Thong tin khoa hpc cong nghe mo Ltfa chon cac thdng so cd ban CHO CONG TAC KHOAN NO MIN KHI DAO GIENG DUTNG Calculating proper drilling and blasting parameters is one of the important factors in incre[.]
Trang 1Thong tin khoa hpc cong nghe m o
Ltfa c h o n c a c thdng so cd ban
CHO CONG TAC KHOAN NO MIN KHI DAO GIENG DUTNG
Calculating proper drilling and blasting parameters
is one of the important factors in increasing
efficiency in drilling and blasting operations and
driving speed In this paper, the authors provide
some calculation methods of proper drilling and
blasting parameters that have been applied in
Vietnam
ThS NGUYEN DUYEN PHONG ThS DANG VAN KIEN ThS PHAM tiLPC THQ
Trwong Dai hoc Md - Dia chat
ThS TRINH DANG HU'NG
Vien Khoa hgc Cdng nghe Md - Vinaconmin
Viee tinh toan eae thdng s l
khoan n l min hgp ly d l lap hp
chilu khoan n l min la y l u t l
quan trpng trong viec nang
cao hieu qua cong tae khoan
n l min va d l y nhanh t i e dp
dap gilng md Bai bao t i n g
hgp mpt s l phuang phap tinh
toan cac thong s l khoan n l
min dang SLP dung tai Viet
Nam, cac phuang phap kinh
nghiem dang SLP dung tai mpt
s l nude tren t h i gidi, g6p
phin hoan thien viec tinh toan
va lap hp chilu khoan n l min
thi cong gilng md
I Cong tac khoan no min
Hien nay, khi t i l n hanh thi
cdng gilng dCpng, ngudi ta
v i n SLP dung hai phuang phap
n l min la: n l min vi sai
thudng, n l min vi sai tao bien
Ngay nay, vdi viee SLP dung
cae loai may khoan cd cdng
suit ldn, thi nhCpng khd khan
do viec tang khii lugng khoan
khdng cdn la d i l u dang ngai
Ngoai ra, ngudi ta cung da
ehu y nhilu han d i n viee
giam he s l thu'a t i l t dien,
nang eao dp I n dinh chp khii
da xung quanh, giam bdt khd
khan cho cdng tac xuc ble,
van ehuyin Do dd phuang
phap khpan n l min tao bien
da dugc SLP dung nhilu han
1 Cac phu'O'ng phap pha
da tren girang g i l n g Tuy thupc vao d i l u kien dja chit, mCpc dp on djnh eua khii
da, dien tieh dao cua guang gilng, ngudi ta SLP dung ba phuang phap pha da:
- Phuang phap khoan n l chia bae:
- Phuang phap khoan n l hinh x o l n Ic;
- Phuang phap khoan n l toan guang
* Phu'O'ng phap no chia bac: Day la phuang phap p h i biln, phu hgp cho cac gilng
hinh vudng hay hinh chCp nhat Cac cdng tae chinh trong mpt chu ky nhu khoan, nap, n l min thdng gid dugc t i l n hanh tren mpt nu'a mat cat ngang CUE gilng, d i t da sau khi n l min dugc b i n vang xuIng mat e l t ngang cdn lai (thip han), nhd do tao ra mpt
dp chenh cao thuan tien cho thoat nude khi c i n thilt
Cong tae khoan n l min duge thyc hien tugng t y nhu
n l min chia bae nhd eho edng trinh ngam vdi mpt mat t y do phu thCp hci (hinh 1) Cdng tac khoan d u g r thyc hien bang t l hgp may khoan tay chay bang nang lugng khi nen
Hinh 1 Phuo'ng phap khoan no min chia bac khi dao gieng [1]
Trang 2Thong tin khoa hpc cong nghe mo
Hinh 2 Phwong phap khoan no hinh xoan 6c Hinh 3 Phwong phap khoan no min toan mat cat ngang vdi dot pha hinh ndn tai trung tam
Nhuge d i l m cua phuang
phap nay la chia guang theo
