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Strength stability and similitude
117A
ted for their relevsnce to the rapid-excavatlon process In rock.
Strength characteristics
zo99 AtTI~O NJ MICHIGAN UNIV,ANN AP~OR,USA SIKARSKIE,DL MICHIGAN UNIV,ANN ARBOR,USA Some experimental obse:cva~lo~s on t h e initiation and p r o p ~ a t i o n o f f r s o t u r e i n e l a s t i c b r i t t l e ~ t erlals s~fl~ected to compressive s t r e s s fields. 13R. PAPE8 TO l ~ ~ I~CH.CONF,NORMAN,OKLA,2~-26 MARCH 1975,PI~-170. Exper~,~tal results have shown e~cellent a~ree~e~t with the predlc~ed fracture initiation lo=ation end force levels and reanc~eble a ~ r e ~ t with the predicted fracture p r o p a g a t i o n .
1104 MURRELL, SA UNIV. COT TRC-E,LONDON, G~ ISMAIL, IA UNIV. COLLEGE, LONDON, GB The effect of temperature on the strength at high confining pressure of granodiorite containing free end chemlcally-bound water. 6F,3T,29R. CONTR .MIN~ .PETROLOG ,VS~,N~, 1976,P317-330. Deformation exper~-~ts have been carried out on a microgrs~odiorite under undrained conditions at a pressure of 0.~/~8 GPa and temperatures up to 720 de~.C. The ~can~diorite contained a small ~m~unt of chlorite end amphibole minerals which Heco~posed at elevated temperatures, giving rise to a pore pressure. Evidence about the de. composition resctio~ was obtained from differential thermal analysis and optical microscopy. In some experiments small amounts of free water were enclosed with the sealed rock sample. The strength (at fracture or 2 percent strain) fell to very low values (about 0.02 GPa) at about 700 deg. C. ~ i at temperatures of 670 de~.C, and above there was evidence of partial malting which led to Hu=tile behaviour. At som~hat lower temperatures the rock was relatively weak but brittle. Auth.
11OO SZCZEPINSKI ,W POL .ACAD .SCI,NARSAN,PL ZAWADA, J POL.ACAD .SC I,WARSAW,PL Note on a f r a c t u r e mode o f c e r t a i n r o c k s under compression. 6R. BULL ~tGAD.POL.SCI, SER .SCI .TECH,V23, N6,1975,P267-273. Certain llmes~c~e epeclme~s compressed between two narrow Ix~ches d i s p l s ~ - d a n interesti~ fracture mechanism. To e x p l a i n such a f r a c t u r e mode, a h y p o t h e s i s i s assum.~i that ~ust before fracture the fully plastic state of the entire cross-section of the specimen is reached. A theoretical plastic s o l u t i o n was o b t a i n e d u n d e r assmnption of the C ~ ~_el~ criterion end non-associated flow rule. Theoretical lines of the velocity ~.Iscontinuity ere close to the real lines, along which the spec~,~n~ were separated into t h e pieces. 1101 NISHD~ATSU, Y MATSUKI,K Com~ter s1-~,lation of the failure process of rock in compression (in Japanese with E~llsh abstract) I~R. J .MIN .MEv~J~. INST. JAPAN,V92, NIO~, JAN. i~76 ~P13.18. Discusses the com~zater simulation model developed which gives @cod results on the failure process of rocks under uniaxial compression. 1102 LITVIN~KII,GG MIN.~TALL INST,KO~Ma~SK, SU Kinetics of brittle fracture of solid rock neer a mine worklu~. 1OR. SOV .MIN.SCI, VI0, F~, S~T-OCT .197~,P538-~3. Ro=k pressure problems are investigated, and differential equations used to express properties. Develol~nent of cracking is estimated by introd~cin~ the te~sor characteristic of the continuity. Tim~ depanHe~ce of rock fracture explains some rock pressure phenom~a, and it is recom~anded for further investigation. 11o3 ~r/AKOV,AP INST .MIN,NOVOSIBIRSK, SU DUDOLADOV LS INST .MIN,NOVOSIB IRSK, SU ~IRNOV,W INST .MIN,NOVOSIBIRSK, SU F r a c t u r e o f finite-sized spec~-~- by wedge-shaped strtMers. ~R. SOV .MIN.SC I,VIO,N6, NOV.DEC .197~,P750-7~. R e s u l t s o f e n i n v e s t i g a t i o n un t h e p e r c u s s i v e cracking of spec ~-w~= of Plexiglas in ~r~ity impact tester by blows from a wedge are reported. The contact forces erising on collision of t h e tool with t h e spec~-~-, t h e p e n e t r a t i o n of the tool into the spsoimen, and the nature of t h e p r o p a ~ a t i o n o f e r - c k ~ t h r o u g h t h e specimen l e a d i ~ to its breakup are discussed. By a n a ~ i n ~ the ex~erim~ ental results eerta:Lu relatlonahll~ in the process of breskin~ of specimens of finite dimensions by percussive splitting were established.
