Trong cac cbng trinh c6ng c$ng ldn, ta thubng gap cic cbng trinh hhm nhu la d cira hang, nha bi6u di&n KCt cdu c6a cbng trinh nghm thubng ki&m nhiem nhih chdc nting nhu 18 tubng mbng c6a nha dhg thbi cting la tubng cGa thg hh Tudng ngoai c6a thg ham, ngoai viec chiu lyc thhng ddng cbn chiu sdc ddy c6a ddt, c6a nudc ngh, do do c"a phhi co d6 cubng dQ va dQ Bn dinh. Chi'eu day c6a tubng do tinh toan quyCt dinh. Ven thg hh ngoai viec chiu thi trong dQt tr$n nh con co Iyc ddy c6a nudc va phhn 1qc c6a ddt. Do do khi thi6t kg thg h"a chung ta ch phAi chu y dCn cac dQc di6m n$u tren- de" dat k6t quA chdng thdm that tdt cho thg hh. 21- Nguyen t6c thikt kk chdng thdm : 2-1 : YCU &u xir 19 chdng thdm : a- Vat lieu lam kCt cdu thg hh phAi dugc chon lqa va dhm bAo kh6ng co 16 rBng (toan khdi). b- DAm bAo nha Iun dh, thi cbng dung ky thuat va thi6t k6 dbng thbi c"a thubng xuyCn kie"m tra phubng phap va vat lieu trong qua trinh thi cbng. 2-2 : Gihi phap ca"u tao : a- Dung kCt cdu chdng thdm : Khi kCt cdu thg hh dugc xd ly dung qui cach thi khA nang chdng thdm cho thg hh dugc dhm bho. Gijli phap ap dung cho t3ng h3m c6 dien tich nh6. b- Thorit nudc ha myc nudc ngh : Ha myc nudc ngb chung quanh nha va ch dudi n'en thg hh b5ng cach dat cac he thdng dng th&t nudc co dQ d6c thich hop de" chAy vao gie"ng tap trung rbi bbm cho thoat di, ho$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$n thg k6t cdu mot ldp vat lieu chdng thdm co th6 la gidy dh, v3a xi mhng chdng thdm, bitum hoQc nhya mat- tit at-fan. Khi ap dung gijli phap nay ch chu y den viec cdu tao ~fung cach d cac khe bi6n dang cOng nhu ch ttang cubng d$ cdng c6a nhh. Tuy tinh chit va y$u ch. sir dung ma ldp chdng thdm c6 the dat bCn ngoai hoQc b$n trong thg hhm. 31- Cdu tao ch8ng thdm : (Hinh 2-28) 3- 1 : Trudng hgp myc nudc ngh d dudi mat n'en thng hh : gihi phap chdng thdm cho t'ang hh 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 lib vdi ldp ling mat n"e tang hh. Dhg thbi d$ ngan kh6ng cho nudc mua tif tr$n, nudc ngh tif dudi do thc dung mao dAn va thdm thdu qua mong, tubng vao nha c"a quuCt 1 hoQc 2 Idp bitum n6ng l$n mat ngoai c6a tubng va dinh m6ng. Nku mgc nuBc ngdm ti6p c$n vdi n6n thng him, cdn c6 ldp ch6ng thdm 6 dudi lilp b&t8ng 16t n&n tAng hdm. 3-2 : Truang hgp mqc nude ngdm cao nhdt, cao hdn cso trinh thi6t kk inat n6n san tdng hdm : Trong tru'2mg hgp ndy, 1Bp ch6ng thdm phAi duqc k6o dai l6n tu6ng d6n vi tri cao hml mqc nuBc nghm cao nhdt > 30cm. Ldp chdng th$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 hm ap lyc thiiy tinh. Truang hdp mqc nude ngdm chi cao hm n&n tdng hdm trong miia mua thi n&n tAng hdm c6 th6 lam rhg, dudi k6't cdu n&n lam cac rhnh tep trung ndc 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 hm inat n6n tdng hAin > 50cin. Dung nl13ng k6t cC$u chju udil dd giCi 1Bp cach nudc ch6ng thdin va du-gc tllqc hien the0 3 phumg cach. bl : Ldp cach nudc ch6ng thdm d$t 6 phia trong tU6ng : lBp cach nu,Bc d~qc 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 lm 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$c gidy ddu. b, : Ldp chch nuuc ch6ng tham duuc chC tao san dat 6 giiia l6p 16t vh ban m6ng, dong thdi duuc be nguuc 1Cn trCn the0 mat ngohi cha tuhg d6n vi tri cao hun muc nuuc ngam, nghia 18 bao toan bo tuhg vh nen tdng ham. Ldp chch nudc c6 th& dung 18 gigy d8u duuc trii vh d6n bang nhua duhg. Ben ngohi Idp chch nubc dgt dimg b tuhg cdn xiy 6p mot tuhg con kiCn b8o ho cao hun muc~nuuc ngdm cao nhgt lh 30cm vh chung quanh hAm nCn dap bing dat sCt deo. Chc mgt trong cua tdng ham d&u lhng, trht ma ximang 1 : 2 hoac 1 13. N&n tdng ham c6 thd d$ bing b$t8ng cot thCp dua rong ra m6ng vh xAy tuhg m6ng 1Cn trCn hoac Ihm ldp bCt6ng 16t phh ra kh6i mat tuhg d& d6 1hm I6p chong tham, vh trCn 66 sE d$ l6p bCt6ng c6t thCp vdi tuhg gach c6 gu bCn trong c6 nh6i sui day t&m nhua dl d& phbng 1un kh6ng d&u. b3 : Ha muc nuuc ngAm : Trong nhiing truung hap di&u kien dja chat c6ng trinh vi dja chat thuf van cho phCp thi nCn dung bicn phhp thho kh8 vung xay dung dl ha muc nubc ng$m trong nhi bang cich dat c8c 6ng tiCu thoit b chung quanh nhh. Dong P n rl h tc Ci h. 'g m lg lg $t a0 Idi lh ng Irn i~ tu. ng m, iu 6p nh Tm im 1% '"g vh ha ing I . xir 19 chdng thdm : a- Vat lieu lam kCt cdu thg hh phAi dugc chon lqa va dhm bAo kh6ng co 16 rBng (toan khdi). b- DAm bAo nha Iun dh, thi cbng dung ky thuat va thi6t k6 dbng thbi c"a. m6ng. Nku mgc nuBc ngdm ti6p c$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. 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 tuhg d6n vi tri cao hun muc