Tiu chun thit k khoan n mn o

TCVN : 2009

TCVN 9161 : 2012TCVN 9161 : 2012

TCVN 9161 : 2012Xut bn ln 1

CNG TRNH THY LI - KHOAN N MN O - PHNG PHP

THIT K, THI CNG V NGHIM THU

Hydraulic structures - Drilling blast holes

Methods in design, construction and acceptance H NI - 2012Mc lcTrangLi ni u . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1 Phm vi p dng . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2 Ti liu vin dn . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

3 Thut ng v nh ngha. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

4 Yu cu k thut chung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

5 N mn l su . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

6 N mn l nng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7 N mn bung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

8 N mn phn b theo chiu di . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

9 N mn bu v n mn bung nh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

10 N mn p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

11 S dng phi hp cc phng php n mn khc nhau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

12 Mt s phng php n mn c bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

13 N mn di nc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

14 N mn ph v kt cu cng trnh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

15 N mn o cc cng trnh ngm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

16 An ton n mn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

17 Kho st phc v n mn v nghim thu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

18 Kim tra, nghim thu v bn giao . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Ph lc A (Tham kho): Mt s bng s liu c th tham kho trong tnh ton thit k khoan n mn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Ph lc B (Tham kho): Tnh nng k thut ca vt liu n v thit b n mn . . . . . . . . . . . . . . . . . . .71

Ph lc C (Ttham kho): Mt s phng php kch n mn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Ph lc D (Tham kho): Phng php tnh ton an ton v a chn i vi cc cng trnh c bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

Ph lc D (Tham kho): H chiu n mn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Li ni u

TCVN 9161 : 2012 Cng trnh thy li - Khoan n mn o - Phng php thit k, thi cng v nghim thu, c chuyn i t QPTL.D.1.82: Quy trnh n mn trong xy dng thy li - thy in, theo quy nh ti khon 1 iu 69 ca Lut Tiu chun v Quy chun k thut v im a, khon 1 iu 7 ca Ngh nh s 127/2007/N-CP ngy 01 thng 8 nm 2007 ca Chnh ph quy nh chi tit thi hnh mt s iu ca Lut Tiu chun v Quy chun k thut.

TCVN 9161 : 2012 do Trung tm Khoa hc v Trin khai k thut thy li thuc trng i hc Thy li bin son, B Nng nghip v Pht trin nng thn ngh, Tng cc Tiu chun o lng Cht lng thm nh, B Khoa hc v Cng ngh cng b.

Cng trnh thy li - Khoan n mn o Phng php thit k, thi cng v nghim thu

Hydraulic structures - Drilling blast holes

Methods in design, construction and acceptance

1 Phm vi p dng

1.1Tiu chun ny quy nh phng php thit k, thi cng v nghim thu cng tc khoan n mn o xy dng cng trnh thy li - thy in v cc cng trnh xy dng khc c yu cu k thut v c im lm vic tng t.1.2Khi thit k v thi cng khoan n mn o xy dng cng trnh, ngoi cc quy nh trong tiu chun ny, cn phi tun th quy nh v an ton trong bo qun, vn chuyn, s dng v tiu hy vt liu n cng nghip (QCVN 02 : 2008/BCT) cng nh cc ti liu hng dn k thut khoan n mn o khc c lin quan.2Ti liu vin dn

Cc ti liu vin dn sau y rt cn thit cho vic p dng tiu chun ny:

TCVN 5178 : 2004 : Quy phm k thut an ton trong khai thc v ch bin l thin;TCVN 5308 : 1991 : Quy phm k thut an ton trong cng tc xy dng.3Thut ng v nh ngha

Tiu chun ny s dng cc thut ng v nh ngha sau:

3.1

N mn l su (Blasting in deep hole)Phng php n cc bao thuc n di (gi chung l qu mn) t trong cc l khoan c ng knh ln hn hoc bng 75 mm v su t 5 m tr ln.

3.2

N mn l nng (Blasting in shallow-hole) Phng php n cc qu mn t trong cc l khoan c ng knh di 75 mm v su di 5 m.

3.3

N mn l khoan ln (Blasting in large diameter hole)Phng php n cc qu mn t trong cc l khoan c ng knh t 75 mm tr ln.3.4N mn l khoan nh (Blasting in small diameter hole)Phng php n cc qu mn t trong cc l khoan c ng knh di 75 mm.3.5N mn phn on (Sectional blasting)Phng php n cc qu mn t trong cc l khoan nhng thuc n np vo l khoan khng lin tc t y l khoan tr ln m c np thnh tng on theo chiu su l khoan. Khong cch gia cc on ny nu c lp y t ct th gi l phn on thng, nu trng th gi l phn on khng kh, cn nu y nc th gi l phn on nc (hay phn on thy lc).

3.6N mn bung (Chamber blasting)Phng php n mn bng cch n cc khi thuc n c khi lng ln c t trong cc bung chuyn dng (cn gi l bung np thuc) o sn trong t .

3.7 N mn bu (Coyote hole blasting)Phng php n cc khi thuc n np tp trung trong khong trng c dng hnh qu bu c to thnh bng cch n m rng y cc l khoan.

3.8N mn vin (Welt blasting)Phng php n cc qu mn t trong cc l khoan c b tr thnh hng song song v cch nhau t 0,6 m n 0,8 m tu theo cng ca . Hng l mn vin c b tr trng vi mi h o to ra mi bng phng v n nh.

3.9

N mn nh hng (Oriented blasting)Phng php n cc qu mn m bo phn ln t sau khi n ch vng v mt pha v ri xung v tr quy nh.3.10

N mn vi sai (Differential blasting)Phng php n mn cho php cc bao thuc c gy n ln lt sau mt khong thi gian (t nht nh, c tnh bng ms. Thi gian vi sai (t ph thuc vo loi vt liu n, c tnh c l ca loi cn n ph v tnh cht ca v n, phi m bo bao thuc n trc to thm c mt thong cho bao thuc n sau v khng lm cm bao thuc sau.3.11N mn p (Veneer blasting)Phng php n cc khi thuc n tp trung t p trc tip ln b mt ca khi cn ph v.

3.12 Lp bua (Backfilling)Bin php dng t hoc ct lp y phn trng ca l khoan tnh t khi thuc n trn cng n mt t nhm ngn chn khng cho cc loi kh c to thnh sau khi n pht ra ngoi theo l khoan lm gim hoc mt hn tc dng ca n mn.

3.13Mn mi (Initiator mine)Mt loi thuc n c khi lng khng ln nhng c sc cng ph rt mnh. Mn mi c t trong khi thuc n kch thch cho khi thuc n n c hon ton, m bo hiu qu n ph.

3.14 Bao thuc n (Pack of blasting powder)Khi thuc n c dng bt k c s dng khi n mn. 3.15 H chiu n mn (Passport of blasting)Loi ti liu k thut quy nh ni dung v phng php t chc thc hin mt v n mn do n v thi cng lp da trn n thit k khoan n mn c duyt. Ni dung h chiu n mn c th tham kho ph lc E.4Yu cu k thut chung

4.1Ch c php khoan n mn o trong xy dng cng trnh thy li, thy in khi c n thit k, h chiu n mn v c bin php m bo an ton trong qu trnh thi cng n mn c c quan c thm quyn ph duyt, c Hi ng nghim thu cng tc chun b n mn chp thun. Phi thc hin ng cc quy nh trong quy chun k thut v khoan n mn o trong xy dng cng trnh thy li.4.2Khoan n mn o phi m bo o c cc h o c hnh dng v kch thc yu cu vi sai lch nh nht so vi ng vin thit k; khi t b n ph ng v tr, c v vn cn thit ph hp vi yu cu bc xc v vn chuyn. 4.3Trc khi np mn vo cc l khoan, cc bu hoc bung phi kim tra xem v tr, chiu su, chiu di, kch thc, tit din ngang ca chng c ph hp vi quy nh ca thit k hay khng. Cc l khoan, bu v bung phi c vt sch cc mt khoan hoc bn khoan, cn cc bung, bu np mn phi c dn sch ht t , g v cc vt l khc.4.4 m bo o ng cc ng vin thit k ca cc h o khi n mn m khng ph hy tnh nguyn vn ca khi cn li, nu khng cha li tng bo v thnh vch v y h o phi p dng phng php to khe s b (n mn theo ng vin). Phi tnh ton xc nh quy m v n m bo cho y v thnh vch h o khng to ra cc khe nt mi hoc m rng thm cc khe nt t nhin v khng gy mt n nh do tc ng ca n mn.

4.5N mn ni gn khu vc c cc cng trnh xy dng nh nh cao tng, cu giao thng, ng dy in cao th, cng trnh ngm, h thng cc cng trnh u mi thy li, cc khi b tng mi v ang trong qu trnh cng ho v.v, ngoi yu cu m bo c ly an ton theo QCVN 02 : 2008/BCT cn phi thc hin cc bin php c bit m bo an ton cho cc cng trnh ny. Tu thuc vo iu kin c th ca khu vc n mn v quy m ca khi t cn phi o ph m p dng cc bin php bo v sau y:a) N mn nh hng, n vi sai;

b) Hn ch khi lng thuc n nhng vn m bo mc v vn cn thit ca t bng cch phn tn ti a cc bao thuc n;

c) B tr cc qu mn c khi lng gim nh phn di thp ca cc l khoan nh hoc l khoan ln khoan gn nhau;

d) Ph ln i tng cn c bo v hoc khi t s c n mn bng cc tm chuyn dng hoc cc phng tin khc;e) To mt khe nh chy dc theo cng trnh phi bo v trong cc t b ph vn t trc;

f) Khi n mn di nc, gn cc phn ngp nc ca cng trnh phi to mt mn ngn bng bt khng kh;g) Cc bin php bo v khc nh dng tm chn bng g c ng knh t 15 cm n 20 cm c ghp li bng cc si thp v ng inh vo g, hoc bng cc li thp c ng knh t 20 mm n 30 mm c hn li vi nhau. C th dng cc tm li dng vm bn trong l nhng cy g, bn ngoi l nhng ai thp hoc nhng lp ph mm dng vi, nhng b cnh cy ch dng mt ln, nhng tm chn bng g x c ghp li v.v4.6 Tu thuc vo yu cu bo v tnh nguyn vn ca nn v thnh ca cc h o, cc cng trnh v hng mc cng trnh thy li, thy in c chia thnh 3 nhm sau:

a) Nhm I : Cc hng mc cng trnh m nn v mi h o ca chng sau khi n mn cho php cc vt nt t nhin c ko di v m rng thm hoc to thm cc vt nt mi, bao gm knh thot nc nh my thy in, knh x, cc on no vt lng sng h lu cng trnh, mt bng cc trm phn phi in ngoi tri, knh dn ra t cc u thuyn, h o xy dng ng giao thng v cc cng trnh tng t khc;

b) Nhm II : Cc hng mc cng trnh m nn v mi h o ca chng cc vt nt n t nhin ca v cc khe nt mi do n mn to ra s c bt kn bng cc lp o hoc khoan pht xi mng, bao gm h mng ca nh my thy in, knh chnh v knh nhnh ca cc h thng ti, knh vn ti thy, knh dn vo cc u thuyn pha thng lu v cc cng trnh tng t;

c) Nhm III : Cc hng mc cng trnh m nn v mi h mng ca chng sau khi n mn khng cho php m rng v ko di khe nt t nhin m cng khng cho php to thm cc khe nt mi, bao gm h mng ca p trn v khng trn bng b tng, knh dn vo nh my thy in kiu sau p, chn khay ca p t, tng chng thm ca p t v p , nh my thy in kiu sau p v cc cng trnh tng t khc.

4.7i vi cc hng mc cng trnh thuc nhm I, c th s dng cc qu mn bung ln, mn bung nh, mn trong l khoan ln v mn trong l khoan nh. Thi cng n mn trong trng hp ny c th tin hnh trong mt tng hoc vi tng (lp) tu thuc vo kh nng thit b bc xc, vn chuyn cng nh cch t chc thi cng. Trn mi h mng ca cng trnh khng phi li tng bo v. Phn y ca h mng cng khng bt buc nhng nu thy cn thit phi li tng bo v th tng bo v ny c o theo mt bc bng bin php khoan n mn trong cc l khoan c ng knh l khoan khng qu 42 mm v khng c php khoan qu.4.8i vi cc hng mc cng trnh thuc nhm II v nhm III, khi chiu su h o ln hn 1,0 m phi chia ra t nht thnh hai tng n ph trong tng di cng l tng bo v. Khi chiu su h o nh hn 1,0 m th ch chia thnh mt tng. Khi chiu su t 1 m n 2 m th chia thnh hai tng c chiu cao bng nhau. Khoan n mn o cc h mng loi ny phi thc hin quy nh sau:a) Ph vn cc tng nm trn tng bo v bng phng php n mn trong l khoan ln. Tu thuc vo thit b s dng, cng ca , kch thc v hnh dng cng trnh, a hnh ni thi cng m quyt nh b dy ca cc tng n mn. Chiu su on khoan qu ca cc l khoan tng trn ly trong phm vi t 10 ln n 15 ln ng knh ca bao thuc n tu thuc vo loi cn n ph nhng khng ln hn 15 ln ng knh ca qu mn. Khi chn tng c cc lp kp l mm hn, hoc khi c cc th nt nm ngang th chiu su ca cc on khoan qu c th gim xung cn t 2 ln n 3 ln ng knh bao thuc n. Khng c khoan qu vo tng bo v. ng knh ca l khoan tng nm ngay trn tng bo v khng ln hn 110 mm;

b) Chiu dy tng bo v ly t nht bng 50 % chiu di tnh ton ca ng cn nh nht nhng khng nh hn 1 m. Tng bo v phi o thnh hai bc: bc trn ch c n mn trong cc l khoan c ng knh l khoan khng qu 42 mm v khng c php khoan qu ra ngoi phm vi bc trn; bc di nm st y mng c chiu dy bng t 5 ln ng knh ca bao thuc n np trong l khoan 42 mm (tng ng vi loi dai v lin khi) n 12 ln ng knh ca bao thuc n (tng ng vi loi dn v nt n) nhng khng nh hn 20 cm v phi o bng thit b cng ngh ph hp, khng dng phng php n mn;c) Khng s dng thuc n ph vn cn st li bc di ca tng bo v. i vi loi khng nt n c cng cao hn cp VII, cho php n cc bao thuc ring l t trong l khoan nh bc di ca tng bo v nhng phi c s ng v ch dn ca t vn thit k v ch u t ;d) Khi o cc mi dc s dng phng php n mn theo ng vin bng cch to khe theo ng vin trc khi n mn nhng phi m bo b dy lp bo v bin khng nh hn 0,3 m v lp ny s c o nt bng c gii hoc th cng, khng c s dng thuc n. Khi dc ca cc mi dc nh hn 40o v kh khoan l to khe h s b theo ng vin th cc mi dc phi c khoan n bng cc bao thuc n ti t trong cc l khoan ln thng ng c cha li lp bo v;e) Phng php n mn cha tng bo v khng p dng cho cng tc o hm dn nc v o tuy nen cng trnh thy cng.4.9Bn knh vng nguy him i vi mi phng php n mn phi c xc nh theo iu kin thc t ca hin trng khu vc khoan n v ph hp vi cc quy nh trong QCVN 02:2008/BCT.