bac, do dd, thdi gian thye hien
eae cong tac keo dai, lam
giam t i e dp xay dyng gilng
Do dd, nd thudng dugc ap
dung cho cac gilng cd dien
tich mat cat ngang Idn, hoac
d i t da y l u Viec n l toan mat
elt ngang gap nhilu khd khan
dp khdng cd cac thilt bj ed
cdng suit ldn
* PhiFcng phap khoan n l
xoln 6c
Phuang phap nay dugc SLP
dung d i u tien tai Thuy D i l n ,
phu hgp khi dao gilng theo
hudng tu' tren xuIng vdi dang
mpt hinh xoln I c Chilu cao
cua bac phu thudc vao dudng
kinh cua gilng va khii lugng
d i t da dy kiln n l ra Trong
mdi dgt n l , mpt mat elt hinh
xpan I c dugc n l vdi mpt gde
du Idn d l ed t h i hoan thien
cac cdng viec trong mpt thdi
gian ehu ky da dy kiln trudc
(hinh 2.) [1] Cac l l min trong
mpt dgt n l dugc khoan song
song va ed chilu dai nhu
nhau nen de thyc hien va ludn
tao 6\j<yc mot mat thoang phu
thCp hai Ngpai nhQ'ng uu dilm
v l gia thanh va sy linh hoat cua phugng phap, cdn mpt uu
d i l m khae la chilu dai cac l l min gilng nhau, cd t h i t i l n hanh eae edng viec mpt each
d i n g thdi Cac thdng s l khoan n l min va bien phap t l chCpc thyc hien cac cdng tac khoan n l min dan gian, khong ddi hdi ngudi thg phai cd qua nhilu kinh nghiem Culi cung,
sy pha va da ludn dugc duy tri trong phin sau nhlt, tao
d i l u kien cac thilt bj van tai lam viee vdi nang suit cao
* Phu'O'ng phap khoan nd
toan mat c i t ngang
Phuang phap toan mat cat ngang duge SLP dung r i t p h i biln trpng dap gilng du'ng, khong chl phu hgp eho cac gilng e6 mat eat ngang hinh chQ' nhat ma c6n phu hgp ehp eae gilng c6 mat elt ngang hinh tr6n
Vdi phuang phap nay, c6
r i t nhilu each b l tri cac cac l l
min tren guang gieng gidng
nhu khi 6<.o cac dudng Id va
dudng hirn nam ngang D l
n l min, trude tien c i n tao ra
b l mat thoang cung vdi mdt
s l l l min (nhdm dot pha) trip khi da cd mpt l l khoan dudng kinh Idn hoac SLP dung phuang phap dao md rpng (da cd gilng khoan tien
phong) Guang 6\ygc md
cung vdi mpt s l loai dot pha, chang har dot pha hinh chdp (hinh 3)
2 Tinh toan va dilu chlnh cac thong sd khoan no min cho phu hcrp
a) Xac djnh chi tieu thudc
no (lu'p'ng thudc no den vj)-q(kg/m'^)
Chl tieu thulc n l phu thupc vao nhilu y l u t l khae nhau nhu: tinh j h i t ca ly cua d i t
da, trang thbi t h i nam eua lap
da, kha nang eong pha cua thulc n l , c h i t lugng va vat lieu lam bua, dien tich guang gilng, chilu sau Id min, k i t
e l u thdi min
Trang 3^ ^ ^ T h o n g tin khoa hpc cong nghe mo
v^iiy
De xae djnh lugng thudc
n l dan vj, cd nhilu phuang
phap khae nhau nhu: dya tren
kinh nghiem thi ccng hoae cac
cong thCpc thye nghiem Trong
dd, cac cong thCpc nay c6 xem
xet tdi cac y l u t l anh hudng
khae nhau bang viee SLP dung
cae he s l d i l u chlnh ed anh
hudng d i n gia tri lugng thulc
n l dan vi Song, lugng thulc
n l dgn vj bi anh hudng bdi
nhilu y l u t l va mCpc dp anh
hudng tdi lugng thulc n l dan
vi cdn ehua duge nghien CCPU
d l y du, nen cac cdng thCpc
thyc nghiem chi cho eae k i t
qua g i n dung va ap dung
trong nhCpng d i l u kien nhlt
