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8/2/2019 cu hi k thut thi cng

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NGN HNG CU HI K THUT THI CNG I

Cu 1: Cng tc t trong xy dng

V tr:L cng tc thng gp khi thi cng cc cng trnh, nhiu khi chim t trng ln. Quytnh cht lng v tin thi cng cng trnh.Phn loi:Theo mc ch:Cng trnh bng t: , p, mng, nn ngCng tc t phc v cc cng tc khc: h mng, rnh t ng ng, Theo thi gian: lu di (, ng) ngn hn (h mng, rnh that nc)Theo khi lng: tp trung (san lp, h mng) chy di (, ng)Cc dng:o: h cao mt t t nhin xung cao thit k (V+)

p: nng cao mt t t nhin ln cao thit k (V-)San: lm phng mt din tch t, bao gm c o v pBc: bc b mt lp t c dy c thit kLp: lm y mt h su n cao bng cao mt t xung quanhm: l truyn xung t nhng ti trng c chu k nhm p y khng kh,nc trong t ra ngoi, lm tng cht, tng mt ht trong 1 n v th tch, tora mt kt cu mi cho t.

Cu 2: m ca t

L t l tnh theo % ca nc cha trong t

W=(G-G0)/G0G: khi lng t nhinG0: khi lng t khnh hng ln n cng lm t. t t qu hay kh qu u kh thi cng.W>30%: tW


2/23

V: th tch t sau khi o lnR c th m, t cng rn ti xp cng ln, cng tn nhiu cng vn chuyn t saukhi o ln hay cng cn nhiu t thc hin cng tc lp.

Cu 4: n nh mi dc:

dc t nhin ca t l gc ln nht ca mi dc khi ta o hay khi ng m khnggy st l cho t.I=tg(anpha)=H/BI ph thuc vo gc ma st trong ca t , dnh ca ht t v ti trng tc dng ln mtt. dc t nhin ca t nh hng rt ln n bin php thi cng o, p t.Bit c dc t nhin ca t ta mi ra bin php thi cng ph hp v c hiuqu v an tonPh tr:Lu tc cho php* nh ngha: Lu tc cho php l tc ti a ca dng chy m khng gy xi l

t.* Tnh cht+ t c lu tc cho php cng ln th kh nng chng xi mn cng cao.+ i vi cc cng trnh bng t tip xc trc tip vi dng chy nh p, knh,mng... ta cn phi quan tm n tnh cht ny khi chn t thi cng. i vi nncng trnh cn quan tm n tnh cht ny c cc bin php phng chng s cuntri ca t khi c dng chy chy qua.+ Mun chng xi l th lu tc dng chy khng c ln hn mt gi tr m ti cc ht t bt u b cun theo dng chy.Phn loi t:Cp t+ Cp t l mc phn loi da trn mc kh hay d khi thi cng hay l mc hao ph cng lao ng (th cng hay c gii) nhiu hay t. Cp t cng cao cngkh thi cng hay hao ph cng lao ng cng nhiu.+ Trong thi cng vic xc nh cp t l rt quan trng. Mi mt loi cp tng vi mt loi dng c hay my thi cng, do vic xc nh cp nh hng trctip n nng sut thi cng v hiu qu kinh t ca cngChng II : Tnh ton khi lng

Cu 5. Nguyn tc tnh khi lng cc cng trnh t:

Vi cng trnh nh ng, mng, nn th ly kch thc bng ng kch thc thc tVi cng trnh phc v cng trnh khc nh h mng, hm th kch thc ly theodng cthi cng. Thi cng th cng th ly rng ra 20-30cm, thi cng c gii th ly rng ra 2-5mty vo loi my thi cngTnh ton khi lng da trn cc cng thc hnh hc c sn. Nu cng trnh c dng phctp th chia ra lm nhiu ming nh tnh.Cu 6 Nguyn tc tnh khi lng t tp trungChia thnh cc khi ch nht, nn.Khi ch nht: V=a*b*hKhi cn li: V2= V3=


3/23

Tng th tch: V=H/6*(a*b+(c+a)*(d+b)+d*c)

Cu 7 Nguyn tc tnh khi lng t chy di:

Cng trnh chy di c kch thc theo phng di ln hn hn kch thc ca 2 phng

cn li. V vy, khi tnh tan c th chia nhthnh nhiu on tnh s n gin ha mvn m bo chnh xcVi l V=Ftb*l (Ftb: din tch mt ct ngang trung bnh)Vi l>50m -> V=(Ftb+m*(h-h)/12)*l (h: chiu cao y ln, h: chiu cao y b, m:thoi mi dcChng III Cng tc chun b v phc v thi cng.

Cu 8 Gii phng mt bng:

Bao gm: di di m m, ph d cng trnh c, h cy ci, o b r, x l thc vt, dnchng ngi vt.

Cng tc gii phng mt bng phi c thc hin theo quy trnhThng bo trn truyn thngDi di m mLm vic vi cc bn lin quan di di ng in, nc, thng tinPh d nh ca theo thit k ph dH cy phi o b ht rLp t mu m cn tn dng s dng trng cy v sauVt sch bn m bo n nh nnTiu nc b mtMc ch: ngn khng cho nc ngm chy vo h mng cng trnh, m bo tiu thotnc sau ma.Thc hin:o rnh cho nc t thatS dng bm tho nc nu cn

Cu 9,10,11,12 H mc nc ngm

Mc ch:H thm mc nc ngm cc b mt khu vc no bng cch ht nc ging osu di tThit b: ng ging lc vi bm ht su; kim lc h mc nc nng; kim lc h mc ncsuKim lc h mc nc nngng dng:Dng khi chiu sau h nc ngm khng ln.u: thi cng gn nh, hiu qu cao.Cu to:Thit b l mt h thng ging lc ng knh nh b tr st nhau theo ng thng quanh h mng hoc theo khu vc cn tiu nc. Nhng ging ny c ni lin vi mybm chung bng ng tp trung nc


4/23

My bm s dng l my bm ly tm, chiu su ht nc 8-9mKim lc l nhiu ng thp c ng knh nh ni li di ~ 10m gm ba phn: ng trn, nglock, ng cui. on trn c chiu di ty chiu su lc, on lc gm 2 ng lng vonhau c khong h, c bc 1 cun dy thp kiu l xo. on ng cui c van cu, vanvnh khuyn v b phn xi t.

