Thong tin khoa hoc cong nghe m o
^NGHIEN COI) QUY LUAT DICH CHUYEN THAN - DA VA BIEN PHAP KIEM SOAT GlTONG HA TRAN THAN NOC
1. IVIdi lien he giCra ddt dd xung quanh vd trgng thai dja tdng tai gu'cng
Kit qua khao sdt vd quan trac tgi 29 guong khai thac bdng phuong phdp hg tran than nde tgi Trung Quoe cho thay, cac d l i tupng via t i i n hanh nghien cuu bao gom cac via doe thoai, doc va die dung, than t u mIm, trung binh d i n eung
Ddc diem co ban v l trgng thai dja tang va ddt da xung quanh tgi ede khu vyc via nhu sau:
- Tai trpng chong thap, khoang 2000kN/ept chlng va 3000-3700 kN/cpt chong doi vdi via cdng (hinh 1)
- Dp ben chong cac cot chlng phia trudc Idn hon cac cOt chlng phia sau (ddn chong loai bin cpt) vd hg s l tai trpng dpng nhd, trung binh khoang 1,3.
- Trong qud trinh hogt dpng, nhin chung, t i n tgi hign tupng cpt chlng giam tai, vd co t h i tdi tren 12%.
- Mli lien hg gida tai trpng chong ban d i u vd tai trpng cong tac cua cpt chlng Id mpt ham tuyin tinh, cy the Id P = 125 + 1,276 Po (hinh 1).
Nhung d l i vdi guong co gidi hoa thong thudng thi Id mpt hdm logarit, cy t h i Id P = A + BIgPo.
Dilu nay cho thay, vigc toe dp gia tang eua tai trpng chlng lam vigc tgi guong ha trin than
KS. SONGXUANMIN KS. JINZHONGMING KS. W/EIJINPING Oai hoc Cdng ngh$ Talyuan
KS. QIAN MINGGAO Dai hoc Cdng nghd Khai thdc Md Trung Qudc khdng cao vd tai trpng chlng ban d i u cua cpt chlng hiln nhien se thIp hon;
- Ngodi ra, vdn t i n tgi mOt tai trpng va dgp nhd tai guong ha t r i n than c6 vdch cung, ede cpt chlng guong ha t r i n cd vach khac chu y l u mang tai trpng tTnh, xap xi tai trpng eua dja tang phia tren, khdng qud 2 lan ehieu cao khai thdc.
N I U tang chilu cao khai thde, hg so gidn nd eua dat da sau khi phd hda tang len, g i n 1,4 -1,5.
- C6 hai dgng co che hg tran vd thu hoi than nde CO ban, loai thd nhlt Id hg trin dam cdngxon dang bac va thu h i i hinh phiu, loai thu hai la hg trdn nua vom vd thu hoi dgng vom. Vi goe gay cua trin than Idn hon 70°- 80°, nen goi tya dan chong vd chan vdm phia sau la khu vyc da khai thdc (hinh 2 vd 3).
Hinh 2. Kit ciu ha trin thu hdi than tai md Wangzhuang
Hinh 1. Mdi liin h$ giua dq bin chdng ban diu vd dd bin chdng Idm vide
Hinh 3. Kit ciu ha trin thu hdi than tai md Gushuyuan
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2. Nghien cu'u k i t c l u vach dipa tren mo hinh tyo'ng dU'O'ng
Dya tren cac ket qua thu nghiem 7 mo hinh tuong duong tai 5 mo, ngydi ta da phan loai 4 dang kit c l u vach khac nhau la:
- Kit ciu nCra vdm "dim khoi gach"
Khi vach true tilp tyong doi day, bi pha huy sau khi than noc dygc thu hfli VI khong gian con lai trong vung da khai thac nho hon chieu day pha hoa cua vach chinh 1 lln, nen co the hinh thanh kit cdu can bang khop cua "dim khli gach", nhy kit clu vach cua gyong s l 13306 tai mo Gushuyuan (Trung Quoc) (hinh 4).
- Ket cau 'dam da dich chuyen " nhwciu vdm Neu vach tryc tiep tyong d l i mong va vach CO ban day, thi vach tryc tilp bj pha hoa sau khi thu hii than noc. Vi khong gian con lai cua khu vyc da khai thac Ion hen chieu cao pha hoa cua vach CO ban 1 lln, nen r l t kho nhan biet dyoc trang thai can bang kh6p n l i khi vach co ban bi pha huy. Sau khi vdch co ban bi pha huy, tai cac vj tri phia tryoc, tren vach tryc tilp va dang sau, o khu vyc da khai thac, d i m da c6 kha nang tilp tuc chiu tai trgng cOa lop mem phia tren, nhy kit cau vach cua gyong so 4309 tai mo Wangzhuang (Trung Quoc) (hinh 5).
