KHOA HOC VA CONG NGHE MO
CNM
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PHAN TICH ANH HUDNG CUA CHIEU DAI LlTONG NO, CHIEU SAU Ld KHOAN DEN HIEU QUA PHA HUY DAT DA
KHI KHOAN NO D U ' 6 N G HAM
TS. OAM TRQNG THANG Bg Tulenh Cong binh
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hi dao cac dLfdng ham khau dp visa va nho (cd tiet dien <16 m^) thi chieu dai lu'dng no trong lo khoan hay chieu sau lo khoan la mpt thdng so' quan trpng, lien quan den bLfdc dich chuyen gi/dng ham va td'c dp dao ham. ThUc tien va ly luan ve vat ly va cd hpc nd trong cac mdi trLfdng khac nhau deu ehl ra rang vdi mdi gia tri dudng kfnh lu'dng thud'c eCia lu'dng no dai khdng doi, khi thay doi chieu dai iLfdng nd thi ban kfnh vung tac dung nd cOng thay ddi theo [1,...10].Vi vay viec phan tfch cac quan diem tfnh toan va de xua't phUdng hu'dng liia chpn tri sd chieu dai lu'dng thud'c, chieu sau Id khoan dam bao hieu qua sCr dung nang lUdng nd cao la mpt viec lam can thiet
1. Cac quan diem xac djnh chieu sau khoan, chieu dai iLTdng thuoc
Chieu dai lu'dng nd hay chieu sau Id khoan la hai thdng sd cd mdi quan he mat thiet vdi nhau, khi biet dLfdc thdng sd nay thi d l dang xac dinh dUdc cae thdng sd cdn lai, cd dang:
Lk=(L,+U)hayL,=(Ti/U) ^ _ (1) Trong dd: Lk, L,, Lb - Tu'dng ufng la chieu dai Id khoan, chieu dai thudc nd va chieu dai bua; rj - He sd nhdi thude nd trong Id khoan.
Vi vay chi can biet du'dc mgt trong hai thdng sd trong bieu thCre (1) cung ddng nghia viec biet du'dc thdng sd cdn lai. Trong thuc te san xua't thu'dng xac dmh chieu sau Id khoan, sau dd tfnh chfeu dai thudc thude theo (1).
Cho den nay viec xac djnh chieu sau Id khoan cd the chia lam bdn quan diem cd ban sau [7]:
• Chieu sau khoan phu thugc vao chieu rpng dydng ham do A. Ph. Xukhanov de xuat nam 1933;
• Chieu sau cac Id khoan dam bao gia thanh nho nha't cua edng tac khoan cung do A. Ph. Xukhanov de xuat nam 1940;
• Chieu sau Id khoan xac dinh theo dieu kien td chLfc lao dgng cua cdng tac khoan nd, xuc bde, van chuyen do N. M. Pakrovski de xua't;
• Chieu sau Id khoan xac djnh theo phLTdng phap thuc nghiem, phu thupc vao dUdng kfnh va dp eung eCia M. M. Prdtddiakdnov cd dang:
0,085d __ rinse 'tVu>.ia '
L k = -
Vf
m•W"
Tai day: d -Oudng kfnh lo khoan, mm; f-Dp cCmg cua da.
Cac quan diem tren mdi chi phan anh anh hudng cua eae yeu to ky thuat khoan, khdng gian khoan, kha nang tao phlu vang, dieu kien bd tri hdp ly nhan li/c cua day chuyen thi cdng, mCfc dp khd khoan... chUa xem xet anh hudng cua chieu dai Id khoan hay chieu dai lu'dng thudc den hieu qua pha huy da't da. Tuy nhien hang loat cac cdng trinh khoa hpc cCia nhieu nude tren the gidi nhu Nga, Thuy Dien, My, Viet Nam... deu khang dinh khi dydng kfnh thudc khdng thay ddi thi mCfc do pha huy phu thupc vao chieu dai IUdng thude.
2. Cac qui luat ve sU anh hirclng cua chieu dai iLTOng no den mure do pha huy da't da
Nhu da biet, cac lUdng nd tap tmng va lUdng nd dai cung nhu" he thdng cac lyong nd khac (nhU cae hang IUdng nd trong Id khoan) deu dydc sLf dung rpng rai trong thuc tien. Trong tat d cac to/dng hdp khac nhau cd cac dang khac nhau cua tac dgng nd dydc xua't hien trong mpt pham vi xae dmh. Neu IUdng nd la tap tmng thi vung pha hoai cd dang hinh d u , neu lUdng nd ngan thi vung pha huy cd dang elipxdit, cdn neu lypng thude cd chieu dai Idn hdn rat nhieu so vdi dudrig kfnh lu'dng nd thi cd the xem vung pha huy ed dang hinh tru. Tren the gidi rat nhieu nha khoa hpc da tien hanh nghien culi ve anh hudng eua chieu dai IUdng thudc den kfnh thude vung pha huy, mufc do dap v8 chan tang...