Nguyn tc:H kim: ng nh kim vo t theo phng thng ng, bm nc vo kim, nc s phunra u lm xi v do t, trng lng ko kim i vo lng tHt nc: Khi ht nc, van cu ngn khng cho t i vo trong kim, ng lc lc giplc bt bn t.

Cu 13,14 Chng vch t:

Khi o t vi chiu su nh, t c kt dnh tt, ta c th o thng ngH=1/gamma(2*c/(K*tg(45-fi/2))-q)H: chiu su cho php

Gamma: trng lng ringC: lc dnh n vFi: gc ma st trongK: h s an ton 1.5-2.5Q: ti trng trn mt tt ct ln sn, h~1m; t pha ct, h~1,25m; t tht,st h~1,5m; t st chc, h~ 2mKhi chiu su o t ln hn. Cn o theo dc t nhin hoc c bin php chng trnh st lChng vch h bng vn ngang:p dng:H c chiu rng nh, thnh ng.Cu to:Khi o sau n 1m bt u lt vn chng, sau c o c 1 thn vn li t tip vnchng.Vi t dnh, vn ngang khng i hi phi xt nhauTnh tan:Tnh ton xc nh kch thc v khong cch ct chng da trn chiu su h, trnglng t, ti trng cng trnh v chiu dy vnVn thng dng l vn cp pha, thanh chng thng l g 60x80. Lc tc dng ln vn lp lc ch ng ca t su ln nht. Vn tnh nh dm n gin, khong cch 2 gil khong cch gia 2 thnh chng ngChng vch t bng thanh chng xinp dng:H o rng, c chiu su >2mCu toKhi o sau n 1m bt u lt vn chng, sau c o c 1 thn vn li t tip vnchng.Vi t dnh, vn ngang khng i hi phi xt nhauTnh tan:


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Tnh ton xc nh kch thc v khong cch ct chng da trn chiu su h, trnglng t, ti trng cng trnh v chiu dy vnVn thng dng l vn cp pha, thanh chng thng l g 60x80. Lc tc dng ln vn lp lc ch ng ca t su ln nht. Vn tnh nh dm n gin, khong cch 2 gil khong cch gia 2 thnh chng ng

Chng IV: K thut thi cng t.Cu 15. Nguyn tc t chc thi cng t th cng

c im: thi cng bng phng php truyn thng. Dng c lm t l xng, cuc,mai, ko ct t, Dng c vn chuyn t l quang gnh, xe ct kt, xe ci tin,

Nguyn tc:Chn dng c thch hp: xc dng xng vung, o dng xng trn, t cng dng cucchim, t mm dng cuc, Tm cch gim cng lao ng trc khi cho thi cng (tng gim m ca t, m ca

mt bng)T chc thc hin hp l: phn cng tuyn lm vic hp l, khng tp trung, trngcho. Hng o t thng gc vi hng vn chuyn,

An ton:Thc hin o t m bo mi dc h o nh hn dc t nhin, khng ph v cutrc to t khu vc c nc cn c rnh that nc, thu nc, rnh phi c hon thnhtrc khi bt u mi t oKhi o t su phi c bin php chng, chn hay o kiu bc thangH phi c mi dc chng st l, vi t yu c th phi dng cc gia c thnh ho.

Cu 17,18,19 My o gu thun

c im:Tay gu kho, ngn, o c t t cp 1 n co 4Kh nng t hnh caoKhi lm vic va o, quay, t ln xe vn chuynDung tch gu t 0.35-6m3Ch lm vic c ni kh roKhi o ng bn di, v vy phi m ng cho my ln xungng dng:o h mng c nn t ti v tr cao trnh my ng n nh, khng b ngpDng vi cng vic c khi lng o ln, chiu su ~ 5mS :Bn knh h


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T=thi gian o+thi gian lm y gu+2xthi gian quay+thi gian ln xe vn chuyn(thi gian quay l quan trng nht)Cu 20,21 My o gu nghchc im:Tay cn di

Kh nng t hnh caoDung tch gu 0,15-0,5m3Nng sut thp hn my o gu thun cng dng tch guKhi o c th ng trn cao o di thp

ng dng:o h nngo cc v tr b ngp nc (ng trn cao o)S :Tng t my o gu thun, nhng c th o tin hoc o lio ngang

Cu 22, 23 My o gu dyc im:Tay cn di, gu c th vng nn phm vi o lnNng sut thp hn my o gu thun v nghch cng dung tch gu t khng linh hot do dng cp mmC kh nng ng cao, o su, o h c ncng dng:Dng khi h o ngp su trong ncDng khi t o ln ch cn thnh ngThng s k thutR1: bn knh qung gu ln nhtH1: chiu su o ln nht mt v tr ngR2: bn knh tH2: chiu cao t ln nhtNng sut my o mt guPkt=3600/Tck*q*Ks/rPkt: nng sut k thut (m3/h)Tck: chu k hot ng (s)Q: dung tch gu (m3)Ks: h s xc tr: ti ban uPtd=Pkt*Z*KtPtd: nng sut thc tZ: s gi lm vic mt caKt: h s s dng thi gianBin php nng cao nng sut:V mt k thut: gim Tck, tng KsV mt t chc: tng KtCu 24 25 My i


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c im:C nhiu loi cng sut v kch thcC c loi bnh lp v bnh xchC th thay i gc y 60-90 theo phng vung gc trc my v 5-6 theo phng

ngangng dng:p nn 1-1,5mo h rnh su 1-1,5mThch hp co lp cy c trn mt t mm, bc lp t mt, lp ch trng,

S hot ngTin li: dng khi cn chuyn t phm vi 10-50m lp h, rnhTin quay:Nng sut:Ptd=3600*Z*q*Ks*Ki*Kt/Tck

