22 TCN 257-2000-Quy Dinh Ky Thuat Thi Cong Va Nghiem Thu Coc Khoan Nhoi

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22 TCN 257-2000-Quy dinh ky thuat thi cong va nghiem thu coc khoan nhoi

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000 CHNG I : QUY NH CHUNG 2 CHNG 2 : CHUN B THI CNG 2 A. CNG TC THIT K T CHC THI CNG CC KHOAN NHI :.......................2 B. VT LIU V THIT B :...............................................................................................3 C. THI CNG CC CNG TRNH PH TR :..................................................................3 CHNG 3 : CNG TC KHOAN TO L 4 A. THIT B KHOAN TO L :..........................................................................................4 B. NG VCH :.....................................................................................................................5 C. CH TO NG VCH :...................................................................................................5 D. NH V V LP T NG VCH :...........................................................................5 E. THIT B H NG VCH :.............................................................................................6 F. CAO NH V CHN NG VCH :......................................................................6 G. CHUN B KHOAN :.......................................................................................................6 H. O T TRONG KHI KHOAN :....................................................................................7 I. KHOAN L :.......................................................................................................................8 J. CAO DUNG DCH KHOAN :.....................................................................................8 K. X L LNG CN :........................................................................................................8 L. PHNG PHP X L LNG CN L LOI HT TH :.......................................8 M. PHNG PHP X L CN LNG L LOI HT RT NH, NI TRONG NC TUN HON HOC NC TRONG L :........................................................................9 CHNG 4 : DUNG DCH KHOAN 9 A. KIM TRA, IU CH, IU CHNH DUNG DCH :..............................................10 B. S DNG LI DUNG DCH VA ST :....................................................................10 CHNG 5 : CNG TC CT THP 10 A. GIA CNG LNG CT THP :....................................................................................10 B. CT THP CH :............................................................................................................10 C. CT THP AI :.............................................................................................................11 D. THIT B NH TM LNG THP :...........................................................................11 E. CT THP TNG CNG CNG LNG THP :..............................................11 F. GI CHN LNG CT THP :....................................................................................12 G. MC TREO :...................................................................................................................12 H. NG THM D :............................................................................................................12 I. NNG CHUYN V XP D LNG THP :..............................................................12 J. DNG V T LNG CT THP VO L KHOAN :.............................................12 CHNG 6 : CNG TC B TNG CC KHOAN 13 A. YU CU V VT LIU :............................................................................................13 B. YU CU K THUT V B TNG DI NC :...............................................14 C. TRM B TNG :..........................................................................................................14 D. VN CHUYN B TNG :...........................................................................................14 E. NG DN B TNG :....................................................................................................14 F. PHU :.......................................................................................................................15 G. QU CU B TNG :............................................................................................15 H. CHUN B L KHOAN V DN Y TRC KHI B TNG :...................15 I. CNG TC B TNG CC :..................................................................................16 J. PHNG PHP DI CHUYN THNG NG NG DN :......................................16 K. PHNG PHP BM B TNG QUA NG DN VO CC :..............................17 L. B TNG BNG THNG C NP VAN :...........................................................17 CHNG 7 : CNG TC KIM TRA, NGHIM THU 17

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

A. YU CU CHUNG :.......................................................................................................17 B. KIM TRA CNG TC KHOAN TO L :................................................................18 C. KIM TRA CHT LNG B TNG CC :.............................................................18 D. KIM TRA CN LNG TRONG L :.........................................................................20 E. KIM TRA CHT LNG DUNG DCH KHOAN :..................................................21 F. KIM TRA SC CHU TI CA CC :......................................................................21 G. NGHIM THU CC KHOAN NHI V I :...........................................................22 CHNG 8 : CC BIN PHP AN TON KHI THI CNG CC KHOAN NHI 22 CHNG I : QUY NH CHUNG 1.1 Qui phm ny p dng cho vic thi cng v nghim thu cc khoan nhi b tng ct thp lm mng cc cng trnh giao thng. 1.2 Cho php s dng p lc ca ct nc hoc dung dch va st gi thnh ng vch l khoan thi cng cc khoan nhi; Nu v tr l khoan nm gn cc ngi nh hoc cng trnh hin c nh hn 40m, cn la chn gii php thi cng thch hp dm bo an ton n nh cho cc cng trnh ln cn . 1.3 Ngi chu trch nhim thit k t chc thi cng, chn bin php, thit b my mc v xy dng cng ngh thi cng chi tit phi c trnh v c kinh nghim v thi cng cc khoan nhi. Cc cn b, k thut vin, cng nhn v.v.. tham gia thi cng cc khoan nhi cn phi c hun luyn v o to tay ngh. 1.4 Phi lp qui trnh cng ngh thi cng i vi tng loi my khoan hng dn cho cn b, cng nhn v mi ngi tham gia hiu r cng ngh trc khi tin hnh thi cng. Thit k t chc thi cng v cng ngh thi cng phi c cp c thm quyn duyt. 1.5 Cc ph lc km theo Qui phm ny c s dng tham kho cho thi cng v nghim thu cc khoan nhi. CHNG 2 : CHUN B THI CNG A. CNG TC THIT K T CHC THI CNG CC KHOAN NHI : 2.1 Khi thit k t chc thi cng cc khoan nhi cn phi iu tra v thu thp cc ti liu sau : 1. Bn v thit k mng cc khoan nhi, kh nng chu ti, cc yu cu th ti v phng php kim tra, nghim thu. 2. Ti liu iu tra v a cht, thu vn, nc ngm. 3. Ti liu v bnh , a hnh ni thi cng, cc cng trnh h tng ti ch, nh ng giao thng, mng in, ngun nc phc v thi cng. 4. 5. 6. 7. 8. Ngun vt liu cung cp cho cng trnh, v tr t khoan. Tnh nng v s lng thit b thi cng c th huy ng cho cng trnh. Cc nh hng c th tc ng ti mi trng v cng trnh ln cn. Trnh cng ngh v k nng ca n v thi cng. Cc yu cu v k thut thi cng v kim tra cht lng i vi cc khoan nhi.

2.2. Cng tc thit k t chc thi cng cc khoan nhi cn thc hin cc hng mc sau : 1. Lp bng v mt bng thi cng tng th bao gm v tr cc, b tr cc cng trnh ph tm nh trm b tng, h thng sn cng tc, dy chuyn cng ngh thit b thi cng nh my khoan, cc thit b ng b i km, h thng cung cp v tun hon va st, h thng cp v x nc, h thng cp in, h thng ng cng v.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

2. Lp cc bn v th hin cc bc thi cng, cc ti liu hng dn cc thao tc thi cng i vi cc thit b ch yu. Lp hng dn cng ngh thi cng v cc hng dn s dng cc thit b ng b. 3. 4. 5. 6. 7. Lp tin thi cng cng trnh. Lp biu k hoch s dng nhn lc. Lp biu k hoch s dng thit b. Lp bng tng hp vt t thi cng cng trnh. Cc bin php m bo an ton lao ng v cht lng cng trnh.