~05 I~IR,RK ~JND~E UNIV,GB •~NGHA, CM IYJNDEE UNIV,GB Criteria for determining the critical stress of rocks in compresaicn. 17R. PROC.IST AUST.CONF.ON E~GNG.MAT~IALS, SYDNEY,26. 28 AUG 1974,P509-~16. The commonly used criteria for predlcting the critical stress of rock have been shown to ~ive incorrect values. An incremental Poisson's ratio criterion proPosed by the authors was found to give more realistic estimates. A m i c r o s c o p i c s t u d y o f t h e mechanism o f f r a c t u r e showed that cracks of approximately equal length continue to develop up to maximum stress. Strength failure has prlrustily related to an increase in crack density and not so ~ c h the length of individual cracks. Tests were per. formed on sandstone, marble end concrete. Methods for estimating impending failure in the case of cyclic l o a d i n g ere also d i s c u s s e d . ME~ZIES,BK ~ R E Y UNIV, GB Strength, stability and similitude. 5F,gR. GROUND ~ G N G .vg,N5, JULY, 1976, ~ 2.36. The e s s e n t i a l n a t u r e of s h e a r s t r e n g t h i s d i s c u s s e d , en~asising the co~on effective stress basis of both u n d r a i n e d and d r a i n e d s h e e r s t r e n g t h . The l i n k b e t w e e n test model snH constvuctic~ p r o t o t y p e i s made i n a statement about similitude. The stability mech~uics of constructional loading chs~es are briefly re-examined. Efforts to obtain similarity between the shear test models and the field prototype are considered. 1107 ISMAIL, IA IRAQ ~TIONAL OIL CO,IRQ ~LL, SA UNIV.COLI~E, LONDON,GB Dilatsn~y and the stcen~h of rocks containing pore water m~ler undrained condltlons. 21F,6T, MSR. G~OPHYS. J .R ,~IR. SOC. ,V~, NI, JAN 1976,PIO7-134. It has been shown that in rocks whose average initial porosities range from 0.5~-II.4X per cent dilate~cy durinE fracture at neer zero effective con~Inln~ pressures, when the strength is low, causes the porosities after fracture to reach very similar values of 8-16 per cent. For rocks whose initial porosity is low this implies very large increases in porosity. The percentage increase in porosity after fracture is however only about I per
ted for their relevsnce to the rapid-excavatlon process In rock.
Strength characteristics
zo99 AtTI~O NJ MICHIGAN UNIV,ANN AP~OR,USA SIKARSKIE,DL MICHIGAN UNIV,ANN ARBOR,USA Some experimental obse:cva~lo~s on t h e initiation and p r o p ~ a t i o n o f f r s o t u r e i n e l a s t i c b r i t t l e ~ t erlals s~fl~ected to compressive s t r e s s fields. 13R. PAPE8 TO l ~ ~ I~CH.CONF,NORMAN,OKLA,2~-26 MARCH 1975,PI~-170. Exper~,~tal results have shown e~cellent a~ree~e~t with the predlc~ed fracture initiation lo=ation end force levels and reanc~eble a ~ r e ~ t with the predicted fracture p r o p a g a t i o n .
1104 MURRELL, SA UNIV. COT TRC-E,LONDON, G~ ISMAIL, IA UNIV. COLLEGE, LONDON, GB The effect of temperature on the strength at high confining pressure of granodiorite containing free end chemlcally-bound water. 6F,3T,29R. CONTR .MIN~ .PETROLOG ,VS~,N~, 1976,P317-330. Deformation exper~-~ts have been carried out on a microgrs~odiorite under undrained conditions at a pressure of 0.~/~8 GPa and temperatures up to 720 de~.C. The ~can~diorite contained a small ~m~unt of chlorite end amphibole minerals which Heco~posed at elevated temperatures, giving rise to a pore pressure. Evidence about the de. composition resctio~ was obtained from differential thermal analysis and optical microscopy. In some experiments small amounts of free water were enclosed with the sealed rock sample. The strength (at fracture or 2 percent strain) fell to very low values (about 0.02 GPa) at about 700 deg. C. ~ i at temperatures of 670 de~.C, and above there was evidence of partial malting which led to Hu=tile behaviour. At som~hat lower temperatures the rock was relatively weak but brittle. Auth.