Ptd: nng sut thc tZ: s gi lm vic mt caQ: dung tch t trc bn gtKs: H s ri vi (cng chy xa cng ri nhiu)Kt: h s thi gianKi: h s ph thuc dc mt tTck=ld/vd+lvc/vvc+(ld+lvc)/v0+tLd,vd: qung ng, vn tc o tLvc,vvc: qung ng, vn tc vn chuyn tV0: vn tc my chy vT0: thi gian my quay, nng h bn gt

Nng cao nng sut:Khong cch vn chuyn hp l 30-40mKhi i khong cch ln, cho i theo rnh, i i hay i thnh tng t

Cu 26, 27 My cp

c im:L my o chuyn t c nng sut cao.Thng dng phi hp vi my i nng cao nng sutDung tch thng cng tc thng t 2,25-10m3ng dng:Thng dng cc cng trnh thy li ln v cng trnh giao thng theo tuynS ct t:Tun t: mt na s nht ct nng, mt na s nht ct nh c: nht ct na u nng na sau nhHnh dng nht ct (tam gic, rng ca, thang) nh hng ln n nng sut, ph thucloi t (ri, m, kh) v cht ca tS hot ng:


8/23

Hnh elipHnh s 8 -> gim gc quay xe mi chu kHnh con thoi -> gim s ln quay myNng sut:Ptd=(3600*Z*q*Ks*Kt)/(Tck*r)

Ptd:nng sut thc tZ: s gi lm vic 1 caQ: dung tch thngKs: h s xc y thngKt: h s thi gianTck: chu kR: cht ban u ca t

Tck=l1/v1+l2/v2+l3/v3+l4/v4L1,v1: qung ng v vn tc cpL2,v2: qung ng v vn tc chuyn

L3,v3: qung ng v vn tc riL4,v4: qung ng v vn tc tr v

Cu 28a . t p

t p thnh tng lp, c chiu dy c tnh tan trc. t c bm nh d lncht. m t sau khi ri tng lp n cht yu cu.Mt t phi c dn c, r cy, thot kit nc v vt ht bn trc khi p t.Khi p t khng ng nht th p t kh thot nc bn di, t d thot nc trn.Nu p lp t that nc nm di th dy phi ln ngn khng cho mao dn.Trnh t ri v dm t l t bin tin vo gia. Nu nn yu th ri t t gia ra. n cao 3m li i trnh t

Cu 28. nh hng m n vic m t:

t ti xp dng p gm 3 thnh phn: ht t rn, nc, khng kh. Phn khng khd dng b y ra khi t khi m. Phn nc kh b y ra khi ht t hn.Vi t dnh, hu nh khng th y cVi t kh, nc trong t c dng mng m, cc ht t c lc ma st vi nhau rt ln,kh m. Khi m trong t tng ln thch hp, s gip gim lc ma st gia cc ht t,gip m d hn.Vi t qu m, trong t khng cn lc ma st, cc ht t khng cn kh nng dnh ktli vi nhau lm cho t c trng thi chy, v vy cng khng th m cCu 29 Mym t:m ln: Lc m tc dng t t qua sc nn ca cc bnh ln c dng mt nhn, chncu hay bnh hi. S trn, tin li, ko theo nhiu qu lu. Khi m cho my chy dnt ngoi vo trong, bng lu ln nhau 20cm, my chy chmMt nhn: t 6-20t, din tip xc b nn p lc gim nhanh theo chiu su, chiu dy milp m khong 15-20cm, thch hp m t dnhChn cu: chiu dy lp m 30-50cm, thch hp m t dnh


9/23

Bnh lp: din tch tip xc ln nht, chiu dy lp m 25-50cm, thch hp vi t ri vdnhm nn: s dng ng nng ca vt ri tc dng ln mt t. Chiu dy lp m 1m vict, 80cm vi t dnh. m t 2 mp dn vo gia.m rung: s dng vi t ri hay t c m cao

Lu : trnh lc m qu ln lm hng cu trc t. sigma~0,9R l hp lPh thm An ton khi thi cng to t su phi c ro chn quanh h o, c n bo hiu ban mQuan st cc vt nt quanh h o v vch h o trc khi vo thi cngKhng o khot kiu hm chKhng cht nng b h, cch mp t nht 2m mi c xp t nhng khng c xpnngLi ln xung phi c bcTrnh va chm vi h thng cp ngm

Cu 35: cc loi cc v vn c, c im v yu cu k thut:

+) Cc loi cc:

Cc tre gi l cc tre nhng trong php tnh ton khng coi cc tre l cc m ch l gii php gia c nn. Cc tre c s dng vng t lun lun m t. tre lm cc phi l tregi (trn nm nm tui) thng v ti. Chiu dy ca tht tre phi t t 10-15 mm. ngknh cc tre trn 60mm, ph bin t 80-100mm.Chiu di cc tre 2-3m. u cc trn caphng cch mu khong 50mm. u di cch mu 200mm vt nhn. Khi ng cn gicho u cc khng b dp v. Mun vy ngi ta dng ci bt u cc bng st c hnh ccvi. Cc ng xong phi dng ca ct b phn tre b dp, ko c dng dao cht. Nu ucc dp v phi nh ln thay cc khc khi cha xung su.

Cc g: G lm cc thng l g d, thng, mung Cc g dng ni t thng xuyn c nc trnh b mc do t lc t lc kh. G lm cc cn ti c m trn23%. Cy g phi thng khng cong. cong cho php l 1% theo chiu di. Trn 1 m di, chnh ng knh thn cy khng qu 10mm. Chiu di thng t 8-12 m. ng knhcy g l 200-300mm. G phi b ht v, vt nhn mi cc. c khi bc mi cc bng thp.Cc di trn 10m nn nh ai cho u cc.

Cc btng ct thp: cc btng ct thp thng c ch to ti xng hay ti hin trng. Cc ph bin c tit din vung t 200 x 200 n 400 x 400. Loi cc mini titdin 150 x 150. Chiu di cc btng ct thp t 3 16 m. Cc mini thng ch to nhiuon ni trong qu trnh p. Mi on di t 1,2 2 m.Mc b tng cc l 200- 300.u cc thng t nm lui ct thp, mi li cch nhau 50mm chng gn sut ccb. Nu sn xut cc to hin trung phi m bo cc yu cu sau: Mt bng sn xut cc phi bng phng, khun phi thng v phng, cn bi cht chngdnh d d vn khun. Chiu dy lp bo v ct thp thng ly l 30mm. b tng cc phi lin tc, khnggin on cho mi cc, st thng l 60mm, bt u t mi cc ln n nh cc, ttnht l m bng my, khng uc rung ct thp.