B. VT LIU V THIT B : 2.3 Cc vt liu, thit b dng trong thi cng cc khoan nhi phi tun th cc yu cu nu trong h s thit k, trong qui nh ca Qui phm ny v cc tiu chun hin hnh. 2.4 Cc thit b s dng nh my cu, my khoan, ba rung v.v.. phi c y ti liu v tnh nng k thut, cng nh chng ch v cht lng, m bo an ton k thut ca nh ch to v phi c ng kim ca c quan thanh tra an ton theo ng cc qui tc k thut an ton hin hnh. 2.5 Vt liu s dng vo cng trnh cc khoan nhi nh xi mng, ct thp, va st, ph gia v.v.. phi c y hng dn s dng v cc chng ch cht lng ca nh sn xut. Cc vt liu nh ct, , nc, va st, b tng phi c cc kt qu th nghim nh gi cht lng cng nh th nghim tuyn chn thnh phn b tng, kt qu p mu v.v.. trc khi a vo s dng. C. THI CNG CC CNG TRNH PH TR : 2.6 Trc khi thi cng cc khoan nhi, phi cn c cc bn v thit k thi cng tin hnh xy dng cc cng trnh ph tr nh : 1. ng cng v vn chuyn my mc, thit b, vt t phc v thi cng. 2. H thng cung cp nc gm ngun nc (ging nc, mng mng dn nc), cc my bm, cc b cha, h thng ng ng. 3. H thng cp in gm ngun in cao th, h thng truyn dn cao v h th, trm bin p, trm my pht in v.v.. 4. H thng cung cp v tun hon va st gm kho cha bt bentonite, trm trn va st, cc my bm, cc b lng, h thng lc xoy, h thng ng ng. 5. H thng cung cp b tng gm cc trm b tng, cc kho xi mng, cc my bm b tng, v h thng ng ng v.v.. 6. Cc sn o thi cng, cc khung dn hng v.v.. 2.7 Mt bng thi cng phi da vo a hnh, v tr xy dng mng m la chn cho ph hp v cn lu nhng im sau : 1. Khi thi cng trn bi cn, phi tin hnh san i, p t to mt bng thi cng, ri cc tm thp dy my khoan bnh xch c th di chuyn khoan cc. 2. Nu thi cng trn cn, c th to mt bng thi cng bng phng php p o t. 3. Ti nhng ni nc su hoc a hnh phc tp bn ly, phi lm sn o cng t my khoan v cc thit b thi cng cc. C th dng h ni nh phao, ph t my khoan nhng phi neo cho h ni n nh. 2.8 Nu thit b khoan thuc loi ln, nng phi iu tra y c phng n v l trnh vn chuyn.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

2.9 Phi m bo c din tch cng trng lp dng thit b, xp dng c. phi gia c nn bi, mt ng to iu kin thun li cho vic lp dng cc thit b thi cng v phng tin vn chuyn i li. 2.10. Phi c phng n vn chuyn t thi, dn dp chng ngi xung quanh v di mt t, trnh gy nhim mi trng. 2.11. Phi xem xt tc hi ca ting n v chn ng v c bin php hn ch nh hng n khu vc xung quanh. 2.12 Trc khi khoan cc phi kim tra li ng c tuyn, lp cc mc cao , cc cc nh tim cc khoan. Cc mc cao v cc nh tim phi c t v tr khng b nh hng khi khoan v phi c bo v cn thn. 2.13. Trc khi thi cng khoan nhng vng c nhiu bom mn trong chin tranh cn phi kho st thm d v c bin php r php bom mn. CHNG 3 : CNG TC KHOAN TO L A. THIT B KHOAN TO L : 3.1. Cng tc to l khoan c th chia thnh hai dng ch yu theo phng thc bo v thnh vch l khoan nh sau : 1. 2. Khoan to l khng c ng vch, dng bentonite gi vch; Khoan to l c ng vch.

Thit b ly t, trong lng l khoan c cc kiu sau: chong p ; gu ngom; gu xoay ht bn theo chu trnh thun, nghch v.v.. 3.2. Vic to l trong lng t c th thc hin bng cc cng ngh, thit b khoan khc nhau. Mi cng ngh khoan cn c qui nh cc thng s khoan c th m bo cht lng to l. B. NG VCH : 3.3. Theo c im k thut c th chia ng vch thnh hai loi: 1. ng vch thuc thit b khoan c kch thc v ng knh, chiu di mi ng c ch to theo tnh nng, cng sut ca tng loi my khoan. ng vch ny c rt ln trong qu trnh b tng; 2. ng vch theo yu cu thi cng khng ph thuc thit b khoan v c li trong kt cu vi mc ch : - Gi thnh vch; - Hoc lm vn khun i vi phn cc ngm trong nc, cao hn y sng; - Bo v cc b tng ct thp trong trng hp sng c vn tc ln v nhiu ph sa. C. CH TO NG VCH : 3.5. ng vch c ch to bng thp bn cun v hn thnh tng on ng ti cc xng c kh chuyn dng. ng knh ng vch theo yu cu thit k, chiu dy ng vch thng t 6-:-16 mm; chiu di cc on ng vch thng t 6-10m ph thuc vo c im thit b, vt t v cu lp, cc yu cu k thut ca cc. ng vch s dng thi cng cc khoan nhi phi c chng ch m bo cht lng. 3.6. Ti cng trng, cc on ng vch ca cc c ni bng ng hn. Vic hn ni ng vch phi c thc hin trn b g. Nu chiu di ng vch cn h ln hn chiu cao ca cu, th c th kt hp gia vic h ng vch v ni ng vch cho n khi chiu cao thit k, nhng phi b tr cc gi ng vch sau khi ni m bo cc yu cu k thut v thng ng, kn v sc chu ti khi ng h ng vch.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

D. NH V V LP T NG VCH : 3.7 Cng tc nh v, lp t ng vch phi tun th theo Qui phm thi cng v nghim thu cu cng v cn lu nhng im sau : 1. Khi lp t ng vch trn cn : cng tc o t nh v thc hin bng my kinh v v thc thp; dng cn cu lp t. 2. Khi lp t ng vch vng nc su : ngoi vic s dng cc loi my mc thit b trn do t v nh v cn dng thm h thng khung dn hng. Khung dn hng dng nh v ng vch phi m bo n nh di tc dng ca lc thu ng 3.8 nh v cc trn mt bng cn da vo cc mc to chun c xc nh v xy dng trc. V tr, kch thc v cao chn ng vch phi c nh v v h ng theo qui nh ca thit k. E. THIT B H NG VCH : 3.9. Tu thuc vo iu kin a cht cng trnh; kch thc ng vch; chiu su h tnh ton v chn thit b h ng vch cho ph hp. Thit b h ng vch thng c nhng dng sau : 1. S dng thit b xi lanh thu lc km theo my khoan xoay lc ng vch h hoc nh ng vch ln. 2. S dng ba rung ng ng vch xung kt hp vi vic ly t bn trong lng ng vch bng my khoan, gu ngom, hoc ht bn. 3. H ng vch bng kch thu lc p xung. F. CAO NH V CHN NG VCH : 3.10. Tu theo iu kin a cht, thu vn; phng php, loi thit b khoan v.v.. m quyt nh t cao nh v y ng vch cho ph hp. 3.11. Trong trng hp khoan cc nhi vng b nh hng ca nc thu triu, nu dng dung dch va st (bentonnite) gi n nh vch, th nh ng vch phi cao hn mc nc cao nht ti thiu l 2m. Khi khoan trn cn, ngoi nhng yu cu trn cn phi t ng vch cao hn mt t hin ti ti thiu 0,3m. 3.12. Khi khoan nhi bng loi my khoan khng c ng vch i km phi dng bentonite gi vch, th tu iu kin a cht c th m t chn ng vch ph (ng vch khng thuc thit b my khoan) ti cao sao cho p lc ca ct dung dch bentonite lun ln hn p lc ch ng ca t cng vi hot ti thi cng pha bn ngoi thnh vch. Nn t chn ng vch vo tng t khng thm nc nm pha di mc nc ngm. 3.13. Chn ng vch phi t pha di ng xi l cc b c tnh ton ti v tr khoan ti thiu l 1m. G. CHUN B KHOAN : 3.14. Trc khi thi cng cc khoan nhi, cn phi chun b h s ti liu, thit b my mc v mt bng thi cng, m bo cc yu cu sau: Khoan thm d a cht ti v tr c l khoan. Ch to lng ct thp. Th nghim chn t l thnh phn hn hp b tng cc.