4.10Lng thuc n cn thit n ph mt n v th tch t hay lng tiu th thuc n v, k hiu l qtt, n v l kg/m3, ph thuc vo loi thuc n c s dng, loi cn n ph, c im v cu to a cht ca . Lng tiu th thuc n v p dng trong tiu chun ny l thuc n amonit 6B. Khi dng loi thuc n khc phi hiu chnh bng cch nhn vi h s e1:

e1 =

(1)

trong :

v6 l sc cng ph (cn gi l uy lc bom ch) ca thuc n amonit 6B: v6 = 360 cm3 ;

v l sc cng ph ca thuc n thc t cn dng, cm3.

c c s liu chnh xc v tr s ca qtt, ngoi yu cu phi tin hnh n th nghim ti hin trng cn phi cn c vo kt qu n mn thc t hiu chnh.

5N mn l su5.1Cc thng s tnh ton thit k5.1.1Thng s tnh ton ch yu khi n mn l su l tr s ng cn ngn nht chn tng hoc khong cch gia cc bao thuc n v khong cch gia cc hng l khoan trong trng hp n nhiu hng mn (xem hnh 1).

CH THCH:L Chiu su l khoan;

H Chiu cao ca tng cn n mn;Lmn Chiu di on l khoan c np mn;Lbua Chiu di bua;Lq Chiu su on khoan qu;a Khong cch gia cc qu mn trong mt hng;

b Khong cch gia cc hng mn;bat Khong cch t mp thnh h o n tim ca hng l khoan;

( Gc nghing ca thnh tng v pha ng cn theo chn tng.

Hnh 1 - S xc nh cc thng s n mn trong cc l khoan ln

su v thng ng trong tng n ph

5.1.2Tr s ng cn ngn nht chn tng k hiu l w, n v l m, c tnh theo cng thc (2)

w = 53.Kt.dm. (2)

Trong :

dm l ng knh tnh ton ca bao thuc n, m. Khi np thuc n dng bt, dng ht hoc thuc n dng lng khng ng bao th ng knh tnh ton ca bao thuc ly bng ng knh l khoan. i vi loi thuc n ng bao hoc p thnh ng, ng knh bao thuc ly bng ng knh ca bao hoc ca ng thuc n.

Kt l h s xt ti cc iu kin a cht ti ni n mn, ly theo bng 1;

( l mt ca thuc n trong bao thuc, t/m3 ;

e l h s nng lng, tnh theo cng thc (3).

e = (3)

v l sc cng ph ca loi thuc n c dng;

( l khi lng ring ca t cn n ph, t/m3.

5.1.3Khi n ph khi c mt mt thong, trong cc gng tng (tng cn n ph), ti cc sn dc, hoc khi c t 3 hng l khoan tr ln th khong cch gia cc bao thuc n v gia cc hng l khoan s phi gim i 10 % so vi khong cch tnh ton.

Bng 1 - Tr s KtM t c trng ca iu kin a chtKt

1. rn chc lin khi, khi ln, kch thc cc khi ln hn khong cch gia hai l khoan0,90

2. b phn chia thnh tng khi ring bit, cc khe nt c xi mng ho hay lp kn 0,95

3. nt n, mt phn cc vt nt h hoc c nht kn bi cc sn phm phong ho mm1,00

4. b nt n mnh phn thnh cc khi nh. Cc vt nt c phng bt k (tr phng nm ngang). Khe nt h hoc b nht y bng cc sn phm phong ho mm1,05

5. b nt n mnh phn thnh cc khi nh. Cc vt nt h hoc b nht y bi cc sn phm phong ho mm. Cc khe nt nm ngang v c cc lp kp mm yu chn tng. na cng ln t nt vn1,10

5.1.4 Cc bao thuc n trong cc l khoan su phi b tr theo mng li vung, c p dng theo cng thc (4):a = b = w (4)trong :

a v b xem ch thch hnh 1; w l tr s ng cn ngn nht chn tng, xc nh theo cng thc (2) .

5.1.5 Cho php thay i khong cch gia cc l khoan trong mt hng trong cc trng hp sau:

a) Khi o ho c b tr hng mn ph m: a = 0,7.w;

b) Trong cc trng hp khi cc kch thc ca h mng hoc h o khng l bi s ca a hoc b.5.1.6Chiu su on khoan qu (on khoan thm) di chn tng ca cc l khoan ln ly trong phm vi t 10 ln n 15 ln ng knh ca bao thuc n tu thuc vo loi nhng khng ln hn 15 ln ng knh ca bao thuc. Khi chn tng c cc lp kp l loi mm hn, hoc khi c cc th nt nm ngang th chiu su ca cc on khoan qu c th gim xung cn t 2 ln n 3 ln ng knh bao thuc n.

5.1.7Khi n mn o mng cng trnh xy dng, bo v nn cng trnh khng c khoan qu xung lp bo v. Trong trng hp ny m bo ct bng chn tng phi thu hp mng li b tr cc l khoan ln bng cch nhn vi h s hiu chnh K quy nh trong bng 2.Bng 2 - Hiu chnh on khoan qu di chn tng ca cc l khoan ln

on khoan qu ti u tnh bng ng knh bao thuc non khoan qu cho php tnh bng ng knh bao thuc n

150 2 5 10

10-025

2--01

H s hiu chnh K i vi ng cn chn tng w0,700,800,900,95

5.1.8Chiu su L ca l khoan ln thng ng ly theo cng thc (5)L = H + Lq

(5)trong :H l chiu cao tng hoc chiu dy ca lp o, m;

Lq l chiu su on khoan qu, m.5.1.9Chiu di bua, k hiu l Lbua, phi di hn ch t tung bay ra qu nhiu v khng cho cc loi kh c to thnh sau khi n pht ra ngoi theo l khoan lm gim hoc mt hn tc dng ca n mn. Chiu di ti u ca bua nm trong phm vi t 20 ln n 25 ln ng knh bao thuc n. Nu h mng c kch thc hn ch, khng c kh nng a thit b ra khi phm vi nguy him hoc gn cc khu vc sn xut, nh ca, cng trnh xy dng, c s h tng v, phi tng chiu di bua ln t 30 ln n 35 ln ng knh bao thuc n v cho php b tr mng li cc l khoan tha hn mt cht trong khi vn gi nguyn lng thuc n n v.5.1.10Khi sn c my xc th cn c vo c my xc v cao trnh cc c trn mi h o xc nh chiu cao tng ti u. Tnh ton xc nh cc thng s n mn ti u khi bit chiu cao tng thc hin theo quy nh ti 5.2.5.1.11Khi c sn loi my khoan, tc l bit trc ng knh l khoan, vic tnh ton xc nh cc thng s n mn ti u thc hin theo quy nh ti 5.3.5.2Tnh ton xc nh cc thng s n mn ti u khi cho trc chiu cao tng o ph5.2.1 Xc nh chiu su L ca cc l khoan theo cng thc (5).

5.2.2La chn chiu di bua: cn c vo yu cu v chiu rng st l ca khi cn n v vng xa ca cc hn khi n mn.

5.2.3Xc nh ng knh bao thuc n ti u o ph tng c chiu cao H theo cng thc (6):dbt =

(6)

trong :

H l chiu cao ca tng cn khoan n mn, m;

dbt l ng knh ti u ca bao thuc n, m;

Klb l h s lp bua v Kkq l h s khoan thm, tnh bng s ln ng knh bao thuc n.5.2.4Xc nh tr s an ton ca ng cn chn tng wat theo cng thc (7):wat = H.cotg( + bat

(7)

trong :

( l gc nghing ca thnh tng v pha ng cn theo chn tng, (o);

bat l khong cch t mp thnh h o n tim l khoan, m : bat ( 2,0 m.5.2.5Tnh ton xc nh tr s ng cn ngn nht chn tng w theo cng thc (2). Nu kt qu tnh ton cho w nh hn wat ca n th x l nh sau:

- Chuyn sang cch n mn trong l khoan nghing;

- Chuyn sang n mn trong l khoan ln gn nhau tng i mt. Trong trng hp ny, tr s ng cn ngn nht chn tng tnh ton c th tng ln t 20 % n 25 %.5.2.6Tnh ton xc nh khong cch gia cc bao thuc n trong mt hng v gia cc hng theo cng thc (4).5.2.7Xc nh s lng hng l khoan b tr theo chiu rng ca khi phi n ph. Nu s lng t 3 hng tr ln th phi gim mng li b tr cc bao thuc n theo 5.1.3. 5.3Tnh ton xc nh cc thng s n mn ti u khi cho trc ng knh bao thuc n5.3.1Khi chiu cao tng H v chiu su on khoan qu Lq nh hn cc tr s ti u: a) Khi lng bao thuc n trong l khoan (Q), kg, tnh theo cng thc (8): Q = (L Lbua).pmn

(8)

trong :

pmn l lng thuc n trong 1 m di l khoan, kg/m;

L l chiu su l khoan, m;

Lbua l chiu di bua, m: Lbua ly theo quy nh ti 5.1.9.

b) Khi chiu cao tng H nh hn 20 ln ng knh bao thuc n th khi lng bao thuc n tnh theo cng thc (9) nh i vi cc bao thuc n tp trung:

Q = qtt.w3.f(n)

(9)

trong :

w l chiu di ng cn chn tng nh nht, m;qtt l lng tiu th thuc n n v, kg/m3;f(n) l hm s m ca tc ng n (ch s tc ng n ph n), quy nh nh sau:

- Khi lm ti mc thp (n lm rung ng), f(n) ly bng 1/6;

- Khi lm ti bnh thng, f(n) ly bng 1/3;

- Khi lm ti mc mnh, f(n) ly t 0,5 n 1,0.

c) ng cn ngn nht chn tng, khong cch gia cc qu mn v khong cch gia cc hng mn c tnh ton theo cng thc (10):w = a = b =

(10)trong :

qtt l lng tiu th thuc n n v, kg/m3;Q l khi lng bao thuc n trong h khoan, kg;

Cc k hiu khc xem ch thch trong hnh 1.5.3.2Khi chiu cao tng H ln hn chiu cao ti u :a) Khi lng bao thuc n trong l khoan tnh ton theo cng thc (8);

b) Tt c cc tham s khc tnh ton theo ch dn ti 5.2;

c) Nu bao thuc n c np lin kht m chiu di bua cn ln hn 35 ln ng knh bao thuc n th phi p dng gii php phn tn thuc n trnh to thnh cc mi pha trn ca gng tng v ph v vn nhanh hn, u hn.5.4N mn trong cc l khoan nghing5.4.1Trong cc trng hp sau y th cn phi xem xt dng cc l khoan nghing n ph:

a) Khi phi ph vn trong iu kin dc ca mi l nh nhng chiu cao tng khoan n l ln, ng cn ngn nht w chn tng ca cc l khoan thng ng vt qu tr s cho php bao thuc n vi ng knh cho;b) Cn to thnh mi nghing cho h o m khng c iu kin p dng phng php n mn vin.

5.4.2Trong cc trng hp sau y cn xem xt p dng bin php n mn trong cc h khoan nm ngang hoc trong cc h khoan c gc nghing ( di 30o so vi mt phng nm ngang:

a) ct tng theo chn tng;b) loi b m chn tng v nhng ch b st li sau khi khoan n.

5.4.3Phng php tnh ton xc nh cc thng s n mn trong cc l khoan nghing tng t nh i vi n mn trong cc h khoan thng ng (xem iu 5.1, iu 5.2 v iu 5.3). 5.4.4Chiu di h khoan L, m, xc nh theo cng thc (11):L = + Lq

(11)trong :

( l gc nghing ca h khoan so vi mt phng nm ngang, (o);

H l chiu cao tng khoan n, m;Lq l chiu su on khoan qu, m.5.4.5Tr s ng cn ngang chn tng wng, m, tnh theo cng thc (12)wng =

(12)trong :( l gc nghing ca h khoan so vi mt phng nm ngang, (o);

Cc k hiu khc nh Kt, dm, (, e, ( xem gii thch cng thc (2).5.4.6Cc h khoan nghing thoi ct tng phi c b tr thnh mt hng vi khong cch gia cc h khoan a xc nh theo cng thc (13):a = 0,85.wng

(13)5.5iu chnh v vn ca cc khi b n ph

5.5.1iu chnh v vn ca khi n mn gim sn lng cc loi khng ng kch c, hoc tng sn lng c ln theo yu cu ca thit k. C th p dng cc bin php sau y iu chnh v vn ca khi khi n mn:a) Thay i khong cch gia cc l khoan v gia cc hng l khoan nhng gi nguyn lng hao thuc n v;

b) Thay i lng tiu hao thuc n n v v phn b thuc n trong a khi phi n ph;

c) Tng thi gian tc ng ca nng lng n vo khi cn n ph bng cch phn on khng kh trong bao thuc;

d) Thay i gc nghing ca cc l khoan n so vi ng thng ng;

e) Thay i s lng hng l khoan n;

f) Kt hp dng cc phng php n vi sai m bo s va p vo nhau gia cc vin b ph v;

g) Quy cc khi cn n ph bng cc mt thong to ra do n ph s b.5.5.2Tnh ton thit k thay i v vn ca b n ph phi xt ti s chia khi t nhin ca trong a khi. xc nh chnh xc lng tiu th thuc n tnh ton i vi tng phn c tch ring phi tin hnh th nghim n mn xc nh sn lng cc vin c 500 mm v v vn thc t khi thi cng n mn ph . 5.5.3Lng tiu th thuc n n v qk khi chuyn sang cc kch c vin khc v thuc n khc c thc hin theo cng thc (14):

qk = qo.Mo.e

(14)trong :qo l lng tiu th thuc n amonit 6B tnh ton chun, kg/m3 ;Mo l h s hiu chnh v kch c vin , ly theo bng 3;e l h s hiu chnh nng lng, xc nh theo cng thc (3).Bng 3 - H s hiu chnh v kch c tnh ton ca vin

Kch c tnh ton ca vin , mm2004005006008001 0001 300

H s hiu chnh Mo i vi lng thuc n tiu th chun1,601,101,000,900,850,750,60

5.5.4Tnh ton xc nh cc thng s khoan n mn iu chnh v vn ca theo phng php sau:a) Xc nh lng tiu th thuc n n v theo cng thc (14);b) Hiu chnh cc tr s w, a v b theo cng thc (15):wk = w.