10/23

Ch d khun khi t 25% cung cc. Mt cc phi nhn , nhgn ch k u n khng qu 5mm, ch li b mt khng qu8mm. cc c vt nt khng oc s dngKhi xp cc loi cc di trn 5m cn k m g v tr t mc cu. nu cc k c mc cu

th v tr buc hay k m g ly bng 0,21 k chiu di cc. Khi xp chgn c c kho bichiu cao chng cc khng qu 2/3chiu rng ca chng cc y v k qu 2m.+) Vn c

Vn c g : vn c g dng lm hng ro, vng vy chng thm, chgn st l cho mng. Vn c g fi l g tui. Nu khng c g toi th fi ngm nuc 24gi tr ln minn dng. chiu di ca thanh ti thiu l 70mm , c khi chn chiu dy n 100 hoc trn100. chiu rng bn c t 100 -150. Trong thi cng thng ly chiu di thanh c di hn thit k quy nh khong 300 500, u di ca thanh c lm vt cho nu chiu di thanh c trn 100 mm lm mng vung ghp c, nu chiu di nh hn

100mm lm mng n.Vn c thp: vn c thp dng lm tng ngn nuc bn chc khi thi cng di nc

chu p lc nuc, p lc t ln. C 3 loi hnh dng tit dit vn c thp ph thng cnhp vo nc ta l : vn c phng, vn c khum v vn c lacsen. chiu di vn c thp t 8-15 mm. chiu dy ca thp vn t 12-16mm. Khong cch gia 2 mp ca thanh vn c t 320-450mm. Vn khum v vn c lacsenthung ghp gi 2 thanh lin nhau mt p mt nga.

Cu 37: Cc loi ba ng cc- Ba treo:+ Cu to: qu nng kim loi 500-2000kg dc buc bng dy cp v treo ln gi cao.+ Nguyn l: ti in nng ba ln cao, th hm cho qu nng ri t do xung u cc.+ Thng s: chiu cao nng 2.5-4m, nng sut 4-10 nht/pht (thp)+ p dng: khi s lg cc t.- Ba hi n ng:+ Dng hi nc hay kh p nng chy ln cao, ri chy ri t do xung u cc nh trng lgbn thn chy.+ trng lg ba 1.5-8T, nng sut 25-30 nht/pht.+ Cu to n gin, bn. Nhc: iu khin =tay, tn hi nc-> t ph bin.- Ba hi song ng:+ Dng kh nn hay hi nc nng chy ln v y thm khi h chy dng cc, tng hiusut.+ Nng sut 200-300 nht/pht.+ t ng, ko cn gi ba, t ph hoi u cc v chy ko nn trc tip cc, kch thc nh-> ph bin hn. Nhc: trng lg hu ch nh so vi ton th ba, phi dng ngun nglc ngoi (ni hi, kh nn).- Ba diezen:+ ng c n 2 k, nng ba ln ri ri t do, va chm ba p vo u cc lm chy nhinliu to p luc nng ba ln li.


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+ Chy 600-1200kg, nng sut 50-60.+ Trng lg nh, ko cn ngun ng lc ngoi-> tt khi ng cc g, thp, btct nh.Cu 38: Chn ba ng cc-Chn s b: E>=25P, kGm.+ E=Q.v.v/2/g= nng lg xung kch ca ba, cho tnh nng k thut ba.

v-tc ri, g- gia tc, Q-trng lg phn chy ca ba.+ P=kh nng chu ti bn trn ca cc,T, (tnh theo t nn?)-Kim tra s ph hp ca ba:+ H s thch dng: K=(M+q+q1)/E phi (Kmax>=K>=Kmin)q-trng lg ton cc, q1-trng lg m cc, M-trng lg ton ba, kG.ba song ng, diezen ng: cc g 3.5-5,thp 3.5-5.5, btct 4-6ba n ng, diezen ct: g 3-3.5, thp 2.5-4, btct 3-5ba treo: g 1.7-2, thp 2-2.5, btct 2-3+ chi: e= Vi e=nFgh/Pgh/(Pgh+nF)*(Q+0.2(q+q1))/(Q+q+q1)= chi 1 xungkch,cm.n-h s=150T/m2 vi cc btct c m m,=100T/m2 vi cc g ko m,=80 vi cc g c

m,=500 vi cc thp ko m.F- tit din ngang cc,m2.Q- trng lg phn xung kch ca ba,T.H- cao ri ba,cmPgh- ti gii hn ca cc,T.Cu 39: K thut ng cc b tng ct thp+ vn chuyn:- Xp cc ngoi khu vc dng cc, g t bi xp n ch ng thun li.- a cc ln xe vn chuyn cn lm 2 thanh cch u v mi cc 0.2l, hoc dng micc xung th im buc 0.3l.+ Lp cc vo gi:- Buc cc vo gi ba th dng 2 mc cu c sn cc, la qua puli gi ba. Nng 2mc ln ng thi, khi ko cc ln ngang tm 1m, rt u cc ln cao trnh mi cc rdi mt t.- Chnh v tr ca cc bng my kinh v cho ng v tr v thng ng.+ ng cc:- ch tnh hnh xung ca cc ko qu nhanh cng ko vng mc. Nhng nht u ngnh, khi ng gn dc phi o ln tng t xc nh chi.- Yu cu : cc chng phi n lp t chng, cc ma st phi t chi thit k.+ S ng cc: Khi s cc nhiu to thnh rung cc th phi nghin cu trnh t ngcc. Phi m bo c t nht 2 pha bin dng t do C 2 s ng cc chnh l: ngkhm cc v ng rung cc (hve t nh)

Cu 40: K thut ng vn c g v thpTng t ng cc nhng c cc yu cu:- ng v tr- m bo ln- ko b bin dng- m bo kn kht vi nhau v thng, trnh chn vn b tch xe ra do lc t.- dm bo n nh


12/23

-> cch ng:+ S ng 1 t+ S ng 2 t: ng ton b vn n 1/2 chiu su. Vng 2 ng tip 1/2 cn li->kht thng nhng ba phi di chuyn nhiu ln.

