Thdng t in khoa hpc edng nghe mo jg CAC GIAI PHAP DAM BAO ON DINH B 0 MO MA tkasi ^m^ Qtal Mine slope deformation in Vietnam has occurred rather frequently, causing a lot of economic losses and instab[.]
T h d n g tin khoa hpc e d n g n g h e mo jg CAC GIAI PHAP DAM BAO ON DINH B MO MA tkasi ^m^ Qtal Mine slope deformation in Vietnam has occurred rather frequently, causing a lot of economic losses and instability for mine sequences, especially at big coal pits being enlarged and deepened Basing on the results from longyear study on slope movement, geological structure, geotechnical properties and hydrogeology, the paper represents measures to ensure the stability of slopes at Deo Nai coal pit The paper also provides general recomendations on ensuring the slope stability of Vietnam open pit coal mines, while Deo Nai is the first one of the process Cong tdc nghien cufu bien dang bd md a Viet Nam Cdc bd md Id thien cd ca'u tao nhu nhijfng mai ddc Idn vdi chieu cao hang trdm met, chieu dai hang ngan met ma khd'i trUpt cd the Idn tdi hang chuc trieu m^ ludn Id dd'i tUdng nghien cifu thiet kd, khai thac md vd phuc hdi da't dai Su thay ddi gdc dd'c ehi 1° eCia nhufng bd md Idn ddn den sU thay ddi tai chinh hang trieu ddla Vi du nhU bd Bac Deo Nai hien cao hdn 200m, dai hdn 1000m thay ddi 1° Id thay ddi lUdng da't bdc hdn trieu m^ vdi chi phf bdc da't hdn 50 ti ddng Hien vd nhieu ndm nua, khai thac Id thien vdn chiem Uu the, san xua't tren TS K l i u KIM TRUC Tap dodn CN Than - Khodng san VN dudi 50% san lupng than Nhu cau than hien tdng cao tren 20%/ndm ddn ndm 2025 theo Quy hoach, phdt trien ngdnh Than [2] Chieu cao bd mo, chieu sdu khai thdc Id thien se Idn hon, van de dn dmh bd md cdng trd nen can thie't Bien dang bd md b nudc ta xay khd phd bidn, gdy nhieu thiet hai cho san xud't, phai bdc xuc ngodi kd hoach, lam ban vd tdng tdn thd't than (Ak >35%) Chi phi xCr li khdi trupt Idn hon nhieu so vdi bien phdp de phdng (bj dpng xuc da't trUdt tu day md len so vdi xuc bdc phia tren trudc) Chinh vi vdy, cdng tdc nghien cufU dn djnh bd md khdng chi Id van de kT thuat vd an toan lao dpng, ma cdn Id van de kinh te Hien nay, Viet Nam cd cdc mo Id thien Idn Id Deo Nai, Cpc Sau, Cao Son, Hd Tu, Nui Beo vd Na DUdng Bdi viet se gidi thieu kdt qua nghien cufu vd xdc (Snh cdc giai phap dam bao dn djnh bd mo, bao gdm ddnh gid dieu kien dja chat kT thudt md, hien trang bidn dang bd md, du bao dn djnh bd md kdt thuc vd dua cdc giai phdp kien nghj vdi cac thdng sd tdi uu Qud trinh nghien cifu da thuc hien nhieu thi nghiem phdng va ngoai hien trudng, phdn tfch ngupc (back analyze) cdc khu vuc bien dang, cap nhdt phdn tfch ca'u true cdc gUdng khai thac v.v de xdc djnh dUdc ddc tfnh cd 1^ ciia khdi dd bd md, tfnh todn, xdc djnh cac thdng sd dn 6\nh cho bd Hinh Md hinh bdmd Deo Nai, cae Id khoan thdm dd vd tuydn quan trde dfeh ddng n KHCNM S6 3/2010* CNKT L THI£N Thong tin khoa hpc cong nghe m o md Cdng tdc xdy diJng vd stf dung Cd sd dijf lieu dia chat quan he (relational geological database) vdi cae phan mem tich hdp vd tfnh todn dn djnh bd md dugc Ung dung rdng rai (phan mem Geolinx, Galena ) Theo thdi gian, mpt sd ban thidt kd ed the thay ddi, hien trang dja hinh ludn bidn dpng, nhung nhufng ddnh gid khoa hpc thi van giijf 6ugc ca nhOfng y nghTa thUc tien Tom tat dac diem dja cha't va bie'n dang bd mo Cdc via than chi'nh dupe khai thdc Id via Ddy