Khi sudn ting dugc cau tgo bdi cdc khoi da phan Idp cdm vao khdng gian khai thdc vdl gdc nghieng p = 20•^50° [3], d l dam I n dinh eho cdc cdc tang khi cat gdc doc sudn tang Idn hon gdc
Trang 1\4JGHIEN CI)U LU'A CHON GIAI PHAP DAM BAO ON DjNH
CHO ztfma nan no THfiN t>EO Nfii
Recently, in the coal mining process, at the South slope
of Deo Nai coal mine, there have the failure phenomena
Basing on the determined reasons causing failures, the
researchers have selected the solutions for ensuring the
stability at the South slope to the level of -345m as its
scheduled design
TS L U U V A N T H I / C
KS Le XUAN THU
ThS D6 KI^N CLJ'6'NG
Vi$n Khoa hoc Cdng ngh$ M6 - Vinacomin
Bien tap: KS Ph^m D$i Hai
Bd try Nam, md than Deo Nai, trong qud trinh
khai thdc, nhieu ndm dd lien tyc xdy ra trugl Id
Tren eo sd nguyen nhan tnj-gt da duge xdc tSnh,
tien hdnh nghien ciru lya chpn giai phdp dam
bao I n djnh cho bd try khai thdc den k i t thue
-345m theo thiet k l
Cdc k i t qua nghien ciru trudc day ve on d\nh
cua bd md Deo Nai da xdc dmh nguyen nhan
gdy trugt Id cua bd try Nam, md than Deo Nai
Theo dd, vigc trugt Id cua bd try Nam dugc
quylt djnh bdi cde y l u t l ty nhien vd cdng nghe,
nhu c l u triic dja tang, tinh ehIt b i n , dae tinh
ehira nudc vd tdng tru nudc nglm cung nhu luu
thdng nudc trong dja t i n g [1 ], [2] Cdc thdng s6
cua hg thong khai thdc, nhu chilu cao bdm try
lien tyc vugt qua chilu cao I n djnh gidi han cho
phep
Bd try Nam dugc c l u tgo bdi cae Idp da elm
vdo khdng gian khai thdc vdi gdc doc tir 25-^35°,
trong dja ting t i n tgi ede mat giam y l u t y nhien
theo tilp xiie Idp vdi dp ben rat thap (C'=0,017
MPa; cp=17.0°), nudc nglm cd mgt trong dia
tang dudi dgng khdng dp, h l u nhu khdng dugc
hg thap trong qud trinh khai thdc xuong sau, khi
do, chilu cao I n djnh gidi han khi cat tang theo
mgt Idp (a = p) H £ 120m De nang eao on djnh
cho bd try cd t h i lya chpn dp dyng mot s l gidi
phdp chu ylu sau:
1 Gia cudng khdi dd bdng be tong phun
Be tdng phun dugc su- dyng rpng rai d l nang
cap I n djnh cdc bd doc, tudng cdc h i ddo sdu
vd cac cdng trinh nglm
Bd tdng phun sir dyng chu y l u d l tdng mu-c
dp on d^nh cho cdc mat Ip dd, be mat dd nirt ne
n l u khdng dugc xir ly b l mgt 10 dd ed t h i bj hu
hgi dudi ede dieu kign biln d l i do udt vd khd
Be tdng phun cOng cd hieu qua doi vdi dit, edt
vd dd dam rdi rac
Be tdng phun dgc bigt ed hieu qud d l nang cao on djnh d cae cdng trinh nglm, thudng kit hgp vdi ludi thep vd khi c l n thiet, kit hgp vdi khung thep nhe; nd Id vgt ligu eo ban trong thi edng dudng ham Ao kilu mdi Hg thing do be tdng phun duy tri sy tiep xue chat che vdi mat
dd vd cung giam sy djch chuyin eiia dd d i n mire dp nhd nhit Cd hai phuong phdp phun be tdng, phun khd vd phun udt
2 Gia c u v n g khdi da va cac mgt y l u bang giai phap xi mang hoa sau
Xi mdng hod sau Id bom phyt dung djch xi mang lap day cde lo rdng, khe nut eua d i t dd Dudi dp lye bom phyt nhat dinh, thdng qua ede
lo khoan hay gieng dirng nham tang cudng dp bin, kha ndng ehju tdi vd ngdn chan ddng ngam, nang cao dp on djnh eho bd md, giam hg so tham nude cua dat dd phan bo sau trong dja tang