Cu 41: X l cc s c khi ng cc- Cc cha t su m ng ko xung, l gp vt cn mi cc: nh cc ln, ng ccthp xung ph vt cn, nu ko dc th dng mn xung ph.- Cc cha xung ti su thit k m t chi thit k, l do chi gi to vng tc qu nhanh->t b dn p nht thi: ngh t ngy ch c cu t tr li bnhthng ri li ng tip.- ang ng cc b lch: ko su lm dng ti chnh dc th tt, ko th nh ln ng li.- u cc b tot: lp m cc.- Cc ko xung m b v, do ba qu nh so vi sc ti ca cc: ly ba khc c chy nnghn ng.- Cc b ni, khi ng qua tng bn hoc nc ngm: thay ba c tn s ng ln hn.

- Khi cn nh cc: nng th dung ti, cn trc, ko th lm ai v kch ln.- Khi cn ct cc: c b phn BT, dng hn ct ct thp.Chng VII. Cng ngh thi cng b tng ct thp.

Cu 42:Bn cht ca cng ngh b tong ct thp ti ch.u nhc im v phm vi pdngBn cht ca cng ngh b tng ct thp ti ch hay cn gi l BT ton khi:ngi ta ghpvn khun,t ct thp v BT ngay ti v tr thit k ca kt cu do cc cu kin dnhvi nhau,to s ng nht trong BT.-u im:+Thi cng c cc loi kt cu c cu to phc tp v hnh dng+ cng cng trnh ln+Chu lc ng tt-Nhc im:+Tn vt liu lm vn khun v ct chng+Thi gian ch i tho vn khun ct chng l kh lu lm cng trnh b ko di nhhng ti tin thi cng+Qu trnh thi cng b nh hng bi thi tit lm gim nng sut cng nh cht lng-Mt s bin php khc phc thi gian thi cng+Dng ph gia ng cng nhanh+Bin php ht nc trong BT sau khi m+Dng phng php hp hi+Dng phng php in cc sy nng VL trc khi trn BT-Phm vi p dng BT ton khi:BT ct thp ti ch dc s dng rng ri trong cccng trnh xy dng hin nay t cc cng trnh cao tng ti cc cng trnh dn dng bnhthng cng nh cc cng trnh thy li ,thy in, Chng cu to nn kt cu chu lcchnh cho cc cng trnh

Cu 43:Dy chuyn cng ngh thi cng BTCT ti ch,c im ca dy chuyn b phnv nhng gin on k thut


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Thi cng BT ti ch chng ta nn t chc thi cng theo phng php dy chuyn.Bi vcc qu trnh cng tc lp i lp li nhiu ln trn cc phn on, trn cc tng nh,s tndng c ti a hiu qu ca cc t chuyn mn ha thi cng BT ti ch.Cc dy chuynb phn l-Dy chuyn ghp vn khun, ct chng, sn thao tc.gi tt l dy chuyn vn khun:thc

hin ghp vn khun ct,dm,sn theo ng thit k,k hoch BT ca tng KC-Dy chuyn ct thp:bao gm 4 qu trnh+Gia cng ct thp:ko ngui,dp ngui,chut ngui+Gia cng ct thp:lm thng,co g,ct,un thp+Hn ni ct thp:ni buc,ni hn(hn tip im,hn oois u,hn h quang,ni dngng ni),ni bng ren+Bo qun ct thp trc khi dung+lp t ct thp ti v tr kt cu-Dy chuyn m, BT:+Trn BT:trn th cng hoc trn bng myti hin trng hoc BT thng phm ti nhmy

+Vn chuyn BT:Vn chuyn t im trn ti cng trng(bng t hoc cc loi phngtin chuyn dng). Vn chuyn n ni cn (dung cu thp,Bm,vn thng)+ BT: BT trc tip t thng BT c cu ln hoc vi ca my bm BT,hay tcc xe ct ct..+m BT:s dng cc loi m nh m bn,m di m ti ni va BT-Dy chuyn dng hBT, tho d vn khun,ct chng+Dng cc thit b k thut dng h BT nh hp hi, phun nc,ngm nc+Tho d VK khi kt cu cng .c quy nh bi thit k-Gin on k thut;l nhng gin on trong cng tc BT ton khi:Khi thi cng BTTKth cn phn ra cc phn on thi cng m bo v mt k thut (nu thi cng qunhiu d gy co ngt rn nt v nhit),ph hp vi iu kin nhn lc,thit b,thi gian 1ca lm vicV vy cn tnh ton cho hp l cc gin onChng VIII: Cng tc vn khun.

Mc ch ca vn khun, ct chng v sn thao tc+ Vn khun lm khun mu tm thi nhm to ra nhng hnh dng kt cu cng trnhtheo yu cu thit k, kin trc.+ Chu cc ti trng (thng ng, nm ngang) do trng lng va b tng t, cc hot tisinh ra trong qu trnh thi cng.+ Quyt nh tnh cht b mt ca kt cu.+ Ct chng m bo cho vn khun cao nht nh theo yu cu+ H ct chng nhn tt c cc ti trng t trn vn khun truyn xung v truyn xungnn.+ Chng li cc lc x ngang, ti trng gi v sn thao tc.Cu 44: nhng yu cu k thut i vi vn khunTr li:p ng cc yu cu k thut sau:+) thit k ng kch thc ca cc b phn kt cu cng trnh+) Phi bn, cng, n nh, k cong vnh+) Phi gn nh, tin dng, d tho lp+ Khng gy kh khn trong vic lp t ct thp, , m b tng


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+ An ton trong s dng.+) Phi dng dc nhiu ln. i vi vn khun g phi c dng t 3-7 ln, vn khun kimloi dng t 50-200 ln. dng dc nhiu ln, vn khun sau khi dng cn dc co, tysch s ; bi du m, ct t vo nhng ni kh ro, g dng lm vn khun phi m bocht lng thng l g nhm V-VII

Cu 45: Phn loi vn khun

Tr li:

