NEN VA MONG NHA DAN DUNG
I- I : Mong bAng dltdi tltdng: (H2-6a)
1.- C~ut~" mong nOng :
§ 3. - Cau tao cac lo~i m6ng.
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II . C"" au t~o mong sau: ',..
1 Mong tr~n gi6ng crum hay t~ chi~c :
.
1-3 : Mong duai tuilng tren. ddt rdn d6c: c4n phai sira soan va chia ddt n~n thanh nhltng m~t phAng ngang co hinh b~c c~p, ddng thdi day mong duqc c~u tao d~t b~c vdi m6ng phan doan d~t c~p. Tnnrng hop d~t chat thi ti s6' gitia chidu cao a cua b~c va chidu rOng I c~a-'b~c khong duqc >1/1, khi a ~ 100C~.Truong hop dAt kheng chat thi a/l =
1/2 khi a <$O~M.(H2-60. '
2. Mong dUdi c9t :
2-1 : Mong chilc dlldi c9t : Mong chiec diroc cau tao bang gach dil xay hoac bang betOng vOi hinh thirc d~t bac, Nhirng loai mong cling nay co nhiroc di~m vi b] khong
che' bdi goc md a cua mong nen khi g~p trudng hop can ino rQng day mong thi phai tang
ca chidu cao g6i mong, tang trong IUC1ngva chieu sau chon mongo Vi the' khi m6ng cling, phai chiu tai trong len hoac vdi tinh hinh dia ch~t phirc tap khong cho phep tang them chi~u sAu chon mong (nhir nucc ngdm cao, tAng d~t t6t khong day ...) thi hop Iy bon ca
Is dung mong batong c6t thep vi co th~ giam duqc chi~u sau chon mong, d6ng thdi co
nhidu uu digm khi chiu tai trong l~ch tfun Ion.
Mong chiec thttdng co kich thiroc khong len, co day hinh vuong, clnr nhat hoac
tron, tuy nhien Vdi day mong vuong t6t hon chir nhat vi dQ lun cua dat l1el1dttdi mong nho hon, Vj trf ddm mong d~ chiu cac tUdng ngoai cua cong trinh c~n hru y ke't hop vdi viec chdng tham cho tuOng va chiu lire dap cua n~n nha. (Hinh 2-7).
-, 2-2 : Mong bang dudi c~t : Mong bang con gQi la mong d4m vdi sudn trsn hoac sttdn dUdi va tao thanh hinh dai lien ke't cac chan cOt. Mong dUdi cOt thudng dttqc che'tlilo bAng betOng c6t thep (mong m~m). Nhttng trudc khi dung giai phap mong bang dUdi cOt thi phai xet den phuC1ng an dung mong chie'c, tuy nhien khi phai md rQng cac m6ng chie'c qua lOn, thi cac mong nay se r6t gan nhau do do t6t nh6t Iii dung' mong bAng, vi no co tac dVng t6t v~ mQi m~t nhtt Vtla co tac dVng lam giam ap lllc day mong, va co tac dVng phan b6 tai trQng d~u len m~t ddt n~n giam thie'u chenh l~ch lun gilta cac cOt va co kha nAng chAn dOng. D~ tAng cuimg sll vitng chac chung cho viec lien ket gitta ket c6u phdn tren vdi mong, cdn phai cau t~o kh6i nach d vj tri giao nhau gitia cQt, d~m mong va g6i mong. (H 2-8a).
2-3 : Mong dudi c~t tr~n ddt nln d6c : D~ tranh hien tUC1ngchdng tn1g sua't trong d6t n~n gilta 2 mong co chi~u sau chOn mong khac nhau d tren dat n~n d6c, khoang cach gilts. 2 mong va vi trl cua chung phai dam bao di~u kien la goc nghieng cua m~t dAt tli day mong d~t nong den day mong d~t sau phai nha hctn ho~c bang goc ma sat trong cua dAt n~n (tri~n d6c tv nhi~n clia lo~i dat n~n) a < cp, . ~Ui da_;. ex= 30°, vdi
dAt a = 60°. (Hinh 2-8b) .