Lp cc qui trnh cng ngh khoan nhi c th hng dn, ph bin cho cn b, cng nhn tham gia thi cng cc khoan nhi lm ch cng ngh. Khi s dng my khoan khng c ng vch i km th cn phi b sung cc yu cu di y: Sn xut cc ng vch thp theo chiu di m thit k thi cng yu cu.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

Lm cc th nghim chn t l pha trn thnh phn va st ph hp vi yu cu ca l khoan. 3.15. Da trn c s phng php v thit b my khoan, tu theo tng v tr c th ca cc m phi chun b mt bng p t my khoan. Khi kh nng chu ti ca t nn khng m bo t my v thit b thi cng c th chn gii php gia c nn t sau : Dng xe i san v nn cht t. o b lp t yu thay t tt. Gia c t bng vi hoc xi mng v.v.. Lt mt bng t vt, vn dy bng g hoc lt bng thp tm, thp hnh.

Khi k bng thp tm cn chng trt v xoay chn chng my khoan. 3.16. i vi cc my khoan xon c hay my khoan gu xoay dng thi cng trn cn, my c bn (b phn chnh ca my) phi c t trn cc tm tn dy 20mm. Cc chn my phi c k cng v cn bng khi khoan khng b nghing hoc di ng. 3.17. i vi cc my khoan tun hon hoc thun nghch, u khoan c treo bng gi khoan hoc bng cn cu, trc khi khoan phi nh v gi khoan cn bng, ng tim cc thit k. Cc sn cng tc phi m bo n nh di ti trng thi cng v ti trng ng. 3.18. nh v my khoan cc nh sau : a. i vi my khoan xoay lc ng vch, c th chn mt trong ba phng php sau y xc nh v tr lp t my: + V chu vi ngoi chn ca ng vch trn mt t. + ng t nht 3 cc nh lm mc trn chu vi t my. + Lm mt vnh ai nh v bng vi chu vi ngoi ca chn ng vch. b. i vi my khoan gu xoa, di chuyn my khoan u khoan vo trng tim cc xc nh. c. i vi phng php khoan tun hon ngc, c th chn mt trong ba thit b nh ba rung, ba xung kch hoc kch thu lc h ng vch xung. Khi nh v, phi kim tra xem ng vch nm ng vo v tr ca cc cha, nu b sai lch phi lp bn thao tc iu chnh li. H. O T TRONG KHI KHOAN : 3.19. Mc tiu ca cng tc o t trong khi khoannhm t c cc mc tiu sau : - nh v chnh xc v tr khoan; - Theo di chiu dy lp a cht ca l khoan; - Xc nh v tr, cao u khoan. 3.20. nh v tim u khoan hoc tim ng vch bng cc thit b o t cng trnh, theo cc cc mc c xy dng t trc. Trong qu trnh khoan phi theo di tim cc bng my kinh v, o t su l khoan, ng thi phi lun quan st v ghi chp s thay i c lp a cht qua mn khoan ly ra. I. KHOAN L : 3.21. Phi la chn thit b khoan nng lc v ph hp vi iu kin a cht, thu vn ca cng trnh m bo cho vic to l khoan t yu cu thit k. Trong qu trnh khoan nu xy ra s c, hin tng bt thng (st l thnh vch, l khoan khng thng, c s sai lch v ng knh l khoan thc t so vi yu cu ca thit k v.v..), th nh thu phi nghin cu,

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

xut gii php x l. Phng n x l s c ca nh thu ch c thc hin khi c ch u t, t vn gim st, t vn thit k thng nht chp thun. 3.22. Phi ch n khi b tng cc bn cnh trong cng mt mng t ti thiu 70% cng thit k mi c khoan tip. Vic quyt nh chn thi im khoan cn ph thuc vo khong cch gia cc cc trong mng. 3.23. i vi nhng l khoan s dng dung dch va st gi thnh vch, cn b ph dung dch lin tc trong qu trnh khoan, ngng khoan hoc b tng. Khng c cao dung dch trong l khoan h xung di mc qui nh gy st l vch. 3.24. Khi ngng khoan lu phi rt u khoan ra khi h khoan, trnh khoan b chn vi khi sp vch, ming h khoan phi c y np. 3.25. Khi a mi khoan ln x t hoc ni di cn khoan phi rt t t, khng c cho u khoan va chm vo vch gy st l. 3.26. Sai s cho php trong cng tc khoan to l c qui nh ti iu 7.4 ca Qui phm ny. 3.27. Sai s cho php ca l cc khoan nhi thi cng xong khng c vt qu cc qui nh nu trong iu 7.5 (Bng 1 v 2) ca Qui phm ny. J. CAO DUNG DCH KHOAN : 3.28. Cao dung dch khoan gi n nh thnh vch phi cao hn mc nc ngm hoc mc nc mt hn 2m. Ti nhng ni nc ngm hoc c p lc ngang khc cn phi tnh ton k quyt nh cao ny. 3.29. Trong qu trnh khoan phi lun theo di vic cp va st cho bm ht (phng php tun hon ngc). Nu ht va st d tr th phi ngng ngay khoan. Trong mi trng hp cm dung dch khoan trong h khoan b h thp hn 1m so vi cao qui nh. K. X L LNG CN : 3.30. Cng tc x l lng cn phi thc hin trc khi b tng. Khi khoan cc n cao thit k, khng c ng bn t hoc va st y l khoan lm gim kh nng chu ti ca cc. i vi mi cc, sau khi khoan u phi thc hin vic x l lng cn k lng. L. PHNG PHP X L LNG CN L LOI HT TH : 3.31. Loi cn lng c ng knh ht tng i ln, x l, sau khi to l t ti su thit k, khng c nng ngay thit b to l ln m phi tip tc thao tc thi t ra ngoi cho n khi kim tra thy sch cn lng y l khoan. 3.32. i vi phng php khoan l tun hon ngc, sau khi kt thc cng tc khoan phi nng u khoan ln cch y khon 20cm, tip tc quay mi khoan v bm ht va st. ng thi tin hnh kim tra dung dch khoan trong l khoan theo cc ch tiu trong iu 7.4 ca Qui phm ny cho n khi t c yu cu. Sau khi hon thnh cng vic phi rt u khoan ln vi tc t 2 n 4m/pht. 3.33. i vi phng php khoan xoay lc ng vch, sau khi kt thc thao tc to l phi ch khong t 15 n 20 pht mi c th nh gu ngom xung y l, ngom cn lng y l ln. Khi cn lng y l cn t, dng bm ht ct th xung y l, khuy nh cn lng ln ht ra ngoi. 3.34 i vi phng php khoan l bng gu xoay, sau khi khoan xong yn t 15 n 20 pht ri dng gu khoan c l chn c bit ly cn lng ln.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