(15)trong :

w xc nh theo cng thc (2);a v b xc nh theo cng thc (4);q l lng tiu th thuc n n v thc t khi n ph, quy i v thuc n chun (thuc n amonit 6B)c) Chnh xc ho khi lng bao thuc n theo cng thc (8).5.6N mn vi sai5.6.1Cn c vo cng ca loi cn n ph xc nh s b thi gian vi sai (t ((t ly n 50 ms i vi n mn l nng, ly n 100 ms i vi n mn l su v n mn hm). Cn c vo tnh nng ca cc loi thit b chuyn dng cho n vi sai la chn thi gian vi sai (t v loi thit b cho ph hp vi thc t. Thit b gy n vi sai gm c kp in vi sai, kp n phi in vi sai, my n mn vi sai, dy n v cc r le vi sai. 5.6.2Thi gian vi sai (t gia cc hng khi n mn l su xc nh theo cng thc (16):

(t = A.w

(16)

trong :

(t l thi gian vi sai, tnh bng phn nghn giy, ms;

w l ng cn ngn nht chn tng hoc khong cch gia cc hng l khoan, m;

A l h s ph thuc vo cng ca , ly theo bng 4.Bng 4 Cc gi tr ca h s cng ca Tn cng ca H s A

1. Granit, pridolit, poocphia thch anh, poocphia rit, xinit, quczit,Rt cng3,0

2. Ct kt, phin bin cht cng, quaczit c cha st, sa thchCng4,0

3. vi, cm thch, manhzit, phin philit, xcpentnitCng va5,0

4. Macn, phn, phin st, than , st kt, alvrlitMm6,0

5.7N mn vng 5.7.1Khi cn o knh hoc o rnh c su t 3 m n 4 m i qua nn khng phi l c th s dng phng php n mn vng trong cc l khoan ln:

a) i vi knh c mt ct ngang khng ln: s dng mt hng h khoan thng ng, c ng knh ln b tr dc theo tim tuyn cng trnh, xem hnh 2;

Hnh 2 S b tr n mn vng trong cc l khoan ln thng ng

b) t sau khi n mn vng v mt pha phi s dng phng php n mn trong cc l khoan xin, xem hnh 3 ;

Hnh 3 S b tr n mn vng trong cc l khoan xinc) Khi o knh trong nn khng cng, cc qu mn trong l khoan xin c phi hp vi cc qu mn xin ngc li n trc dng dn hng c ng knh nh hn;d) to c cc h o c mt ct ngang rng phi s dng phi hp gia mt hng l khoan thng ng b tr dc theo tim tuyn v hai hng l khoan xin b tr hai bn, xem hnh 4.

Hnh 4 S b tr cc bao thuc n trong cc l khoan thng ng v l khoan xin to thnh cc h o c mt ct rng5.7.2Tnh ton xc nh cc thng s khi s dng phng php mn n vng trong cc l khoan ln thng ng o knh mng c su t 3 m n 4 m nh sau:a) ng knh ti thiu ca cc l khoan xc nh theo bng 5;b) Chiu su l khoan tnh theo cng thc (17):

L = Kq.H

(17)

trong :

L l chiu su l khoan ln, m;

H l chiu su thit k ca h o hoc knh, m;

Kq l h s khoan qu, ly theo bng 6.

Bng 5 ng knh ti thiu ca cc l khoan o knh, rnh c su t 3,0 m n 4,0 m

Loi tng knh cn thit ca l khoanmm

1. st m T 50 n 80

2. St do, st m, do T 80 n 100

3. t hong th v tng tT 100 n 130

4. ctT 130 n 160

Bng 6 H s khoan qu (Kq) khi n mn vng

Loi tH s khoan qu Kq

1. ct, t hong th v tng tT 1,15 n 1,20

2. stT 1,15 n 1,10

3. StT 1,10 n 1,05

4. St v st gly ho T 1,05 n 0,95

c) Trng lng bao thuc n np trong l khoan tnh theo cng thc (18) v khong cch gia cc l khoan xc nh theo cng thc (19):

Q = Lmn.p

(18)

a = Cn.dn

(19)trong :

Q l trng lng bao thuc n (hay qu mn), kg;

a l khong cch gia cc bao thuc n, m ;Lmn l chiu di bao thuc n trong l khoan, m: Lmn = 0,75.L;

p l sc cha thuc n ca l khoan, kg/m;dn l ng knh ca bao thuc n np vo l khoan, m;Cn l h s to bu ca t: Cn = 1,9.;( l mt ca thuc n trong bao thuc, t/m3;

Bt l ch s to bu, m3/t. C th tham kho tr s Bt trong bng A.2, ph lc A.5.7.3Tnh ton xc nh cc thng s n mn vng bng cc l khoan xin nh sau:

a) Gc nghing ca cc l khoan xin ch c php nm trong phm vi t 45o n 50o, tu thuc vo chiu rng ca tuyn knh hoc h o;

b) Chiu di ca cc l khoan xc nh theo cng thc (20) v khong cch A t tim h o thit k n ming l khoan xc nh theo cng thc (21):L =

(20)A = w.ctg(

(21)trong :Kq l h s khoan qu, ly theo bng 6;

H l chiu su thit k ca h o, m;

( l gc nghing ca l khoan, (o);A v w xem hnh 3.c) Cc thng s tnh ton khc theo 5.7.2.

5.7.4Lm n vng cc bao thuc n b tr thnh mt hng trong cc l khoan ln thng ng hoc xin phi tin hnh tc thi bng dy n hoc kp in tc thi. Trong mi trng hp im kch n ca cc bao thuc n phi c b tr u pha trn ca bao thuc n.5.7.5Khi s dng phng php n mn ph dn hng th hng cc l khoan xin ngc li phi c khoan vi cng khong cch gia cc l khoan v cng gc nghing ca hng l khoan c bn. ng knh ca cc l khoan ny nh hn hai ln so vi ng knh cc l khoan c bn. Trng hp ng knh cc l khoan bng nhau th ng knh ca cc bao thuc dn hng phi nh hn hai ln so vi ng knh ca cc bao thuc c bn.5.7.6Khi np thuc n vo cc l khoan xin m ng knh ca cc bao thuc n li nh hn nhiu so vi ng knh ca l khoan (mn dn hng) th cc bao thuc n phi c buc xon vo thanh g. Khe h gia bao thuc n v thnh l khoan phi c lp y bng vt liu dng np bua.5.7.7Khi s dng cc bao thuc n trong l khoan xin phi hp vi cc l khoan dn hng, ch c gy n bng dy n t ming cc l khoan v phi n cc bao thuc n dn hng trc. Bt k s thay i no v trnh t kch n cc bao thuc cng s dn ti cc kt qu n ph khng hiu qu.5.7.8Khi b tr ba hng l khoan ln to cc h o c mt ct ngang rng (mt hng l khoan thng ng, hai hng l khoan xin, xem hnh 4), khong cch gia cc hng l khoan tnh theo ming l khoan ph thuc vo chiu rng cho trc ca h o nhng khng c vt qu khong cch gia cc l khoan trong hng gia.5.7.9Khi n mn phi cho n tc thi cc hng ngoi cng cn hng gia n chm hn t 50 ms n 100 ms v phi tin hnh t phn trn cng ca cc bao thuc n.5.8Mt s yu cu khc

5.8.1Cc l khoan sau khi khoan xong phi c nt kn.5.8.2Sau khi khoan xong khi phi o c kim tra tr s ng cn chn tng, khong cch gia cc l khoan trong mt hng v gia cc hng l khoan, chiu su v gc nghing ca cc l khoan. Trong cc h o c mt ct ring phi kim tra v tr ca cc hng l khoan phi hp v ca tng l khoan ring bit.5.8.3Dung sai cho php ca cc l khoan quy nh nh sau:

a) i vi ng cn chn tng: ( 5.dlk, trong dlk l ng knh l khoan;

b) i vi khong cch gia cc l khoan trong mt hng v gia cc hng: ( 3.dlk;c) Trong cc hng phi hp ngoi cng (hng l khoan nm gn mp thnh h o) ch cho php c nhng sai lch nm trong mt phng song song vi thnh gng tng.

5.8.4Cc l khoan khng ng vi thit k, vt qu dung sai cho php coi nh b hng buc phi khoan li hoc phi sa li. Nu ng cn chn tng vt qu ng cn tnh ton c xt c dung sai th phi o bt chn tng v trong trng hp khi chnh lch vt qu 25 % th phi khoan l khoan th hai gn hn.5.8.5Khi khoan cc gng tng c iu kin a cht thy vn phc tp, gy h hi cc h khoan c khoan th phi np bao thuc vo cc l khoan ny ngay sau khi rt dng c khoan ra nhng phi tun theo cc yu cu quy nh trong QCVN 02 : 2008/BCT.5.8.6Trc khi np thuc n phi tin hnh kim tra chiu su l khoan. Nu trong l khoan c mn khoan v t ct th phi vt sch. Cc on khoan su qu cao trnh thit k phi c lp li bng ct hoc mt, khng c dng mn khoan.5.8.7Khi np thuc n vo l khoan, ng knh ca bao thuc n phi nh hn ng knh ca l khoan t 15 % n 20 %.5.8.8 kim tra chiu cao ca qu mn, trong qu trnh np thuc n vo h khoan phi nh k o phn cn li ca l khoan cha c np thuc n.5.8.9Trong mi bao thuc n np vo l khoan phi t mt hoc hai qu mn mi. Cc qu mn mi vi dy n b tr pha di cng hoc phn gia ca bao thuc n. Cc qu mn mi v kp in b tr phn trn cng ca bao thuc n. Nu l khoan ch b tr mt qu mn mi th qu mn ny phi c ni vo hai ng dy n hoc hai kp in. Khi b tr thuc n phn tn (phn on khng kh) th trong mi on cha thuc n phi c mt qu mn mi. Khi s dng dy n c mc n thp th cc qu mn mi phi c t phn di cng ca bao thuc n.5.8.10Phi s dng vt liu ri ht mn lp bua. Khi np bua, dy mn, dy in phi c gt v mt pha thnh l khoan v khng c ko cng. Nu ming l khoan c cc ng chn, nu c th th nn ko cc ng chn ny ra sau khi np thuc n.5.8.11C th tham kho phng php tnh ton xc nh cc thng s khoan n mn nh chiu su l khoan, khong cch gia hai l lin nhau, khi lng thuc n np trong mt l khoan v.v theo cc ti liu chuyn ngnh n khc. Trong mi trng hp thit k khoan n mn phi c bin php phng nga v x l mn cm.

6N mn l nng6.1Trong nhng trng hp sau y cn s dng phng php n mn l nng: - Cng trnh nh, hp, khi lng khoan n khng ln;

- Ph b tng bo v cha li y v thnh bn ca h o hoc nhng ch o st khi dng phng php n mn l su;

- Ph v cc hn m ci hoc qu c.

6.2 Tnh ton xc nh cc thng s k thut khi lp s cng ngh khoan n mn o cc lp t dy trn 1,0 m nh sau:a) ng cn tnh ton w khi n mn trong cc l khoan nh lm vic vi hai mt thong c xc nh theo cng thc (22):w = 47 kt.dm.

(22)Cc k hiu trong cng thc (22) xem cng thc (2);b) di khoan qu ca cc l khoan nh ly bng 10 ln ng knh bao thuc n. Khi tng cn n ph c th nm ngang th khng c on khoan qu;

c) Tu thuc vo phng php n mn c la chn, khong cch gia cc l khoan trong cng mt hng nm trong khong t 0,8 ln n 1,4 ln ng cn chn tng: a = (0,8 ( 1,4).w . Khi gy n bng in (n mn tc thi) th ly tr s nh hn. Khi gy n bng dy chy chm v kp la th ly tr s ln hn;d) Khong cch b gia cc hng: b = 0,85.w. Khi n vi sai th ly b = w;

e) Khi lng Q, kg, cn np vo l khoan xc nh theo cng thc (23):Q = q.w.a.H

(23)trong :

q l lng hao thuc n v, kg/m3;H l chiu cao tng n mn, m.

6.3Khi n mn ph v vn trn mt phm vi rng th cc qu mn tnh ton theo cng thc (22) s c b tr theo mng li gn nh vung hoc hoa th: a = b = 0,90.w.6.4Trng lng nh nht cho php ca cc bao thuc n t 0,2 kg n 0,3 kg. Cc tham s ca bao thuc n dng san mt bng c xc nh xut pht t trng lng bao thuc n cho php nh nht v t lng tiu th thuc n nh mc hoc t lng tiu th thuc n thc t tnh theo cng thc (8).6.5Thit k n mn o ho hp dng cho mng cng trnh hoc cc mng li k thut khc sau thu dn t bng c gii hoc th cng, phi ph v vn theo tng lp c chiu su khng qu 1 m. Cc h mng c chiu su trn 1 m phi c n mn cho v vn thnh hai lp hoc nhiu hn hai lp. Nu chiu rng h mng khng qu 1 m phi b tr hai hng hoc ba hng h khoan. Nu chiu rng ho ln hn, s hng h khoan phi tng ln.6.6Khi b tr hai hng mn th cc l khoan phi c khoan theo ng vin ca ca h mng (hoc tuyn ho). Nu b tr ba hng th khoan mt hng tim ho v hai hng khoan theo ng vin. Cc l khoan c khoan theo hng thng ng. N mn theo phng php vi sai, theo s n tng hng vi cc khong cch thi gian t 3 ms n 5 ms.6.7Khi b tr nhiu hng l khoan, trc ht phi cho n hng gia sau n cc hng bin. Khi b tr hai hng, cho n hng l khoan no trc cng c. Khi c hai mt thong v khi trong ho c khong trng dnh cho t b ph v c th p dng phng php n mn bng kp la v dy chy chm (n mn chm ngi) s m bo o y tt hn v to c mi dc hn. Khi n mn chm ngi phi gi ng trnh t n nh, vi cc khong cch thi gian (t khng nh hn 7 s, xem hnh 5. Hnh 5 S trnh t t dy chy chm khi n mn chm ngi o tuyn ho hp6.8Cc l khoan nh kh nn np thuc n bng thit b np dng kh nn. Khi khng c thit b chuyn dng c th np thuc n bng th cng. Cc l khoan c nc phi c np bng cc loi thuc n chu nc v c ng vo bao gi. Khi np thuc n dng bt vo cc l khoan nh bng phng php th cng phi dng xng nh thuc n vo l khoan v sau mi m phi nn cht bng bng gy g hoc nhm. Sau khi np c 80 % lng thuc n vo l khoan phi np gi mn mi, sau np nt ch thuc n cn li vo l khoan nhng khng c m cht. Nu thuc n b vn cc, bt buc phi v cho ti mm ri mi c np vo l khoan.6.9Phn l khoan khng c thuc n phi c y bng bua. Vi cc l khoan khoan t trn xung, vt liu lm bua c ct liu nh, ri rc nh ct, bt , v.v Vi cc l khoan nm ngang hoc khoan t di ln bt bng hn hp st v ct. Bua phi c m cht trong l khoan bng gy np thuc n. Trong qu trnh lp bua phi m bo dy dn ca kp in hoc dy mn khng b h hi.6.10Trng hp phi ph v cc tng qu c hoc m ci bng n mn l nng (thng dng khoan cm tay c ng knh mi khoan 42 mm to l khoan) phi p ng cc yu cu sau:a) To hin trng thun li cho vic khoan n;b) L khoan phi c khoan theo hng n trng tm ca tng vi chiu su m bo b tr c qu mn nm trng tm ca tng . i vi cc tng khng ln cho php gim chiu su ca l khoan. Chiu su nh nht ca l khoan khng di 25 cm;c) i vi cc tng c hnh dng dt, l khoan phi c khoan vo tm. i vi cc tng c hnh dng khng u th khoan t pha c mt ct ngang ln hn. i vi cc tng qu ln cn b tr vi l khoan v khoan t b mt c din tch ln nht.

