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Thong tin khoa hoc cong nghe mo THIET KE CHONG NEO CAP CHO CAC LO KHAI THAC BANG NOC PHANG TRONG MO HAM LO able bolt is one of supports for tunneling construction, i Nowadays, it is widely used at und[.]
Thong tin khoa hoc cong nghe m o THIET KE CHONG NEO CAP CHO CAC LO KHAI THAC BANG NOC PHANG TRONG MO HAM LO able bolt is one of supports for tunneling construction, i Nowadays, it is widely used at underground coal mines However, the acknowledgement about its mechanism and designation is limited This article refers to the problems , about the designation of cable bolts for longwall flat roof at ' underground mines Dat va'n de Ke't ca'u neo va neo cap da dugc SLf dung tCf lau de chd'ng giCf cac dudng Id ehuan bi va Id khai thac Neo cap cd ca'u tao tCf cac sgi thep duge ghep lai vdi Thdng thudng, sd sgi cap duge ben vdi la sd le, thudng la hoac sgi, theo tCfng trudng hgp cu the Khi ke't hgp vdi vua bgm vao Id neo, kha nang dinh ke't eua neo cap tang len sdi cap cd dien tfch be mat tie'p xue ldn hdn so vdi cdt thep ddn thdng thudng, nen hieu qua chd'ng giuf cao hdn Hien nay, viee suf dung ke't ca'u neo cap cac budng cdt edn ban ehe u Viet Nam v l n SLf dung ket eau chd'ng giu" khung gd, khung thep truyen thd'ng Gan day viec sCf dung be tdng phun, neo hoac ke't hgp giu'a be tdng phun va neo chd'ng giu' da cd hieu qua nha't djnh Tuy nhien, hien da phan cac md thudng SLf dung ke't ca'u neo vdi cdt neo bang thep ke't hgp vdi be tdng phun chd'ng giur cho cac dudng Id dao da Viec bd sung hoac suf dung ke't cau neo cap se cd hieu qua chd'ng giu" cao hdn rat nhieu Bai bao gidi thieu viec thie't ke neo cap d cac dudng Id khai thac cac md than ham Id NCS TRAN TUAN MINH Trudng Dai hoc Mo Moskva (LBNga) Ca'u tao va cd che lam viec cua neo cap Ca'u tao ciia mdt neo cap bao gdm mdt bd sgi cap dai, dau cap dygc bd chat vdi va cho phep neo dugc lap dat va xoay dugc, d phan than cap cd cac tam de tang cCfng eho cap va d l dieu chinh qua trinh lap dat De tien lgi, d dudi neo cd Id hdng de bgm vu'a va tam dem de bgm vUa thi vufa khdng the bj day ngygc trd lai Dau neo cung dugc thiet ke de viec lap dat cac tam thep dem va cac thie't bj dieu chinh khac d be mat ngoai mdt each d l dang He thd'ng cae tam buldng va dai dc cung dugc sCf dung de chd'ng lai sy djch chuyen cua phan dau cap KHCNM SO 8/2010* CNKT HAM LO Hinh Bo cap e6 sgi, mat eat ngang eua neo cap va vua, neo cap thue the chdng giCt Cap va bd cap mem de udn nen khd thi cdng De lam cCfng bd cap tren, chieu dai bd cap va dau cap thudng phai them chi tie't tang cCfng hoac nut cCfng Chi tiet tang cCfng cd chieu dai tUdng ty nhu chieu dai cua thdi chat deo, eho phep thyc hien d l dang qua trinh lap dat Mat khac, chi tie't tang cCfng lam nhiem vu ngan can sy dich ehuyen cua neo qua trinh lap dat TUdng ty nhy cac neo khac, neo cap lam viec dya tren cac nguyen ly sau: - Nguyen ly treo: Vdi nguyen ly treo, trudng hgp dgn gian nhat la neo treo cac khd'i da bj tach rdi sap vao Idp da ben vCfng ben tren ndc, tCf dd se lam eho ndc Id dn dinh tranh dugc sap hinh Thong tin khoa hoc cong nghe m o Ne'u pha buy ndc Id d dang vdm thi dd cac tru than se mang mdt phan tai trgng, cac