M. PHNG PHP X L CN LNG L LOI HT RT NH, NI TRONG NC TUN HON HOC NC TRONG L : 3.35. Cn phi x l lng cn ht nh trc khi th lng ct thp hoc trc khi b tng. C th dng phng php bm khng kh xung (phng php ht bn khng kh) hoc phng php bm ht tun hon ngc ht bn: - Nu dng phng php bm kh xung l khoan ht bn, phi u ht bn hoc ming phun nm cng su vo trong nc cng hiu qu. - Nu dng phng php tun hon ngc th cn phi cho ming ng ht bn di ng y l khoan y cn lng ln. Trong qu trnh ht phi lun lun b sung dung dch khoan vo trong ng, khng c nc trong ng b h thp gy st l thnh vch. 3.36. i vi cc loi cc c su nh hn 10m, th khng nn dng phng php ht bn khng kh v hiu qu km; nn dng phng php bm ht tun hon ngc. CHNG 4 : DUNG DCH KHOAN 4.1. Tu theo iu kin a cht, thu vn, nc ngm, thit b khoan m chn phng php gi thnh vch l khoan v chn dung dch khoan cho thch hp. 4.2. Dung dch va st (bentonite) dng gi thnh vch gm : nc, bt st, CMC v tc nhn phn tn khc. Dung dch va st c th s dng i vi ni c lp a tng d st l v m bo c cc yu cu k thut sau : - C th dng mi loi a tng. - Dng cho mi loi thit b khoan v dng mi khoan. - Gi cho mn khoan khng lng ng di y h khoan v a chng theo dung dch ra ngoi. 4.3. Dung dch khoan c th l nc thng ti ni m a tng l t dnh nh: t st, st, t tht, hoc g nai phong ho, v.v.. 4.4. Dung dch khoan phi chn da trn c s tnh ton theo nguyn l cn bng p luc ngang, gia ct dung dch trong h khoan v p lc ca t v nc quanh vch l. i vi cc l khoan c lp a tng d st l, p lc ca ct dung dch phi lun ln hn p lc ngang ca t v nc bn ngoi. 4.5. Trng hp pha trn h khoan chu ti trng ca cc thit b thi cng nng hoc cc cng trnh xy dng ln cn, phi s dng ng vch chng st l. su ca ng vch trong trng hp ny phi cn c vo kt qu tnh ton c th, sao cho on l khoan khng ng vch c p lc ca ct dung dch ln hn p lc t nc xung quanh thnh vch. 4.6. Nu p lc nc ngm cao hn mc bnh thng (v d trong trong trng hp nc ngm trn ln c mt t) th cn phi tng t trng dung dch va st ln cho ph hp. t c mc ch trn c php trn thm vo dung dch cc cht c t trng cao nh barit hoc magnetic v.v.. 4.7. Dung dch dng trong khoan nhi phi c cht lng tt v khng b h hng theo thi gian. Thnh phn v tnh cht ca dung dch va st s dng cho mi l khoan cn phi bo m s n nh trong thi gian thi cng. Cc thng s ca dung dch phi c chn thch hp vi iu kin ca khu vc xy dng v m bo cc yu cu quy nh trong iu 7.10. Tu theo iu kin a cht ti v tr khoan cc m chn cc ch tiu v nht v kh lng ring ca dung dch cho thch hp (tham kho ph lc khoan km theo). A. KIM TRA, IU CH, IU CHNH DUNG DCH : 4.8. S ln th nghim, v tr ly mu c php ph hp (tham kho ph lc dung dch khoan km theo) ca Tiu chun ny vn dng cho cng tc khoan cc nhi ti cng trnh c th.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

4.9. Dung dch va st sau khi iu ch phi m bo c yu cu gi n nh thnh vch i vi loi t ni khoan cc. Trong qu trnh s dng va st, phi th nghim v iu chnh cc ch tiu k thut ca dung dch cho ph hp. B. S DNG LI DUNG DCH VA ST : 4.10. Qua vic kim tra v iu chnh ng qui nh, dung dch va st c th ti s dng nhiu ln trong thi gian thi cng. Nu cng tc kim tra, iu chnh c thc hin y th c th s dng li dung dch va st trong khong thi gian thi cng cng trnh, nhng khng c qu 6 thng. 4.11. Nu dung dch b nhim xi mng khng th iu chnh bng cht phn tn c na th phi loi b. CHNG 5 : CNG TC CT THP A. GIA CNG LNG CT THP : 5.1. Lng ct thp phi gia cng m bo yu cu ca thit k v : qui cch, chng loi ct thp, phm cp que hn, qui cch mi hn, di ng hn v.v.. 5.2. Ct thp c ch to sn ti nh my hoc cng trng v c h xung h khoan. Lng ct thp phi c gia cng ng thit k. Cc ct dc v ngang ghp thnh lng ct thp bng cch buc hoc hn. Cc thanh ct thp c bit nh : vng ai gi c lp dng, khung quay dng lng v.v.. phi c hn vi ct thp ch. Ct thp dng cho cc phi l thp chu hn . B. CT THP CH : 5.3. ng knh ct thp theo ch nh ca n thit k . 5.4. S lng ct thp theo ch nh ca n thit k. 5.5. Chiu di ct thp ch ph thuc vo on chia. Lng ct thp phi ch to thnh tng on cn c vo chiu di tng th ca cc. Thng thng cc on chia c th l 12 v 14m, ln nht l 15m v chiu cao ca mc cu thng khng vt qua 15m. Lng ct thp ca cc c chiu di ln (ln hn 15m) phi c phn thnh tng t, sau c t hp li cng trng khi h lng vo trong h khoan. Cn lu khi ghp lng, t di nht phi t pha di vic h lng ct thp xung l khoan c d dng. 5.6. Mi ni cc on lng ct thp nn dng bng hn hoc bng phng php dp p ng ni theo tiu chun TCXD 234-1999. Ch s dng mi ni buc ct thp i vi cc cc c ng knh nh hn 1,2m v chiu di ton b lng thp khng qu 25m. C. CT THP AI : 5.7. ng knh vng ai hay vng l xo ca lng ct thp theo ch nh ca n thit k. Khi gia cng ct thp ai cn lu nhng im sau : - ng knh danh nh ca vng thp ai nh hn ng knh cc 10 cm (2x5 cm lp b tng phng h) i vi cc cc thi cng khng ng vch. - ng knh danh nh ca vng ct thp ai nh hn ng knh cc 6cm i vi cc khoan c ng vch. - ng knh ct thp ai t 6-16 mm, khong cch gia cc vng ai thc hin theo n thit k . 5.8. d dng cho vic th to lng, cn phi s dng cc ct thp c bit lm vng ai lp dng hoc vng c. ng knh vng ai phi tun th theo ng h s thit k. Vng ai phi m bo cng c th gi vng lng thp v cc ng thm d khuyt tt khi nng chuyn. Vng ai c ni kn bng hn chng hoc hn i u.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

