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KHOA HOC VA CONG NGHC MO X/NGHIEN CUU sir PHAT TRIEN CUA VI KHE Nurr TRONG VRT ufu Dfl, BC TONG DE DU BAO THdl GIAN PHA HUY V gt lieu da vd bd tdng Id nhung logi vgt lieu d eau trtjc phirc tap vd ludn[.]
KHOA HOC VA CONG NGHC MO X/NGHIEN CUU sir PHAT TRIEN CUA VI KHE Nurr TRONG VRT ufu Dfl, BC TONG DE DU BAO THdl GIAN PHA HUY TS NGUYEN VAN M A N H ^ Trwimg Dai hgc M6-Dia chat gt lieu da vd bd tdng Id nhung logi vgt lieu d eau trtjc phirc tap vd ludn ludn tdn tgi cdc vi khe nirt lo rong nd hay d n gpi la d c khuyit tat d u tnJC- Do ludn cd s y ton tai cita cdc khuyit tgt vdt lieu dd, be tdng ndn chiing d u g c xem la mpt nhii'ng y i u td chinh dnh hudng d i n b i n vd t u i i thg cua vat lieu Khi vdt lidu chju tdc ddng cua tai trpng, cac vi khe nirt cd t h i phat trien va lien k i t vdi tao thdnh cac v i t nut ldn d i n den gay phd hiJy vdt ligu Khi v i t nut hlnh vd phdt t r i i n vat ligu d i n mdt thdi d i i m ndo se ldm m i t kha nang lam vide an todn ciia edng trinh hogc gay pha htjy cdng trinh Thdi diem vet nCet phat trien vugt qud gidi han cho phep ddn tdi nguy co m i t an toan ciia edng trinh la rat quan trgng vige dua eae giai phap xiy ly thich hgp, d l dam bao cho cdng trinh lam vigc gldi hgn an todn V D i n trdn the gidi da cd r i t n h i i u md hinh duge de x u i t vd dp dung de d y bao, phan tieh s y phdt t r i i n ciia v i t nut vat lieu da vd bd tdng [IJ, [2] nudc ta vide sir dung cae md hinh d i phan tich, ddnh gid s u pha hogi eae bd phan k i t eau cdng trinh da va dang dugc dp dyng tinh todn thiet k i n h i m ndng cao dd chfnh xdc, dp tin cdy tinh todn t u i i thp cOa cdng trinh Ly thuyit Cff hpc pha hiiy bd tdng da d u g c dp dyng d nudc ta d i phdn tfch s y pha hoai ciJa d c bd phdn k i t cau niiu d i m , vd ham hay tudng chan bd tdng s y x u i t hidn vd lan t m y i n eae khe nirt [4], [5] Tuy nhien, dp dung phijgng phap ndy de danh gia s y lam vide ciia k i t d u be tdng ddi hdi phdi ttln hanh r i t nhieu thf nghiem 6e xdc (Tmh d c dge trung eo hge eua vdt ligu dac bigt la eae dac tmng ni>t CO ban ciia vat ligu bg tdng, de lam eo s d cho vi^c tfnh todn t h i i t k i va d y dodn s y pha hogi Cdc dgc t m n g nirt eiia mgt s i loai bd tdng thudng diing xay dyng d Viet Nam dd dugc xdc djnh thdng qua thi nghidm [6] Ddy id cdc thdng sd r i t m GONB NGHlfP MO, S - I huu fch viec tfnh toan d y bdo s y phat trien eua cac khe nirt k i t c l u cdng trinh bdng be tdng va bd tdng d t thep Nhin chung cdc md hinh ly t h u y i t d u g c de xuat de nghien cuu s y phdt t r i i n eua vet nirt vdt lieu da va bd tdng d i u d y a trdn co s o la cdc khe nirt ban d i u d dgng m d vd don le, t u dd phat triln cac phuang phdp tfnh toan s y phdt trien nirt ti> vet nirt m d ban ddu Trong thyc te ngodi cdc khe nirt m d ban d i u edn d cdc vi khe n&t kin phdn bo vdt