3 Gia cud'ng mai d i e bdng neo Vigc diing neo de dam bao on djnh eua mai doc da mdi hoac da cd vd cdc ho dao nglm trong dd dd dugc thilt lap tot cho hau hit cde loai dd Tuy theo hoan canh quy djnh, cdc neo
cd t h i disac diing lam phuong tien rieng d l tao
on djnh hogc ehung sir dyng phli hgp vdi cdc dang gia c l khdc nhu be tdng phun, xd thep, k i t
c l u giu bdng be tdng
Cdc kilu phd hoai chinh phai k l d i n trong mdi doc vd cdt da dugc the hign tren hinh 1 Cac
eo c h l sau day cd t h i dugc ghi nhgn, don le hoae phoi hgp:
- Pha hogi theo mat tilp xiic dd y l u ;
- Phd hogi djnh trudc dgc theo mgt hogc
KHCNM S 6 2/2015* DIA CO MO
Trang 2Phan IIJC phdp tuyfr
a) Trt/gf diy hoic cic mit phing lOp;
b) Tnfot trin cic khe nOt;
c) Trupt trin chd dui doan hoic cic mit phing
nghlOng; d) Lit; e) Ndm phi ho$i;
Hinh 1 Cic kliu phi ho^i nguyin tic trong mii ddc
vi chd cit di
nhilu khe nirt;
- Phd hogi kilu nem dgc theo cae khe nirt
giao nhau;
- Phd hogi dpc theo cdc c h l phan each yeu
cdc viing cat hogc be mat phd hogi cd tip trudc;
- Pha hogi Igt trong dd cd cdc khe nirt an sau
Phdn tich khli dd hoac nhO'ng viing cd khd
nang khdng I n djnh cd t h i thuc hien bang cdch
xem xet cdc lye ngodi tdc dgng tren khoi vd cdc
vung don khi diing phdp phdn tich dOng hgc don
W = Trpng lupng kh6i
Hinh 2 Phin tich dan giin dn dinh ciJa cic mii dOc
trong di
gian (hinh 2),
De chl ddn, do sau cua neo ed t h i dugc xdc djnh bing cdch diing cdc thdng so thich hgp
trong cdng thCyc cua bang 1
Trong dd:
T - Dg b i n ehju eat eua da, kN/m^;
St - Hg so an todn ve phd hoai (trong thyc t l diing gid trj tip 2-5-3),
s - Khoang cdch gitra cae neo, m;
O' - Gde ma sdt cd hieu qua di qua eae cho
nirt gay trong khoi dd, dp;
Tw- Tdi trpng lam vigc tren neo, kN;
Y - Trpng lugng don vi cua dd, kN/m^;
yw - Trpng lugng don vj eua nude, kN/m^ Kinh nghi$m thuc t l vdi cdc neo nghieng hudng xuIng trong dd cho thiy, phd hogi ehung cCing vdi b l mgt lop tren khdng xay ra d l i vdi t j
s l dp manh (h/D) vugt qua 15, (h Id dg sau tinh
d i n dinh cua bau neo va D la dudng kinh cua
Lo^i da
Di khflng dong nhit
Bd niPt ne kh6ng theo
quy ludt
oa nirt ne bj ngdp kh6ng
theo quy lu$t
Cong thOv cho d^ siu cdn
Mdt neo
•^1^4.441
%m't
•1 "'""• 1 iW-r.W*)
Tuyin nhiiu neo
2.830
vl?^J
vlo-j-.wvj
C/Jliy
Si2+4: GSc dinh bSng 90° (gia
thik)
KMCNM 5 6 2/2015* D|A CO MO
Trang 3CO bio v$ neo cd djnh
(a) Ki^u A (b) Kilu 8 (c) tGiu C (d) Kilu D
Cic kliu neo phun vQ'a xl ming Hinh 3 Neo diin hinh trong di, khdng dinh bim trdn sudt chidu dii diy neo ti/ do
b l u neo) Ooi vdi cae neo manh (h/D>15) co che
pha hogi trong da cd xu hudng cue bg d viing
b l u neo Da nirt ne bj ngdp khdng theo quy luat
Hi$n nay d l gia co cae mdi doe, bd md ngudi
ta dp dyng p h i biln hai logi neo' Neo be tdng
cot thep vd neo chat deo c l t thep Tinh chat co
ban cua chiing dugc t h i hign tren hinh 3
Khi sudn ting dugc cau tgo bdi cdc khoi da
phan Idp cdm vao khdng gian khai thdc vdl gdc
nghieng p = 20•^50° [3], d l dam I n dinh eho cdc