vd via G, theo thif tu tu dUdi len, chu ydu tai via G1 khu Cdng trudng chinh tru nam vd khu moong thudc tru bac Dja tang chCfa than thupc tram tfch Mezdzdi tudi Trias thupng Nham thach bao gdm san kdt, cat ket hat thd, hat mjn, bdt ket, set kdt vd than Rupng md bj phdn eat manh me bdi he thdng dift gdy phUe tap thdnh cdc khdi kidn tao gdm bd tdy bac, bd bac, bd ddng bac (bd vdch, bd cdng tac) vd bd tru nam, dd bd vdch (tdy bac) vd bd tm (nam) Id ddc trung chung cho cdc md Id thien khai thdc qudng dang via Cac bd md chfnh deu dang bj bidn dang Bidn dang Idm bung nen day hao, day giy via than, triim lap tru via, lam ban than, gdy khd khdn cho viec khai thdc vd ddnh gid truf lupng Khdi lUdng than dat tfnh theo cap nhdt trac dja so vdi thdng ke thudng giam hon 57% (hinh 2, 4) 2.1 Bd tru nam: phdn bd tren cdnh nam cua khodng sang cd ddc diem nham tang Id cdc Idp dd dudi than cd thd nam ddn ta cam xudi theo bd md vdo khdng gian khai thdc tu 20° den 37° Via GI khu Cdng trudng chi'nh phfa nam cd hudng cam bac tuong ddi dn djnh, cd eau true mdt ddn ta Khu VLfc trung tdm khodng sang gidi han giufa ddt gay A3 vd A2 Id cdc tap than via G md trudc ddy gpi Id via Ddy, cd hudng cam ddng nam dd'c hdn 40° Bd tru nam ed cdu true dd tru via than cam xudi theo chieu ddc bd md, ddc 15-37° TU ndm 1976 bd md dd bi bidn dang, mUc dp tdng nhanh dan den ndm 1981 vd phd hCiy vdo ndm 1983 (chiem pham vi 17 ha, sdu 10 -20m) Luc dd md phai cai tao lai bd, bdc gan hdt cdc Idp dd ydu da trUpt Id (hdn trieu m^) Do vdy, tU dd ddn ndm 1995, mUc dp djch chuyen thuyen giam ddng ke Tuy nhien, tU ndm 1995 den sU djch chuyen dang gia tdng mdt cdeh ddng lo ngai, eu the Id phfa ddng khu Cdng trudng chfnh (hinh 2) Bd bidn dang kieu trUdt khd'i theo mdt tidp xiic ydu Van tdc djch chuyen dn djnh Vo =1mm/ng.d Van td'c djch cliuyen tdi han V^, = - mm/ng.d (miia khd) Miia mUa van tdc tdng len 20 lan (hinh 3) Thdi gian bidn dang keo ddi nhieu ndm, giai doan bidn dang tich cUc - ndm, phd hCiy xay nhanh, manh, dudi ndm Sau phd hiiy phfa Tdy, hien dang tUOng dd'i dn djnh Khu vUe giufa dang bj phd hCiy tu dudi mUc +130m Khu VLfc phia Ddng truf lUpng than cdn sdu tdi -200m, dp ddc Idn, cdng tac xud'ng sau tap trung ddy nen tU ndm 1995 ddn nay, td'c dp cd chieu Hinh Bidn dang bd trp nam: nUt khdi dd vd trupt theo mat try KHCNM S6 3/2010* CNKT L THI£N Thong tin khoa hpc cong nghe m o Vdi ca'u true phifc tap ciia bd bac, thi hien tupng thao khd bd md (timg tang chifa nU6c rieng biet) chi xay tdi dp cao bdc Id nhiifng tang dd vd eac ddi dUt gay cat vao phUdng via than Hien dp cao xua't Id nudc ngam quan trac 6ugc tai +100m - +75m tren bd bac day md +60m vd +280 m tai bd tay bac (Lp TrQ ddy md tai day Id +140 m Qua trinh bien dang cung tdng CUdng thao khd bd md hudng gia tang tU 1-2 mm/ng.d hang ndm len hdn 14mm/ng.d nam 2001, vectd djch chuyen tU dudi Im hang ndm len 5m ndm 2001 Viec khai thdc via GI xudng sau b day se lam cho bd md bj bien dang phd hCiy todn bp chieu cao bd neu khdng cd bien phap phdng chd'ng hufu hieu Nguyen nhdn chfnh la hien tupng cat chdn cdc Idp da yeu ddc hon 17° (p>(p'= 17°) tren cac tang vd tdn truf nudc ngam cd dp nham thach gan tru via ma chua bj bdc Id Bd bac vdi ddc trimg la da cam ngUde chieu ddc bd md, ddc 30°- 40° Phfa Tdy bj chia eat chang ehjt bdi dirt gay a, A1 (ngang) vd A2, A3, A4 (dpc) vd mpt nep Idi tU dp cao +160m lam nham thach phfa dudi