neo cap ehi cd tac dung de treo giiJf trgng lygng cCia khd'i da ben dudi vdm sap 60 (hinh 4) Chieu cao cCia vdm sap 60 phu thude vao chieu rdng budng, vao dieu kien dia chat, tac ddng cua Cfng sua't thing dung va nam ngang tac ddng cCia cdng tac khai thac md Rd rang, chieu dai va sd lUdng neg cap se phu thugc vao chieu cao eCia vdm pha huy va dygc xac dinh dya vao chieu cao vdm pha huy (hinh 4) Mdt nguyen 1^ lam viec cCia neo cap nu'a la nguyen Iv/- dam mang tai (hinh 5) Chieu rdng cCia ram phu thugc vao kha nang mang tai cua tru than (hinh 6) Chieu rdng cCia budng dygc xac dinh theo cdng thufc cCia Wilson va nd phu thugc vao ben cCia cac tru than (Wilson 1972) C^c neo ic^ cap Dau cap —' Chi tiet tang cCfng Nut Cac nut neo Doan cap phong He thong bao boc Dam sap lap tijfc Hinh Kfch thude cua vung pha huy tru than, (B^ - ket qua eua chieu rgng 16 hoat dgng khai dao; yp^- vung pha huy tru than 1; yp2 -vung pha huy tru than 2) Chi tiet tang cCfng Cac nut neo Hinh Neo cap va cac yeu tdcau neo cap Vung noc {i CO cau true -=•• on dinh ,- Cac neo cap , iTrS'-ii-".,^ •' »'j.ji5S^."t^T' Hinh Khdi bj tach rdi duge neo glut bdi eac neo cap ';•'- i \ : ^ a -* , ' • * -^ '^ ^* * ^ ,••'» Vung noc 6n (Jlnh , - , • • , ""'^mSf^ ' Tru than \ t Cac neo Hinh Vdm ap luc ehi tiet eho trudng hgp pha huy dang vdm - Nguyen ly dam mang tai: KHCNM SO 8/2010* CNKT HAM LO Hinh Neo cap surdung de bo sung tao dam mang tai giam kha nang chju tai eho tru than va neo cap surdung ket hgp vdi ludi thep chdng giOt dudng 16 n6e phang thue ti' Khi pha buy phat then rdng sang hai ben cija ndc Id thi viec sCf dung cap bd sung (hinh Thong tin khoa hoc cong nghe m o Nut cap nghieng Cac nut ^ Cap giira cac nut Cap nghieng ' Nut giOr Cac tam mang tai Hinh 7a Doan cap lien tue ong noi Hinh 7b Dam cap ba doan b) gngij nst f'^ '"^^ ' Hinh Luge dd than cap eua mgt nua cap chju tai Hinh 8b Luge dd cua mgt nua cap, quan sat cae tai trgng tTnh phat trien c6 tam dem phia dudi noc 7) la dieu can thie't Cap mang tai bd sung dygc tao nen tCf cac sgi cap lien tuc (hinh 7a) hoac dugc tao nen tCf doan cap (hinh 7b) theo dieu kien thi cdng cu tlie Cac tai trgng phat trien dd'i vdi mdt bd cap cd the dugc xac djnii ddn gian bang cac tai trgng tTnh tac dung len cap Gidi thieu gian 66 ddn gian eae loai tai trgng cCia mdt nijfa bd cap (hinh 8) Tinh toan cac thong so cua neo - Do cumg cua he thong cap Do cung cua neo cap dygc xac djnh bang chieu dai doan neo khdng cd vu'a Id khoan va cac dac tfnh bie'n dang ciia cap Tuy nhien, phan bie'n dang dan dai phan chat deo cua cap se anh hudng de'n cung va eung phai dygc xem xet Cac dac tfnh bie'n dang cua cap yeu td la cCfng che tao, dac tfnh dan hdi va sy dan dai Do cufng che tao la cd dinh, yeu td xoay trdn thudng la boat ddng quay qua trinh lap dat, ye'u td dan hdi phu thude mdt phan vao cae md dun dan hdi cCia vat lieu cap Md dun dan hdi cCia thep khoang 203,4GPa Tuy nhien, md dun dan hdi ciia cap cdn phu thugc vao cdng nghe che tao cap Do eCfng cCia cap dugc xac djnh thee cdng thCfc sau (Maryland va American Iron 1985): K = E A/L (1) Trong dd: or; KHCNM SO 8/2010* CNKT H A M L K - Do cufng cCia cap (kN/cm) A - Dien tfch mat cat ngang cap (cm^) L - Chieu dai