Pakrovski G. I. 1954 va Vlaxov O. E. 1957 bang cac phUdng phap khac nhau hai dng da thiet lap be mat trudng sdng pha huy da theo chieu dai tUdng ddi cua IUdng nd. Ket qua ly luan cung da chi ra, khi tang chieu dai tydng ddi lydng nd den gia trj tdi han thi ban kfnh pha hoai tang, sau dd neu tiep tuc tang thi ban kfnh pha hoai dat trang thai bao hoa [4, 5].
CONG NGHIEP MO SO 3 - 2 0 1 0
CNM KHOA HOC VA CONG NGHE MO
Neyman nam 1976 da sCf dung md hinh thuy ddng iLfc hpe (hydrodinamic model) de tfnh toan tdc dp Idn nha't cCia phan tCr xung quanh lydng thudc nd (Vk) va dua vao do de dy doan dUdc ban kfnh vung pha hCiy xung quanh IUdng thudc nd. Cac ket qua tfnh toan cua Neyman cung chi ra rang vdi ty sd chieu dai lydng thud'c tren dudng kfnh cua nd la trong pham vi (L/d)<20-Hl0 thi ban kfnh pha huy cua lydng thudc nd dai khdng ddi. Trong pham vi (L/d)>20-f4b thi khi tang chieu dai lu'dng thude thi ban kfnh pha hCiy cua lUdng nd daf tang va tdc dp Idn nhat cua cac phan tCr da't da xung quanh IUdng thudc cung tang len [10].
Langerfor va Rune Gustafsson cung chi ra rang khi tang chieu dai lUdng thudc thi dudng khang chan tang cung tang, bang thuc nghiem nhan dydc tri sd dudng khang tdi UU tydng Cmg vdi gia tii chieu dai tdi han [8,9].
Hanies va Hagan 1979 da chung minh rang ung sua't pha huy sinh ra khi nd tang len khi chieu dai lUdng nd tUdng ddi dydc tang len tCf 0 den 20, va sau dd giu' nguyen khdng thay ddi. Theo dd, khi suf dung bl sd chieu dai tydng ddi lydng nd bang 20 se dat dUdc mCfc dp dap vd Idn nha't vdi gia tii dydng d n tdi uli [8, 9].
Theo Bhadari 1997 chieu dai lydng thudc nd d mpt anh hudng manh den ban kinh pha huy cua lypng thudc nd dai. Khi lUdng thudc nd ngan viec sCf dung cac lo min dudng kfnh Idn khdng hieu qua. Vdi mpt gia tri dudng d n da cho, khi chieu dai IUdng thudc nd va chieu sau lo khoan tang thi khoang each giCfa cac lo min bat dau tang nhanh, sau do tang vdi mgt tdc dd cham hdn va cudi cung giu' lai d mpt gia tri cd dmh. Ty sd Idn nha't cua khoang each giufa cac Id min va dudng d n ddi vdi mdt loai dat da nao dd co the khdng dat tdi gia tii tdi Uli neu khdng vUdt qua mpt gia tri gidi han cua chieu dai IUdng thudc nd. NhU vay, chieu sau Id khoan (va qua dd la chieu dai lydng thudc nd) d n phai dat mpt gia tii gidi han nao dd de lydng thudc nd dai phat huy dUde hieu qua tdi da cCia nd [8, 9].
Theo Xukhanov, Kutuzov, Ruxov tdn tai mgt ty sd tdi han giu'a chieu dai IUdng thudc nd va dudng ki'nh IUdng thudc nd (L/d);. ma neu Idn hdn hoac bang ty sd nay thi ban thi ban kfnh pha huy da't da xung quanh IUdng thude khdng tang [6]. Nhd nhung ket qua tren, ti-ong cdng tac nd min khai thac md Id thien, da sd eae cdng thCifc tfnh toan cae thdng sd nd min deu ap dung cho tn/dng hdp ty sd (L/d) Idn hdn 20 den 40.