6.11Khi lng thuc n cn np trong mt l khoan l Q, kg, c xc nh theo cng thc (24):

Q = qtt.V

(24)

Trong :

qtt l lng tiu th thuc n n v, kg/m3. Vi thuc n amonit 6B, tr s ca qtt c th ly t 0,1 kg/m3 n 0,2 kg/m3 tu theo mm hay cng;V l th tch ca tng , m3 .6.12Khi n nhiu bao thuc n trong cng mt tng , phi s dng phng php n bng in hoc bng dy n. Cho php n chm ngi nhng phi t dy mn (dy chy chm) pha tng c chiu dy nh nht khi bao thuc u tin n khng lm t dy mn bn cnh.6.13Khi n bng chm ngi hoc n bng in, phi cho kp n hoc kp in lp rp sn vo l khoan trc sau mi np thuc n vo. Phi dng ct, t st, bi khoan np bua.6.14 nhng ni hp, gn cc cng trnh d b h hng do vng khi n mn, cn phi s dng cc bin php sau gim vng:

a) Lp bua bng nc;b) Dng cc tm ph ph trn b mt khu vc khoan n. Cu to ca tm ph c th l cc tm li thp, g, cnh cy, cnh tre, thm ch c th l c, rm chng ln nhau v c np bi cc thanh st, g hoc cy tre. Tm ph c cu to nh trn s cho php cc cht kh n i qua d dng nhng s cn li cc mnh vng. Ngoi ra cng c th dng cc tm che chn.6.15C th tham kho phng php tnh ton xc nh cc thng s khoan n mn l nng v cc bin php chng vng theo cc ti liu chuyn ngnh n khc. Trong mi trng hp thit k phi c bin php phng nga v x l mn cm. 7N mn bung7.1iu kin p dng

Nhng trng hp sau y cn nghin cu s dng phng php n mn bung:

a) Khng p dng c phng php n mn trong cc l khoan ln do iu kin khoan o, a cht phc tp hoc khng c thit b khoan thch hp;b) Bt ni lm ng hoc cn y nhanh tin thi cng cng trnh m khng phi ch n nh hng ca cng tc khoan n n cc khu vc xung quanh;

c) a hnh rng ri v mi thit k ca h o khng dc hn 300. 7.2N ti7.2.1N ti hay n om, n ph v vn ti ch. Tu thuc vo chiu rng v nghing ca khi t phi o m la chn phng php b tr cc qu mn bung theo s mt hng (s a, hnh 6), hai hng (s b, hnh 6) hoc hai bc (s c, hnh 6).

a) B tr mt hng mnb) B tr hai hng mnc) B tr hai bc

Hnh 6 S b tr cc qu mn bung

7.2.2Trong cc tng a cht n nh v kh b sp l, t l gia chiu di ng cn ngn nht chn tng w v chiu cao tng H nm trong phm vi t 0,8 n 1,0. cc tng cao dc ng trong cc tng a cht d b sp l th t l w/H ly t 0,5 n 0,7.

7.2.3Khong cch a gia cc qu mn ly theo quy nh sau:

a) Trong tng lin khi khng c hng phn va hoc t nt n : a = (1,0 ( 1,2).wtb ;b) Trong cc tng c th nm ngang hoc c hng phn va v khng c s lin kt chc chn gia cc va: a = 1,4.wtb.trong wtb l chiu di trung bnh ca cc ng cn ngn nht ca cc qu mn k nhau .7.2.4Khi b tr cc qu mn theo s hai hng th ng cn nh nht ca cc qu mn hng th hai ly bng khong cch gia cc hng mn.

7.2.5Khi b tr cc qu mn theo s hai bc, bc trn phi t cch bc di mt on b bng t 1,4 ln n 1,6 ln chiu di ng cn nh nht ca qu mn bc di (w1): b = (1,4 ( 1,6).w1 .7.2.6Khi dng phng php n mn bung o ho th ng cn nh nht ly bng chiu su ca ho. Khi tm ca cc qu mn phi c b tr cao trnh thit k. Trong cc mt ct ngang ca ho c cc qu mn c b tr theo li vung m bo o theo ng mt ct thit k. Khong cch gii hn gia cc qu mn v gia cc hng mn khng vt qu chiu di ca ng cn nh nht. 7.2.7Khi lng qu mn bung n ti t tnh theo cng thc (9). Khi n cc gng tng trn sn ni dc, kt qu tnh ton cc qu mn ngoi cng trong hng cng nh cc qu mn ca hng th hai c tng thm 20 %.7.2.8Trnh t n cc qu mn bung nh sau:

a) Khi b tr mt hng mn bung: n tc thi hoc n vi sai theo s sng;

b) Khi b tr hai hay nhiu hng mn: n vi sai tng hng (vi sai gia cc hng) hoc n vi sai trong tng hng;

c) Khi b tr cc qu mn thnh hai bc: n vi sai tng bc, bt u t bc trn trc. 7.3N vng7.3.1Cc thng s chnh cn tnh ton khi n vng o knh hoc h o di, xem hnh 7:

Hnh 7 S b tr mn tp trung khi n vnga) Ch s tc dng n ph, k hiu l n:

n =

(25)trong r l na chiu rng ming h o (knh) v w l ng cn nh nht. Tr s n ly nh sau:

- i vi khi o l : n ly t 2,0 n 2,5;

- i vi khi o khng phi l : n ly t 2,0 n 3,0;b) Chiu su ca h o, k hiu l P, n v l m:

- i vi khi o khng phi l xc nh theo cng thc (26):P = 0,5.n.w

(26)- i vi khi o l , P ph thuc vo ch s tc dng n ph:

Khi n ( 2 : P = 0,33.w.(2.n 1)

(27)

Khi n > 2: P = (0,135.n + 0,8).w

(28)

c) Chiu rng xung k hiu Lp, n v l m, xc nh theo cng thc (29):

Lp = Kp.w.

(29)

trong Kp l h s ph thuc vo cht v thnh phn ht ca t b ph v bng n mn:

- i vi t : Kp = 2,0;

- i vi : Kp = 4,0.

d) Chiu cao ln nht ca ng xung k hiu l Hp, n v l m, xc nh theo cng thc (30):

Hp = 0,35.P

(30)

7.3.2Khi lng thuc n Q dng n vng, kg, tnh ton theo cng thc (31):

Q = Ks.qtt.w3.(0,4 + 0,6.n3)

(31)trong :

qtt l lng tiu th thuc n n v i vi loi amonit 6B;w l ng cn ngn nht chn tng, m;

n l ch s tc dng n ph;Ks l h s hiu chnh v chiu su t cc bao thuc n:

- Khi w < 25 m : Ks = 1,0;

- Khi w ( 25 m : Ks =

(32)

Khi dng loi thuc n khc, qtt phi hiu chnh theo iu 4.10. 7.3.3Tnh ton xc nh chiu su t cc bao thuc n (ng cn ngn nht): a) Trong t mm:- i vi cc h o c dc mi m ( 2,0: w =

(33)

- i vi cc h o c dc mi m > 2,0: w =

(34)trong D l b rng trn mt h o, m;

b) Trong cng (khng ph thuc vo dc ca mi o):

w =

(35)7.3.4 Khong cch a gia cc qu mn n vng trong mt hng xc nh theo cng thc (36):

a = 0,55.w.(n + 1)

(36)7.3.5 Cc qu mn n vng c th b tr theo s mt hng, hai hng, ba hng, hoc nhiu hn ba hng tu thuc vo kch thc yu cu ca h o:

a) Khi n mn vng sang hai bn th b tr s mt hng mn theo tim dc ca h o. Trong trng hp ny tt c cc qu mn phi c n ng thi;

b) Khi thc hin n mn vng nh hng nn b tr s hai hng. Cc hng mn phi b tr song song vi tim dc h o. Chiu su t mn, v tr tng h ca cc hng mn v ch s tc dng n ph thuc vo kch thc thit k v iu kin a cht ca h o. Khong cch gia cc qu mn trong mt hng xc nh theo cng thc (36). Cn c vo cc ng vin thit k ca h o xc nh khong cch gia cc hng mn.7.3.6 Khi b rng h o ln c th s dng s b tr cc qu mn thnh hai hng hoc ba hng v cho n vng sang hai pha. Cc qu mn b tr cc hng c cng su nh nhau:

a) Khi b tr cc qu mn thnh hai hng, ch s tc dng n n ly nh nhau cho c hai hng mn theo quy nh ti khon a ca 7.3.1;

b) Khi mn b tr thnh ba hng, ch s tc dng n ph n i vi cc qu mn hng gia ly ln hn 0,5 so vi tr s tnh ton quy nh ti khon a ca 7.3.1;

c) Khong cch gia cc qu mn trong mt hng v gia cc hng mn theo cng thc (36);d) Tt c cc qu mn khi b tr thnh hai hng phi n ng thi. Khi b tr thnh ba hng th hng gia phi n chm hn hai hng bin. Thi gian n chm (t, n v ms, tnh ton theo cng thc (37):(t = 2.A.w

(37)trong A l h s ph thuc vo cng ca b n ph, quy nh nh sau:- t nhm VI n nhm IX: A ly t 6 n 8;

- t nhm IV n nhm V: A ly t 10 n 12;

- Khng phi l

: A ly t 16 n 24. cng ca tham kho bng A.2 ph lc A.7.3.7 Khi n vng trn cc khu vc c b mt nghing th cc qu mn n vng phi chuyn dch t tim h o v pha cao (pha ni). Mc chuyn dch ph thuc vo dc ca mt nghing.7.4N sp

7.4.1Tu iu kin c th ca khu vc d nh n ph c th b tr cc qu mn n sp theo s mt hng, hai hng, mt bc, hai bc hoc nhiu hn hai hng mn, xem hnh 9. S b tr cc qu mn mt hng, mt bc l s thi cng c bn. Loi s khc ch c p dng khi s b tr mt hng v mt bc khng m bo cc kch thc yu cu ca h o.

a) B tr cc qu mn thnh mt hngb) B tr cc qu mn thnh hai hngc) B tr cc qu mn thnh hai bc

Hnh 9 S b tr cc qu mn n sp

7.4.2p dng cc cng thc (31) v (32) quy nh ti 7.3.2 tnh ton xc nh cc thng s k thut c bn ca phng php n sp. Tu thuc vo iu kin thi cng n mn la chn ch s tc dng n ph n v hiu chnh khong cch gia cc qu mn theo cng thc (36).7.4.3N mn bc ht tng ph c mi nm ngang m khng lm hng mt trn ca tng di (xem hnh 10), thc hin theo quy nh sau :

Hnh 10 - B tr cc qu mn n sp trong tnga) Ch s tc dng n n ly t 1,2 n 1,3;

b) ng cn nh nht w c hng ln pha trn ;

c) Khong cch R1 t tm qu mn ti mt gng tng: R1 = (1,2 ( 1,2).w ;

d) Tnh ton xc nh chiu cao b tr qu mn tho mn iu kin bn knh R ca phiu n c to thnh tip xc vi mp trn ca tng di:

R = w.

(38)

e) Khong cch gia cc qu mn xc nh theo cng thc (36).

7.4.4N mn nh sp mi dc cao c gc nghing trn 40o hoc chiu cao H ca mi dc cn n ph ln hn hai ln ng cn chn tng nh nht (xem s c, hnh 9), thc hin theo quy nh sau:

a) Cc qu mn b tr thnh hai bc hoc nhiu hn hai bc. Khong cch gia cc bc, k hiu l b, ly t 1,4 ln n 1,6 ln ng cn ngn nht chn tng:

b = (1,4 ( 1,6).w

(39)b) Nhng qu mn bc trn ly n bng 1. Tnh ton xc nh chiu cao b tr mn trn chn tng (khi n tng bc l qu mn di) tho mn iu kin bn knh R ca phiu n c to thnh tip xc vi mp ngoi ca tng thit k. R tnh ton theo cng thc (38);c) Ch s tc dng n ph n ca qu mn (khi n tng bc l qu mn di) ly nh sau:- i vi c cng trung bnh v th nm cm chc xung, nu ng phng thng gc vi mt gng tng th n ly t 1,25 n 1,50, nu ng phng song song vi mt gng tng th n ly t 1,1 n 1,25. i vi yu th n ly bng 1,0;- i vi cc c cng t trung bnh tr ln, c th nm bt k, b che ph bi nham thch khng phi l th n ly t 1,25 n 1,35 vi trng hp mn b tr theo s mt bc v n ly t 1,15 n 1,25 vi trng hp mn b tr theo s nhiu bc;

d) Khong cch gia cc qu mn tng ln t 50 % n 70 % so vi s liu tnh ton khi th nm ca cc va song song. Khi ng phng ca loi ny ct thng gc vi mt chnh din gng tng th khong cch gia cc qu mn ly nh hn t 10 % n 20 % so vi tnh ton. Trong cc trng hp cn li, khong cch gia cc qu mn ly theo kt qu tnh ton t cng thc (36). 7.4.5N mn o ph nh o c gc mi dc trn 30o bng cch lm khi t sp xung c hai pha. Vic n mn c thc hin theo s mt hng mn vi ng cn nh nht hng v cc mi dc i din nhau ca o. Qu mn b tr cao trnh thit k ca h o. Tu thuc vo dc ca mi m chn ch s tc dng n ph ca cc qu mn ph hp: khi gc ca mi dc bng 30o th chn n bng 1,8; khi gc ca mi dc bng 50o th chn n bng 1,20. Cc trng hp gc ca mi dc nm trong khong t 30o n 50o s c ni suy t hai tr s ni trn. 7.4.6 Khi b tr mn theo s hai hng v nhiu bc phi p dng phng php n mn vi sai vi khong thi gian chnh nhau c xc nh theo cng thc (37). Khi b tr cc qu mn theo s nhiu bc, phi n mn theo th t t trn xung di.