doan cap ty (cm) E - Md dun dan hdi cCia cap (GPa) Md dun dan hdi, chieu dai, dien tfch, tie't dien va cufng cCia cap dygc xac dinh tCf tai trgng lap dat Do cufng ciia cap dygc xac djnh tCf viec SLf dung thf nghiem keo tut cap dygc lap dat da't da ndc cac dudng Id - Trong lUdng vung da't da sap Trudng hgp neo treo (hinh 3): Trgng lugng cCia khd'i vat lieu cd the duoc xac dinh tCfcdng thCfc sau: F„ = B.H3.Y (2) Trong dd: F„ - Trgng lugng ciia khd'i da tren mdt ddn vi chieu dai (kN/m) B - Chieu rdng ciia dydng Id (m) Ha- Khoang each tCf ndc Id than de'n mat phang pha buy tren cung (chieu cao vung pha hu:/) (m) - Trgng lygng the tich da (kN/m^) Trudng hgp sap dang vdm (hinh 4): Trgng lygng cCia khd'i vat lieu vdm ed the dugc xae djnh tCf cdng thCfc sau: K = 'lB.H^r (3) Thong tin khoa hoc cong nghe m o Trong dd: F„ - Trgng lugng CLia khd'i da ben dydi vdm ap lye (kN/m) Ha - Chieu cao vdm ap lye (m) y - Trong lygng the tfch da (kN/m^) - Chieu cao da't da sap 60 gay tai trgng (Kha nang mang tai/mang neo): Chap nhan chieu cao Idp da't da sap gay tai trgng tTnh Terzaghi (1946) da dya dudoan tai trgng tac dung len cac ke't ca'u chd'ng giu" tren cd sd chat lugng khd'i da va khau cdng trinh ngam Unal (1984) da xac djnh chieu cao gay tai trgng tTnh eho eac dudng Id cac md than theo cdng thCfc: // =5 ^100-RMR (4) 100 Trudng hgfp dam mang tai: Kha nang mang tai cCia tru than bi anh hudng bdi cae dieu kien khac nhu chieu rong ciia cae budng (hinh 5)Theo Wilson (1972) chieu day tru than dygc xac dinh theo cac dieu kien sau: Khi nen Id eCfng vung: r \ q w = — In (5) F P + (^n Khi nen - ndc ed bieu hien dan hdi w=m F= -1 P + (^n (6) , (^-1) Trong dd 'tgyfk Dugc tfnh bang radian tgy/Ic m - Chieu davia (m) q - Tai trgng pha buy (t/m^) p - Lye hinh ben ria tru than dugc gidi han de'n gia trj t/m^ a„ - Do ben nen dgn true ciia than k - He sd Cfng sua't ba chieu; k = 1+ sincp/lsin cp (p - Gdc ma sat (do) TCf nhung cdng thCfc (5), (6) xac djnh dUdc Idn cua vung bie'n dang pha hiiy D6 thi (9) xae dinh gdc ma sat la 35° Hieu qua cua khoang trdng khai dao hay chieu rdng cua budng cd the dugc xac djnh bang cdng thCfc sau: KHCNM SO 8/2010* CNKT H.^M LO B, = B + Y,, + YP2 m Trong dd: B - Chieu rdng cCia budng dUdc khai dao (m) Ypi - Vung pha hCiy cho tru (m) Yp2 - Vung pha hCiy cho tru (m) Trudng hgp dam nghieng gia cdtang cudng: Y, = T.sina (8) X, = H- Tcosa (9) Trong dd: T - Thanh phan Iyc keo H - Thanh phan Iyc keo nam ngang Yr - Thanh phan phan lye thing dCfng X, - Thanh phan phan Iyc nam ngang a - Gdc nghieng cua cap - Chieu dai neo cap Chieu dai cua cap la van de quan trgng nha't thie't ke he thd'ng neo cap Chieu dai cap phu thugc vao cac dieu kien dja chat, bien dang djch ehuyen, cdng nghe thi edng va eac yeu cau khac Thdng thudng, chieu dai cCia neo cap cac dudng Id ehuan bj thudng tCf 3,7m - 4,9m Tuy nhien, chieu dai neo nhd nha't phai ngoai vung da bj pha buy Tuy nhien, cd rat nhieu mat pha buy phat trien d phfa tren ke't ca'u chd'ng tam nen nhieu trudng hgp can chieu dai neo Idn hgn Cac vung tiem an nguy hiem ed the la mdt khd'i da dang hop hay be mat dang cung trdn, phu thude vao dang pha buy cCia ndc dudng Id nhu hinh va Chieu dai thfch hgp eCia neo dugc de xua't