D. THIT B NH TM LNG THP : 5.9. Khi lp t lng thp trong l khoan, nh v chnh xc tm v trnh s va chm ca lng ct thp vo thnh vch, cn s dng cc thit b nh tm lng thp hoc con m : + Cc con c (Tai nh v): Con c c lm bng ct thp trn, hn vo ct thp dc v c gi l thanh trt. Kch thc ca thanh trt c chn cn c vo kch thc lng ct thp v ng kinh l khoan thc t. + Cc con m bng b tng: m bo tng phng h lng ct thp v nh tm lng thp c th dng cc con m, hnh trn bng xi mng. trnh s thm nhp ca nc gy ra g ct thp dc, khng c c nh con m trn ct thp dc . Nn hn c nh con m vo gia 2 thanh ct thp dc cnh nhau bng mt thanh thp nh . E. CT THP TNG CNG CNG LNG THP : 5.10. Trong trng hp ton b h thng ct thp vnh ai khng lm cng lng khi nng chuyn, cn phi gia cng tng cng lng cc ct thp c bit. Cc ct thp ny c th c nm li hoc c tho d dn khi h lng vo trong h khoan nu gy cn tr vic h cc ng b tng. Ct thp tng cng ny gm cc loi sau : - Cc thanh ging chng li s lm mo van lng ct thp. - Cc thanh ct thp gi cho lng ct thp khng nghing v b xon. F. GI CHN LNG CT THP : 5.11. Phn ct thp dc u mi cc c un vo tm cc gi l gi chn lng ct thp . Vic gia cng gi chn lng ct thp phi tun th ng h s thit k. G. MC TREO : 5.14. Mc treo phi b tr sao cho khi cu lng ct thp khng b bin dng ln. Cn phi chn ct thp chuyn dng lm mc cu v phi gia cng mc treo theo ng v tr mc cu c tnh ton trc . H. NG THM D : 5.15. kim tra khng ph hu cc cc thi cng xong, cn phi t trc cc ng thm d bng thp hoc bng nha c np y y, c kch thc ph hp vi phng php thm d trn sut chiu di cc : dng ng 50/60 mm thm d bng siu m v ng 102/114 mm khoan ly mu b tng y h khoan. i vi cc cc khoan nhi ng knh ln hn 1,5m hoc c chiu di ln hn 25m cn phi s dng ng thm d bng thp. 5.16. Cc ng thm d c hn trc tip ln vnh ai hoc dng thanh thp hn kp ng vo ai. 5.17. i vi cc ng 102/114mm dng khoan mu phi t cao hn chn lng thp 1m v khng trng vo v tr ct thp ch. 5.18. Phi c bit lu n v tr ca ng thm d ti mi ni cc on lng ct thp m bo cho ng chc chn, lin tc. i vi cc khoan su khng qu 20m vi ng knh cc khng qu 0,80m th khng cn t ng thm d. I. NNG CHUYN V XP D LNG THP : 5.19. i vi cc cc c ng knh ln, khng c nng chuyn lng ct thp ti 1 hoc 2 im, phi gi lng ct thp ti nhiu im hn ch bin dng . 5.20. Lng ct thp phi c tp kt trn nn bi lng bng b tng hoc nhng khu bi sch s, kh ro. Lng ct thp phi c xp trn nhiu con k bng g trnh bin dng v khng c chng ln nhau.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

J. DNG V T LNG CT THP VO L KHOAN : 5.21 Trc khi h lng ct thp vo v tr, cn o t kim tra li cao ti 4 im xung quanh v 1 im gia y l khoan. Cao y khng c sai lch vt qu qui nh cho php (h 100 mm). 5.22 Cc thao tc dng v t lng ct thp vo l khoan phi c thc hin khn trng hn ch ti a lng mn khoan sinh ra trc khi b tng (khng c qu 1 gi k t khi thu dn xong l khoan). 5.23. Khi h lng ct thp n cao thit k phi treo lng pha trn khi b tng lng ct thp khng b ung dc v m thng nn t y l khoan. Lng ct thp phi c gi cch y h khoan 10cm. 5.24. Cc bc c bn lp t v h cc on lng ct thp nh sau : + No vt y l. + H t t on th nht vo trong h khoan cho n cao m bo thun tin cho vic kt ni t tip theo. + Gi lng ct thp bng gi chuyn dng c ch to bng ct thp ng knh ln hoc thp hnh. + a on tip theo v thc hin cng tc ni lng ct thp (hn cc thanh ct dc vi nhau hoc ni buc ti ch hay bt ni bng cc hoc ni bng dy p ng ni ). + Tho gi v h tip lng ct thp xung. + Lp li cc thao tc trn i vi vic ni cc on tip theo cho n on cui cng. + Kim tra cao pha trn ca lng ct thp. + Kim tra y l khoan. + Neo lng ct thp khi b tng lng ct thp khng b tri ln. 5.25. Lng ct thp sau khi kt ni phi thng, cc ng thm d phi thng v thng sut ; lch tm ca ng ti v tr ni lng ct thp khng c vt qu 1cm. CHNG 6 : CNG TC B TNG CC KHOAN A. YU CU V VT LIU : 6.1. thnh phn hn hp b tng phi c thit k v iu chnh bng th nghim sao cho m bo cc yu cu ca thit k. 6.2. Cc loi vt liu cu thnh hn hp b tng phi c kim tra v cht lng trc khi s dng v tun th theo cc tiu chun ca Vit nam hin hnh : + Xi mng : dng xi mng Portland PC 40 tr ln m bo tiu chun TCVN 2682 - 1999. + Ct liu th : dng c thnh phn ht cp phi lin tc Dmin = 5 / 25 mm, tun th theo tiu chun TCVN 4453 1995. + Ct : dng ct vng c Module 2,5 tun th theo tiu chun TCVN 4453- 1995. + Nc : Sch, khng c tp cht, tun th theo qui nh ca tiu chun TCVN 4506-87 . + Ph gia : C th dng ph gia cho b tng tng tnh cng tc ca b tng v ko di thi gian ninh kt ca b tng cho ph hp vi kh nng cung cp b tng. Khi s dng ph gia phi tun th cc qui nh ca Nh nc v thc hin ng ch dn ca nh sn xut. + T l nc / xi mng : N /XM 0,45.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