lieu Do dd, vige nghien eiru md phdng sy lam vide eua cde vi khe nirt kin vat ligu dd vd bg tdng se giiip hieu rd hon ban chat ciia s y phd huy cung nhu de d y bdo thdi glan pha hiiy, Mo hinh n u ^ va he s i tdp t r u n g ii>ng suat K C o e h i nirt va lan t r u y i n cae vet nirt cac vdt lieu dudi tde ddng cua tai tn?ng ed the chia thdnh dang chinh ggi la Mode I, Mode II vd Mode III vd dang hon hgp giua chiing [7] Cac kieu nirt dugc t h i hidn n h u trdn hinh H l Trong thyc t i , cdc Mode hdn hgp la Mode k i t hgp hai hogc ba Mode c a ban ndi trdn la thudng gap hgn ea V i du, e g che nijt irng suit keo chfnh cac d i m chiu uon la Mode I va Mode II gay Be xdc dinh trgng thai ung suit nhung t m d n g hgp phirc tgp, t m d c het d n phai tfnh todn cho tirng dang c a ban rieng bigt He sd tap tmng irng s u i t (K) la mdt khai nidni d u g c Irwin [4] de d p l l n dau ttgn vao nam 1957 Inwin chirng minh r i n g t i t ca cac trudng &ng s u i t dan hdi xung quanh v i t nu't d i u phdn b i giong va tt Id vdi a V n a De phdn bidt cdc dgng phat t r i i n cua v i t nut, n g u d i ta ddnh chi s i I, II va III eho ba Mode c o ban ndi trgn vd tinh todn hg s i tap ti-ung irng s u i t n h u sau [4]: K,=aV2^ (1) KHOA HOC VA CfiNG NGHE MO '^/ _^^ Trong dd: a - NCra chieu dai vet nut; o, T va T' - Lan l y g t la cdc phan irng s u i t phdp, ii-ng suat cat mgt phang va ngoai mat phang ti Cac Mode nui cua v$t lieu [7]: Mode I Id d^ng ma rdng cdc vet ntW hl$u ijng phdp tuyin gay ra; Mode 11 la dfng cit phing cac hieu Ong cit gay ra; Mode III Id dang cit ngoai m$t phdng cdc hieu Cmg xoin gay Trong thyc td cac v i t nirt khdng chl phat trien theo mpt dgng c o ban d trgn md la s y to hgp eua hai hay ba dang khdc Mgt khae, cae gid trj K|, Kn va Km d n phu thudc vdo vi tri v i t n i i i trgn vdt t h i , tt Id kich t h u d c cua vet nirt so vdi vgt t h i Chinh vi vgy, vide xdc djnh cdc gia tri ndy se phirc tap hon rat nhieu doi vdi cac trudng hgp cd s y t i n g hgp ciia cdc Mode phd hogi Khi he so tgp trung irng s u i t K dgt den gia trj gidi han Kc thi vet ntjt se phdt t r i i n vd lan t m y i n ngoai thi v i t nirt van tri on djnh, Gia tn hg so tap trung irng s u i t gidi han Kc phu thudc vdo loai vgt ligu va d u g c xac djnh thdng qua thi nghidm Tinh toan toe phat trien nui Charies (1958) da dd xuat bieu thirc tfnh todn toe dp phdt t r i i n v i t nirt nhu sau [5]: v = v„K''e'-"'"^»"'* (4) Trong dd: Vo - Hang s i vdt lidu; n - Chi s i suy giam irng s u i t ; K - Hg so tgp trung u'ng s u i t ; u - Ndng lugng hogt ddng; T - Nhidt dp tuygt ddi; Kb - H l n g sd Boltzman Tren hinh H.2 t h i hign m i i quan he gl&a t i e dp lan t m y i n nirt (v) va he so tap tmng irng s u i t (K) Vdi gia thiet nhidt dd (T) Id h l n g so, phugng trinh (4) cd t h i v i i t Igi d u d i dang don gian n h u sau [5]: V = CK" (5) Trong dd: C - Hang so vgt lieu