de xac dinh nhu sau: L'= B^'(Lang vaBischoff 1982) (10) L = B/3(Bienawski 1987) (11) RMR\ B (Unal 1984) (12) 100Z= ,2A 100; Trong dd: L - Chieu dai neo (m) B - Chieu rdng dudng ham (khau do) (m) RMR - Chi sd chat lugng khd'i da (Bieniawski, 1987) - Chieu dai neo trudng hdp vdm sap dd: Neo phai dii dai de neo giu' eac dieu kien dja chat, da't da khae thi cdng dudng ham Chieu dai neo cd the dugc tinh toan theo edng thCfc thyc nghiem cua Stillborg (1986) nhy sau: L =1,4 + 0,1846 (13) Hoac tinh theo cdng thCfe: L ' = B^'^ (14) Thong tin khoa hoc cong nghe m o Trong dd: B - la chieu rdng eCia dudng ham (m) - Khoang each giufa cac neo: Hinh dd thj xac djnh khoang each neo vdi chieu rdng dudng Id 7,6m va lugng the tfch cua da 2,403T/ml + Khoang each giCfa cac neo theo cdng thufc thyc nghiem cCia Stillborg (1986): a = 3xe (15) e - Khoang each giCfa eac khe nCft gan nha't + Khoang each giu'a eac neo theo Lang (1961): a < L/2 vdi L - Chieu dai neo (16) Chieu sau Idp bao phu, ft 1t.9 1,000 1,500 it: dJ c ro- •a roc "'32 cua neo chd'ng lai sy tach ldp dat da phan Idp nhy sau: -(.tg(p)k.Dlr n.y.AR l-e (18) T = -(,lg 18m, L = 0,2H Gia tri nho nhat a) 0,5xL b)1,5xchieu rong gidi han cOa cac khdi da mat dn djnh c) 0,9-1,2m Bang Kinh nghiem thiet ke he thdng ket cau neo khai dao nhQng dudng ham c6 chieu rgng < 15m (Famer va Shelton 1980) So luong mat phan Chieu dai neo thiet ke each < goc nghieng - 45° L = 0,3B vdi phirang nam ngang a = 0,5L (Phu thuoc vao chieu day va Cfng sua't cCia dia tang) viec lap dat neo c6 the ke't hop ludi thep chdnq da roi nhCfng noi c6 the < goc nghieng v|; = 45 - Cho cac neo ben sudn 90° vdi phuong nam L > h.sinv|/ (neu neo lap dat vuong goc vdi mat ngang phan each) L > h.tgvt/ (neu neo duoc lap dat song song) < vdi be mat phing, L = 2a, a = - 4x kfch thudc khdi da Lap dat chCfa nLfdc neo vuong goc vdi mat phan each khai dao sdf dung ke't hop vdi lifdi thep de chdng da roi KHCNM SO 8/2010* CNKT HAM LO Chu dan Muc dfch cOa neo la tao mot dam mang tai Idn hdn chieu rpng ham Lap dat neo noc nhU tren, neo hong chdng lai kha nang c6 the truot cua mat phan each Neo duoc lap dat nhanh sau khai dao de tranh hien tLfong da roi vao dudng ham Thong tin khoa hoc cong nghe m o Bang Ky thuat khai dao va qua trinh lua chgn ket cau chdng tren cdsdRMR Hinh dang: Vom mong ngUa, chieu rong 10m, ung suat dumg, ufng suat ngang = 25 Mpa, phiTdng phap khai dao, khoan va no Phan loai khoi da Da rat tot loai RMR: 81 - 100 Da tot loai II RMR:'61 - Da trung binh III RMR: 41 - 60 Da yeu loai IV RMR: 21 - 40 Khai dao Toan gifdng, tien 3m Toan gi/cfng, Tie'n 1,5m chong giuf co djnh phfa sau gu'dng 20m Gifdng tie'n trifdc va bac (chia gUdng) tie'n 1,5 -3m Chong tam sau no min, chong co dinh sau gifdng^ 10m Gifdng tie'n trifdc va bac (chia gUdng) tien dp - 1,5m Chd'ng tam sau nd min, chdng co' dinh sau gifdng tie'n tru'dc Ket cau chdng Be tdng phun Cac khung thep Neo (d =20mm) neo toan bd bien - Khdng can chd'ng giif - Khi can cd the cho phep suf dung neo diem Khdng Neo toan bd vdi chieu 50 m m d dai 3m khoang each nhOfng ndi can neo 2,5m cd the dung thiet them lirdi thep He thd'ng cac neo dai 50-100 mm Khdng 4m, khoang each neo va ben tudng 1,5 - 2m ben tifdng cd 