cdc tang khi cat gdc doc sudn tang Idn hon gdc
nghieng cua Idp at > p, ed the ap dung giai phap
gia cudng sudn tang bang cpe neo be tdng elt
thdp, so do b l tri cac cgc neo tren tang diyoc
gidi thi§u tren hinh 4
S O D O B O T R I C ^ C I - W
Hinh 4 So dd bd tr! h$ thdng cic cgc neo bO tdng
cdt thip gia ci/Ong suxyn ting kdt thuc
Trong trudng hgp ndy, cdc cgc neo can dugc ddt sau hgn mgt trugt thir d p (cdc mat yeu) trong ting tip 3-H5m
Sire ehju tai cua cgc neo vd cdc thdng so neo theo Iln lugt duge tinh todn xdc djnh theo cdc c6ng thirc:
- Sire ehju tdi cua epc neo Q:
Q = RaFa + RbFb, T; (1) Trong dd:
Ra - Khdng lue cat tinh todn cua cot thep, kG/em^;
Fa - Dign tich mat cdt cua cot thep, em^;
Rb - Khdng lye cat cua be tdng, kG/cm^,
Fb - Dien tich mat cat cua cpe be tdng, cm^;
- So lugng epc neo theo mat cat:
" = - ; (2) Trong dd:
AT - Lye gay truot eua khoi dd, T;
Q - Sire ehju tdi eua epc, T;
L - Chieu dai eua mgt y l u , m;
D l i vdi bd try Nam, md than Deo Nai, de
dam bao on dvnh eho sudn tang bang phuong
phdp neo bang cgc be tdng c l t thep, cac thdng
so neo duge xdc djnh nhu sau:
- Dudng kinh lo khoan neo: DK = 230mm;
- Dudng kinh epc neo: DN = 200mm (tilt dign trdn hoac vudng);
Trang 4- Chieu ddi neo: Li = 14m; L2 = 8m;
- Khoang cdch giii'a eae epc neo tren mat tang
ai = 7m;
- Khodng each tir mep tang d i n hang neo thir
nhat: 3m;
- Khoang each gCra eae hang neo: az = 5m
Doi vdi cdc bd md Ip thien Viet Nam, giai
phdp ndng cao on djnh bang neo ehua dugc dp
dyng do chi phi Idn vd thi edng phirc tgp
4 Phu'cng phdp d i l u k h i l n I n djnh
Dam bdo dp on ^nh cho cdc bd md trong qua
trinh md rpng vd ddo sdu cde md lg thien bang
giai phdp dieu khien tire Id sir dyng cde gidi phdp
cdng nghg d l dieu chfnh trgng thdi vd cdc thdng
s l hinh hgc cua bd md trong tirng giai dogn khai
thdc cy t h i , dam bao cho bd md ludn on djnh
Trong qud trinh thilt ke khai thdc, c l n ldm rd
cdc khu vye ed t h i bj biln dgng can cu vdo sy
cd mgt cdc Idp dat dd y l u , cde mat y l u ty nhien
nhu mat Idp, phan Idp, mat pha huy elm vao
khdng gian khai thac Trong qua trinh khai thde,
trinh ty khai thde c l n tinh tdi cdc khu vyc nay
Cde hao md vfa c l n duge dat trong viing dat da
I n djnh Trong dilu kign cho phep cde viing cd
c l u trOe mlm yeu nen dua vdo khai thac sau
ciing de dam bao thdi gian ton tgi Id ngan nhat
Trinh t y khai thdc can dugc lya chgn sao cho
bd c6 djnh khdng edt chdn cde Idp dd cam vao
khdng gian khai thde, tao gde doe sudn tang
theo gde die mat Idp vdi chilu cao gidi hgn on
djnh cho tirng khu vuc cy the
Trong khu vye y l u , c l n tang eudng dp khai
thac d l dam bdo kit thiic khai thde khi bat d i u
xay ra pha biln dgng tieh cue mdi (nhu cudng
dg djch ehuyin tuyen edng tdc, t i e dp xuong
sau ) Khi edng tdc md t i l n g i n tdi bien gidi k i t
thiic bd dirng tgm thdi, n l u dieu kidn eho phep
thi khai thde theo Idp ngang va n l min tap bien
bang cac Id khoan nghieng
Trong thyc t l khai thdc, nhilu khi khdng the
dipng dugc qud trinh khai thae, ma can phai khai
thdc trong viing bj bien dgng, vdi toe dp biln