d u g c xac djnh t u thf nghigm Ngodi s y phat t r i i n nirt keo, ehOng ta eung d n chii y den phdt t r i i n nirt eat Gidi t h i i t toe phdt t r i i n nirt Id s y k i t hgp ciia ea nirt kdo va n&t d t , dd t i c dd phat trien n&t ciia md hinh k i t hgp se Id; V = V{K,)+V(K,|) (6) Vdi d c hd so tdp trung ung s u i t K| va Kn d u g c tinh todn theo d n g th&c (1) va (2) H.2 Quan he giu^ tdc phdt tridn nui _ vd hd sd tdp trung mg suat TCr (6) cd the nhdn thay rang t i c phat t r i i n nirt phu thugc rat ldn vao c h i i u ddi v i t nut vd dd Idn ciia t m d n g irng s u i t tdc dyng S y phat t r i i n ndt didn cho den he s i tdp trung irng s u i t dat d i n gia tri gidi han Kc va Knc - Cac hang so Xay dung mo hinh dir bao thoi gian pha huy Tuoi thg ctia vdt lieu ran d u d i tdc dijng ciia tdi trgng kdo da d u g c nhieu tdc gid nghien cuu [3], [8] Tuy nhidn, cdc nghidn c&u ndy chi phit hgp eho vdt lieu r i n va dge hodn todn De h i i u sdu hon ve tuoi thg cita vat ligu r i n d n chu y den cae k h u y i t tdt (lo rdng, vi khe nirt,,.) vdt lidu Qud trinh pha huy vdt ligu la mdt qud trinh pha huy d u d i tac dung ciia tdi trpng vd d u g c ggi la s y phdt trien tdi hgn cua vet nirt Ndi dung cua md hinh d i md phdng s y phat trien cua vi khe nut de d y bao t u i i thp cua vgt ligu chju tac dyng ciia tai trgng dya trdn viec s& dyng ngon n g u FISH cita chuong trinh FLAC 2D Gia s u rang mdi p h i n t& cua md hinh cd chira mgt vi khe nut d c h i i u ddi cho trudc S y phan bo trang thai ung s u i t d u g c tinh toan theo tidu chuan b i n Mohr- CONG NGHIEP MO so 1-2016 ^ ^ _ KHOA HOC U CfiNG NGH| MO Coulomb Hg so tdp tmng irng suat ctia m i l phan t u d u g c tinh toan cho d c vi khe ni>t tuong ung theo d n g thirc (1) va (2) N i u hd s6 t#p tmng ung s u i t dgt d i n gid trj tdi han Kc liodc c h i i u dai v i t nirt dat den gia tii kich thudc cua phan t& thi phan t u se bj coi Id pha hiiy vd d u g c gan sang trgng thdi sau pha hiiy vdi tri so b i n bang khdng Qua trinh phat trien v i t nirt Id mdt qua trinh r i t phirc tap, bdi vi nd lien quan d i n s y phdn bo Igi trgng thai irng s u i t phdn t u va s y tuong tdc gi&a cac v i t nut T u do, d the xdc djnh tuoi thg cua moi phan t u bang each I l y tfch phan trdn todn bg chiiu ddi cua vet nt>t n h u sau [5]: _ f dc m J V Trong do: Co - Chieu ddi ban dau cua vi khe nirt; Cc - Chieu ddi tdi hgn ciia vi khe n u t v - T i c dg phat t r i i n cda vl khe nut theo b i i u thirc Charies S u dung eac p h u o n g trinh (5) vd (6) thay vao p h u o n g trinh (7), chiing ta cd the viet lgi dugc n h u sau: = lcK^4lkH "cp ^l(^J^f(^: (9) Vdi dpt Id kich thudc tmng binh ciia phdn tti md hinh va d u g c tinh theo dign tich p h i n t u nhu sau [5]: Md hinh md phdng dugc chia nhiiu phan tir, moi phan tir tudn theo quy lugt Mohr-Coulomb, do can cdc tham so vgt ligu sau: md dun ddn hdi (E), he