*) Theo vt liu- vn khun g- vn khun kim loi- Vn khun bng tm b tng ct thp- Vn khun bng cao su, cht do*) Theo cu kin

- Vn khun mng- Vn khun ct- Vn khun dm, sn- Vn khun tng*) Theo k thut tho lp thi cng- Vn khun c nh- Vn khun di ng (di ng ng, di ng ngang)- Vn khun lun chuyn- Vn khun p mtCu 46: Chc nng cc b phn ca vn khunTr li:+) Vn khun: c chc nng lm khun c nh hnh cho b tng khi b tng cn chang kt, m bo cc kch thc thit k ca cc cu kin,+) Np : i vi cc cu kin ln th vn khun dc ghp t nhiu cc vn nh m bokch thc cu kin, khi np c tc dng lin kt cc tm vi nhau, ng thi chu titrng cng vn khun+) X g: nh mt dm n gin chu ti trng trc tip t vn khun sn, gip vn khunsn khng b mt n nh khi thi cng+) Ct chng: gip truyn ti trng t vn khun, x g xung t, cng m bo cho xg, vn y dm khng b vng+) Ging: c tc dng lm cho ct chng k b mt n nh ngang, gip to thnh h ctchng vi kh nng chu ti trng tt hn+) Nm: gip chng ta c th linh hot thay i chiu cao ct chng trong thi cng, ngthi cho php tho lp vn khun d dng v nhanh chng

Cu 47: Cu to vn khun mng n, mng bng


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+ Vn thnh mng c cu to t 1 hay nhiu tm khun c lin kt li vi nhau nhnp vn thnh, s lng ph thuc vo chiu cao ca thnh mng. ( chiu cao ln hnchiu cao ca mng 5-10cm ) Dc theo chiu di vn thnh ngi ta b tr cc khung ( thanh chng xin v g nh v ) vi khong cch c tnh ton hp l nhm chu cc plc ngang do va b tng cn t gy ra v nhng hot ti pht sinh trong qu trnh b

tng nh: p lc m, p lc do b tng.+ Nu mng gm nhiu bc th bc trn li da vo bc di v cng c lin kt vi ccim c nh xung quanh.+ Vn khun c mng: c cu to ging vn khun ct gm 4 tm khun c lin kt livi nhau nh inh v gng c mng. Gng c mng va lm nhim v lin kt cc vnkhun li vi nhau, va l gi ta cho vn khun chu cc lc ngang do va b tng tiv cc hot ti sinh ra trong qu trnh thi cng b tng.

Cu 48: Cu to vn khun ct

Cu to vn khun ct bao gm: 4 hoc nhiu mng ghp li vi nhau bng np g. Gia

cc mnh vn khun lin kt vi nhau thnh hnh dng kt cu nh h gng ct. Khongcch gia cc gng v chiu dy vn thit k chng lc x ngang.Pha chn ct cha ca nh v sinh, u ct c cha ghp vn dm.Khi ct cao hn 2.5m phi cha ca b tng khong gia.Cu 49: Cu to vn khun dm, snCu 51: Cu to vn khun sn.Cu 50: Cu to vn khun tng.

Cu 54: Nghim thu vn khun:Trc khi lp t ct thp cn phi nghim thu vn khun.Mc ch:- Trnh nhng sai st ng tic xy ra sau ny.- Xem xt nh gi li nhng yu cu nu ra c p ng hay khng.Ni dung nghim thu:- Kim tra li tim, ct, cao v v tr ca vn khun c b sai lch vi thit k hay khng.- Kim tra li hnh dng, kch thc va vn khun.- Kim tra li bng phng, cc khe ni, khe h gia cc tm vn.- Kim tra n nh ca vn khun, gio v sn cng tc.- Kim tra nghim thu cc gii php an ton lao ng, phng chy cha chy.- Chng dnh cho vn khun: Lp chng dnh phi ph kn cc mt vn khun tip xc vib tng.- V sinh bn trong vn khun: khng cn rc, bn t v cc cht bn khc bn trong vnkhun.- m ca vn khun g: Vn khun g phi c ti nc trc khi b tng.Phn ph: Nghim thu gio. gio+ Kt cu gio: gio phi c lp t m bo kch thc, s lng theo thit k.+ Chng ct: Phi c k, m, t ln trn nn cng, m bo n nh. Hn ch ni ctchng, cc mi ni khng c b tr trn cng mt mt ct ngang v v tr chu lc ln.


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+ cng v n nh: ct chng c ging cho v ging ngang s lng, kchthc v v tr theo thit k.Cu 55: K thut tho d vn khun:+ Phi tho d theo ng trnh t c qui nh sao cho trong qu trnh tho d, kt culm vic theo ng s kt cu c tnh ton. Khi tho d vn khun, gio trnh

khng gy ra ng sut t ngt hay va chm mnh lm h hi n kt cu.+ Vn khun v gio ch c tho d khi b tng t c cng cn thit.+ i vi cc vn khun khng chu lc (vn khun thnh, ct, tng...) c tho d khib tng t c cng ti thiu l 25kg/cm2.+i vi vn khun, gio chu lc ca kt cu (vn khun y dm, sn...) nu khngc ch dn ca thit k th c tho d theo qui nh sau:

Loi kt cu Cng b tng phi t (%R28) Thi gian ti thiu tho vn khun(ngy)+ Bn, dm, vm c nhp nh hn 2m 50 7+ Bn, dm, vm c nhp t 2m 8m 70 10

+ Bn, dm, vm c nhp ln hn 8m 100 28+ Cc kt cu vng, console, s n ch c tho d ct chng v vn khun y khicng b tng t mc thit k v c i trng chng lt.+ Tho d vn khun gio cc tm sn cc nh nhiu tng c thc hin nh sau:- Gi li ton b gio v ct chng tm sn nm k di tm sn sp b tng.- Tho d tng b phn ct chng vn khun ca tm sn k di na theo nguyn tc 2tng ri. Gi li cc ct chng gia sn, dm ph thuc chiu di kt cu.