djnh Chang han, lugng thuoc
n l dan vj ed t h i tinh theo
eong thCpc cua
Pocrovxki.MN[2]:
q = qi.fc.Vc e.kd(kg/m^) (1)
Trong dd:
qi - Lugng thuoc n l chuin
ein d l pha v g 1m^ da trong
trudng hgp n l vang tieu
ehuan, td'c la n l d l tao thanh
mpt phiu n l sau I m va ban
kinh phiu n l 1m (r = W =1m)
(phu thupc vap he s l kien c l
cua d i t da f), cd t h i ehpn gia
tri qi dya tren thye nghiem:
qi»0,1f;
fc - He s l anh hudng eua
dac dilm e l u true d i t da tren
gugng, gia tri fc cd t h i xae
djnh bang thyc nghiem phu
thupc vao dae tinh eua d i t da;
Vc - He s l anh hudng cua
mu'c dp nen ep d i t da, phu
thudc vao s l mat t y do khi
guang ed hai mat t y do hoac
Sg > ISm^ thi Vc= 1,2^1,5,
nguge lai, n l u ed mpt mat t y
do, Vc tinh theo cong thCpc:
V , = - 6,5
(vdi Sg la Dien tich dao eua gilng (m^) [2]); hoac theo Taranop, v^ 3./ (vdi
no, e = - 380em^ la su'c
Sc la dien tieh ben trong vo ehing cua gilng (m^) [2]) D l i vdi gilng dao trong da dinh
k i t ran cCpng, thudng ehpn Vc
=2, khi dd ccng thCpc tinh lugng thulc n l dan vi khi dao gilng cua Poerovxki.MN ed dang:
q = 2.qi.fce.kd;(kg/m') (2)
- e: He sl anh hudng bdi kha nang edng nl cua thulc
380
cdng pha cua thulc no chuan Dinamit 62% ;
- Ps: SCPC edng n l eua thulc n l SLP dung (cm^);
- kd: He so anh hudng eua dudng kinh thdi thulc:
k - ^ •
- 6( Dudng kinh eua thdi
thulc duge SLP dung (m)
Ngoai ra, theo tieu chuin xay dyng SNIP (Nga), thi lugng thulc n l dan vj cdn cd
t h i xae djnh theo cdng thCpc:
(5,4 + 0 , 8 5 / , ).e.;t
Cd t h i t h i y nhuge dilm eg ban cua cac cdng thCpc thyc nghiem tren la gia tri q tren chua xet d i n anh hudng cua nhdm dot pha dugc SLP dung, chilu sau lo khoan tren gugng H l u h i t cac cdng thCpc tren dugc xay dyng trong nhQ'ng d i l u kien nhlt djnh nen khi tinh eho nhQ'ng
d i l u kien khae ta chl thu dugc nhQ'ng gia trj g i n dung Ngoai
ra Wild (1984) da dua ra mii quan he giCpa gia trj lugng thuoc
n l dan vj vdi dien tich guang gilng dya tren kinh nghiem thi cong mpt s l gilng tai Nam Phi vdi dudng kinh thdi thulc 32mm nhu hinh 4 [1]:
(kg/m^) (3)
P va
K = 36
b) 8 6 lu'p'ng 16 min tren gu-o-ng (NQ); 16
s l lugng 16 min tren gugng gilng phu thudc vao dien tieh mat cat ngang eua guang, tinh chit ea ly cua d i t
da, loai va d i e tinh thulc n l
va he s l nap min Ngugc lai,
s l lugng l l min lai anh hudng
d i n khii lugng eong tac khoan, mCpc dp dap va d i t da, mCpc dp ehinh xac v l tao bien cua gilng va cac y l u t l khae Trong thyc t l xay dyng gilng,
s l lugng l l min cd t h i tinh theo nhilu phuang phap khae nhau Tuy nhien, thudng SLP dung phugng phap xac djnh
s l 16 min xult phat tu' dieu kien b l tri het lugng thulc n l tieu hap cua mpt chu ky dao eho cac l l min, d l dap vd
d i n g d i u d i t da va tap bien chinh xac chp gilng Cpng thCpc cua Poerovxki.MN [2] da xay dyng tren eg sd dd:
Trang 4Thong tin khoa hpc cong nghe m o
1,27.^.5, _
Trong dd: y - Lugng thulc
n l nap trung binh tren I m dai
eua Id min:
r- n.d^ .a.t^.k ;kg/m
a- He sd nap min ; k- He
s l nen chat thdi thulc khi nap,
