Trong cac cbng trinh c6ng c$ng ldn, ta thubng gap c i c cbng trinh hhm nhu la d cira hang, nha bi6u di&n ...

KCt cdu c6a cbng trinh nghm thubng ki&m nhiem n h i h chdc nting nhu 18 tubng mbng c6a nha d h g thbi cting la tubng cGa t h g h h ... Tudng ngoai c6a t h g ham, ngoai viec chiu lyc thhng ddng cbn chiu sdc ddy c6a ddt, c6a nudc n g h , do d o c"a phhi co d 6 cubng dQ va dQ Bn dinh. Chi'eu day c6a tubng d o tinh toan quyCt dinh. Ven t h g h h ngoai viec chiu thi trong dQt tr$n n h con co Iyc ddy c6a nudc va phhn 1qc c6a ddt. D o d o khi thi6t kg t h g h"a chung ta c h phAi chu y dCn cac dQc di6m n$u tren- de" dat k6t quA chdng thdm that tdt cho t h g h h .

21- Nguyen t6c thikt kk chdng thdm :

2 - 1 : YCU &u xir 19 chdng thdm :

a- Vat lieu lam kCt cdu t h g h h phAi dugc chon lqa va dhm bAo kh6ng co 16 rBng (toan khdi).

b- DAm bAo nha Iun d h , thi cbng dung ky thuat va thi6t k6 dbng thbi c"a thubng xuyCn kie"m tra phubng phap va vat lieu trong qua trinh thi cbng.

2 - 2 : Gihi phap ca"u tao : a- Dung kCt cdu chdng thdm : Khi kCt cdu t h g h h dugc xd ly dung

qui cach thi khA nang chdng thdm cho t h g h h dugc dhm bho. Gijli phap a p dung cho t3ng h3m c6 dien tich nh6.

b- Thorit nudc ha myc nudc n g h : Ha myc nudc n g b chung quanh nha va ch dudi n'en t h g h h b5ng cach dat cac he thdng dng th&t nudc co dQ d6c thich hop de" chAy vao gie"ng tap trung rbi bbm cho thoat di, ho$c c6 the" cho chAy vao he thdng cdng thoat nudc c6a thanh phd nCu he thdng dng thoat nay cao hdn.

c- Dung vat lieu chdng thdm : Ph6 l$n t h g k6t cdu mot ldp vat lieu chdng thdm co th6 la gidy d h , v3a xi mhng chdng thdm, bitum hoQc nhya mat- tit at-fan. Khi a p dung gijli phap nay c h chu y den viec cdu tao ~ f u n g cach d cac khe bi6n dang cOng nhu c h ttang cubng d$ cdng c6a nhh. Tuy tinh ch i t va y$u c h . sir dung ma ldp chdng thdm c6 the dat bCn ngoai hoQc b$n trong t h g hhm.

31- Cdu tao ch8ng thdm : (Hinh 2-28) 3- 1 : Trudng hgp myc nudc n g h d dudi mat n'en thng h h : gihi phap

chdng thdm cho t'ang h h trong tubng hop nay ch6 yeu la cdu tao phong dm. b5ng cach dung vira xi mang : 1 : 3 t6 trat kjj mat trong c6a tudng l i b vdi ldp ling mat n"e tang h h . D h g thbi d$ ngan kh6ng cho nudc mua tif tr$n, nudc n g h tif dudi do thc dung mao dAn va thdm thdu qua mong, tubng vao nha c"a quuCt 1 hoQc 2 Idp bitum n6ng l$n mat ngoai c6a tubng va dinh m6ng.

Nku mgc nuBc ngdm ti6p c$n vdi n6n thng him, cdn c6 ldp ch6ng thdm 6 dudi lilp b&t8ng 16t n&n tAng hdm.