Trong edng tac nd pha da ngam dudi nU6c tu" nam 1989 den 2006, cac nhdm nghien cCry chung tdi do tien sT Le Van Tmng dung dau va giao sy Belin V. A. eua Dai hpc Tdng hdp Qudc gia Md Matxcdva da cd mpt vai cdng trinh nghien cufu ly thuyet va thuc nghiem ve anh hudng cua chieu dai tUdng ddi lydng nd den ban kfnh vung pha huy, kit qua cung nhan dUdc cac qui luat tUdng tu tren. Ket qua nghien cCru da cung da dUdc ap dung vao thUe tien de nd IUdng nd dai nam song song vdi mat thoang khi dao kenh [1, 2].
TC/ viee phan tfch kit qua nghien cuu cua cac tac gia khae nhau ve anh hudng cua chieu dai tUdng ddi lydng nd den tri sd ban kfnh vung tac dung nd bang cac phUdng phap tiep can khac nhau va d pham vi ap dung khac nhau, cd the mt ra mpt qui luat chung la: Dkhi tang chieu dai tUdng ddi lUdng nd den mgt gia tri. tdi han thi kfch thydc vung tae dung nd tang len va neu tiep tuc tang chieu dai tUdng ddi lupng nd thi kfch thudc vung pha huy dat bao hoaD, hinh H.1.
H.1. St/phu thudc cCia ban kinh pha vd dat da cOa luang thuoc no vao t^ sd' l/d: 1 - Viing chieu dai tuang doi luang no nhd han gia tri tdi han; 2 - Viing chieu dai tuang doi lugng no Idn han gia tn tdi han (vung bao hoa).
Bang con dudng thuc nghiem khi nd cac lydng nd dai khac nhau b-ong da't da nhan dUdc dang phu thupc eCia IUdng tieu hao thudc nd ddn vj vao chieu dai tUdng ddi cLia lUdng nd cd dang hinh H.1 [2]. Ket qua nay phan anh nhu mpt budng hdp npi suy qui luat md ta d H.2.
5
0
il,td). L,!d
H.2. Suphu thudc cCia luang tieu hao thuoc no dan vi cOa viing dap va vao chieu dai tuang dd'i cCia lugng no (L/d): 1 - Viing chieu dai tuang dd'i luang no nho han gia tri tdi han; 2 - Viing chieu dai tuang dd'i luang no Idn han gia tri tdi han (viing bao hoa).
Nhin chung cac cdng trinh nghien cCfU deu nhan dUdc gia tri chieu dai lUdng nd tUdng ddi tdi han trong cac da khac nhau dao ddng trong pham vi (L/d),=(20^0).d.
3. PhLTdng hLTdng suf dung hdp ly chieu dai lu'dng no de nang cao hieu qua suf dung nang liTdng no
Phan tfch qui luat ve sU anh hudng cCia chieu dai tUdng ddi lUdng nd den hieu qua pha huy da't da ma md ta d hinh H.2 va H.3 chi ra rang: trong pham vi
CONG NGHIEP MO SO 3 - 2 0 1 0
KHOA HOC VA CONG NGHE MO CNM
chieu dai tUdng ddi cua lUdng thudc nhd hdn gia trj tdi han, thi khi tang chieu dai lydng nd thi kfch thydc vung pha huy tang va lUdng tieu had thud'c hd dan vj giam va khi chieu dai tUdng ddi cCia IUdng thudc vydt qua gia tri tdi han thi hieu qua dap vd dat gia trj bao hoa mac du tiep tuc tang chieu dai lypng thudc.
Phan tfch cac lUdng nd khi dao cdng trinh ngam nhan tha'y rang da sd suf dung IUdng thudc cd dudng kfnh tmng binh tCr 36 den 38 mm, khi dd tri sd chieu dai IUdng thudc tdi han dat (20^0)d=(1080+1520) mm. Trong thUc te vdi dudng ham khau dp vCra va nhd thi trj sd chieu dai IUdng nd hau het la nam dUdi ngudng nay.
Dieu nay cd nghTa la chieu dai IUdng nd thay ddi thi anh hudng den hieu qCia va mCfc dp pha da, tuy nhien khi thiet ke nd thi cdng dydng ham thi yeu td nay hoan toan chua dydc quan tam, chfnh vi vay viee dieu chinh ehl tieu thude nd ngoai thUc te mang tfnh cam tfnh.
Nhu vay de nang eao hieu qua sCf dung nang IUdng nd khi dao ham khau dp vCfa va nhd ti viec tang chieu dai IUdng nd Idn hdn hoac bang gia trj tdi han va khi dd d n tang chieu dai Id khoan tUdng Cmg. Day ed the gpi la quan diem xac djnh chieu sau Id khoan hay chieu dai hdp ly cCia lUdng nd trong dudng ham theo quan diem nang cao hieu qua sCr dung nang lUdng nd.