Cu 56: phn loi ct thp

+) theo hnh thc ng kin vn chuyn- dng cun (thng c < 10mm)- thp thanh c chiu di t 6-12m(thng c > 10mm)+) theo hnh th- thp trn. thp nh


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- thp cu to- thp phn b- thp s ng lcCu 57: Gia cng ct thpGia cng l lm cho ct thp tng cng chu lc bng cch lm cho thanh thp chu

ti vt qu gii hn chy ta thu dc thanh thp c cng ln hn trcCh p dng cho thp AI, AII v mt phn vi thp AIII1. Gia cng ct thp bng ko nguiGy bin dng cho thanh thp do ko, lm cho thanh thp dn ra khong 3-8%, cng chu lc tng 20-30%. p dng cho ct thp


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Un thp c th lm th cng hoc my. Khi un phi c cht gi thanh thp ng yn,cht c nh lm im t un v cht di ng quay thanh thp quanh cht c nh,khi lm th cng c thay cht di ng bng vam, ng thp, thpcng cng th cnh tay n(vam, ng thp) phi cng diKhi un li thp phi c b gi v bn un

Cu 60: Hn i uNi hai thanh thp i u vi nhauK thut: dng dong in h th 1,2 9V chy qua hai thanh thp nh hn, ti u tipxc gia hai thanh thp c in tr ln nn lm sinh nhit t u hai thanh thp, khi dng p lc khong 200 600 KG/cm2 p li hai u thanh thp li vi nhau.iu kin p dng : ch p dng cho thanh thp >12mm- hn lin tc vi thp nhm C1- hn k lin tc vi thp nhm C2, C3(s hn t v^^)Cu 61 : Hn tip imin dc h p t 380V xung cn 3 9V, hai thanh thp dc dt tip xc vi nhau ti im

nh hn v kp gia hai cc ca my hn, dng in th cp dc phng qua hai cc camy hn v gia hai thanh thp, lm thp nung ln, dng lc p hai thanh thp vo vinhau gip chng dc hn ti im tip xcC hai ch hn- hn cng : dng cho thp mm, s/d dng in mnh I=300.10^6 A/m2. thi gian hn ngnt= 0.01-0.5s- Hn mm: dng cho thp cng, s/d dng in yu hn I


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a).Hn tip im s k thut hn iu kin p dng?- Nguyn l :in p c h p qua bin th t 380V xung 3-9V .Hai thanh thp C1;C2c t tip xc nhau ti im nh hn kp gia hai cc ca my hn .Dng th cp camy hn c t gia hai cc ca my.Khi mch in ng dng in phng qua 2 ccv hai thanh thp hn lam no nung ln ,dng mt lc mnh p hai cc hn li lm cho 2

thanh thp lin li vi nhau im tip xcin tr ca h thng hn :R=R1+R2+R3+R4+R5R1,2:in tr ti tip im gia cc va thanh thpR3,4:in tr ca hai thanh thp hnR5:in tr ti tip im gia hai thanh thp- iu kin s dng:C hai ch hn : hn cng: dng cho thp mm s dng dng in mnh I


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- t tng phn: Ct thp dc buc thnh tng phn sau a vo khun ng ta mi thchin lin kt cc ohn vi nhau. PP ny gim dc mt phn nhn cng nhng vn phichuyn ct thp vo khun bng tay nn vn nguy him nht l khi khi lng ct thp ln- t ton b : Ct thp dc hn, buc hon ton to thnh khung, li ngay ti xng ctthp, sau c a ln t vp khun, ng ta ch b sung mt vi chi tit lin kt chng vi

nhau. Pp ny gim lao ng ti cng trng xung mc ti thiu, nhng i hi c phngtin vn chuyn, nng, lp tng ng- Cu 64: Nghim thu ct thpTrc khi btng phi tin hnh nghim thu ct thp vi cc ni dung sau:+ Chng loi thp v s ph hp v vic thay i ct thp so vi thit k.+ Cng tc gia cng ct thp: ct, un, lm sch ct thp.+ Hnh dng, kch thc ca ct thp, s thanh, khong cch gia cc thanh so vi thit k.+ S thch hp ca cc con k to lp bo v ct thp: Kch thc vt liu ch to, mt (khng c ln hn 1m mt con k ).+ n nh ca ct thp trong khun: n nh ca cc thanh thp, gia cc lp thp, vton b ct thp trong khun.

+ Cc h s cn c khi nghim thu ct thp:- Cc bn v thit k c ghi y s thay i v ct thp trong qu trnh thi cng v kmtheo bin bn v quyt inh thay i.- Cc kt qu kim tra mu th v cht lng thp, mi hn v cht lng gia cng ctthp.- Cc bin bn thay i ct thp trn cng trng so vi thit k.- Cc bin bn nghim thu k thut trong qu trnh gia cng v lp dng ct thp.- Nht k cng trnh.Chng X. Cng tc b tng.66. Yu cu cht lng i vi va b tng:- Va b tng phi c trn u, m bo thnh phn ng cp phi. Va b tng saukhi trn phi m bo c cc yu caauf ca thi cng. Phi m bo st hnh chp ( linh ng ) d , m. chy lp kn cc ch ct thp ken dy hoc cc gc cnhca vn khun.- Vt liu trong cp phi phi ng quy cch v m bo sch.- B tng m bo do cn thit.- Va b tng phi c thi gian ch trn vn chuyn, m b tng ngn nht. Thi gianhon thnh tt c cc qu trnh ny phi nh hn thi gian ninh kt ca xi mng. ( khong 2h ) .67. Cch xc nh cp phi mt m trn:T mc ca cc cu kin ngi thi cng c th xc nh c cp phi cho cc loi mc btng. Cp phi l thnh phn vt liu theo t l trong mt n v sn phm b tng no .T l ny ph thuc vo cng b tng, vo tnh cht ca va b tng nh st hnhchp ca va b tng.Vic xc nh chnh xc cp phi c mc b tng hin trng l rt kh. V vy trongphm vi thi cng cng trng ta quan tm n cp phi b tng theo nh mc nh ncban hnh. Hoc theo cng thc kinh nghim theo thc t thi cng. ( Dng th tch xc nhgn ng thnh phn cp phi m trn b tng l 1:2:3 ra c mc b tng khong200kg/cm2 )


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^^ cu hi ph :So snh gia va kh v va t. u im va kh:+ Lng xi mng tiu th c th t hn.+ Thi gian ninh kt nhanh v lng nc dng t hn.+ Lc dnh gia b tng v ct thp tng ln.