dgng chua vugt qud toe dp biin dang gidi han,
khi dd, vigc khai thae can dugc tiln hanh vdi
thilt bj boe xuc cd tinh eg ddng cao, nhu may
xiic thuy lye g i u ngugc, mdy xiic tai
Vdi cac bd md cd ehilu cao Idn hon 200m va
duge eau tao bdi eae idp ddt dd cam vdo khdng gian khai thdc vdi gdc d i e p > 20°, c l n cat gde doc sudn tang bang gdc doe mat Idp (a = p) Trinh ty dp dyng giai phap dilu khiln SLP
dyng edng nghe khai thde d\xqc thyc hign theo
tuan t y sau:
- Bang thye nghi$m, xdc djnh t i e dp biln dang gidi han cho phep (Vgh) cho tirng khu vyc
bd md cy the
- Thilt ke bd md cdt tang vdo tm vdi hg so dy tru on djnh n = 1,11
- Tiln hdnh lap cdc tuyln quan trie djch dgng
vd quan trac (^nh k>f, xac djnh tie dp djch chuyin cua bd V
- Khi t i c dg djch ehuyin V > 10mm/ngdy dem vdo miia khd vd > 20 mm/ngdy dem vgo miia mua, kilm tra Igi dp I n djnh cua bd md Neu hd
so on djnh tinh todn cua bd n < 1,05 ein dilu chfnh ede thdng so hinh hpe cua tang bang cdch
md rpng chieu rdng mat tang, giam chieu cao ciia ting Tiln hdnh kiem tra dO I n djnh eua todn
bd, dua bd ve trgng thdi I n djnh vdi hg s l dy tru'n = 1,10
Ap dyng giai phap dilu khien on dinh bd mo trong qua trinh khai thdc cho phep hodn todn chu dpng dieu khiln qud trinh biln dang cua bd dam bdo khdng nhO'ng an todn eho qud trinh khai thac xuong sau ma edn cho phep giam d i n mirc
it nhat khli lugng dat bde xir 1;^ ngoai gidi hgn trong ting giai doan khai thac xuIng sdu cua mo
5 LiKa chpn giai phdp dam bao I n djnh cho b d tru Nam
Can cir vdo thilt ke khai thde vd nguyen nhan trugt Id tgi bd try Nam, bd try se khdng dam bao
on djnh khi tien hdnh khai thdc bdm try lien tyc den k i t thuc -330m theo thilt k l (chilu cao bd
md 450^80m; a = p = 25^33°)
Vdi c l u tn^c dia tang cua bd try Nam cho phep xem xet dp dyng gidi phdp gia eudng khli
dd bdng neo be tdng e l t thep, neo irng suit trudc bing thanh neo, day neo hay neo chit deo; han che eua giai phdp nay Id chilu sdu neo
bi hgn che Hien nay, phin Idn cdc logi neo dugc che tao cd chilu dai khdng qud 10m Vige dp
dung giai phap neo dk gia cudng khli dd theo
mat Idp gap phai nhimg hgn che sau: Chilu sau mat trugt tir 30+50m bi pha huy do trugt Id vdi
Trang 5chieu cao tip SO^ISOm, khdng dam bao an todn
cho qua trinh thi cdng Do vay, giai phdp neo d l i
vdi bd tn,! Nam chl cho phep xem xet k i t hgp vdi
giai phdp hg thip gdc d i e cua bd d nh&ng khu
vyc xay ra bien dang thir c i p vdi chieu ddy khoi
trugt nhd hon 5m de ehong lai qua trinh bong
Idp va sir dyng epc neo be tdng cdt thep khi tien
hdnh cat ting bd try d giai doan kit thiic
Gidi phap dilu khien on djnh bdng cdng nghe
khai thdc doi vdi bd tru Nam Id tinh todn dilu
khiln cae thdng so hinh hpe eua bd, dua bd v l
trgng thai on djnh mdi, do vgy, giai phdp ndy
thudng dugc dp dyng phli hgp vdi giai phdp hg
thip gdc doc eua bd
K i t qua nghien ciru cho thay, bd try Nam, md
Deo Nai hien nay dang d trong trgng thai I n djnh
gidi han (n = 0,983) Qua trinh khai thdc xuong
sdu d i n kit thuc -330m theo thilt k l bam tn^ lien
tyc (a = p) bd try Nam cd chilu eao tip
450-^480m, khdng on djnh (hg so on dinh n =