theo s l lieu thuc t l k = 0,85-^
0,9;
A - Trpng lugng rieng cua
thulc nl;kg/m^
Khi bilt trpng lugng,
dudng kinh va chilu dai cua
thdi thulc, tinh dugc t i n g s l
Id min tren guang gilng (5):
iV = ^ - ^ ^ ; ( l 6 ) (5)
6" day : Ith - Chilu dai thdi
thulc, m, mth - Trpng lugng
cua thdi thulc, kg
s l lo min theo tinh toan se
dugc d i l u chlnh qua cdng tac
no thyc t l Ngoai ra, s l lugng
lo min c i n thilt tren mpt
gugng gilng (chua bao gom
cac 16 min tren bien) cd t h i
dugc xac djnh theo kinh nghiem Nam Phi vdi dudng kinh thdi thulc 32mm (Espley-Jones va Wilson, 1979) [1] (6):
NG = 2 D] + 20; (16) (6)
s l l l min tren 1m^ guang gilng dugc xac dinh:
N
(ll)
c) Chieu sau 16 min trung binh (I); m
Chilu sau lo min (I) la thong s l quan trpng nhlt, anh hugng tdi khii lugng edng viee, chi phi nhan cdng cua chu ky dao gilng Chilu sau
l l min phu thupc vao cac tinh
c h i t ca ly cua da, dien tich mat cat ngang dao cua gilng, chung loai thilt bj khoan, sa
do t l chCpc edng tae, t i e dp dao gilng va mpt s l y l u t l khae Chilu sau Id min hgp
ly la chilu sau ma Crng vdi nd thi ehi phi SCPC lao dpng, thdi gian va phuang tien dao I m gilng la nhd nhlt Hay ndi each khae, n l u chpn dugc chilu sau Id min hgp ly se
gdp p h i n lam gia tang t i e dp dao gilng, tang nang suit lao dpng va giam gia thanh xay dyng gilng Khi chilu sau Id min nhd (l<2m) thi thdi gian
t i l n hanh cae cdng tac phu tinh chp I m tiln guang gilng
se tang len Cac edng tae phu
d n k l d i n d day la thdng gid, cong tac chuin kit khi khoan Id, nap va n l min Khi chilu sau
16 min Idn thi t i c dp khoan se giam xuIng dac biet la khi khoan bing may khoan tay va
he s l SU' dung 16 min cung giam, ca hat d i t da tang len Khi n l cac 16 min chilu sau nhd thi mpt p h i n nang lugng
n l se t h i t thoat theo cac khe nCpt ra ngoai kh6ng khi Cang tang chilu sau l l min thi phin nang lugng n l duge SLP dung hQ'u ich se tang len, vi t h i lugng thulc n l dan vi se giam khi r|= const, edn khi chilu sau l l min Idn I > 1^, do cac Idp da d trong bj nen ep
r i t manh dan tdi lam giam r|
va lam tang ca hat cua d i t da
n l ra Bdi vay, 6k he s l SLP
dung Id min khdng doi
^, ^
f(l) khi q = const
O Q "^ 20 30 40 50 60 70 80
Sa(m
Hinh 4 Sy phu thudc cua luo'ng thuoc no don W Hinh 5 Bieu do quan he giwa he so sw dung lo
vao dien tich gwang gieng [1] min, Iwgng thudc no don vj v&i chieu sau 16 min
Trang 5Thong tin khoa hpc cong nghe m o
r|=const c i n tang lugng thulc
n l dan vj len Nhu vay, t i n tai
gia tri chilu sau l l min hgp ly,
Cpng vdi nd thi nang lugng n l
se dugc SLP dung t l i da bao
dam he s l ri la Idn nhlt va
lugng thulc n l dan vj la nhd
nhlt trong d i l u kien tinh c h i t
cua d i t da va dien tich mat cat
ngang guang gilng da xac
djnh Vdi gilng dCrng thi Im =
( 3 ^ ) m , gia trj nay se tang len
Sy anh hudng cua chilu sau l l
min tdi lugng thulc n l dan vj
va he s l SLP dung l l min 6wac
t h i hien tren hinh 5 [3]
Khi he s l kien s l eua d i t
da giam, dien tieh guang
gilng tang va nguge lai