3-2 : Truang hgp mqc nude ngdm cao nhdt, cao hdn cso trinh thi6t kk inat n6n san tdng hdm : Trong tru'2mg hgp ndy, 1Bp ch6ng thdm phAi duqc k6o dai l6n tu6ng d6n vi

t r i cao hml mqc nuBc nghm cao nhdt > 30cm. Ldp chdng th$m sE chju ap lqc th6y tinh cho n&n mu6n dinh vi lBp nAy the0 y&u cdu thikt kk thi cdn phai co ilhilng k6t cdu dac bigt co khA nhng ch6ng lai ap lqc nutrc. C6 hai trubng hdp.

a- Mqc nudc ngdm cao hdn mat tAng hdm < 50cm. Diiilg mot idp b6t8ng dd gid ldp cach nude ch6ng thdm, trong luqng ldp b&t8ng ndy phai ldn h m ap lyc thiiy tinh. Truang hdp mqc nude ngdm chi cao h m n&n tdng hdm trong miia mua thi n&n tAng hdm c6 th6 lam r h g , dudi k6't cdu n&n lam cac rhnh tep trung n d c vao gi6'ng d6 born cho thoat ra ngoai. Tudng ngoai cdn dugc trat mot ldp vita xiinhilg cat 1 : 3

b- Mqc nu'Clc ngdm hang nhm cao h m inat n6n tdng hAin > 50cin. Dung nl13ng k6t cC$u chju udil dd giCi 1Bp cach nudc ch6ng thdin va du-gc tllqc hien the0 3 phumg cach.

b l : Ldp cach nudc ch6ng thdm d$t 6 phia trong tU6ng : lBp cach nu,Bc d ~ q c dat sau khi xAy m6ng va dung ban bet6ng c6t th6p c6 thanh d6 d6 l&n than11 ban 6p vao phhn nh6 ra cua tu'ang hoac ap vao trAn nghn tdng hAm d6 kh6ng bj tac dong ddy ndi c6a nude. BAn b&t8ng sE 1Gm tang Ap lqc 6 day m6ng c8ng trinh do do cdn l m y khi tinh toan big11 dailg c6a n6n c6ng trinh. Ngoai ra d6' d& phhng lun kll6ng d6u gAy a1111 11u.iing dQi11Bp cach nLfdc ch6ng thdm thi tdt nhdt ni?n lam t&ng in6ng cua nha va phhn hAm cach ly nhau bhng cach 15111 mot ldp b&tbng c6t thbp, ri&ng 3 b&n trong sau khi dh xAy mong nl1i va c11o"ng th&n cho mat tu'ung 6 phia trong bang vila xilnhilg ho$c gidy ddu.

b, : Ldp chch nuuc ch6ng tham duuc chC tao san dat 6 giiia l6p 16t vh ban m6ng, dong thdi duuc be nguuc 1Cn trCn the0 mat ngohi cha t u h g d6n vi tri cao hun muc nuuc ngam, nghia 18 bao toan bo t u h g vh nen tdng ham. Ldp chch nudc c6 th& dung 18 gigy d8u duuc trii vh d6n bang nhua d u h g . Ben ngohi Idp chch nubc dgt dimg b t u h g cdn xiy 6p mot t u h g con kiCn b8o ho cao hun muc~nuuc ngdm cao nhgt lh 30cm vh chung quanh hAm nCn dap bing dat sCt deo.

Chc mgt trong cua tdng ham d&u lhng, trht m a ximang 1 : 2 hoac 1 13. N&n tdng ham c6 thd d$ bing b$t8ng cot thCp dua rong ra m6ng vh xAy t u h g m6ng 1Cn trCn hoac Ihm ldp bCt6ng 16t phh ra kh6i mat t u h g d& d6 1hm I6p chong tham, vh trCn 66 sE d$ l6p bCt6ng c6t thCp vdi t u h g gach c6 gu bCn trong c6 nh6i sui day t&m nhua d l d& phbng 1un kh6ng d&u.

b3 : Ha muc nuuc ngAm : Trong nhiing truung hap di&u kien dja chat c6ng trinh v i dja chat thuf van cho phCp thi nCn dung bicn phhp thho kh8 vung xay dung d l ha muc nubc ng$m trong nh i bang cich dat c8c 6ng tiCu thoit b chung quanh nhh. Dong

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