11OO SZCZEPINSKI ,W POL .ACAD .SCI,NARSAN,PL ZAWADA, J POL.ACAD .SC I,WARSAW,PL Note on a f r a c t u r e mode o f c e r t a i n r o c k s under compression. 6R. BULL ~tGAD.POL.SCI, SER .SCI .TECH,V23, N6,1975,P267-273. Certain llmes~c~e epeclme~s compressed between two narrow Ix~ches d i s p l s ~ - d a n interesti~ fracture mechanism. To e x p l a i n such a f r a c t u r e mode, a h y p o t h e s i s i s assum.~i that ~ust before fracture the fully plastic state of the entire cross-section of the specimen is reached. A theoretical plastic s o l u t i o n was o b t a i n e d u n d e r assmnption of the C ~ ~_el~ criterion end non-associated flow rule. Theoretical lines of the velocity ~.Iscontinuity ere close to the real lines, along which the spec~,~n~ were separated into t h e pieces. 1101 NISHD~ATSU, Y MATSUKI,K Com~ter s1-~,lation of the failure process of rock in compression (in Japanese with E~llsh abstract) I~R. J .MIN .MEv~J~. INST. JAPAN,V92, NIO~, JAN. i~76 ~P13.18. Discusses the com~zater simulation model developed which gives @cod results on the failure process of rocks under uniaxial compression. 1102 LITVIN~KII,GG MIN.~TALL INST,KO~Ma~SK, SU Kinetics of brittle fracture of solid rock neer a mine worklu~. 1OR. SOV .MIN.SCI, VI0, F~, S~T-OCT .197~,P538-~3. Ro=k pressure problems are investigated, and differential equations used to express properties. Develol~nent of cracking is estimated by introd~cin~ the te~sor characteristic of the continuity. Tim~ depanHe~ce of rock fracture explains some rock pressure phenom~a, and it is recom~anded for further investigation. 11o3 ~r/AKOV,AP INST .MIN,NOVOSIBIRSK, SU DUDOLADOV LS INST .MIN,NOVOSIB IRSK, SU ~IRNOV,W INST .MIN,NOVOSIBIRSK, SU F r a c t u r e o f finite-sized spec~-~- by wedge-shaped strtMers. ~R. SOV .MIN.SC I,VIO,N6, NOV.DEC .197~,P750-7~. R e s u l t s o f e n i n v e s t i g a t i o n un t h e p e r c u s s i v e cracking of spec ~-w~= of Plexiglas in ~r~ity impact tester by blows from a wedge are reported. The contact forces erising on collision of t h e tool with t h e spec~-~-, t h e p e n e t r a t i o n of the tool into the spsoimen, and the nature of t h e p r o p a ~ a t i o n o f e r - c k ~ t h r o u g h t h e specimen l e a d i ~ to its breakup are discussed. By a n a ~ i n ~ the ex~erim~ ental results eerta:Lu relatlonahll~ in the process of breskin~ of specimens of finite dimensions by percussive splitting were established.
~05 I~IR,RK ~JND~E UNIV,GB •~NGHA, CM IYJNDEE UNIV,GB Criteria for determining the critical stress of rocks in compresaicn. 17R. PROC.IST AUST.CONF.ON E~GNG.MAT~IALS, SYDNEY,26. 28 AUG 1974,P509-~16. The commonly used criteria for predlcting the critical stress of rock have been shown to ~ive incorrect values. An incremental Poisson's ratio criterion proPosed by the authors was found to give more realistic estimates. A m i c r o s c o p i c s t u d y o f t h e mechanism o f f r a c t u r e showed that cracks of approximately equal length continue to develop up to maximum stress. Strength failure has prlrustily related to an increase in crack density and not so ~ c h the length of individual cracks. Tests were per. formed on sandstone, marble end concrete. Methods for estimating impending failure in the case of cyclic l o a d i n g ere also d i s c u s s e d . ME~ZIES,BK ~ R E Y UNIV, GB Strength, stability and similitude. 5F,gR. GROUND ~ G N G .vg,N5, JULY, 1976, ~ 2.36. The e s s e n t i a l n a t u r e of s h e a r s t r e n g t h i s d i s c u s s e d , en~asising the co~on effective stress basis of both u n d r a i n e d and d r a i n e d s h e e r s t r e n g t h . The l i n k b e t w e e n test model snH constvuctic~ p r o t o t y p e i s made i n a statement about similitude. The stability mech~uics of constructional loading chs~es are briefly re-examined. Efforts to obtain similarity between the shear test models and the field prototype are considered. 1107 ISMAIL, IA IRAQ ~TIONAL OIL CO,IRQ ~LL, SA UNIV.COLI~E, LONDON,GB Dilatsn~y and the stcen~h of rocks containing pore water m~ler undrained condltlons. 21F,6T, MSR. G~OPHYS. J .R ,~IR. SOC. ,V~, NI, JAN 1976,PIO7-134. It has been shown that in rocks whose average initial porosities range from 0.5~-II.4X per cent dilate~cy durinE fracture at neer zero effective con~Inln~ pressures, when the strength is low, causes the porosities after fracture to reach very similar values of 8-16 per cent. For rocks whose initial porosity is low this implies very large increases in porosity. The percentage increase in porosity after fracture is however only about I per