Hinh 4. Kit ciu dich chuyin vich tai md Gushuyuan
- Kit cau "dam congxon"
Khi khong o6 vach tryc tilp hoac vach rat mong va cyng, thi khong gian con lai c khu vyc da khai thac sau khi thu hoi than la r l t Ion, hinh thanh d i m congxon tci 15-25m ke t y guong se dyt gay djnh ky, va khi noc bi pha hoa se xuat hien mpt tai trgng va dap . Dam nho ra sau khi pha hoa khong the lien tuc truyen tai trgng dja ting phia tren, nhy kit cau vach cua gyong s l 8911 tai mo Xinzhouyao (Trung QuIc) (hinh 6).
Hinh 6. Kit du dich chuyin v^ch tai md Xinzhuoyao
Hinh 5 Kit ciu dich chuyin vdch tai md Wangzhuang
Hinh 7. Kit ciu dich chuyin vdch tai mo Weijiadi - Ket ciu vdm dp !i/c
Khi vdch day vd mIm, no nhanh ehdng bi pha huy sau khi than noc bi thu hoi Do nhdng biln dang, sut lun va ddt gay eua than n6c d phia trudc, tren vach co t h i xuat hien ede vet nut va dut gdy. Vdi kilu thu hoi than noc dang vdm, eijng c6 the hinh thdnh k i t eau v6m can bang, chdn v6m phia trudc nam phia trong guong, chan vom phia sau Id khu vue da khai thac, nhu kit clu vach cua guong s l 110 tai mo Weijiadi (Trung QuIe) (hinh 7).
3. Md hinh cdu true k i t hp<p than dd tai guong ha trdn than
- Kit cau kit hop "vdm-vom"
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Hinh 8. Kit cdu kSt hap "vdm-vom"
Kit c l u bao gom pha hoa nua vdm, thu hoi v6m than nde va k i t elu vom dp lye noc, (hinh 8). Khi than noc ed dp cung trung binh hoge thap, noc mIm vd ddy, giai dogn trude biln dgng vd dut gay xudt hien them nhieu vet nut va hinh thdnh k i t clu vom cdn bang dp lyc len tren than noc. Dua tren quy ludt vdm cdn bdng tu nhien, dp cao vd ehieu rdng vom tren nde t h i hien trong he thue sau:
H = {b + M . ctga) 12 . tgq) (1) Trong dd, H - Chieu cao vom;
M - Chieu rpng vdm;
b- Khoang cdch giua guong va mat ben bang tai;
a - Gde cua than- dd, thudng la 45''-55°;
<p - Goc ma sat trong cua dd.
Tai trpng len c6t chong bing tdi trpng ting eua than n6e vd da bj phd huy trong vdm. Id:
P = M27 2+H.y(kN/m2) (2) Trong do. Ma, yi - Chilu day than noc vd ty trpng cua nd;
H, 7 - Chilu cao vom va ty trpng noc Vi dy nhu guong s l 8316, H = 8,3 m va M2 = 2,4m, nhu vdy P = 211 kN/m^. Gid tri quan trdc Id 186kN/m2. Nhu vdy, kit qua tinh toan phu hpp vdi k i t qua quan trac.
- Kit ciu ket hop dam khdi vdm gach Kit cdu gIm nua vom ha trin than nde, dang vom hoac thu hoi truot va can bdng eua dam khoi ggch trong vdch eo ban (hinh 9).
Khi dp eung cua than nde nhd hon muc tmng binh, vdch tryc tilp ddy vd vach co ban ed t h i xem nhu kit c l u cdn bang eua d i m khoi gach, dp b i n chlng dap dng dupe dieu kien cdn bang nua vom cua dam khoi gach va co kha nang chju
HInh 9 Kit ciu kit hqrp dim khdi vdm gach duoc tai trpng eua than nde vd vach tryc tilp:
Pq = Q . [ 1 - L . fg((p - G) 72 (H - S) ] /I (3) S = M-M2.(1-K2) K p ' - 2 H . ( K p - 1 ) (4) Trong do, ZH - Dp day vdch tryc tilp;
K2 - Ty Ig thu hoi than nde;
Kp' vd Kp - He so gian nd cua than nde vd vdch true tiep;
Q - Trpng lup'ng dd cua vdch chinh vd tai trpng len vach co ban;
I - Khoang each dilu chinh eua guong;
L - Khoang each gia trpng djnh ky;
8 - Gdc cat cua vdch eo ban;
H - Vdch eo ban trong 1 l l n chieu cao bj phd hda;
S - Sut lun t i i da do quay vdch co ban gay ra.