Lya chpn chilu sau 16 min
c i n tinh d i n trinh dp t l ehCrc
va ca khi hoa cdng tac d
guang gilng Thdi gian hoan
thanh mdi nguyen cdng cQng
nhu thdi gian toan bd chu ky
dao d i u phu thudc vao chilu
sau Id min duge lya ehpn
Chp nen, d l thuan Igi cho
edng tae t l chCpc thi chilu sau
16 min c i n dugc chpn sao cho
thdi gian cua mpt chu ky dao
gilng la udc s l cua thdi gian
mpt ngay dem lam viec tCpc la
hoan thanh mdt hoae hai ehu
ky trong mpt ngay dem
Chilu sau Id min ed t h i
dugc lya chpn theo kinh
nghiem hoae tinh toan theo
eae cdng thCre thye nghiem
Hien nay, ed r i t nhilu cong
thCpc thye nghiem de tinh
chilu sau 16 min Chang han,
6k bao dam SLP dung h i t cong
suit eua cac thilt bj thi cong
trong nhQ'ng d i l u kien dja c h i t
md khae nhau, to chCpc t i t
cac cdng viec tai guang gilng, thi chilu sau 16 min hgp ly phai duge xac djnh theo thdi gian thyc hien cac cdng viec trong mpt ehu ky, nghTa la:
/-/(?-«) = /(Z^) (7)
Vdi tj - Thdi gian thyc hien eae edng tac trong mpt chu ky dao gilng
Xae djnh chilu sau 16 min theo dilu kien bilt trudc thdi gian mpt chu ky dap, mCpc dp
t l chCpc va ca gidi hoa eae cdng tac thi cong (c6ng thCpc Poerovxki.MN )
- Trudng hgp dap gilng theo sa d l phli hgp: thdi gian cua mpt ehu ky dao gilng (Tck) dugc tinh theo cong thCpc:
+ tbx + 1 , •ch
Tck - tk + tn + ttg tp; (8)
Trong dd:
tk - Thdi gian khoan 16 min tren guang,h; tp- Thdi gian nap thulc n l min, h; ttg - Thai gian thdng gid va dua guang vao trang thai an toan sau khi
n l min,h; tbx- Thai gian b l e xuc d i t da d guang gilng,h;
tch- Thdi gian ching gilng (ching tam hay ching c l djnh) h; tp - Thdi gian hoan thanh cac cdng tae phu nhu dua guang vao trang thai an toan, dua ngudi len xuIng, nang ha san treo
Thay eae gia trj thdi gian tren vao edng thCpc (8) ta e6 [3]:
T
-^CK
N.t„
+ ' « + ^
Khi ching e l djnh bang be tong:
L N •
K.T,, S,.ri
- - - + (Sr
"cl,
-5,,
•M,
)ri
1 =
(10)
- Trudng hgp dao gilng theo sa d l nii tilp hoae song song: thdi gian ching c l djnh hoan toan n i i tilp (theo sa d l dao gilng n i i tilp) hay tnjng (theo sa d l dao gilng song song) vdi thdi gian khoan l l min, ble xue d i t da va ching tam thdi Thdi gian ching tam thdi cd t h i trung vdi thdi gian khoan l l min va ble xuc dit da
Do dd chilu sau l l min cd t h i xae djnh theo cdng thCpc (11) [3]:
K.Tr,
(11)
Trong dd:
8 - He s l lam d i n g thdi giCpa cdng tac ching tam thdi
va dao, b i c xuc d i t da, s = 0,2^1
Thdi gian hoan thanh cac cdng tae phu, phu thupc vap
sa d l cdng nghp dao gilng cd
t h i chpn nhu sau: Khi su' dung sa d l n i i t i l p va song song thi tp =(0,75^1,25)h, khi SLP dung sa d l phli hgp: n l u khoan bang bua khoan tay va
b l e bang may b l e loai nhe: tp
= (0,5^1,1)h; khi khoan bing khoan t l hgp va b l e bang may b i c loai nang thi tp =(1,0 -^1,5)h Khi SLP dung sa do song song vd bao hilm (vd Chan) [3] (12):
/ =
-NX
"- + t,.,+t
n IS (12)
N S ?j.k^^
~ + —5
(9)
Chieu sau Id min cdn ed
t h i xac djnh theo nang s u i t
Trang 6Thong tin khoa hpc cong nghe m o