chuyen sang cam Nam, gay bat ldi cho dn djnh bd md 2.2 Bd bac: nam cdnh treo khoang sang, tren phan Idn chieu cao phia tren nham tang gdm cdc Idp dd tuong dd'i dn djnh vdi the nam cam ngupc vao bd md Phia dUdi chan bd md lai the hien cac Idp da thay ddi hudng cam Bidn dang xay tren pham vi 40 ha, the tfch 10 trieu m^(ndm 1990), theo kieu trUdt khdi cdc Idp bj udn tdeh (udn 60, hinh 4), tao nen cdc khe nUt them bdc ngUdc Van tdc djch chuyen giai doan dn djnh Vo=3-4 mm/ng.d Van tdc djch chuyen tdi han Vu,=10 mm/ng.d vao mua khd (hinh 5) Miia mUa van tdc tdng len 5-10 lan Giai doan tfch cue keo dai ndm (1984 -1990), thdi gian phd hCiy keo ddi ndm (1988 -1990) Djch chuyen giam dan, ddn ndm 1995 lai bat dau gia tdng ehu ky mdi (hinh 6) Ndm 2001, djch chuyen di 10 - 20m Bd md da bj phd hCiy mat tfnh nguyen khdi, ehi eon lai Id sU trUdt Id theo qudn tfnh hdng chuc met, moi ndm bdc xuc phfa dudi khu moong Khdi trupt vd hinh chung dupc Luong mira th^ng, mm Van toe dich chuyen, mm/nd mm/nd h SO 60 40 20 • ^ ^ ^ - — ' ^ i \ \ ^^^^^ m \ ^B-, ^^^ Na m §ii£l^i 1978 i / ^/"l li .^SLJSKL 1979 BH ^ 1980 H / My\ T ^ ^ ««jJi 1981 / ^^"\ V' 1982 1983 Hinh Bidn dang bd vdch tdy bdc: ud'n ddvd trupt khdi THI£N ^** ^soo »Wi yiMa\ N ywji^*'^ j^^A ~-'^'wiUKkJl!s — \ ^ r ^ ° Hinh Xdc djnh van tdc djch chuyen tdi han bdtru nam KHCNM s o 3/2010* CNKT LO "*" T h o n g tin k h o a hpc c o n g n g h e m o bdc xuc dan tU phfa dudi Dinh khd'i trupt ndm 1988 da thd'p hdng chuc met Nguyen nhdn chfnh cua qua trinh bien dang b ddy Id gdc dd'c bd md qua cao dieu kien dja chat kT thudt khdng thuan Ipi Nham tang bj anh hudng phd huy kien tao, ddt dd yeu, bd sung nude tren phan Idn chieu cao Cao trinh xud't Id nude ngam xudng hien la anh hudng cua qua trinh bien dang Ddnh gid va xac djnh cac giai phap dam bao dn djnh bd md Deo Nai 3.1 Bdtru nam Bien phdp giuf dn djnh bd tru la giam tdi da cdc nguyen nhdn gdy trupt nhu hien tupng eat chdn tang vd gia cdng sudn tang theo mdt Idp de giam tdc ddng eiia phong hda Chieu cao tang tdi da phu thudc gdc ddc Idp dd khdng vupt qud gidi han xdc dinh [3] Chieu rdng tang giufa cae nhdm tang phai Idn hon 10% chieu rdng Idng tru trupt NhU vay, mdi khu vUc se bien dang mdt cdeh ddc lap, cdn cdc dudng van tai tren dd van 6ugc sd dung lau ddi Phai theo doi sU thodt nUde ngam qua cdc dirt gay vd ddy md de cd cd sd di den giai phap khoan giam dp vd quan trac djch ddng Cdc giai phap cu the dam bao dn djnh bd tru nam Id: - Loai bd cdc hien tupng cat chan Idp da de cat tang gdc ddc Idp da Idn hon gdc ma sat mdt Idp nham thach, tai day Id 17° - Trong qua trinh khai thac xudng sdu se van tdn truf dp luc nude ngam tru via Do dd can khoan eac Id lHH 3.JI H ap ripaBHJia o6ecneMeHHfl ycTOHqHBOCTH S.OHCCHKO OTKOCOB pa3pe3ax Ha C 1998 207 tr yrOJILHUX rierepGypr ... Bidn dang Idm bung nen day hao, day giy via than, triim lap tru via, lam ban than, gdy khd khdn cho viec khai thdc vd ddnh gid truf lupng Khdi lUdng than dat tfnh theo cap nhdt trac dja so vdi... bd mo Cdc via than chi''nh dupe khai thdc Id via Ddy vd via G, theo thif tu tu dUdi len, chu ydu tai via G1 khu Cdng trudng chinh tru nam vd khu moong thudc tru bac Dja tang chCfa than thupc tram... gidi han giufa ddt gay A3 vd A2 Id cdc tap than via G md trudc ddy gpi Id via Ddy, cd hudng cam ddng nam dd''c hdn 40° Bd tru nam ed cdu true dd tru via than cam xudi theo chieu ddc bd md, ddc 15-37°