B. YU CU K THUT V B TNG DI NC : 6.3. Phi bo m cc yu cu ca va b tng khi b tng di nc ng qui trnh qui phm hin hnh. Cng b tng di nc phi t yu cu ca thit k. Trc khi b tng di nc phi tin hnh th nghim la chn thnh phn cp phi b tng m bo yu cu v cng thit k. 6.4. Cc ch tiu v st, tch va v tch nc v.v.. s c qui nh c th trn c s kt qu th nghim thnh phn hn hp b tng v phng php bm b tng. Hn hp b tng trc khi vo cc phi c kim tra nghim thu m bo cc ch tiu k thut qui nh trong bng 2 ca iu 7.9. C. TRM B TNG : 6.5. Phi cn c vo khi lng cn tnh ra cng sut my trn. My trn b tng phi cng sut m bo cung cp b tng lin tc trong qu trnh thi cng. Nn b tr my trn gn v tr thi cng cc gim thi gian ch i do vn chuyn. 6.6. H thng trm trn phi c kim tra v iu chnh chnh xc, thng xuyn vic cn ong ct liu m bo ng v . 6.7. Thi gian trn m bo theo tnh nng my trn phi c cn b th nghim c trch vic theo di cng tc trn b tng v th nghim st ca tng m trn v ghi s theo di y . D. VN CHUYN B TNG : 6.8. Cc phng tin vn chuyn b tng phi bo m kn, khng lm chy mt va xi mng. Nu trm trn xa cng trng th phi vn chuyn b tng bng xe trn t hnh. Xe trn cp b tng ti trc tip vo ng dn, hoc cho my bm b tng. My bm cung cp b tng phi m bo tt, cng sut thi cng cc lin tc. Thi gian t khi trn b tng xong n khi vo cc khng c qu 30 pht. E. NG DN B TNG : 6.9. ng dn phi m bo cc yu cu k thut sau : + ng phi kn chu p lc trong qu trnh bm b tng, ng phi nhn c bn trong v bn ngoi, cc mi ni ng khng c li ra v mc vo lng thp trong khi b tng. + Mi t ca ng ni di khong 3 m, mi ni phi c cu to d tho lp (c ren vung, hoc mi ni hnh thang). + Chiu dy thnh ng ti thiu l 8mm. + ng knh trong ng ti thiu phi gp 4 ln ng knh ct liu to nht ca hn hp b tng. + ng knh ngoi ca ng khng c vt qu 1 /2 ng knh danh nh ca cc. + on ng c bit ni t my bm ti ng dn b tng phi c cu to cong c th thot c bt kh ln trong hn hp b tng ra ngoi (Xem cc iu 6.20 v 6.21). + Chiu di ng cn c vo cao y l khoan v cao sn kp c ng tnh ton quyt nh. Thng thng on mi ng dn c b tr bng 1 m ng c bit. 6.10. Lc t ng dn vo l khoan gm cc bc sau : + nh du chiu cao ng. + Lp t h dm k kp c trn sn cng hoc mt ng vch. Dng cu lp tng on ng dn vo l khoan theo t hp c tnh ton. + Ton b h thng ng dn c treo bng kp c trn sn kp phi m bo ng thng ng.

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+ ng dn c th c rt ln h xung bng cn cu. + Sau khi t hp xong, dng cu h mi ng cch y l khoan 2 m; nh v ng dn ng tm l khi thao tc ng khng chm vo lng thp. F. PHU : 6.11 Phu c gn vo pha trn ca ng dn bng ren vic tho lp c d dng, gc gia hai thnh phu khong t 60/80 b tng d xung. G. QU CU B TNG : 6.12 Qu cu b tng dng ngn cch b tng trong ng dn vi nc hoc dung dch khoan. Qu cu b tng c th lm bng hai tm : + G tin trn hnh cu hoc bn cu, bc bng vi bc; + Nha hnh chu hoc cc ming xp nh v.v 6.13 Trc khi b tng, phi t qu cu ti v tr pha di ca phu khong 20 40 cm khi b tng chy trong ng qu cu i trc y dung dch khoan ra khi ng dn. H. CHUN B L KHOAN V DN Y TRC KHI B TNG : 6.14. Sau khi h lng ct thp vo v tr, cn o c kim tra li cao y l khoan v ton b lng thp trong l khoan, chnh sa m bo ng yu cu thit k trc khi tin hnh b tng. 6.16. Khi khoan n cao thit k, tu theo phng php khoan m chn cch x l cn lng theo quy nh ca Quy phm ny (t iu 3.23 n 3.31) lm sch mn trong l khoan. 6.17. Trc khi b tng dng ng dn lp trong l khoan lm sch li y l khoan. phi th nghim dung trng v hm lng ct v.v.trong dung dch va st, n khi t yu cu quy nh trong iu 7.11 ca Quy phm ny mi dng cng tc dn y. Thi gian t khi dng cng tc dn y n lc bt u b tng khng vt qu 1 gi. I. CNG TC B TNG CC : 6.18. Trong trng hp th tch b tng cc khi sai lch so vi tnh ton thit k hn 30% th phi kim tra v c bin php x l thch hp v s sai lch ng knh cc. 6.19. C th b tng cc theo cc phng php c bn sau : + Phng php di chuyn thng ng ng dn; + Phng php bm b tng qua ng dn vo cc; + Phng php dng gu ng m c iu khin (ch c dng vi cc ging khoan c ng knh ln). J. PHNG PHP DI CHUYN THNG NG NG DN : 6.20. Khi s dng phng php di chuyn thng ng ng dn cn tun th cc quy nh sau : 1. Trc khi b tng cc khoan, h thng ng dn c h xung cch y h khoan 20 cm. Lp phu vo u trn ng dn 2. Treo qu cu b tng bng dy thp 2 hoc 3mm hoc dy thng. Qu cu c t thng bng trong ng dn ti v tr di c phu khong t 20 n 40 cm v phi tip xc kn kht vi thnh ng dn. 3. Dng my bm rt dn b tng vo cnh phu, khng c rt trc tip b tng ln cu lm lt cu. Khng c vo cc phn b tng bi trn my bm. 4. Khi b tng y phu, th si dy thp gi cu b tng p cu xung v tip tc cp b tng vo phu.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