7.5T chc thi cng theo phng php n mn bung

7.5.1o hm cha thuc n7.5.1.1 Th tch bung t thuc n phi m bo t c khi lng thuc n tnh ton, c tnh ton theo cng thc (40):Vb = K1.K2.K3.

(40)trong :

Vb l th tch thc o theo yu cu ca bung t mn, m3;K1 l h s xt n iu kin phi gia c, chng bung. Thng thng K1 ly t 1,05 n 1,10. i vi bung o m khng phi gia c th K1 c th ly bng 1,0 ;K2 l h s xt n nh hng ca bao gi thuc n vn chuyn. Tu theo loi bao gi m h s K2 ly t 1,10 n 1,40. Khi trc tip thuc n vo bung khng cn ng vo bao gi th chn K2 = 1,0;K3 l h s xt n iu kin thi cng (s dng khng gian ca bung np thuc). Thng thng K3 ly t 1,1 n 1,2;

Q l khi lng thuc n cn np vo bung theo tnh ton, t;( l mt (t trng) thuc n khi np bnh thng (khng nn), t/m3 .7.5.1.2 Tu thuc vo iu kin a cht ni t bung thuc n v iu kin thi cng m la chn hnh dng mt ct ngang ca bung cho ph hp.7.5.1.3 B tr bung np thuc n phi p ng cc yu cu sau:

a) Khi n vng: tim dc ca bung song song vi tim ca h o s c to thnh do n ph;b) Khi n ti v n sp: trc chnh ca bung song song vi mt thong ca khu vc n ph.

7.5.1.4 Cng trnh dn vo bung np thuc c th l ng hm thng ng (ging) hoc ng hm nm ngang v cc hm ngch i t bn ngoi vo n bung np thuc n. Tu thuc vo iu kin a hnh v iu kin a cht ca khu vc n mn m la chn loi cng trnh o dn vo bung np thuc ph hp. 7.5.1.5 Ging dn vo bung np thuc n c kch thc mt ct ngang hiu dng (khng k phn gia c, chng ) khng nh hn 1,0 m2 (1,0 m x 1,0 m). Bung np thuc b tr k ngay vi ging hoc phn di cng ca ging c m rng. Trong khu vc c iu kin a cht khng n nh cho php ni ging vi bung np thuc n bng cc hm ngch. Khi o ging trong tng b ngp nc phi b tr cc ging bm nc c cao y thp hn y bung np thuc khng di 0,5 m. 7.5.1.6 Hm ngang v hm ngch dn vo bung np thuc n c mt ct hiu dng sau khi gia c khng nh hn 1,2 m2 v chiu rng ti thiu l 0,8 m khi tng chiu di ca hm di 10 m; khng nh hn 1,8 m2 v chiu rng ti thiu l 1,0 m khi tng chiu di ca hm t 10 m tr ln. Cc bung np thuc n phi b tr cui ng hm ngang hoc ni vi hm ngch. Nu khi lng ca tng qu mn bung ring bit khng vt qu 5 tn th cc qu mn c th t trc tip vo cc hm ngch, khng cn phi m rng chng lm bung np thuc n. Cc hm ngang v hm ngch phi c dc v pha ca vo khng nh hn 0,003 tiu thot nc thm. 7.5.1.7 Trong qu trnh thi cng o hm phi c bin php gia c thch hp gi n nh cc thnh vch ca bung np thuc n, ging, hm ngang v hm ngch. Trn ca vo phi lm mt mi chn cha ra ngoi phng cc hn t trn cao ri xung. 7.5.2Np thuc n, np bua, ni mng gy n

7.5.2.1 Nu thuc n c ng thnh bao gi th phi s dng cc loi thit b chuyn dng ph hp a xung ging, vn chuyn qua hm ngang, hm ngch a thuc n vo bung. Tuyt i khng c vn chuyn thuc n bng cch nm cc hm hoc bao ti thuc n xung ging. Cc bao thuc n c thnh tng chng, xp cht cn thn trong bung.7.5.2.2 Thuc n ri (khng ng trong bao gi) c th np trc tip vo bung t trn mt t qua cc l khoan ln theo mng hoc theo ng ng di tc dng ca trng lng bn thn hoc bng cc thit b np thuc n chuyn dng. Nu khng th c gii ho v t ng ho qu trnh np mn trc tip th trong ging phi t ng ng chuyn dng (ng g, ng vi bt) c mt ct khng nh hn 0,2 m x 0,2 m hoc c ng knh khng nh hn 0,2 m. Phn trn ca ng phi t mt ci phu cn pha di ng ni vi mt mng nghing thuc n vo bung. trnh hin tng thuc n b tc trong qu trnh np thuc, trong l khoan ln hoc trong ng phi th mt si dy thng c cc nt buc. Khi s dng cc l khoan ln vi ng knh trn 150 mm khoan t trn mt t vo ti bung np thuc n, k thut np cng tng t nh khi np qua ng ng chuyn dng. 7.5.2.3 Cc qu mn mi c ch to trong cc thng chuyn dng np thuc n v cc ngi n, kp in hoc dy n. Khi phi thi cng trong iu kin b ngp nc, cc qu mn mi phi c gi trong bao khng thm nc, on dy in hay dy n i vo qu mn mi phi m bo cch ly vi nc mt cch tuyt i. Chiu di on u dy phi m bo ni t do vi ng dy chnh.7.5.2.4 Khi n bng kp in, trong mi qu mn mi phi lp hai kp in mc ni tip. Khi n khng c kp, trong mi qu mn mi phi t cc on dy n vi cc nt tht. Phi m bo c nh cc dy in hoc dy n trong qu mn mi khng b h hng hoc x dch trong qu trnh di chuyn v lp t. mi qu mn mi chun b xong phi ghi y cc thng s chnh ca n khi s dng kch n.

7.5.2.5 Trong mi qu mn bung phi t hai qu mn mi, mt qu mc vo mng n chnh, qu th hai mc vo mng n lp thm m bo tin cy khi kch n. Cc qu mn mi phi t vo trong qu mn sau khi a c 80 % lng thuc n tnh ton vo trong bung.7.5.2.6 Khng c cc loi dy dn in trong cc bung np mn. Phi c h thng chiu sng chuyn dng cho cc hm l v cho n mn, chiu sng t ging hoc t ng hm vo bung m bo vic np mn an ton v ng quy cch. Vic tho d mng in chiu sng cng cc thit b in c s dng trong qu trnh o ra khi ging hoc ng hm thc hin theo quy nh sau:

a) Khi s dng cc qu mn mi vi cc kp in: hon thnh trc lc t xong cc qu mn mi;

b) Khi s dng cc qu mn mi vi cc dy n: hon thnh trc lc np bua.7.5.2.7 Dy dn ca mng in gy n hoc dy n t trong qu mn phi c cun bc bng cc lp giy cht, bn. Dy dn ca mng in gy n v dy n b tr dc theo ging hoc ng hm phi t trong cc ng ng bo v. 7.5.2.8 Sau khi np xong thuc n vo bung phi np y bua vo tt c cc cng trnh dn vo bung. Dng t, ct lp kn c m cht cc hm ngch v mt on di ti thiu 3 m tip theo ca hm ngang. Vi cc ging ng th phi lp y ton b chiu su ca ging. 7.5.3Xc nh cc vng nguy him khi n mn

7.5.3.1 Khi thit k phng php n mn bung phi tnh ton xc nh cc bn knh ca cc vng nguy him sau y:

a) Bn knh vng xa ca t khi n mn;b) Vng b chn ng khi n mn;

c) Vng chu tc ng ca sng xung kch trong khng kh;

d) Vng nguy him do kh c.7.5.3.2 Tnh ton xc nh cc bn knh vng nguy him theo QCVN 02 : 2008/BCT.7.5.4N mn

Ch thc hin n mn bung sau khi hon tt ton b cc cng tc chun b t lc khoan o, np mn, lp t cc thit b kch n vo bung, lp bua n cng tc m bo an ton n mn theo quy nh hin hnh.8N mn phn b theo chiu di8.1Phm vi p dng

Cc qu mn n vng hoc n sp phn b theo chiu di c s dng o cc h mng cng trnh c dng ko di, o knh, o ph ni lm ng v.v Khi n mn cc nham thch khng phi l , cc bao thuc n c b tr trong cc tuyn ho h c o bng cc thit b c gii. Khi n mn trong cc nham thch l , cc bao thuc n c b tr trong cc tuyn hm nm ngang c o ngm dnh ring cho mc ch n mn.8.2Xc nh cc thng s n mnKhi p dng phng php n mn phn b theo chiu di phi xc nh cc thng s sau y:a) Ch s tc ng n n c li nht i vi cc qu mn: - Mn b tr trong hm ngang: n ly t 1,8 n 2,2;

- Mn t trong ho

: n ly t 4,0 n 6,0;

b) Khi lng thuc n Q yu cu trn mt mt di, kg/m :

- Thuc n t trong ho tnh theo cng thc (41): Q = 0,6.qtt.w2.

(41)- Thuc n t trong hm ngang tnh theo cng thc (42):

Q = 1,2.qtt.w2.(n2 n + 1)

(42)c) Chiu su P ca h o xc nh theo cng thc (43), m:P = C.w.n

(43)

d) vng xa ca tng cc t c bit Lp xc nh theo cng thc (44), m:Lp = 260.K.

(44)

trong :

w l chiu di ng cn trung bnh, m;

qtt l lng tiu th thuc n n v tnh ton i vi loi amonit 6B, kg/m3. Khi dng loi thuc n khc, qtt phi hiu chnh theo iu 4.10;C l h s iu kin a cht ca khi t c n ph:

- i vi t st v st : C = 0,45 ( 0,55;

- i vi tng si v t ct:C = 0,40 ( 0,50.

K l h s tnh cht n o ca cc vin t b n ph:- Vi t st

:

K = 0,6 ( 0,9 ;- Vi t st:

:

K = 1,1 ( 1,3 ;- Vi thng:

K = 1,2 ( 1,4 ;- Vi tng

:

K = 1,4 ( 1,7 . 8.3Bin php thi cng 8.3.1S dng thit b c gii ph hp o mt hng ho hp dc theo tim ca tuyn o thit k. t o ho c v mt bn ho. Dng cc thit b c gii ph hp np thuc n vo lng ho thnh tng lp lin tc sau dng my i np bua (lp li ho). Kch n c thc hin bng qu mn mi mnh b tr mt trong hai u mt ca qu mn trong ho.8.3.2Khi n mn t trong hm ngang, thuc n c np bng thit b chuyn dng nh np thuc n bng kh nn vi thuc n khng ng gi hoc t cc bao thuc n lin tc trong hm ngang ph hp vi khi lng tnh ton cho mt mt di. Nu ng cn ngn nht dc theo ng hm c thay i th lng thuc n np cho mt mt di cng phi thay i ph hp vi tnh ton. Qu mn mi c t sau cng. Ming hm hoc ng dn ti ng hm np thuc n c lp kn bng vt liu np bua vi chiu di lp bua khng ngn hn 5 m.9N mn bu v n mn bung nh9.1Phm vi p dng

n ph cc loi t nhm IV n nhm VI c ch s to bu Bt t 10 dm3/kg tr ln m khng th s dng phng php n mn trong l khoan ln.9.2Xc nh cc thng s n mn

9.2.1 Tnh ton xc nh khi lng qu mn chnh tng t nh i vi qu mn bung. Khi lng qu mn to bu Qb, kg, xc nh theo cng thc (45):Qb =

(45)

trong :Q l khi lng thuc n cn np khi n mn bu, kg;

Bt l ch s to bu, dm3/kg, ly tr s nh nht trong bng A.2 ca ph lc A;

( l mt ca thuc n c np, kg/dm3.

9.2.2 Khong cch gia cc qu mn trong mt hng (a) v khong cch gia cc hng mn (b) khi n ti xc nh nh sau:

a) Nu n trong nham thch l :

a = b = w;

b) Nu n trong nham thch na :

a = (1,2 ( 1,4).w;

b = w.9.2.3 Tnh ton xc nh cc tham s chnh trong phng php n mn bung nh nh sau:a) Chiu di ca bung nh Ln khng ln hn 3 m;

b) Chiu di tnh ton ca ng cn nh nht ly bng chiu di ca bung nh: w = Ln;

c) Khong cch a gia cc bung nh ly nh sau:

- Khi n tc thi, khong cch a phi bng chiu di ca ng cn nh nht: a = w;

- Khi n vi sai hoc n ring r: a = (1,3 ( 1,4).w;d) Khi lng qu mn (bao thuc n) tnh ton theo cng thc (9).

9.3Yu cu k thut

9.3.1S dng thuc n dng bt n to bu trong cc h khoan kh thng ng. S dng cc bao thuc n chu c nc n to bu trong cc h khoan ng b ngp nc, cc h khoan nghing v h khoan nm ngang.9.3.2 bu np thuc c cao trnh ng nh yu cu, h khoan dng to bu phi c chiu su khoan qu bng na chiu cao ca qu mn tnh ton.9.3.3Khi n mn to bu bng thuc n dng bt phi np mt na lng thuc to bu vo h khoan, tip th qu mn mi xung, cui cng np nt na lng thuc cn li. h khoan khng b h hng trong qu trnh n mn to bu, ngay bn trn qu mn to bu phi c np bua bng vt liu ri, nh trn chiu di khng qu hai ln chiu di ca qu mn to bu.

9.3.4Khi n mn to bu bng cc bao thuc n, qu mn c th gm mt bao mn mi hoc vi bao mn. Khi np vi bao mn th bao mn cui cng a xung h khoan l bao mn mi. Chiu di np bua ly nh trng hp dng thuc n dng bt.9.3.5 trnh khng lm cho a khi b ph hy trong qu trnh to bu, n mn to bu cho cc h khoan phi c tin hnh ln lt, mi ln ch cho n khng qu hai qu mn. Sau mi ln n mn to bu, cc h khoan phi c thi ht kh c v bi trong bu bng kh nn.