Tai trong len edt chlng c6 t h i dup'c tinh bang edng thue sau:
P= M2 . Y 2 + Eh . y + q/r + Pq (5) Trong do, q - Tai trpng d i m congxon eua vach true tilp.
Vi du, d guong s l 2311 eua mo Shigejie, tai trong eua than noc Id 52 kN/m^ tai trpng cua vach tryc tiep Id 240 kN/m^ chilu cao phd hoa cua vach co ban Id 3m va khu vuc dd khai thac la 1m, khi do Pq = 72 kN/m^ Bang tinh todn, P = 364 kN/m^. Cudng do chlng trung binh dat 383 kN/m^ nhu vgy. k i t qua tinh todn phu hpp vdi k i t qua quan trie.
- Ket cau kit hop dam chuyen thanh vdm K i t elu bao gIm phd hoa nua vdm than noc, thu hoi truot hoge dgng vdm vd k i t eau "dam dd djch chuyen" cua vdch eo ban nhu clu-vom (hinh 10). Khi do cung cua than nde nhd hon dp
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Hinh 10. Kit cdu kit hop dim chuyin thdnh vdm
Hinh 11 Kit ciu kit ha^
"dim cdngxon - khdi gach dang bLrdc"
cung trung binh, vdch tryc tilp mdng, vdch co ban bj pha huy theo ldp vd khdng d l ddng hinh thdnh kit cau can bang co khdp do khu vue da khai thde Idn hon dp ddy phd hda eua vdch co ban mot lan, khi do vdch co ban eo the xem nhu met kit clu "dim djch chuyin" nhu cau-v6m. Tai trpng len cpt chlng theo "dim djch chuyen" Id:
Pc = L. H . Y/2 . I (6)
Tu do, tai trpng len cpt chlng c6 the dupe tinh bang cong thuc
P = M2 . Y2 + Sh. Y + L . H y/ 2 .1 (7) Tgi guong so 4309 eua mo Wangzhuang, tai trpng eua than noc Id 52 kN/m^, tai trpng vdch true tilp id 175 kN/m^ va tai trpng len cpt chlng theo eau trude cua vdch co ban Id 146,5 kN/m^, khi dd tai trpng chong theo tinh toan la 373,5 kN/m^. Vl luc can quan sdt dupc Id 359,3 kN/m^, nen hai kit qua la phu hpp.
- Ket cau ket hap "dam cdngxon - khdi gach dang bLfdc"
Day Id k i t clu md than nde va vdch tryc tilp dupe phd hoa bang dam cdngxon dgng budc.
thu hoi than noc dang phiu vd vach eo ban hinh thdnh k i t c l u "dam khli ggch" (hinh 11). Trong dieu kien than nde edng, vach tryc tiep day, phd hoa nhilu lan vd chilu cao pha hoa cua vach co ban Idn hon 1 lln so vdi khoang khong edn lai d khu vue da khai thde, cot chlng kh6ng ehi chiu tai trpng cua than noc va vach tryc tilp md c6n chiu mpt lyc de tao su can bang d vach co ban. Trong khi do, tai trpng than nde vd vdch tryc tilp bao gIm tai trpng cua phln dam cdngxon.
Nhu vdy, tai trpng eua than noc Id:
PM = Ms. 72 + Mh . Y2 .ctga/2 .1 (8) Tai trpng cua vdch tryc tilp Id:
Pz = Sh . Y + (Eh + 2M2). Xh . y . ctga/2 .1 (9)
Vi vdy, tai trpng len cpt chong c6 t h i dupc tinh toan bang:
P = P M + P Z + Pq (10) Trong do, Pq la luc can bing dam khli ggch, gilng nhu eong thuc (3)
Tgi guong s l 13306 cua md Gushuyuan, tai trpng eua than nde Id 48,4 kN/m^, tai trpng eua vdch true t i l p Id 381,5 kN/m^, lye cdn bdng cua dam khoi gach Id 42 kN/m^ khi d6 tai trpng chlng Id 472 kN/m^. Tai trong quan sat 482,6 kN/m^ cho thay eo ban cdc dilu kien tren phu hpp.