5. Phi b tng vi tc chm khng lm chuyn dch lng thp v trnh lm b tng b phn tng. 6. Trong qu trnh b tng phi gi ng dn lun ngp vo trong b tng ti thiu l 2 m v khng vt qu 5 m. Khng c cho ng chuyn ng ngang. Khi dch chuyn ng thng ng phi tnh ton xc nh chnh xc mi ca ng dn m bo khng c a mi ng dn b tng sai vi quy nh ca iu ny. Tc rt h ng khng ch khong 1,5 m / pht. 7. B tng ti trc khi x vo my bm phi c th nghim bng mt v bng cch o st. 8. Nu st khng m bo (thp so vi thit k) th phi iu chnh nhng khng c cho thm nc vo va. 9. Trong qu trnh b tng, nu tc ng, cm khng c lc ng ngang, cm dng n kim loi p vo vch ng lm mo ng, phi s dng v g g hoc dng bin php ko ln h xung nhanh b tng trong ng tt ra. Khi x l tc ng theo phng php ny phi xc nh chnh xc cao mt b tng v cao mi ng dn trnh rt ng sai vi quy nh. 10. Trong khi b tng, phi o t v ghi chp quan h gia lng b tng v cao mt b tng trong l kim tra tng i ng knh trung bnh v tnh trng thnh vch ca l khoan. 11. Khi b tng cc giai on cui thng gp va ht nh ni ln, v vy phi tip tc b tng ton b va ng nht dng n cao nh cc theo thit k. xc nh mt dm trn lp mt b tng phi ly mu trc tip th nghim kim tra i chng theo tiu chun TCVN 3110-1979. Ngi thc hin cng tc o phi l chuyn trch v c kinh nghim. K. PHNG PHP BM B TNG QUA NG DN VO CC : 6.21. Phng php bm b tng c thc hin theo qui nh sau : 1. B tng c bm qua ng dn xung l khoan. 2. Phn mi ng dn phi c l trng thot khng kh, nc hoc bn. ng dn b tng phi c bt kn u trn bng np vn, phn u ng dn ny phi c cu to trong trng hp my bm hng hoc gp s c khc c th t c phu b tng theo phng php khc. 6.22. Cng vic mi khi bm c thc hin theo cc bc sau y : + M np bt ca ng b tng v a vo mt nt mi. + Trong thi gian bm u tin phi h np cho khng kh thot ra ngoi. Ch ng np li khi hn hp b tng y v bt u tro ra ngoi ng. 6.23. Vic cp b tng phi u n v lin tc t khi bt u cho n khi hon thnh khi lng b tng ca ton cc. Khng c di chuyn ng dn mnh, khng c lm tt mt nt mi. L. B TNG BNG THNG C NP VAN : 6.24. Phng php ny ch p dng cho vic b tng cc ging khoan c ng knh ln, chiu di cc nh (ng knh trn 3m, chiu di cc nh hn 20m) v iu kin b tng phi thun li. 6.25. Ch c thc hin b tng bng thng khi phng n thi cng m bo khng lm nh hng n cht lng ca cc theo qui nh ca n thit k v c c quan c thm quyn chp thun. 6.26. Trng hp gp l khoan kh trong lp ct, l khoan c ng vch (ng thp hoc BTCT) cng nh l khoan khng c ng vch do xuyn qua a tng st v st ti v tr cao hn mc

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

nc ngm nhng khng xut hin lp ct hoc ct y l, cho php b tng lng cc khng dng ng dn m rt t do cao ri khng qu 6m. Trng hp gp l khoan y nc, thi cng b tng trong lng cc theo phng php rt ng theo chiu thng ng, c qui nh trong Qui trnh Thi cng b tng di nc bng phng php va dng. CHNG 7 : CNG TC KIM TRA, NGHIM THU A. YU CU CHUNG : 7.1. Vic kim tra, gim st cht lng v nghim thu cc khoan nhi phi c thc hin ti hin trng v phi cn c vo kt qu th nghim ca cc phng th nghim hp chun. 7.2. Cc dng c, thit b kim tra cht lng thi cng cc phi m bo chnh xc, tin cy. Cc h s, ti liu nghim thu, cc kt qu th nghim v.v phi c y v m bo chnh xc. 7.3. Cc cn b k thut, cc th nghim vin lm cng tc th nghim, kim tra, gim st v nghim thu k thut cht lng phi c trnh chuyn mn v c o to, hng dn cng ngh thi cng cc khoan nhi. B. KIM TRA CNG TC KHOAN TO L : 7.4. Trong qu trnh khoan cc cn kim tra cc thng s v s l khoan theo Bng 1 sau y: Bng 1 TT 1 2 Thng s Phng php kim tra kim tra Tnh trng - Kim tra bng mt v n di l - Dng phng php siu m hoc camera ghi chp thnh l khoan thng - So snh khi lng t ly ln vi th tch hnh hc ca cc ng v - Theo lng dung dch gi thnh vch su - Theo chiu di cn khoan - Dng qu di - My o nghing, phng php siu m 3 Kch thc - Mu, calip, thc xp m v t ghi ln nh ca ng knh l - Theo ng knh ng vch - Theo m ca cnh mi khoan khi m rng y 4 Tnh trng y l khoan v su ca mi cc - Ly mu v so snh vi t, lc khoan. o su trong khong thi gian khng nh hn 4 gi - sch ca nc thi ra - Dng phng php th qu ri hoc xuyn ng - Phng php in (in tr, in rung v.v) 7.5. Trc khi btng cn phi thc hin kim tra l cc theo cc thng s Bng 1 v lp thnh bin bn lm cn c nghim thu. 7.6. Cng tc thi cng v kim tra nghim thu v: v tr v kch thc hnh hc l khoan; cng tc gia cng lp t lng chng ct thp; cht lng btng cc khoan nhi c quy nh trong Bng 2.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

C. KIM TRA CHT LNG B TNG CC : 7.7. Tt c cc ch tiu k thut ca ct liu ln th theo TCVN 1772:1987 , si xy dng Phng php th. Cc loi vt liu khc thc hin cng tc kim tra theo iu 6.2. Th nghim xc nh thnh phn hn hp btng cc thc hin theo iu 6.3. 7.8. S lng cc phi kim tra ty theo mc quan trng ca cng trnh cng nh ty vo s hon thin ca thit b v kinh nghim ca n v thi cng m c quan thit k hoc t chc t vn quyt nh nhng khng t hn t l % (so vi tng s cc) quy nh trong Bng 2. Bng 2 Sai s cho php (1) 1. sai lch cho php v v tr mt bng nh v v trc xin (tg) ca cc khoan so vi thit k: (tnh theo gi tr d ng knh cc): Khi b tr mt hng cc theo mt chnh cu: 0,04 ; 1:200 - Trng hp thi cng trn nc -nt 0,02 ; 1:200 - Trng hp thi cng trn cn Khi b tr hai hoc nhiu hng cc theo mt chnh cu: 0,1 ; 1:100 - Trng hp thi cng trn nc 0,05 ; 1:100 - Trng hp thi cng trn cn 2. Sai s cho php (tnh theo cm) v kch thc thc t ca l khoan v kch thc m rng bu y cc: 25 - Chiu su l khoan ( cao trnh) 5 Theo ng knh l 10 theo chiu su ca on hnh tr m rng bu. 10 Theo ng knh m rng. Tng lng ct thp Tng l khoan -ntTng on m rng nt nt -nt-nt-nt-ntTng cc Nghim thu (o bng my thy bnh, ng di v thc dy) -nti tng kim tra (2) Phng php kim tra (3)

Kim tra (o theo ch dn ca thit k mng cc) -nt nt nt nt

Kim tra (bng thc cun thp v nc dt) nt

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

5 Theo chiu cao on hnh tr m rng. 3. Sai s cho php (tnh theo cm) v v tr t lng ct thp trong lng cc khoan so vi thit k: 1 Theo v tr t ct thp dc vi nhau trn ton chu vi ca lng. 5- Theo chiu di thanh thp. 2- Theo c ly cc bc ai xon c 10- Theo khong cch cc vng ai cng mt lng thp 10- Theo khong cch cc con k to lp bo v ct thp. 1- Theo chiu cao con k. 2- Theo ng knh ca lng thp ti v tr t vng ai cng. 4. Sai s cho php v ch tiu va b tng vi ln kim hnh chp 16-10cm, b tng trong nc vo lng cc theo phng php rt ng theo chiu thng ng: 2cm theo tr s st 2% - theo tch va v tch nc. 5. Sai s cho php v ch tiu b tng lm cc khoan : Khng c vi phm v tnh lin tc trn ton chiu di cc.