30mm lirdi thep He thd'ng cac neo dai - 5m, khoang each neo -1,5m ben tifdng cd lu'di thep 100- 150mm va ben tu'dng 50mm Khung chdng, bifdc chd'ng 1,5m He thd'ng cac neo dai -6m, khoang each neo - 1,5m ben ti/dng cd lifdi thep Neo ca nen cdng trinh 150-200mm Yeu cau suf dung khung thep cifng bifdc 0,75' va phan life nen Idn thi dung vdm ngifdc ibm Da rat yeu loai V RMR < 20 Birdc dao 0,5 - 1,5m dao chia gifdng, lap dSt ket ca'u chdng sau khai dao, be tdng phun cd the difdc lap dSt sau nd Ket luan va kien nghi TCf ke't qua phan tich va mdt sd ehi dan thie't ke d tren cd the nhan tha'y rang, de thie't ke duge ke't ca'u neo cap cd hieu qua, dau tien can xae djnh rd va chfnh xac cd che lam viec ciia neo Theo dd, can phai xac djnh cu the dieu kien dja chat tai khu vyc khai dao, tfnh toan xac djnh tai trgng tTnh tac dung len neo va cac tai cd the xua't hien qua trinh khai dao dudng Id khai thac Khi tfnh toan cac gia thie't lam viec cua neo can tien hanh so sanh va kiem nghiem cae ke't qua thyc nghiem de chon cae thdng sd chieu dai neo, mat neo phu hgp nha't Can xem xet chi tie't hydng va mat khe nCft cung nhu dieu kien nydc ngam khu vyc tfnh toan, lya chgn cap va chat lygng cap hgp 1^, trgng qua trinh thi cdng lap dat can thie't phai thCf tai dd'i vdi neo va tuan thCi nghiem ngat quy trinh lap dat neo Neu cd hien tuong bat thydng nha't thiet phai dCfng viec lap dat va xem xet lai toan bd dieu kien thie't ke va lap dat tCf dau Viee cang cap trydng hgp neo ddc lap va neo ke't hop vdi dam cap nha't thie't phai tie'n hanh theo dung trinh ty, tranh KHCNM S 8/2010* CNKT HAM LO 150 ben tu'dng va 50 dirdi nen tang tai dot ngdt d i n den dut cap, khdng dam bao dieu kien lam viec ciia neo Khi sii" dung neo cap ke't hgp vdi vu'a be tdng can chu y den cap phdi vu'a xi mang de cho vu'a xi mang chui he't vao khoang khdng giiia cac sgi cap, tranh nudc xam thyc va an mdn cap va eac tam nut qua trinh sCr dung ke't ca'u./ Tai lieu tham khao US Department of health and human servieesm Proceedings: New technology for coal mine roof support, October 2000 AT Hale, DM Grave, C sevume and Kle Bron, Strata control in tunnels and an evaluation of support units and systems currently used with a view to improving the affectiveness of support, stability and safety of tunnels, December 1998 Alan Thompson, Curtin University of technology, WA school of mines, Kalgooriie, Western Australia, Performance of cable bolt anchors - An Update, Maiek Bouteldja, Design of cable bolts using numerical modelling, Department of mining and metallurgical engineering, McGill University, Montreal, Canada, April 2000 ... khung thep Neo (d =20mm) neo toan bd bien - Khdng can chd''ng giif - Khi can cd the cho phep suf dung neo diem Khdng Neo toan bd vdi chieu 50 m m d dai 3m khoang each nhOfng ndi can neo 2,5m cd... va Bischoff (1982) da dya cdng thCfc tfnh toan Iyc keo KHCNM SO 8/2010* CNKT HAM LO Chu dan: A- neo cap O-3 neo cap D-2 neo cap Hinh 10 Dd thj mdi lien he giOta eae phan ket cau chdng neo cap,... dan Muc dfch cOa neo la tao mot dam mang tai Idn hdn chieu rpng ham Lap dat neo noc nhU tren, neo hong chdng lai kha nang c6 the truot cua mat phan each Neo duoc lap dat nhanh sau khai dao de tranh