s i Poat-xdng (v), lyc dfnh (c), gdc ma sdt (iji) vd ben keo (at) Ngoai m i l phan t u cd chua mdt vi khe nirt Cac vi khe n&t dugc gid thiet la ed hudng n i m ngang Do dd, ung s u i t e l t Idn n h l t m i l p h i n t& vd d c thdnh p h i n &ng suat chfnh d n dugc tfnh todn than trgng qud trinh lan truyin niii Thdi gian cua budc tfnh toan dugc giu du nhd d i phu hgp vdi s y phan bd Igi trgng thdi ung s u i t lan truyin v i t n&t C h i i u dai v i t nirt hidn tgi anew d u g c ttnh todn theo thdi gian nhu sau [5]: a.ew=ao,d + v.At (11) Trong do: aow - C h i i u ddi v i t nut cu; anew - C h i i u ddi v i t nut mdi; v - T i c dp lan tmyen nirt; At Khoang thoi gian lan tmydn ntjt Cac vi khe nirt phan bd cac p h i n t u theo phdn phdi c h u i n Do dd cac phan ung suat p h i n t& d u g c s u dyng d i tinh toan s y phat t r i i n n&ftdi han CfiNG NGHllP MO, S01 - 2016 (8) 1-n/2 Trong dd: Co - C h i i u ddi tdi hgn ciia v i t ntit C h i i u ddi tdi hgn eua v i t nirt d u g c xdc dinh theo d i i u kien sau; la gia tri nhd nhat ciia thdng s i : chieu ddi n&t tdl han tinh theo Kic, Knc vd kich thudc eua p h i n t& md hinh ed nghTa Id [5]: Ket qua md phdng S& dung ngdn ng& FISH d i xdy d y n g md hinh md phdng bai toan va tinh todn tuoi thg eiia vgt lidu VI du dugc tfnh todn cho vdt lieu dd granit chju ndn vd chju keo vdi d c thdng sd eua vgt ll^u nhu trdn Bang Bang Cac thdng s6 cua vat lieu [1] ThSng so B e n vj 1^5 dun dan h6i H f so Poat-xong Khoi lu-onq rignq G6c ma sat tronq LU'C dfnh lng suSt H f so t i p trung u-ng suat tCTi hgn Kic H f so t i p trung ung suat lo'i han Knc Hang s6 phat trien nutC GPa - T/m" Ba IWPa IVIPa - Gl'^'Mj 75 j 0,231 , ^ ^ ^ ^ 32 ^ IvlPa.m'" 1,8 IWPa.m'" 1,8 II pham (m/s)(Pa.m'°)-" J ••,'»?4S Md hinh md phdng mau dd cd kieh thudc 2x2 (m) chju tai trpng keo (8 MPa) va nen (15 MPa) Mo hinh dugc chia thdnh 50x50 phan t u , moi phan tu cd kieh thudc la 4x4 cm Hg t h i n g vi khe nirt ban dau phan bo v|t lidu ed c h i i u dai tmng binh la 1,0 cm vdi dd Idch c h u i n la 0,2 em va tao vdi phuang nam ngang mpt gdc 0° (hinh H.3) Tien hanh nghidn c&u s y phdt trien n&t chiu tai trgng keo vd nen don tryc _^^ KHOA HOC VA CtNG NGHl MO K i t qua trang thai phdt trien nut theo thoi gian d c md hinh chju keo vd nen don true n h u trdn hinh H.4 va H.5 T u ket qua cd t h i n h | n thay rang d u d i tac dung cua tai trgng keo chl cd mgt dai nirt phat t r i i n theo phuong ngang (hinh H.4) Trong d u d i tdc dung cua tai trpng nen, s y phat t r i i n nirt xay d n h i i u vj tri khdc md hinh H.3 Phdn bd chudn cac vet nui ban dau phin tir md hinh (chiiu dai trung binh cua vit nui la 1,0 cm vai lech chuin la 0,2 cm) I I gid 28 phiit 30 giay (10 phan t& bi phd huy) Ml H.4 Si/phdt 22 gio 35 phut (1 phan tip bj phd huy) D i i u ndy cd nghTa la s y phat trien nirt t u cac vi khe nirt d i u ttdn xay d n h i i u vi