- Ket cau ket hap "dam cdngxon- dim chia dang buuc"
Trong k i t cau nay, than nde vd vach dupe xem nhu d i m chia dgng budc nghjeh vd vdch eo ban Id "dam dd d i m chia" (hinh 12). Kit edu la dang k i t hop than - dd trong dilu kign via eung va vach eung. Dk tinh toan tai trpng va dap khi vach edng bi phd huy, c6 t h i thilt Igp cdc m6 hinh CO hpe bang each su dyng can bang tgm thdi va ly thuylt dilu khien dam cdngxon pha huy. Neu P' Id dp b i n chlng len vdch eo ban khi vdch bi pha huy, thi dilm tac dpng each guong 1/3 khoang each. Q la luc b6 sung khi vdch co ban bj phd huy, q la trpng luong eua mli met dam congxon.
Tren eo sd ly thuylt dan hoi, ung suit nam ngang trong dam congxon Id:
ax = - 6q . x^ y/H^ + 4q . f/H= -3q . y/S . H Be duy tri dp on dinh vach trong pham vi dieu
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" l i i i j i i i i i i i A i i i i
Hinh 12. Kit ciu kit hop • dim cdngxon- dim chia dang budc"
khiln vSch v^ noc d i m congxon 6 khu vyc da khai th^c, c l t h i pha hoa chinh xac o" vi tri cat noc. Cin thilt d l cx tai dilm B dat toi dg b i n keo khli Si at.
Gia si> X = L - LI/3, y = - H/2 va ox = m, khi do ot = 3q (L - L i / 3 ) W - q/5 (11) P' = q.L,/3 + q (L - Li/3) + Q, Q = 3q (L - USf . L i - q . L 1 / 6
Vi vay, P '= q Li/6 + q (L - L,/3) + 3q (L - L,/3)2.Li (12)
TLP c6ng thi>c (11) c6 t h i thu dyoc phyong trinh sau:
q (L - L,/3)2 = H2 (ai+ q/5)/3 va q (L - Li/3)
= H=(<rt + q/5)/3 (L - L,/3)
Thay t h i c^c thong s l tren vao cong thyc (12), khi do:
P • = q . L,/6 + H2(L + Li/3). {at + q/5)/2 L, (L-L,/3) (13)
Tai trgng chong la:
P = Pn+ P,+ P'/l (14) Trong do, Pz, Pm : Nhy trong cong thirc (8), (9):
L: Khoang each gia trgng anh ky; L = I + (IW2 + Sh). c(ga;
H: Dg can ph4 hoa mgt l l n ciJa vach co ban;
Z/i: Chilu d i y phln v^oh dydi da xy ly sobg.
Tai gyong s l 8914 cQa mo Xinzhouyao, tai trgng than ndo la 84kN/m^, tai trgng than noc phln vach dyoi Qi x y ly so b | ti igOkN/m^ va tai trgng va d i p cua d i m cdngxon tao ra boi cgt chlng P' \i 546kN/m2, khi do tai trgng chlng IS P = 820kN/m^. GIS trj tinh toSn P tai gyong la 6151kN/m^ va gia trj quan s i t l§n 161 5885kN/do'n vj. VI vay, v l co ban, ca hai diu phu hep.
- So sanh giCra g i i trj tinh toan cua cac mo hinh c l u true hdn hgp v i mo hinh tai trgng da don giin hda
Theo quan sat tai hign tryd'ng v i kit qua nghien cyu mo hinh tyong dyong, thong thyong, xult hien hi$n tyg-ng chia 16'p giua vach thy nhlt va vach co ban tai khu vyc dilu khiln vach trong khai thic ha trin than.
Vi ly do niy, c i n xem xet yoc tinh tai trgng chong bing cich tinh dg cac pha hda cua dja ting bao phlj sao cho co t h i hoan toan lip kin khu vyc da khai thac. Cdng thyc tinh toin l i :
P = Ka.l\;i. v/(Ka-1) (15) Trong do, Ka: H# s l trgng lygng, Ko = 1,3;
Kp: He so trgng lycng gian no cOa d i vich, Kp = 1,4
Cac kit qua tinh t o i n theo cong thyc (15) cho thay thIy sai s l tmng binh khoang 42,9%, trong khi do, theo 5 loai phyong trinh co hgc kit cau hdn hep k l tren thi sai so trung binh chf bang 9,8% . Nhy vay, ly thuylt ve kit c l u hIn hgp la hgp ly.
4. K i t luan
Sy dung mo hinh cc hgc cua k i t c l u hIn hop than - d i trong gyong ha tran than noc d l dilu khien noc la khoa hgc v i hgp ly. Ap dung cic phyong phap dilu khiln niy trong qua trinh khai thic p h i hoa ha tran than giup dat dycc ning suit va hi§u qua cao./.
Quic Trung (biin dich) Nguon: Proceedings of '99 International Workshop on Underground thick seam mining
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