9.3.6Khi n mn to bu trong t v nham thch do, trc khi np mn phi khoan li cc on b bt kn do n mn to bu gy ra, m bo ng knh tiu chun ca h khoan.9.3.7S dng thuc n dng bt hoc dng ht np vo bu hoc cc hm ngch. Sau khi np c 80 % lng thuc n tnh ton vo trong bu mi t qu mn mi, sau np ht s thuc n cn li. i vi n mn bu, phn l khoan khng c thuc phi c y bng vt liu np bua v chiu di bua pha trn bu khng nh hn chiu cao bu. i vi n mn bung nh, khong trng cn li ca hm ngch cng phi c np bua bng vt liu ht mn.9.3.8Phng php n mn bu v n mn bung nh tng t nh phng php n mn bung, quy nh ti iu 7.10N mn p

10.1Phng php n mn p c p dng ph v vn cc tng c bit c nhiu mt thong xung quanh hoc ct t cc vt c chiu di ln. 10.2Khi lng thuc n cn thit ph v cc tng c tnh theo cng thc (46):

Q = K2. Vn

(46)

trong :

Q l khi lng thuc n cn thit ph , kg;

K2 l lng tiu th thuc n v i vi cn n ph, kg/m3. i vi cng chc, khi dng thuc n loi amonit 6B, K2 c th ly trong phm vi t 2 kg/m3 n 3 kg/m3;Vn l th tch khi cn ph v, m3.10.3Khi cn n ct cc vt th di nh thanh g, st, thp v.v, khi lng thuc n c tnh theo cng thc (47):

Qc = Kni. Si

(47)

trong :

Qc l lng thuc n cn thit ct vt th, g ;Kni l lng tiu th thuc n v, g/cm2. Khi dng thuc n loi amonit 6B, Kni c th tham kho trong bng A.3 ca ph lc A;Si l din tch mt ct ngang ca vt th phi lm gy, cm2.10.4Qu mn p nn c dng dt, c b tr vo ch c b mt phng hoc lm, vng i din vi trng tm ca vt th n ph. 10.5Thuc n dng bt phi ng thnh bnh trong cc bao n hi, phi c nh chc chn vo vt th cn n ph. Cc qu mn p phi c che ph bng bua c chiu dy khng nh hn chiu dy ca khi thuc n. Vt liu lm bua c th l vng c lt p mt c xung di, cc loi t ct nghin nh. Khng c s dng vt liu c ln cc vt cng v nng nh , cc kim loi v.v lm bua. 10.6C th s dng phng php n chm ngi, n in v n bng dy n n cc qu mn p. Khi s dng phng php n chm ngi th khong cch gia cc qu mn phi m bo khi mt trong cc qu mn pht n khng lm vng i cc qu khc.

11S dng phi hp cc phng php n mn khc nhau

11.1Khi cc tng phi n ph c chiu cao thay i nn kt hp phng php n mn trong l khoan ln (l khoan su) v n mn trong l khoan nh (l khoan nng). N mn trong l khoan ln lm v vn phn ln th tch ca tng cn n ph cn n mn trong h khoan nh bo m o ph cc phn ranh gii ca a khi cn phi n ph, xem hnh 11.

CH THCH: 1 Cc h khoan su; 2 Cc h khoan nng.Hnh 11 - N phi hp gia cc qu mn trong h khoan su v mn trong h khoan nng

11.2Khi n ph ti cc tng cao nn p dng phng php n mn trong cc l khoan ln cho phn trn v n mn bung cho phn di thp ca tng c n ph, xem hnh 12. Cc qu mn trong tng phng php n c th n tc thi hoc n vi sai nhng cc qu mn trong h khoan ln phi n sm hn cc qu mn bung.

CH THCH: 1 Cc qu mn trong h khoan ln; 2 Cc qu mn bung.Hnh 12 - N phi hp gia cc qu mn bung v mn trong h khoan ln11.3 Khi n ph ti cc tng c mi thoi, nu n mn trong cc h khoan ln thng ng khng m bo ct c chn tng th p dng s n phi hp gia cc qu mn trong h khoan ln thng ng v nghing hoc gia cc qu mn trong cc l khoan ln thng ng v nm ngang, xem hnh 13. Trong s n mn phi hp gia cc qu mn trong cc l khoan ln thng ng v nm ngang th cc qu mn trong cc h khoan nm ngang c n trc.

CH THCH:

1 Cc qu mn trong h khoan ng, nghing;

2 Cc qu mn h khoan nm ngang.

Hnh 13 S phi hp gia cc qu mn trong l khoan ng nghing v nm ngang

11.4Hnh 14 gii thiu mt s n mn phi hp nhiu phng php n mn o h mng cng trnh thy li. Trong s ny, hnh a p dng cho trng hp nn v thnh h mng sau khi n mn khng cho php m rng, ko di thm cc vt nt t nhin hoc to thnh cc vt nt mi; hnh b p dng cho trng hp nn v thnh h mng sau khi n mn cho php cc vt nt thin nhin c ko di v m rng thm hoc to thm cc vt nt mi.

a) p dng cho cng trnh thuc nhm II v nhm III

b) p dng cho cng trnh thuc nhm I

CH DN: 1 ng vin thit k ca h mng;

2 Lp bo v mi h mng;

3 Lp bo v nn;

4 L khoan n vin;5 Tng khoan n th nht;

6 Tng khoan n th 2;

7 Mt trn ca tng bo v;8 Lp cha li cui cng cy dn bng th cng v chong my;

9 Khu vc n mn l su vi l khoan c ng knh ( 200 mm;

10 Khu vc n mn l su vi l khoan c ng knh ( 110 mm;

11 Khu vc n mn l nng;

12 Cc l khoan n mn l su c ng knh ( 110 mm.

Hnh 14 - S b tr s dng phi hp cc phng php n mn l nng, l su v n vin khoan n o mng cng trnh thu li12Mt s phng php n mn c bit

12.1N mn theo ng vin

12.1.1N mn theo ng vin bo v thnh vch xung quanh h o. Cc l khoan b tr theo ng vin thit k ca h mng c n trc lm xi ti t bn trong. Do c mt khe hp c to ra dc theo ng vin thit k ngn cch khi cn n ti bn trong h mng vi khi cn gi li bn ngoi ng vai tr ca mt mn ngn sng a chn do n mn ph ti pha trong gy ra, hn ch h hi cho thnh h mng. nn cng t nt n th cht lng b mt mi h mng do n mn vin to ra cng tt. 12.1.2Khong cch a gia cc l khoan n mn to khe trc xc nh theo cng thc (48).a = 22.d.Kv.K

(48)trong :d l ng knh bao thuc n, m;

Kv l h s kp ca ng vin: - Khi kp hon ton (vin quanh h mng v.v): Kv = 0,85;- Khi n mn trn sn dc hoc trn tng v n o theo ng vin: vi hng l khoan nhiu hn ba hng Kv ly bng 1,0; t ba hng tr xung Kv ly bng 1,1;K l h s c im nham thch phi n ph: - Vi phn phin lin khi v t nt n : K = 1,0;- Vi b nt n, nu hng khe nt v th nm ca nham thch to vi hng ca khe hp mt gc 90o, K ly bng 0,90; nu to thnh gc t 20o n 70o, K ly bng 0,85. Khi nham thch c th nm ngang cng nh khi cc mt a cht trng vi khe hp, K ly bng 1,15.12.1.3Khi lng thuc n cn np trong mt mt di h khoan k hiu l P1 ph thuc vo tnh cht ca nham thch cn n ph v loi thuc n c s dng. i vi thuc n loi amonit 6B, trong cc nham thch cng khng b ph hoi bi qu trnh phong ho, P1 ly t 0,4 kg/m n 0,6 kg/m; trong cc nham thch c cng trung bnh, pha trn b phong ho, P1 phn di ca h khoan ly 0,4 kg/m cn phn trn t 0,2 kg/m n 0,3 kg/m; trong cc nham thch b phong ho nh, P1 ly t 0,2 kg/m n 0,3 kg/m.12.1.4Vi cc h o sau khi n mn cho php cc vt nt thin nhin c ko di v m rng thm hoc to thm cc vt nt mi nn v thnh h mng, cc h khoan trn ng vin phi khoan ti chiu su bng chiu su ca cc h khoan n ti. Vi cc h mng khng cho php nn v thnh mng sau khi n mn b h hng, chiu su cc h khoan n vin phi su hn chiu su cc h khoan n ti khng di 10 ln ng knh cc qu mn trong cc h khoan n ti. Cc h khoan n mn to ng vin phi m bo song song vi nhau trn khong cch cho.12.1.5C th s dng cc loi thuc n c sc cng ph trung bnh, chu c nc n to ng vin.12.1.6Qu mn n to khe trc l mt chui cc bao thuc n buc vo dy n. np mn vo cc l khoan thng ng, chui cc bao thuc n c buc vo dy thng. np mn vo cc l khoan nm ngang, nghing hoc ngc ln, cc bao thuc n phi buc vo thanh g c cng v di ph hp. Nu chui cc bao thuc n c th xung bng dy thng th dy thng phi c buc vo mt vt chc chn t ngang ming l khoan v khong khng gian cn t do ca h khoan c y bng vt liu lm bua ht mn. Nu chui mn c a vo l khoan bng thc g (hoc vt liu cng thch hp) th dy n v cc bao thuc phi c buc vo cng mt pha ca thc g, m bo qu mn t ng tim h khoan v khng tip xc vi thnh h khoan. Trong trng hp ny ch cn np bua phn ming ca l khoan khng c thuc n.12.1.7 Bao thuc n nm pha trn cng ca chui phi cch ming l khoan t 3 m n 4 m i vi cc nham thch b ph hy v 2 m i vi cc nham thch khng b ph hy.12.1.8 N mn to khe phi thc hin trc khi khoan hoc trc khi tin hnh n ti. Cho php n mn trong cc l khoan ln n ti c n vi sai so vi n mn trong cc l khoan to khe trc. Thi gian vi sai i vi cc nham thch yu khng nh hn 75 ms, cn trong cc nham thch cng khng nh hn 50 ms.12.1.9i vi h o c chiu di ln th khe n ph trc theo ng vin phi c thi cng vt trc ranh gii khu vc n ph mt khong cch khng t hn 10 m. Tu thuc vo cng ca m y ca hng l khoan ln n om phi cch hng mn n vin t nht t 1,0 m n 1,5 m nhng ti a khng c qu 4,0 m.12.1.10 Khi n ph cc nham thch yu, trong mi l khoan c th t t 3 si n 4 si dy n thay th cho thuc n v khong cch gia cc l khoan theo ng vin t 0,3 m n 0,5 m. Khi n ph cc nham thch cng, khong cch gia cc l khoan theo ng vin ly t 0,5 m n 0,8 m.12.2Xc nh chiu dy lp bo v v thi cng o lp bo v y cc h o12.2.1 trnh lm h hi y h o do sc n ph ca mn trong cc l khoan ln, cc l khoan ln khng c khoan ti cao trnh thit k ca y h o. Lp nham thch nm gia y l khoan v cao trnh thit k ca y h o gi l lp bo v. 12.2.2Chiu dy lp bo v ly bng bn knh tc ng ca n mn vo su trong lng t. Chiu dy lp bo v ph thuc vo c im a cht nn, thng thng nm trong phm vi t 5 ln ng knh qu mn (tng ng vi nham thch dai v lin khi) n 12 ln ng knh ca qu mn (tng ng vi nham thch dn v nt n). 12.2.3Cho php ng thi p dng nhiu phng php khc nhau nh gi tc ng n ph vo su trong lng a khi. Tu tng trng hp c th khi n mn, c th p dng cc phng php nh gi thng dng sau y :

a) Quan st thnh ca khe n ph theo ng vin;

b) Phng php o ging;

c) Phng php khoan ly nn;

c) Xc nh lng ht nc hoc lng ht khng kh;

d) Phng php a vt l.

12.2.4 Phi chia lp bo v thnh hai bc o. Bc mt o bng phng php n mn trong l khoan nh. Bc th hai nm st y mng c chiu dy bng 5 ln n 12 ln ng knh qu mn trong cc l khoan nh nhng khng nh hn 20 cm v phi o bng thit b cng ngh ph hp, khng c dng phng php n mn.12.2.5 C th p dng phng php n mn phn on khng kh di y l khoan bo v y mng.

12.3Lm sp cc a khi khng n nh tim tng bo m an ton cho cng trnh

12.3.1 Lm sp cc a khi khng n nh tim tng bng phng php n mn theo ng vin hoc phi hp gia n mn theo ng vin pha trn v n mn trong h khoan nm ngang hoc xin ct y a khi. Khi thi cng n mn lm sp cc a khi ny phi c bin php m bo an ton cho ngi v thit b t lc khoan to l n khi hon thnh cng tc n mn.12.3.2 Cc tham s v cch b tr, khi lng v kt cu ca qu mn chui xc nh nh i vi cc trng hp n mn theo ng vin. lm tng kh nng lm sp cc khi , cho php s dng cc qu mn b sung nng hn cc qu mn theo tnh ton thng thng t y cc h khoan ring bit trn ng vin. Vi thuc n amonit 6B, cc qu mn b sung c th nng ti 10 kg.12.3.3 Khi a khi c chiu cao di 25 m v chiu dy di 6 m th ch cn p dng phng php n mn theo ng vin. Khi a khi c chiu cao t 25 m tr ln v chiu dy t 6 m tr ln th chn ca n phi b tr thm cc qu mn n ti trong cc l khoan ln n nt phn chn khi. Nu a khi l nhng nham thch khi ln, c chiu cao v chiu dy ln, ngoi p dng phng php n mn theo ng vin cn phi s dng cc qu mn n ti b sung trong cc l khoan ln.12.3.4 Khi thi cng cc l khoan ln nm ngang v hi nghing n ph ht chn ca a khi c khoan phn di ca a khi phi m bo iu kin lm vic an ton cho cng nhn.

12.3.5 Tnh ton xc nh cc thng s, v tr v phng php np thuc n vo cc l khoan dng ph nt chn a khi c tnh ton theo quy nh ti cc iu 5, iu 6, iu 7 v iu 12.1.12.3.6 Cc qu mn phi c kch n bng dy n kt hp vi kp in. Khi c cc qu mn t trong l khoan pha di n ct chn a khi khng n nh, phi kch n chng ng thi vi cc qu mn theo ng vin hoc chm hn khng qu 10 ms. Khi c nhng h khoan b sung n ti, cc qu mn trong phi c n chm hn thi gian n cc qu mn trong cc h khoan theo ng vin t 10 ms n 20 ms.

12.3.7 Khi cc a khi phi n sp c chiu cao ln nhng khng c ng vo v khng c mt bng an ton t my khoan, cho php s dng cc s thi cng n theo ng vin vi cc qu mn n ti t trong cc h khoan ln b tr theo hnh qut v vic chun b n mn c thc hin t cc hm o c tit din t 8 m2 ti 9 m2 nm ngoi phm vi ca a khi.