tri khae nhung sau 36 chiing hgp lai mgt vai dai nut nghieng va tao vet nii't Idn gay pha hiiy vat lieu ihinh H ) trien nui chiu tai keo MPa 16 gio 55 phiit (10 p h i n t& bj pha hiiy) H.5 Sl/phat gid 34 phiit 27 gidy (50 p h i n t u bj phd hiiy) gid 30 phiit (50 phan t& bi phd hiiy) trien nui chju tdi trgng nen Md hinh bj coi la pha hiiy vet n&t phdt trien va d t ngang qua md hinh nhu trdn hinh H.4 K i t qua cho t h i y d u d i tae dyng cua tdi trpng keo khdng doi Id MPa thi md hinh bj pha huy sau khoang thdi gian la g i d 34 phut 27 gidy Khi tai trpng keo tdc dijng Id MPa thi md hinh bj pha huy sau khoang thdi gian Id 12 gid 56 phut 51 gidy D i i u ndy cho t h i y s y tuong quan phi t u y i n giua tuoi thg eua vgt ligu vd d p dd tai tn?ng eung n h u kieu tdi trgng tdc dyng So sanh k i t qua phdt t r i i n nirt eiia m l u chju tdi trpng keo vd nen cho t h i y t u i i thp ciia m l u chju nen 15 MPa Idn han r i t nhieu so vol t u i i thg cua mau chju keo 17 ngdy gid 40 phut (319 p h i n t u bi phd huy) 15MPa MPa Dieu ndy Id hoan toan phit hgp vl vdi eae vdt lieu ddn nhu da va bd tdng thi dp ben keo nhd hon rdt n h i i u so vdi dp b i n nen eua vat lieu T u hinh H.4 va H.S d t h i nhgn thay khodng thdi gian x u i t hign phan t u bj phd huy dau ttgn cung n h u khoang thdi gian t& p h i n t& d i u tten bj pha huy ddn mau coi n h u pha hiiy cung khdc chju tdi trpng keo vd ndn Trudng hgp chiu tai trgng keo thi khoang thdi glan t u p h i n t u d i u tidn bi pha hOy d i n m i u bj pha huy la phut 27 giay, d n chju tai trgng nen thi khoang thdi gian id 16 ngdy 10 gid 05 phut CfiNG NGHllP MO, Sfi 1-2016 KHOA HOC VA CfiNG N6H| MO Ket luan Bai bdo da tiinh bdy thuat toan md phdng tfnh todn thdi gian phd huy vdt lieu da, be tong chju tai trpng keo va nen Co s d d a phuang phap tfnh t d n la chieu dai nirt tdi hgn vd s y hgp nhat d a d c vi khe ntit thdnh v i t ntjt ldn dya tren eg s d co hge phd huy dan hoi tuyin tinh (LEFM - Linear Elastic Fracture Mechanics) C6 the de ddng nhdn t h i y s y khae bidt d a phd huy keo vd cat Dudi tdc dyng d a tai trgng nen, d c qua trinh phdt t i i n nut tiip dien d i n quan sdt dugc phd huy Ngugc Igi, dudi tac dyng d a tai ttTpng keo, thi d i x u i t hidn d c v i t nirt don Khi so sdnh giira tai trgng nen va keo d o t h i y s y khac bigt ro rgt ve ttidi diem pha huy d a k i t d u vd mang v i t nut phd huy.G T A I LIEU THAM KHAO Atkinson BK (1987) Fracture mechanics of rock Academic Press, London, p.534 Griflith A.A (1920) The phenomena of mpture and flow in solids Philosophical Transactions of the Royal Society of India, series A221,pp.241-257 Hilleriaorg A, Modeer M, Petersson P.E (1976) Analysis of crack formation and crack growrth in concrete by means of fracture mechanics and finite elements Cement and ConCTete Res 6: pp.773-782 Ifwin G.R (1957) Analysis of sfresses and stiains near