Chung ta de dang nhan thay quan diem cua M. M.
Prdtddiakanov the hien trong cdng thCfc (2) chi la mpt trudng hdp dae biet cua quan diem dUa ra, tUdng Cmg vdi chieu dai lUdng thudc nam d vung bao hoa.
4. Kit luan
Khi thiet ke cdng tac khoan nd trong dudng ham khau dp vCfa va nhd can lull y hudng nang cao hieu qua nd nhd viec tang chieu dai luong thudc trong pham vi chieu dai lydng thudc nhd hdn gia trj tdi han.
Viec tang chieu dai lydng thudc (hay chieu sau khoan) khdng chi lam tang hieu qua sCr dung nang lUdng nd, ma cdn d i n den tang tdc dp dao Id va lam giam tieu hao thdi gian cho cdng tac nhdi len thude nd, bua, djnh vj Id khoan va viec sCr dung thiet bj khoan, may xuc bdc tdt hdn dan den lam tang thdi gian huU fch cho mgt chu ky va lam giam thdi gian phu trd lien quan den day chuyen san xua't
Khi chieu dai lUdng nd tang vUdt qua gia trj tdi han thi hieu qua nd dat trang thai bao hoa (khdng thay ddi), khi dd can xem xet ky ludng cac anh hudng xau xua't hien do viec tang chieu sau khoan den ehi tieu hieu qua kinh te tdng hdp cua day chuyen khoan, nd, xuc bdc, van tai trong dudng ham.
Tren cd sd danh gia, dU bao cac anh hudng nay, ket hdp vdi nd thuc nghiem cac ddt nd ban dau se cho phep nhan dUdc trj sd chieu sau Id khoan, chieu dai IUdng thudc hop ly.n
TAI LIEU THAM KHAO
1. Le Van Tmng, Bao cao tdng ket de tai d p nha nudc DNd md ludng tren nen da san hoD. Bp Tu lenh Cdng binh. 1990.
2. BennH B. A, flaw MoHr TxaHr.
OKcnepuMeHTanbHoe MayneHne BJinflHUfl flnnHbi noABOflHoro flOHHoro aapafla Ha nonepeMHbie pasMepbi B3opBaHHOM BbieMKM M onpefleneHne
MMHMManbHOM flJlMHbl flOHHblX nHHeMHblX SapflflOB.
BapbiBHoe fleno. MfrV. 2007.
3. BayM O. A., CiaHiOKOBMH K. fl., LUexrep B. 14.
OnsMKa Bspbiaa. TocyAapcTBeHHoe usAarenbCTBO c})M3MKO-MaTeMaTMHeeKoPi nmeparypbi, MocKsa 1975.
4. riOKpOBCKMPi r. H. SaBMCMMOCTb CfjOpMbl 30Hbl AePicTBMH B3pbiBa OT 4)opMbi n pacnonoKeHMfl sapnaos.
BspbiBHoe Aeno N254/11. HeApa. MocKsa. 1954.
5. BnacoB O. E. OcHOBbi repnn AewcTBUfl Bspbisa.
BMA. MocKsa. 1957.
6. KyryaoB B. H., PydyoB B. K. OnanKa aapbiBHoro paspymeHna ropHbix nopoA. MPry, MocKsa 1970. :
7. BepnujBMnM f. A. KopoTK03MeAneHHoe BspbiBaHne npn npoBeAeHnn ropHbix BbipadoTOK.
HeApa. MocKsa. 1969. ^ 8. U. Langerfors, B. Kihistrom. The modern
technique of rock blasting. Stockholm. 1967.
9. Rune Gustafsson. Swedish blasting technique.
Published by SPI. Sweden. 1977.
10. I. B. Neiman. Determination of dimensions of the zone of cmshing of rock in place by balasting.
Gidrospetsproekt, Moscow. Translated from Fiziko- Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 62-67, September-October, 1979. Original article submitted September 13, 1977.
480 0038-5581/79/1505-0480507.50 -9 1980 Plenum Publishing Corporation.
Ngifdi bien. tap: Ho Sy Giao
SUMMARY
Exploitation and analysis of physical and mechanical laws of the lengthy charge to show that, when increase in the length of the charge to the critical value, the dimensions of the demolition area are increased* a specific charge is be on the decrees, if the length of charge is continued more than the critical value, effect explosion attain to saturation.
Thus, to improve the efficiency for using energy of explosion in tunnel blasting must choose the depth of hole with tendency for increase in the length of charge in reasonable zones.
CONG NGHIEP MO SO 3 - 2 0 1 0