12.4N mn ph quai12.4.1N mn ph quai bng b tng hoc xy12.4.1.1 Tu thuc vo kt cu ca quai v yu cu khai thng dng chy m p dng bin php n mn vng hoc n ti. quai c dng tng c ph bng n ti. Cc l khoan c khoan qu mt on so vi y thit k ca h o v b tr thnh nhiu hng: phn gia ca mt ct ngang l cc l khoan thng ng, gn mi l cc l khoan nghing. Chiu su on khoan qu cng nh cc tham s v b tr v tnh ton n mn trong l khoan ln thc hin theo cc quy nh ti iu 5, iu 6 v iu 7. Cc l khoan gn mi dng nc, ng cn theo chn tng ly bng 50 % n 70 % ng cn theo chn tng tnh ton i vi cc qu mn c ng knh c la chn. Trng hp cn phi bc xc thu dn vt liu n ph bng cc my thu dn chuyn dng th chiu su n ti thit k c xt ti su d phng khi no vt phi c tng thm 0,5 m. Khi n ph cc khi xy c ln, mng li cc h khoan phi c b tr dn st li gn nhau, bng t 50 % n 70 % khong cch tnh ton nhng vn gi nguyn khi lng tnh ton cc qu mn trong mi h khoan.

a) S quai chu p lc nc mt phab) S quai chu p lc nc c hai pha

CH THCH : I, II, III, IV l cc hng mn.

Hnh 15 Cc s ph quai bng b tng hoc xy

12.4.1.2 N ph quai (tng) theo s hnh 15. S thi cng c bn l n vi sai tng hng vi khong cch thi gian vi sai xc nh theo cng thc (37). Khi n mn theo s a hnh 15, phn ln khi vt liu b n ph s c cun i theo dng nc, s cn li s c thu dn bng cc loi my chuyn dng. Khi n mn theo s b hnh 15, hu ht khi lng vt liu b n ph u nm ti khu vc n mn v c dn sch bng cc loi my mc chuyn dng.

12.4.1.3 Trc khi n mn ph quai, pha h lu quai phi o cc h by c dung tch ln m bo cha ht ton b khi vt liu b v vn sau khi n ph.12.4.2 N mn ph quai bng t hoc 12.4.2.1 Khi p dng phng php n ti, cc l khoan thng s dng ng vch bo v v c khoan qu mt on su hn so vi cao trnh y ca on thot nc do n ph to nn. Cc h khoan c b tr theo mng li vung. Cc thng s b tr v khi lng qu mn ly theo quy nh ti iu 5, iu 6 v iu 7. Cc hng l khoan ngoi cng b tr ngay gn mp thng lu quai nn phi c bin php m bo an ton cho my khoan.12.4.2.2 Chiu di on quai cn ph thot nc c xc nh tu theo yu cu ca thit k dn dng thi cng. S n mn l n tng hng, n vi sai vi cc khong thi gian vi sai c tnh ton theo cng thc (37). Khi n ph quai c kt hp xi tri bng dng nc nn n vi sai theo tng hng ngang. Cc trng hp cn li nn n vi sai theo hng dc.12.4.2.3 Nu ph quai bng phng php n mn vng, cn b tr thnh nhiu hng. Cc thng s b tr v khi lng cc qu mn n vng xc nh theo quy nh ti iu 5, iu 6 v iu 7. Ch s tc ng n n ly t 2,5 n 3,0. Chiu su t mn (ng cn nh nht) xc nh theo cng thc (49). Cc qu mn c th n tc thi hoc n vi sai.w =

(49)trong h l chiu su thit k ca on thot nc, m.12.4.2.4 Vi quai c kt cu phc tp: gm khi v tng nghing chng thm bng t st th phn ca quai c ph hy bng phng php n vng, cn trong phm vi tng nghing st th thc hin bng phng php n ti12.4.2.5 Nu mc nc pha thng lu quai h thp th nn dng c gii o h thp v thu nh mt ct trc khi n mn gim nh khi lng cn n ph.

12.5N mn nh hng p p

12.5.1N mn nh hng thi cng p t, p b tr ti khu vc sng c lng hp, b dc, p bng vt liu ti ch. Nu n mn t hai b th cao ca b khng thp hn 1,5 ln chiu cao thit k ca p. Nu n mn mt b th chiu cao b phi ln hn 2 ln chiu cao thit k ca p.

12.5.2 Tu thuc vo iu kin c th ca tng cng trnh m p dng phng php n mn l su hoc n mn bung p p. 12.5.3 Tnh ton xc nh cc thng s k thut n mn l su thc hin theo quy nh ti iu 4 v c kim tra v khong cch vng xa ca t theo cng thc (50):R = 10.

(50)trong :R l khong cch vng xa ca t sau khi n mn, m;

q l lng tiu th thuc n n v, kg/m3;

H l chiu cao ca tng n ph, m.Nu khong cch vng xa ca t theo tnh ton khng ngn dng chy mt cch chc chn, phi cho trc gi tr R v dng cng thc (50) tnh lng thuc n n v. Cng theo cch hiu chnh li khong cch gia cc l khoan tnh ton theo cng thc (51):a =

(51)trong :

L l chiu su l khoan, m;

C l h s y l khoan bng thuc n;

p l kh nng np thuc n ca l khoan, kg/m.

12.5.4 Khi dng phng php n mn l su, phi b tr cc l khoan thnh nhiu hng. v tr tuyn nh cng trnh (p hoc quai) c s lng hng l khoan nhiu nht. Khu vc bn ngoi ng vi chn p hoc quai c s lng l khoan t nht. Cc l khoan c th thng ng hoc xin. Khi b tr thnh nhiu hng th y cc l khoan cc hng khc nhau phi cng nm trn mt phng to vi mt phng nm ngang mt gc khng nh hn 45o, xem s a, hnh 16. Trnh t n cc qu mn trong cc l khoan su p ng yu cu ht tp trung t v pha nh cng trnh (p, quai), xem s b hnh 16.

a)b)

Hnh 16 S b tr cc qu mn trong l khoan ln ngn dng chy trong sng

12.5.5 Khi p dng phng php n mn bung, cc qu mn bung c b tr thnh mt hng, hai hng v trng hp c bit c th b tr thnh ba hng. Cc qu mn bung tt c cc hng u c cng cao . Khi n mn ph cc mi ni cao c th b tr cc qu mn cc bc khc nhau. Tnh ton khi lng qu mn bung theo cng thc (9) vi ch s tc ng n ph n ly t 1,0 n 1,5 tu thuc vo yu cu v khong cch vng xa ca t . Tu thuc vo c im a hnh v cu trc ca khi t phi n ph, khong cch gia cc qu mn ly trong phm vi t 0,8 ln n 1,5 ln chiu di ng cn w .12.5.6 Trnh t n mn bung ph thuc vo iu kin ht t tp trung theo hng nh cng trnh. Khi b tr cc qu mn bung vi cc tr s ng cn nh nht khc nhau th phi ly cc tr s ln nht i vi cc qu mn gia v cc tr s nh hn i vi cc qu mn ngoi ra. Khi b tr cc qu mn thnh mt hng c th n ng thi (tc thi). Trong cc iu kin tng t, khi cc qu mn c cc tr s ng cn nh nhau th p dng phng php n vi sai: cc qu mn ngoi ra n chm hn cc qu mn gia. Khong thi gian vi sai xc nh theo cng thc (37). Khi b tr cc qu mn thnh hai hng phi s dng s n tng hng hoc s hnh nm.12.5.7 Khi n mn nh sp t vo dng nc ang chy to quai bng t st, th tch n phi c ly vi h s d phng cao nht. Khi th tch khu vc n ph khng m bo tr lng cn thit th phi s dng s ngn dng hai giai on.

12.5.8 Th tch vt liu V b dng nc cun tri khi ngn dng tnh ton theo cng thc (52):

V = H.B.(v vH).tn

(52)

trong :

H v B l chiu su v chiu rng ca dng chy, m;

v l tc trung bnh thc t ca dng chy, m/s;

vH l tc khng xi gii hn, m/s. vH ph thuc vo thnh phn vt liu b ph sp:

- Vt liu l ct st: vH = 0,5 m/s;

- Vt liu l si - cui: vH = 2,0 m/s;

- Vt liu l khi : vH = 5,0 m/s; tn l thi gian ngn dng, s.

13N mn di nc

13.1Yu cu chung 13.1.1 N mn di nc h thp cao y hoc dn sch lng dn v.v khi khng p dng c cc bin php c gii .13.1.2 Ngoi m bo cc yu cu k thut v an ton chung v cng tc n mn, khi n mn di nc cn phi thc hin theo ng yu cu ca cc c quan qun l lin quan n bo v mi trng nc, bo v v khai thc ngun li thy sn. Nu n mn trn cc sng c tu thuyn qua li phi thc hin theo yu cu ca c quan qun l v khai thc vn ti trn sng.13.1.3Tt c cc vt liu n c dng n mn phi c kh nng chu nc. Mng gy n phi m bo tin cy, khng b r in gy n c an ton.

13.2N mn o su y 13.2.1Khi chiu su lp y lng dn cn n ph nh hn 1,5 m th p dng phng php n mn trong cc l khoan nh. Khi b dy cn n ph ln hn 1,5 m th n mn trong l khoan ln. Trong trng hp c bit cho php s dng mn p n ph cc doi khng ln, c chiu su cn n ph nh hn 0,4 m.

13.2.2Trong mi trng hp u phi tin hnh n mn cng mt lc trn ton b chiu su ca h khoan k c phn chiu su d phng t 0,3 m n 0,5 m tu thuc vo tng chiu dy ca lp phi o.

13.2.3Tu tng trng hp c th, mi i tng n mn ch nn s dng mt phng php n p ng c yu cu h thp lng dn ti cao thit k.

13.2.4Tnh ton xc nh cc thng s khi o su y lng dn bng n mn trong l khoan nh tng t nh tnh ton n mn trn mt t, quy nh ti iu 6 nhng khong cch gia cc l khoan gim xung cn t 70 % n 90 % tr s tnh ton v khi lng ca cc bao thuc n trong l khoan (qu mn) khng thay i. Cc l khoan nh b tr thnh tng hng t h lu ln thng lu dng chy. Hng u tin v hng to rch phi c chiu di on khoan qu ln hn 1,5 ln chiu di tnh ton. Tip theo hng to rch ph m l ba hng n ph, sau li tip n hng to rch ph m v.v Phi tin hnh n mn theo s n mn vi sai tng hng. Khoan v np thuc n vo l khoan c thc hin trn mt cc sn chuyn dng t ni v c nh trn mt nc.13.2.5Tnh ton xc nh cc tham s n mn o su y bng phng php n mn trong l khoan ln tng t nh trn mt t, quy nh ti iu 5 nhng khong cch gia cc l khoan ln v gia cc hng l khoan ch bng t 50 % n 80 % cc tr s khong cch tnh ton. Khoan v np thuc n cng thc hin trn cc sn ni chuyn dng c nh trn mt nc, tng t nh thc hin n mn trong h khoan nh.13.3N mn dn sch lng dn13.3.1Dn sch lng dn nhm m bo an ton cho cc phng tin vn ti thy qua li bao gm n ph cc vt cn nm di lng dn hay phn cn li ca cng trnh nm ngm di nc v.v....13.3.2 Khi cn n mn ph hng c phi dng cc qu mn c dng bao thuc n hnh di t dc theo ng d nh cn ct. Cc qu mn di buc vo cc cc nh cch nhau khng qu 3 m. Cc cc nh c ng xung t nn m bo mn c p cht vo chn hng c. Khi lng thuc n cn thit Qc ph hng c tnh theo cng thc (53), ng knh d ca qu mn xc nh theo cng thc (54):

Qc = Kc.Dc.Lc.

(53)

d =

(54)

trong :

Kc l lng hao thuc n v ct cc vt th hnh di, g/cm2;Dc l chiu dy hng c, cm;Lc l chiu di hng c cn n ph, cm ;( l mt thuc n s dng, g/cm3.13.3.3Khi cn ct cc thanh thp, dm thp v.v phi s dng hai khi thuc n t hai pha ca vt cn ct m bo y ca qu mn s 1 bng cao trnh nh ca qu mn s 2 (xem hnh 17). Vi loi thuc n tiu chun (thuc n amonit 6B), lng tiu hao thuc n v Kc ly bng 50 g/cm2 khi chiu dy tm thp di 4 cm v ly bng 100 g/cm2 khi tm thp dy t 4 cm tr ln. Tng lng thuc n tnh ton phi chia thnh 2 khi v gn cht vo thanh thp theo s hnh 17. Phi n tc thi c hai qu mn (hay khi thuc n) ny.

CH THCH:

1 v 2 Khi thuc n t so le ; 3 Thanh thp.Hnh 17 - S b tr n mn ct thanh thp13.3.4 N ph cc tng ngm cn tr lng dn bng mn p. Tnh ton xc nh cc thng s n mn p theo quy nh ti iu 10.13.4Bo v thy sn khi n mn di nc

13.4.1p lc u sng xung kch do n mn gy ra trong nc phi nh hn 3 atm m bo an ton cho cc loi thy sn. Bn knh an ton cho c khi n mn xc nh theo cng thc (55)

Rac = C.

(55)

trong :

Rac l bn knh vng an ton cho c khi n mn, m;

Q l khi lng ca tt c cc qu mn c gy n trong mt t n vi sai, kg;C l h s hiu chnh. i vi cc qu mn t trn mt nc (l thin), h s C ly bng 100. i vi cc qu mn t su trong nc th C ly bng 20.

13.4.2Khi n mn nhiu ln th phi dng li quy xung quanh khu vc nguy him. Khi ch n mn mt ln th trc khi n cn nn cho n mt s qu mn nh xua ui c ra xa. Khng n mn vo ma c .

14N mn ph v kt cu cng trnh

14.1Tu theo chiu dy ca cc kt cu b tng hoc b tng ct thp cn n ph m s dng bin php n mn trong h khoan nh hoc h khoan ln. Trong mt s cng trnh hoc kt cu cng trnh c sn mt s v tr rng trong c th b tr cc khi thuc n tp trung n ph.

14.2Trng hp n mn trong cc l khoan nh v dng my xc hoc my i thu dn b tng v vn th chiu su cc l khoan phi bng 0,9 ln chiu dy ca kt cu cn n ph. Cc h khoan cn b tr u theo hnh thc hoa mai. Tng khi lng thuc n cn dng n ph kt cu b tng tnh theo cng thc (56) v s lng cc l khoan nh xc nh theo cng thc (57):

Qtc = VKc.K2

(56)N =

(57)

trong :

Qtc l tng khi lng thuc n cn thit, kg ;

Vkc l th tch khi b tng cn n ph, m3 ;K2 l lng tiu th thuc n v. i vi b tng, K2 ly t 0,4 kg/m3 n 0,5 kg/m3 ng vi thuc n tiu chun;N l s lng qu mn;

d l ng knh qu mn, dm;

L l chiu di qu mn, dm;

( l mt np thuc n, kg/dm3.