nt nt nt

nt nt nt

nt nt nt nt nt

Theo TCVN 3106:1993 Theo TCVN 3106 : 1993 Theo TCVN 3109: 1993 Kim tra bng thit b c chng v quan st Kim tra 6 mu t li khoan qua cc. 2 cc cho 1 cu Theo TCVN 3106:1993

nt

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

+ 20; -5% Cng b tng D. KIM TRA CN LNG TRONG L : 7.9. Cng tc kim tra cn lng trong l phi thc hin ngay sau khi kt thc vic to l v x l lng cn. Trc khi b tng phi o li cao y l khoan, chiu dy ca lp cn lng xung di y l (nu cn) phi ghi vo nht k khoan l v khng c vt qu quy nh trong Bng 3. Bng 3 TT 1 2 3 Loi cc Cc chng Cc chng + ma st Cc ma st Sai s cho php h 5 cm h 10 cm h 20cm

E. KIM TRA CHT LNG DUNG DCH KHOAN : 7.10. Trc khi b tng, khi lng ring ca dung dch trong khong 50cm k t y l khoan phi nh hn 1,25, hm lng ct 8%, nht 28s. Dung dch va st dng thi cng cc khoan nhi phi c cc ch tiu k thut ban u ph hp vi cc quy nh trong Bng 4. Bng 4 Tn cc ch tiu 1. Khi lng ring 2. nht 3. Hm lng ct 4. T l keo 5. Lng mt nc 6. dy ca o st 7. Lc ct tinh Yu cu T 1,05 1,15 T 18 45 sec < 6% > 95% < 30 cc/30 pht T 1-3 mm/ 30 pht 1 pht: mg/cm2 10 pht: mg/cm2 8. Tnh n nh 9. Tr s pH < 0,03 g/cm2 T 7-9 Giy th pH 20-30 50-100 Phng php ong cc Dng c o mt nc Dng c o mt nc Lc k ct tnh Phng php kim tra T trng dung dch st hoc Bomeke Phng php phu 500/700cc

F. KIM TRA SC CHU TI CA CC : 7.11. m bo chnh xc sc chu ti gii hn ca cc n phi cn c vo tnh cht trng yu v cp ca cng trnh, iu kin thc t a cht cng trnh, yu cu thit k v tnh hnh thi cng cng trnh m t chc th tnh hoc th ng c tin cy cho cc n v lu nhng im sau: 1. Khi khng th tin hnh nn tnh cc n n ti trng gii hn th c quan t vn thit k phi quy nh ti trng nn ti thiu ln cc theo quy nh ca tiu chun th tnh cc. 2. Vic la chn phng php th tnh cc n phi da trn cc tiu chun do c quan t vn thit k yu cu vi s chp nhn ca ch u t.

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

7.12. Khi ri vo mt trong cc trng hp sau y th phi th nn tnh cc n theo phng thng ng: 1. Mng cc ca cng trnh quan trng. 2. Trc khi thi cng cc ca cng trnh cha thc hin th tnh cc n m c mt trong cc trng hp sau y: iu kin a cht phc tp; tin cy v cht lng thi cng cc thp; Mng cc ca cng trnh t quan trng nhng c s lng hn 30 cc. 3. Cng trnh mng cc chu tc dng ca lc ko hoc lc nn ngang ln theo quy nh ca tiu chun xy dng TCXD 88: 1982 Cc- Phng php th nghim hin trng phi thc hin cng tc th tnh. S lng cc cn th thng thng ly 2% tng s cc nhng khng t hn 3 cc, i vi cng trnh c tng s cc di 50 cc th phi th nghim 2 cc. 7.13. C th p dng kim tra sc chu ti thng ng cc n bng phng php th ng c tin cy. Khi ri vo mt trong cc trng hp sau y th phi kim tra th ti cc bng phng php th ng: 1. 2. Mng ca cng trnh quan trng m khng c kh nng thc hin th nn tnh cc n. Kim tra b sung cho vic th cc bng nn tnh.

3. Mng cc ca cng trnh thng thng, t quan trng v c c quan t vn thit k yu cu. S lng cc cn phi th ng do c quan t vn thit k yu cu thng thng ly 4% tng s cc nhng khng t hn 5 cc. Nhng im cn lu i vi phng php th ng nh sau: 1. Phng php bin dng ln (PDA) thng c dng trong th ng cho cc. Khi th ng phi c y cc loi thit b o c nh: o c chi; chi n hi, v.v Vic th ng theo phng php hin i phi do nhng k s c trnh v kinh nghim thc t thc hin. 2. Kt qu ca phng php th ng c xem l tin cy nu n c so snh i chng vi kt qu th nn tnh cc trong iu kin a cht cng trnh tng t v khng c sai lch nhau qu, sau dng phng php ng kim tra vi s lng ln cc thi cng. G. NGHIM THU CC KHOAN NHI V I : 7.14. Cc phi c kim tra trong tt c cc cng on lm cc, ghi vo cc mu bin bn qun l cht lng c ch u t thng nht v chp nhn lc trng thu, lp thnh h s nghim thu v c lu tr theo quy nh ca nh nc. CHNG 8 : CC BIN PHP AN TON KHI THI CNG CC KHOAN NHI 8.1. Phi tin hnh t chc hng dn cng ngh cng nh hng dn bo m an ton cho mi ngi lm vic trong cng trng thi cng cc khoan nhi. Ngi cng nhn phi c y cc dng c bo h lao ng cn thit nh : m, giy, gng tay, mt n phng h v.v.. lm vic, nu thiu thit b bo h lao ng khng c vo cng trng. Phi b tr ngi c trch nhim lm cng tc an ton. Tt c mi ngi phi tun theo lnh ca ngi ch huy chung. 8.2. Trc khi thi cng cc phi nm y cc thng tin v kh tng thu vn ti khu vc thi cng, khng c b tng khi tri ma v khi c gi trn cp 5. 8.3. Cc sn cng tc dnh cho ngi lm vic, ng i li trn h ni phi lt vn, b tr lan can v li an ton ti nhng ch cn thit, ban m phi b tr nh sng y . Cc v tr nguy him phi c bin bo hiu v c ngi canh gc. Phi dng np y l khi ngng khoan. Khi thi

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QUY NH K THUT THI CNG V NGHIM THU CC KHOAN NHI - 22TCN 257-2000

cng trn sng phi c trang b phao cu sinh, xung cu sinh, phi c y n hiu, bin bo tn hiu hng dn giao thng ng thu. 8.4. Trong qu trnh thi cng, mi ngi phi lm vic ng v tr ca mnh, tp trung t tng iu khin my mc thit b. Nhng ngi khng c phn s cm khng c i li trong cng trng. 8.5. Tt c cc my mc vn hnh phi tuyt i tun theo qui trnh thao tc v an ton hin hnh. H thng in hin trng phi b tr hp l, nghim chnh chp hnh cc qui nh an ton s dng in. Phi c cng nhn chuyn mn ph trch h thng in. 8.6. Khi gp s c nh cht lng b tng khng m bo, khi tc ng phi bo co ngay ch huy khu vc x l v ch x l theo lnh ca ngi ch huy chung. 8.7. Phi tun th mi qui trnh an ton lao ng hin hnh c lin quan.

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