cc.+ K, kch h dm I. Thi c vn khun y dm.+ Thi cng ct thp dm.+ Lp dng vn khun thnh.+ Kim tra, nghip thu vn khun.- Vn khun y c gc ngang qua h dm I v c lin kt vi nhau bng bng inh.- Vn khun thnh bng nha c lin kt vi nhau bng cc con cht ca nh sn xut vn khun. H np bng thp ng tit in 4x4cm gi cho vn khun thnh c n nh. Cc ty ren loi D17 c bt vo hai mt i din ca vn khun thnh v xit vo cc thanh np bng thp ng gi cho vn khun thnh n nh, khng b bin dng di tc dng ca ti trong ngang khi b tng dm.- Trc khi lp dng, ton b b mt vn khun c v sinh sch s v c qut mt lp vt liu chng dnh, m bo khi tho d vn khun b mt b tng khi b bong trc, dnh bm b tng vo vn khun. Khe h gia cc tm vn khun c b tr cc tm chn, nhm tranh mt nc xi mng khi b tng.* Tho d vn khun.- Tho d vn khun: Tun th theo quy nh TCVN 4452-1995, TCVN 4453-1995 tu tng loi cu kin thi gian tho d. + Vi vn khun thnh thi gian ti thiu sau mt ngy v phi t ti thiu 25% cng mi c php tho d. + i vi cc vn khun y b tng phi t ti thiu 75% cng mi c php tho d.- Khi tho d vn khun cc cu kin phi bo co TVGS v c TVGS kim tra chp thun.- Trnh t tho d vn khun ngc vi vic lp t. Trc tin phi tho d cc con nm sau mi tin hnh tho d. Cu kin lp sau tho trc theo trnh t t trn xung di.- Vn khun tho d ra c v sinh tp kt ti v tr quy nh lun chuyn cho cc cng vic tip theo.III.2.1. Cng tc sn xut b tng.- Sau khi tin hnh th nghip xc nh cp phi b tng ph hp vi yu cu ca b thit k, b tng c t mua ti cc x nghip sn xut b tng thng phm v c vn chuyn n cng trng bng tng vn chuyn b tng thng phm chuyn dng.- Mi t b tng, ty vo khng lng b tng mi ln , tin hnh ly mu kim tra st v mu nn kim tra cng chu nn ca b tng.III.2.2. Cng tc vn chuyn, b tng- Va b tng c t mua thng phm nn vic vn chuyn va t xe vn chuyn n v tr thng qua my bm b tng. Xe vn chuyn sau khi vo v tr, tin hnh b tng vo thng cha ca my bm. T my bm, thng qua h thng ng ng, b tng c bm n v tr thi cng.- Va b tng vo cc v tr v b tng theo phng php ln dn t u cu kin n cui cu kin (hoc t u phn on n cui phn on) theo tng lp t di ln trn vi chiu dy mi lt khng qu 50cm i vi cu kin c chiu dy >50cm v lin tc khng gin on gia 2 lt qu lu.- Khi va b tng gia hai khi (mi ni thi cng) k tip nhau hoc gia hai phn on phi m bo khi trc b tng t ti thiu 75% cng mi c php khi tip theo. Trc khi b tng lp tip theo b mt b tng khi trc phi c c ty v sinh sch s v mt lp nc xi mng c ln ton b b mt sau mi c va b tng ln hai khi lin kt vi nhau to thnh mt khi vng chc.III.2.3. Cng tc m b tng- Cng tc m b tng dng m di D45mm. i vi cc kt cu c chiu dy, sau khi b tng lp u (