0,68-^0,85)
Vdi eo c h l trugt Id xay ra tgi bd tm Nam,
theo cae k i t qua nghien ciru da dugc thye hien,
giai phap xu ly duge kiln nghj ap dyng la cat
ting vao try vdi cac thdng so ting duge xdc djnh
nhu sau:
Chieu cao tang: ht = 80-^150m;
Gdc doc sudn ting: at = p = 25-5-33°;
Chilu rgng mat ting: bt = 20^25m
Uu diem cua giai phap nay la dam bao on
djnh cho bd md ( n = 1,145); qua trinh thi cdng
su* dyng ngay cac thilt bj khai thac cua md va
cae dang cdng nghg khoan n l min, b i c xiic van
tai dang duge sip dyng se eho nang suit vd higu
qua cao Qud trinh XLP ly dugc thyc hien theo
trinh ty khai thac xuong sdu da duge thilt k l , do
vgy, trong qua trinh xu ly, ed t h i theo doi qua
trinh on djnh cua bd d l dieu khien cho phep
giam khli lugng theo tinh toan
D I SO sanh higu qua kinh t l ky thugt cua giai
phap dugc lya chgn, tiln hanh tinh toan so sanh
gidl phap dieu khien I n djnh bang phugng phap
c l t ting vdo try theo cdc thdng sd thilt k l da
dir(yc xdc djnh tren todn bd md {phuong an XCF
iy 1) vdi giai phdp neo bdng epc be tdng cot thep
k i t hgp cat t i n g tir eao trinh - 200 den -100m
(phugng dn xCr ly 2) K i t qua tinh todn eho thiy,
vdi 2 phugng dn XLP ly duge thilt ke, dg dn tSnh eua bd tru Nam dugc dam bao vdi he s l on ^ n h n>1,10
Ve mat kinh t l , kinh phi thyc hign ciia phuong dn XLP ly 1 Id 458 ty dong, phuong dn
x\> ly 2 Id 487 ty dong, do do, ve hieu qua kinh
t l , kinh phi xCr ly on djnh cua bd try Nam theo phuong an XLP ly 2 Idn hon phuong dn xu ly 11d
29 ty ddng
Tip cdc tinh todn thu dugc cho thay, phuong
an XLP ly dam bao on djnh cho bd try Nam khai thdc d i n kit thuc ddy md d mire -330m bdng eat tang vdo try (phuong an XLP ly 1) khdng ehf toi
uu v l mat kinh t l - ky thugt md cdng tdc thi cdng cho phep sip dyng toi da cdng nghe khai thac hien nay md dang dp dung Ket qua thir nghiem xip ly cdng nghg cat tang vdo try dugc thyc hign tgi 2 khu vyc tai bd try Nam trong ndm 2014 da xae nhdn tinh kha thi cua giai phap XLP ly dugc lua chgn
K i t lugn
Dk dam bao on djnh cho bd try Nam, md than
Deo Nai, trong qud trinh khai thae xuong sdu d i n
k i t thiic theo thilt k l (-330m), giai phap xiy ly
dugc lya chgn Id giam gdc doe cua bd bdng bign phap edt tang vdo try vdi gdc doe sudn ting bdng gdc doc mgt Idp (a = p)
Trong qud trinh khai thde xuIng sau tiln hdnh quan trie djeh ddng k i t hgp tinh todn dieu khien
hg so on djnh eua bd theo tirng ehdng xuIng sau 50m vdi he so I n ^ n h n =1,1, cho phep dam bdo
an toan eho qud trinh khai thac vd gidm khoi
lugng dat bdc xie ly d i n mirc thap nhit tgi bd tnj
Nam, md than Deo Nai./
Tai lieu tham khao:
1 Bdo cdo k i t qua {^990y'Nghien cO-u on dinh bo mo IQ thien Vi$t Nam va kidn nghi cic glai phap nang cao Sn dinh bo mo", Vien Nghien
ciru Khoa hpe Ky thugt Md - Hd Npl, 2003
2 Bdo edo tong kit d l tdi "Nghien cCru bien dang ba mo va cac bien phap dam bao on dinh
bo mo 16 thien a cac mo: Deo Nai, CQC Sau, Ha
Tu, Na Duong, Nui Beo va Cao Son" Vien khoa
hpe Cdng nghe Md, Hd Npi,
4 B.P Beliaeb 1973"Gdn ket dat da', Nhd
xuat ban Nhetdra - Matscova