thiet bj (cdng
X.A.Fodrop)
/ = - 0,8.7;,
thCpc cua
,[3] (13)
/W
m.v
V7
Pit,
Trong do: A, - He s l lam viec
ding thdi giQ'a cdng tac khoan
Id min va ble xue d i t da,
X = 0,2^0,6 Ngoai ra, cd
t h i xac djnh chilu sau Id min
dya tren t i c dp dap gilng yeu
c l u (dy kiln) trong mpt thang
(V,h) theo cong thuc (14) [4]:
V T
1 = '-J^^ (14)
Trong do: Nth - S l ngay
cong tac trong thang (thudng
chpn 26 ngay), Tck - Thai gian
mpt chu ky thi cong gilng; nca
- So ca lam viec trong ngay
dem; Tc - Thdi gian mpt ca, h;
kt - He s l ehuin bj; kt =
0,7-^0,8, Vth - T i c dp dao d y
kiln trong thang, (m/thang)
Chilu sau Id min xac djnh
theo cac dilu kien tren c i n
thda man d i l u kien (15) [5]:
l t r > l > l b (15)
Trong dd: Itr, lb - Chilu sau
16 min tinh theo d i l u kien bam
nudc va true tai
Ngoai ra, chilu sau Id min
CO t h i xac dinh gian t i l p qua
bilu dp xac djnh chilu sau 16
min Wild (1984) da d l nghj
chpn t i l n dp gan dung theo
dien tich guang (hinh 6)
d Chi phi t h u l c no cho
mot chu ky dao: La lygng
thulc no tieu hao d l no d i n g
thdi t h i tich d i t da d guang
trong mpt chu ky dap gieng:
Q= q.Sg.l;(kg)
3 Phu'O'ng phap tinh toan
cac thong s6 co* ban theo
t h y c nghiem
- Xac djnh dudng can:
Dudng can cua gilng hinh trdn dugc xac dinh [6]:
W = 0 , 0 1 2 ( ^ + l,5)rf,m
(16)
Trong dd:
/i - Trpng lugng rieng cua
thulc no;(g/cm^), y^- Trpng
lugng rieng cua da;(g/cm^)
dt - Dudng kinh cua thdi thulc; mm
- s l lugng 16 min tren guang gilng:
Trong dd: Rg - Ban kinh dao cua gilng; m
- Dudng can thyc t l :
IR B„ = ^ ; m [ 6 ] (18)
" 2 7 V G - 1
- Khoang each giQ'a cac 16 min trong mpt vdng;
b = W;m(19)
- s l lugng Id min trong mpt vdng [6]:
K 2.n.R, •G
; 16 (20)
- Khoang each thyc t l giQ'a cac Id min[6]:
2 ^ ^ ^ ^ (21)
K
- Chilu dai tien dp n l [6]:
Ltd= 2W; m (22)
- Chilu dai khpan them [6]:
Ikt = 0,3W (23)
- Chilu bua min thulc [6]:
lb = 0,5.W (24) -Khpang khoan ra ngoai [6]: L^ = 0,1+ l.tg(2°); m, / = : ^ ; m (25)
/ / /
y'
' • ^
^^
^ r-i''"
cf- 7-0 S
; *>
Hinh 6 Lya ehgn tien do gin dung theo dien tieh gwong
gieng [1]
II K i t luan Nhin chung, cd nhilu phuang phap d l xac djnh cac thdng s l khoan n l min khi dao gilng dCpng d md Cac thdng s l nay thudng phu thupc vap r i t nhilu y l u t l khae nhau, do dd cae gia tri tren cd tinh c h i t djnh hudng ban dau Gia tri nay c i n dugc
d i l u chlnh theo hien trudng
d l phu hgp han vdi d i l u kien thyc t l
Tai lieu tham khao
[1] Carios Lopez Jimeno Drilling and Blasting of Rock -Rotterdam -1995
[2] Nguyin Cong Trjnh
-Hudng din thi cong gieng dung
- T1,T2- Dai hpc mo - Dia chit
-1971
[3] - Pakrovxki N.M - Oao
va dao sau gilng mo (ban tiing Nga) Nha xult ban Ldng d i t -Moskva- 1967
[4] - Boki B.V.va nnk - Cong nghe va co khi hoa xay dyng cong trinh ngim va m6-(Ban tiing Nga) Nha xult ban Long dit -Moskva-1971
[5] Kartojia B.A.va nnk -Xay dyng md va cong trinh nglmTap 1 (ban tiing Nga) -Nha xult ban Vien Han lam Khoa hpc Mo - Moskva- 2001 [6] Calvin J.Kenya,Ph.D Blasting Design Rotterdam -Ohio-USA-1995