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2-1 : CQc dong:
0: H,'nh thUe : LO'iliCQC duqc ch6 t'ilOsAn vdi tiet di~n hinh vuOng, chti nh~t, tron, bat giac va co hinh 6ng, hinh thap theo chi~u dai.
b Yeu ro'u khi dOng cpc : D~ dua CQC vao dAt n~n, d'ilt chi~u sau thie't ke, co th~
do~g vdi vo bAng gO, betOng, ho~c bua may hay do tac dOng rung clla may chAn dOng, sac xoi clla tia nUdc dUdi ap 111c.D~u cll va miii cU-d~u phai duqc bao v~ khi dong CQC,
d6ng thdi cling phsi d~c biet quan tam trong viec n6i cu va xAy dlfng cu khi dua vao vi tri dong. Khoang cach gitia cac CQC phsi Idn hdn ho~c bAng 31~n trl1c ki'nh cua CQC d~
dam bao sttc chju tsi cua m6i CQC th6ng qua sll rna sat.
e Yiu ro'u cua IOQ.i cpc :
•
c1 : V6'iCQC bang g6 : DAu CQC phai lu6n lu6n nam dUdi m\tc nUdc ngam thAp nh~t trong nam Iii > 15cm d~ dam bao d~u CQC khOng bj m\Jc. Sau khi hoan tAt vi~c dong CQC, cac d~u CQC phai duqc cua phAng ngang nhau, nia lAy h6t bun non va phu len m¢t Idp dem bAng cat va bet6ng. (Hinh 2-10a).
C2: V6'iCQC bang beMng ctit thep : Sau khi hoan tat vi~c dong thi tien hanh lien ket
~
1-1 : MtJ tci : Gi6ng hay tru co ti6t dien hinh tron vuOng, chti nhat vdi khoang rOng ben trong >1,00m t6i thi~u phai du d~ mOt ngltdi thao tac. Gieng chim dircc c~u tao vdi
" .... .
thanh gi6ng co thA dung van g~ gO ghep (thung ruC1U),xAy gach hoac due bAng b~te,ng c6t thep. Khi gi6ng diroc ha d6n dO sAu thi6t k~ thi ruOt gi6ng se diroc tram kin bAng b~te,ng. TUy theo khoang each giiia cac gi~ng rna chung se duqc n6i lel d trsn dAu bang each xAy vom cu6n da khi I < 4M hoac dAm b~te,ng c6t thep khi I < 6M, dong thci k6t
hC1PdA chiu tudng bsn trsn, (Hinh 2-9).
1-2 : .Ap dung : Glai phap mong trsn gi6ng chim duqc ap dung cho trudng hop d~t n~n y6u tr~n m~t va co y~u cAu cho gi~ng ti tlla vao Idp da cirng d dUdi sau, Truong hop Idp d~t n~n chiu tai d dUdl sAu, nhirng mu6n d'ilt tdi phai xuyen qua Idp mnrc ngAm thi
phat chon giai phap h~n hC1Pgie'ng tr~n cir vdi phdn cir nAm trong JdP dAt co mnrc ngAm.
2/ Mong tr~n coc, cU-:
La loai mong duqc c~u tao g6m cac CQC ri~ng re dong sAu xu6ng dAt va cac d~u cOt duqc n6i vdi nhau bang ban dai CQC co cAu tao tUC1ngtll nhu cac loai mong nong. Mong
tr~n CQC co 11U di~m la giam nhidu kh6i hrong dao h6 mong, ti6t kiem v~t lieu, cd gidi
hoa thi cong. V$t lieu lam CQC co th~ la bAng gO, thep, bet6ng, betOng c6t thep h04c cat.
Pham vi irng dung rOng rai phd bl6n trong cac trtnrng hC1Pnhu d nhirng noi dAt y6u rna phat chiu tSi trong km nhirng not co mnrc m~t mnrc ngAm k6 cs nhirng not d~t khOng x~u lAm. Tuy theo phuC1ng cach thi cOng mong tren CQC duqc phAn thanh 3 lo~i chinh nhu sau :
ã~
27 Mong Is bO phan vira pha! truy~n IlIC,lai dUQcchon sdu dUdi d~t hoac ngam trong
mnrc. Dat va nUdc d~u co kha nang An man mong v~ mat hoa va Iy, cac sinh v$t trong 2 moi trinrng do cling co th~ gAytac dOng pha hoai mongo Cho n~n mong can dU<1Ceach
ly va bao v~ nham 2 m\1Cdich :
1/ Cheng mroc ngam xam thuc v$t lieu thuc hien mong nhir gach, da, betong, b~tong c6t thep.
2/ Dam bao kho rao cho ket c6u phdn tren.