+ Mau chng d c vn khun, ct chng sn thao tc, rt ngn thi gian thi cng .+ Cng b tng tng hn so vi dng va b tng nho, nhng vi va kh phi dngm my mi m bo cht lng.68. Dy chuyn cng ngh ca cng tc b tng.69. K thut trn b tng bng th cng:Yu cu k thut: - Phi m bo trn u v thnh phn.- Phi t yu cu vi va b tng ( thnh phn , t l cp phi, thi gian trn nh hnthi gian cho php )Phng php: a. Chun b: Sn trn b tng c knh thc ti thiu 3*3m2 Sn phi cdn dp bng phng, khng ngm nc. Sn c th lt bng gch hoc lt tn. Sn trnphi c mi che ma nng. Tt c cc vt liu ct, , xi mng chun b quanh sn.

b. Trnh t trn: ct vo sn , trn ct v xi mng trc sau khi ct xi mng u mu thtip tc cho vo. Khi cho vo xi mng ct, va cho va o n khi ng u dngxng cuc o th cho 1 phn nc vo. Cho t t lng nc cn li vo hn hp v trnu.

70. K thut trn b tng bng my:C th chia ra lm 3 loi chnh:- My trn nghing thng lt c- My trn ng- My trn nm ngang theo kiu hnh trMy trn lm vic theo nguyn tc ri t do hay cng bc.Trnh t trn b tng bng my:- Cho my chy khng ti vi vng.- Nu trn m u tin nn mt t nc vo cho t ci trn v bn gt; ct liu vnc vo trn u sau cho xi mng vo trn cho n khi c.Nng sut ca my trn c tnh theo cng thc:P=Vnk1k2/1000. (m3/h )V: dung tch my trn ( lt )n: S m trn trong 1 gi.k1: H s thnh phm ca b tng ( 0.67-0.72 )k2: H s s dng my trn theo thi gian ( 0.9 0.95 )

Ch ph: Cc yu cu khi vn chuyn b tng:- Khi vn chuyn b tng khng c lm vng vi dc ng.- Phng tin vn chuyn phi kn kht, khng lm d r dc ng.- Tuyt i trnh s phn tng ca b tng trong qu trnh vn chuyn.- Thi gian vn chuyn phi cng t cng tt v thi gian vn chuyn s gim cht lngca b tng. Tt nht thi gian vn chuyn khng c qu 2 h ng h.


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71. Vn chuyn b tng theo phng ngang: ( vn chuyn ni b cng trng )C th s dng nhiu loi phng tin khc nhau, vic la chn mt trong cc loi phngtin phi cn c vo khi lng b tng.a. Vn chuyn bng xe ct kt, c ly nh hn hoc bng 70m, ng bng phng, khnggh gh, dc ti a 12%.

b. Vn chuyn bng xe ba gc: Vn chuyn b tng cng trng nh, Dung tch thng120-200l, khong cch vn chuyn 70-150m.Cc loi xe ny c th kt hp vi cc phng tin vn chuyn ln cao nh cn trc, thngti v.v.vc. Vn chuyn bng ng goong.Khi khi lng b tng ln, thi cng trong thi gian di c th lm cc ng ray vnchuyn b tng. Nhng thng xe c dung tch 0.5 0.75 m3 b tng, c th di chuyn trnqung ng 50-200m, y bng tay hoc dng ti tay, ti in.

72. Vn chuyn va b tng theo phng ng.

C th s dng cc phng tin sau:- My thng ti: Ngoi nng cc xe ct kt, ci tin ch va ln cao, cn c th dng vnchuyn b tng ln cc tng nh cao trc tip vo phng tin vn chuyn hoc thnh ng trn sn nh.- Vn chuyn ln cao nh cn cu thiu nhi hay cc loi cu khc, va b tng c ttrong thng cha, hoc trong xe ct kt, ci tin nh cc cn cu ny nng ln v tr . Cth vn chuyn b tng ln cao 15-20m- Vn chuyn bng cn cu thp: Dng cc thng cha va chuyn dng trc tip vokt cu. y l phng tin vn chuyn b tng ln cao v ngay rt thun li, gimc cng vn chuyn trung gian, rt ngn thi gian thi cng, nhn lc, hiu qu thi cngcao.- Vn chuyn va b tng ln cao bng bng chuyn: Khi lng yu cu ln, vn chuynv ngay. Hn ch khi s dng bng chuyn vn chuyn b tng l qung ngkhng c xa, yu cu va phi do ko nho.- Vn chuyn va b tng bng my bm b tng: Dng my bm b tng vn chuyn btng ti trc tip vo cc phng tin vn chuyn nh xe ci tin. Nu trong c ly gnth vn chuyn b tng bng my bm trc tip vo cc kt cu cn .

- 73. b tng.

Nhng yu cu cn ch khi b tng.- Trc khi b tng cn phi kim tra, nghim thu vn khun, ct thp, h thng snthao tc .- Phi lm sch vn khun, ct thp. Sa cha cc khuyt tt nu c.- Ti nc vn khun vn khun khng ht nc xi mng ( nu dng vn khun g ).- Khi va b tng ln lp va kh trc th phi lm sch mt b tng. ti vo nc h xi mng ri mi b tng mi vo.- Phi c k hoch cung ng va b tng b tng lin tc trong 1 ca, mt kp.Nhng nguyn tc v bin php b tng:


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Nguyn tc 1: Khi b tng cc kt cu xy dng, ngi ta khng ch chiu cao btng khng c vt qu 2.5 m. b tng khng b phn tng. m bo nguyn tc ny khi b tng c chiu cao > 2.5 m ngi ta s dng cc bpsau:- Dng ng vi voi.

- Dng mng nghing. ( mng )- Dng l ch sn. ( ct )Nguyn tc 2: b tng t trn xung nng cao nng sut lao ng. Khi b tngdm, va b tng c trt t v tr cao hn ming dm, khi b tng ct va b tngphi cao hn ca v

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