ttie end of a crack traversing a plate J Applied Medanics, ASME, New York 24(3): pp.351-369 Konietzky H Heftenberger A and Feige M (2009) Life-time prediction for rocks under static compressive and tensile loads: a new simulation approach Acta Geoteehniea, No 4, pp.73-78 Tran T h i T m y i n , N g u y i n Xuan Huy, (2011) Pha hiiy, rgn nut be tdng: e g hgc vd &ng dyng, NXB Xdy d y n g Ha Ngi, Vidt Nam 200 trang, 2011 Shailendra K and Sudhirkumar V.B (2011) Concrete fracture models and applications Springer-Veriag Beriin Heidelberg, p.1-286 Zhurkov SN (1965) Kinetic concept of the strengtti of solids Int J Fract Mech (4):311 AfgifOT bien tap: Vo Trgng Hung For many years, mines put forward an increase in the rock and concrete always contain the microstructural like micro-crack, voils etc These parameters are effected to lifetime of materials This article presents a computation algorithm to predict the lifetime of brittle materials like rock and concrete which depends on the distribution of microcrack in the materials The proposed model is based on subcritieal crack grc the linear elastic fracture n approach The algorithm considers both tensile and shear fracturing The proposed model was applied to rock samples under uniaxial compressive and tensile loads for prediction of lifetime The results showed that a significant difference of failure zones under uniaxial compressive and tensile MOT SO VAN DE (T/dp theo trang 54) Ngwdfi bien tdp: Trin Van Trach Mau Due-Ha Giang Antimony Mine is preparing deep exploitation However, using current mining technology for deep-down period is inappropriate In this paper, the authors assess the current state of the mine, which offer a number of issues to consider about mining technology in the next stage deep down in the mine CONG NGHIEP MO, S - Chon d u d n g doi lap v d i loi mdn vd bgn gan n h u se ludn Idm t i t Jean Jacques j Rousseau Hanh phuc khdng phai la thir c6 san ' Hanh phiic d i n tip hanh dgng cita chfnh ta \ DCFC Dat Lal Lat ma Ban than dirng qua lo l i n g hay nghiem hda van de, chang quan tam n h u J bgn lo s g dau Regina Brett Kha nang thay b i i roi t r u d c s y v$t s y J viec la tien de cho mpi sdng tgo, dii Id ngh0 thuat hay khoa hgc William Carlos Williams V VTHswutim^ ... nt>t n h u sau [5]: _ f dc m J V Trong do: Co - Chieu ddi ban dau cua vi khe nirt; Cc - Chieu ddi tdi hgn ciia vi khe n u t v - T i c dg phat t r i i n cda vl khe nut theo b i i u thirc Charies... Poat-xdng (v), lyc dfnh (c), gdc ma sdt (iji) vd ben keo (at) Ngoai m i l phan t u cd chua mdt vi khe nirt Cac vi khe n&t dugc gid thiet la ed hudng n i m ngang Do dd, ung s u i t e l t Idn n h l t m... a.ew=ao,d + v.At (11) Trong do: aow - C h i i u ddi v i t nut cu; anew - C h i i u ddi v i t nut mdi; v - T i c dp lan tmyen nirt; At Khoang thoi gian lan tmydn ntjt Cac vi khe nirt phan bd cac