14.3Cc l khoan c th khoan t trn xung hoc t mt bn ca khi s n ph vo tu theo kt cu nm ngang hay thng ng. Nu cc l khoan c khoan t trn xung dui th c th np thuc n dng bt hoc dng ng thnh bao. Nu khoan t mt bn vo th ch c np thuc n dng ng thnh bao. Phi p dng phng php n mn vi sai.14.4Nu bin php thu dn b tng b n ph bng cn cu v xe chuyn dng th khi s n ph phi c chia ct thnh cc tng c khi lng v kch thc ph hp cho vn chuyn. lm cng vic ny phi vch cc ng ct trn khi s n ph bng phn mu hoc sn v tin hnh khoan theo cc ng vch ni trn vi khong cch gia 2 l khoan l 20 cm. Khi lng qu mn v phng php np thuc n trong cc l khoan ging phng php n mn vin quy nh ti 12.1.14.4Nu khi b tng s n ph c chiu dy ln v kch thc theo ng thng trong c 3 chiu ln hn 50 ln ng knh qu mn trong l khoan ln th phi s dng phng php n mn trong l khoan ln. Nu kch thc theo hng bt k ca khi b tng khng vt qu 50 ln ng knh th cc l khoan ln ch cn b tr thnh mt hng, nu chiu dy ln hn th b tr t hai hng tr ln theo dng li vung hoc hnh hoa mai. Khong cch gia cc l khoan v ng cn nh nht ca qu mn ly trong khong t 25 ln n 27 ln ng knh qu mn trong l khoan.14.5 Nu khoan cc l khoan ln t trn xung di, y ca l khoan phi cch mt di ca khi b tng mt on bng 5 ln ng knh qu mn. Khi khoan t mt bn vo, y l khoan phi cch mt bn i din ca khi b tng mt on t 10 ln n 15 ln ng knh qu mn.14.6Khi trong khi b tng c cc khong trng b tr cc qu mn tp trung, khi lng cc qu mn ny c tnh ton theo cng thc (9). Tu theo cng b tng cn n ph, lng tiu th thuc n n v K2 c th ly bng 1,3 kg/m3 n 1,7 kg/m3 ng vi loi thuc n tiu chun.

14.7 Khi n mn ph cc mng b tng di su nn s dng phng php n mn trong l khoan nh. Trc khi khoan phi o mt ho chy dc theo mt trong cc cnh ca chn mng v su ti chn mng. Nu mng nm trong khu vc khng c cng trnh d b h hi do n mn th vic b tr cc qu mn cng nh tnh ton xc nh cc thng s n mn tng t nh n mn ph cc khi b tng nm trn mt t. Nu gn mng c cc cng trnh d b h hi do n mn th chiu su ca cc h khoan nh ly bng 80 % chiu dy ca khi b tng, s cc l khoan tng ln gp hai ln so vi tnh ton v chiu di ca mi qu mn trong l khoan ly bng 40 % chiu di l khoan nh. Khi n mn, ton b khi b tng cn n ph u phi c che chn bng cc kt cu ph thch hp.14.8 Khi cn n ph mt phn mng m khng gy h hng phn cn li bt buc phi n mn ct rnh trc theo ng ct vi khong cch gia cc l khoan t 0,2 m n 0,4 m v qu mn gm 2 si hoc 3 si dy n. N mn phn mng c ct phi thc hin theo ng quy nh t 14.1 n 14.7 vi thi gian n chm khng nh hn 50 ms so vi thi gian n to rnh ct.

14.9 Khi n mn ph cc kt cu b tng ct thp th phi n ph lm ti ri phn b tng, sau mi ct b ct thp bng cc dng c hoc thit b ca ct khc. Phi p dng phng php n vin chia ct kt cu thnh cc khi nh c kch thc ph hp vi yu cu vn chuyn ra ngoi. cc ng ranh gii ca khi s n ph phi b tr n cc qu mn c sc cng ph mnh. 14.10Ct cc tm b tng c chiu dy di 40 cm nn dng mn p trn b mt ph nt b tng. Khi lng thuc n cho 1 m di qu mn loi amonit 6B s b ly theo bng 8. Khi lng quy i ca cc qu mn khc loi trn phi c chnh xc ho theo kt qu n mn th nghim trong giai on u n ph. Cc qu mn phi c ph kn bng ct hoc vng c c chiu dy khng nh hn chiu dy bao thuc n.

Bng 8 - Khi lng thuc n p cho 1 m di bao thuc n loi amonit 6B ct cc tm b tng ct thp c chiu dy di 40 mm Chiu dy tm, cm5101520253040

Lng thuc n, kg/m12345,5711

14.11Khi ct cc tm c chiu dy trn 40 cm th dc theo ng ct phi khoan cc l khoan nh c chiu su bng 2/3 chiu dy tm, khong cch gia cc l khoan lin nhau ly t 10 ln n 15 ln ng knh bao thuc n. Cc khong cch ny phi c chnh xc ho theo kt qu n mn th nghim trong giai on u n ph. Khi lng thuc n np trong mt l khoan xc nh theo cng thc (58)Q = 0,5.d2. .(

(58)

trong :

Q l khi lng thuc n np trong mt l khoan, kg;

d l ng knh qu mn trong h khoan, dm; l chiu dy tm b tng cn n ph, dm;( l mt thuc n, kg/dm3.14.12 ct cc ct bng b tng ct thp phi dng phng php n mn trong l khoan nh. Cc l khoan phi b tr thnh hai hng vi khong cch gia cc l trong hng v khong cch gia hai hng bng 15 ln ng knh qu mn. Khi lng thuc n np trong mt l khoan tnh theo cng thc (58).14.13 ct cc thanh dm bng g, b tng ct thp hay thp phi p dng phng php n mn p quy nh ti iu 10.

15N mn o cc cng trnh ngm15.1Quy nh chung

15.1.1Khoan n mn o cc cng trnh ngm di t phi m bo cc yu cu k thut sau:

a) C hnh dng v kch thc yu cu. Cc ch o b lm vo phi x l theo ng yu cu thit k;

b) v vn ca t b n ph ph hp vi yu cu bc xc v vn chuyn bng c gii;c) S dng ti a chiu di cc l khoan;

d) Khng nh hng n cc hng mc cng trnh xy dng ln cn nh gin gio, chng k c lp v cng trnh bng b tng ct thp va mi thi cng xong;e) Tng lng kh c sinh ra trong mt chu k khoan n phi ph hp vi nng lc vn hnh ca h thng thng gi.15.1.2Hng o ca cc cng trnh ngm c th nm ngang, thng ng hoc xin vi phng ngang mt gc di 90o. Theo din tch mt ct ngang, cng trnh ngm c chia thnh cc loi sau:

a) Cng trnh ngm loi nh: c din tch di 4,0 m2;b) Cng trnh ngm loi trung bnh: c din tch t 4,0 m2 n 60 m2;c) Cng trnh ngm loi ln: c din tch trn 60 m2.15.1.3Ph vn cc nham thch khi o ton b gng tng bng phng php n mn l khoan nh. Ph nham thch v to ng vin bc di ca gng tng bng phng php n mn l khoan ln. Khi o m rng cc ng hm nh c th thc hin bng phng php n mn l khoan ln hoc l khoan nh.15.1.4Chiu su ca cc l khoan nh ph thuc vo chiu di bc tin nh (chiu di o thm sau mi ln n mn). Cng trnh o c mt ct nh trong nham thch n nh, chiu di bc tin ly bng chiu rng ca cng trnh o nhng khng ln hn 1,7 m. Cng trnh o c mt ct ln v trung bnh th chiu di bc tin ph thuc vo kh nng ca thit b khoan o hin c nhng khng ln hn chiu rng ca cng trnh o. Chiu di bc tin trong nham thch khng n nh c xc nh bng tr s cho php o l nc nhng khng b sp.15.1.5Tu theo chc nng lm vic m cc l khoan nh c chia thnh cc loi sau:

a) L khoan to rch: dng to thm mt thong b sung cho cc qu mn trong l khoan to rch c n u tin;b) L khoan ph: dng m rng phn rch c to ra khi n mn trong cc l khoan to rch. S lng l khoan ph tu thuc vo vo kch thc mt ct ngang;c) L khoan bin: dng ph nham thch cho n v tr ng vin thit k. Cc l khoan ny c b tr theo ng vin thit k cng trnh o v c n ph sau cng;d) L khoan theo ng vin: dng to ng vin chnh xc cho cng trnh o. Cc l khoan ny c n vo t u tin cng vi cc l khoan to rch khi n mn to khe trc, hoc c n ph vo t cui cng khi n mn ln lt t gia ra ngoi.15.1.6Rch thng c s dng o cc cng trnh ngm nm ngang v cng trnh ngm thng ng t di ln trn. Rch hi t c s dng khi o cc ging thng ng t trn xung di. Cho php s dng rch hi t hnh nm trong cc cng trnh ngm nm ngang nu s phn va ca nham thch khng th s dng rch thng.15.1.7 Chiu su L ca cc l khoan c ng knh nh xc nh s b nh sau:

a) Cc l khoan bin, l khoan ph v l khoan theo ng vin xc nh theo cng thc (59) :L =

(59) b) Cc l khoan to rch thng xc nh theo cng thc (60):

L = 1,1.

(60) c) Cc l khoan to rch hi t xc nh theo cng thc (61):

L = 1,1.

(61) trong :wz l chiu di bc tin nh;( l h s s dng l khoan, ly bng 0,8 n 0,9;( l gc nghing ca h khoan so vi mt phng ngang ca gng tng.d) Chiu su chnh xc ca L phi cn c vo kt qu n mn th nghim ngoi hin trng.15.1.8S lng l khoan nh to rch v s b tr l khoan ph thuc vo cng, dai v n nh ca nham thch, ly trong phm vi nh sau:a) i vi rch thng: b tr t 6 l khoan n 8 l khoan, khong cch gia cc l khoan lin k nhau t 0,15 m n 0,30 m;

b) i vi rch hnh nm: b tr t 4 l khoan n 8 l khoan, khong cch gia cc l khoan lin k nhau t 0,30 m n 0,50 m;

c) i vi rch hnh thp: khong cch gia cc l khoan lin k nhau t 0,60 m n 1,00 m. S lng Nrch cc l khoan trong rch hnh thp xc nh theo cng thc (62): Nrch =

(62)trong :R l bn knh tnh t tm cng trnh o ti ming l khoan, m;

ar l khong cch gia cc h khoan rch, m;d) Cng trnh o c mt ct nh, s lng l khoan to rch c th gim xung cn t 2 l n 4 l.15.1.9 S lng l khoan to ng vin trong gng tng (Nvin) xc nh theo cng thc (63):

Nvin =

(63)trong :U l chu vi cng trnh o, m;ak l khong cch gia cc h khoan trn ng vin, m. Tu theo cng ca nham thch, ak c th ly trong phm vi t 0,3 m n 0,6 m.

Cng trnh khng c o bng phng php n mn theo ng vin th s lng l khoan bin cng xc nh theo cng thc (63) nhng khong cch ak ly trong phm vi t 0,7 m n 1,0 m.15.1.10 S lng Nph l khoan ph xc nh theo cng thc (64):

Nph =

(64)trong :Sdao l din tch mt ct cng trnh o trong khi thi cng, m2;

Srach l din tch y ca rch, m2;

Sk l din tch gng tng ng vi mt l khoan ph, m2.15.1.11 Tng s cc l khoan trn gng tng, k hiu N, c xc nh theo cng thc (65)

N = Nrch + Nvin + Nph

(65)15.1.12 Khi lng Q ca bao thuc n trong l khoan xc nh theo cng thc (66)

Q = C.L.P

(66)

trong :L l chiu di (chiu su) l khoan, m;

P l sc cha thuc n ca l khoan, kg/m;C l h s np y l khoan:- i vi h khoan to rch: C ly t 0,7 n 0,8; - i vi h khoan ph v h khoan bin: C ly t 0,5 n 0,7;15.1.13 Khi lng bao thuc n trong cc l khoan theo ng vin ly trong phm vi t 0,2 kg/m n 0,4 kg/m chiu di h khoan.GHI CH: i vi cc cng trnh c bit quan trng phi dng qu mn gm t 2 si n 4 si dy n thay cho thuc n.15.2Yu cu v h chiu khoan n mn15.2.1Thi cng o cc cng trnh ngm di t bng phng php khoan n mn phi c tin hnh theo ng bn h chiu n mn c cp c thm quyn ph duyt.15.2.2H chiu n mn c lp cho mi cng trnh o da trn c s cc s liu tnh ton, c chnh xc ho bng th nghim hin trng v phi th hin c cc ni dung sau:a) Cc bn thit k cng trnh o: mt bng, mt ct dc, mt ct ngang v mt s chi tit cn thit;

b) c im a cht cng trnh v a cht thy vn;c) Din tch mt ct ngang khi o. Tr s tin ln ca gng tng trong mt chu trnh;

d) S lng, chiu su v s b tr cc loi l khoan trong cng trnh o;

e) Khi lng khoan v chiu di l khoan, lng tiu th thuc n v lng kp mn cn thit cho 1 m di cng trnh o, cho 1 m3 nham thch phi n ph v cho mt chu trnh o;

f) Cc loi thuc n v phng tin kch n;

g) S ln n chm, trnh t n, khi lng tng cng ca cc qu mn trong mt ln n chm;h) Vt liu np bua v khi lng vt liu np bua;

i) H s s dng h khoan;

k) Khi lng nham thch s phi n ph;

l) Bin php thng gi, chng bi v thi gian thng gi cho gng tng;

m) Bin php bo m an ton trong qu trnh n mn;n) Cc ti liu cn thit khc c lin quan n cng tc n mn.

15.2.3H chiu n mn l ti liu c bn thc hin mt v n mn. H chiu n mn phi c tt c cn b, nhn vin, cng nhn v k thut vin, nhng ngi s tham gia thc hin cng tc khoan n mn nghin cu k trc khi tin hnh v n.15.3N mn o cc cng trnh ngm nm ngang15.3.1Cng trnh o c mt ct nh

15.3.1.1 S dng cc l khoan nh gm l khoan to rch v l khoan bin, xem hnh 18.

15.3.1.2 N mn bng chm ngi, chm la in v in theo phng php n chm hoc n vi sai.

Hnh 18 S n mn ton b cc l khoan nh

15.3.2 Cng trnh o c mt ct trung bnh

15.3.2.1 S dng cc l khoan nh gm l khoan to rch, l khoan ph v l khoan theo ng vin. Trong cc cng trnh o tm thi phi thay cc l khoan trn ng vin bng cc l khoan bin nm trn chu vi mt ct ngang.

15.3.2.2 Khi o cc