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Experimental investigation of the elastic modulus of a fractal system - a model of fractured rocks
70A 912056 Determination of rock mass modulus nonlinear variation with loading and depth Afrouz, A ?,tin Sci Technol V11. N2. Sept 1990, P179-183 Analytical solutions and plate loading tests on mine floors show the in situ rock modulus varies nonlinearly with depth, down to a critical depth after which it remains relatively constant. This critical depth varies mainly with ratio of support base perimeter to area, strata load exerted on the support base, and degree of fracturing of the rock mass beneath the support base, and may be approximated as 1.6x smallest dimension of the support base. The nonlinear variation of modulus is greater for materials of higher initial modulus and bearing capacity.
912057 Experimental investigation of the elastic modulus of a fractal system - a model of fractured rocks Chelidze, T L; Spetzler, H; Getting, I C; Avaliani, Z A Pure Appl Geophys VI34, NI. Aug 1990, P31-43 The elastic properties of a physical model representing a damaged rock matrix were studied using a square plastic lattice containing approximately 10000 bonds and under tensile loading. Random breaking of the bonds was used to simulate the degree of damage. The elastic modulus obtained is in agreement with that from percolation theory. The scale effect was studied using progressively smaller samples cut from the original large lattice. Results are pertinent to elastic properties of fault zones.
9 ! 2058 Shear strength of uni-sized gravels under triaxial compression Moroto, N; Ishii, T Soils Found V30, N2, June 1990, P23-32 Drained triaxial tests were carried out on two rounded natural gravels and six angular crushed gravels at confining pressure 196 kPa. Corrected Rowe's friction angle was closely related to minimum void ratio. The relation of strength components due to dilatancy and interlocking against Marsal's breakage factor is different for rounded and angular gravels. Dilatancy rate at failure is uniquely expressed by Moroto's parameter. Shear strength is directly related to failure probability of the grains. Results indicate geotechnical and geometrical parameters of gravels must be assessed for predicting their mechanical performance.
9 i 2059 Deformation and recrystallization mechanisms in naturally deformed sillimanites Lambregts, P J; van Roermund, H L M Tectonophysics V179, N3/4, July 1990, P371-378 Prismatic sillimanite of unit length 0.3-2.5mm, obtained from a garnet migmatite, was deformed at 750 deg C under confining pressure 6bar. Optical microscopy showed sharp, deformation-induced subgrain boundaries and minor recrystallisation. Transmission electron microscopy showed free dislocations, dislocation loops, planar defects and tiltwalls. The microstructure indicates recrystallisation occurred by a rotation mechanism, with single crystals becoming polycrystals by progressive development of internal high angle boundaries. Grain boundary migration follows recrystallisation.
912060 Kaiser effect and frictional deformation Dunning, J D; Leaird, J D; Miller, M E
Proc 4th Conference on Acoustic Emission[?'licroseismic Activity in Geological Structures and Materials, Pennsylvania, 22-24 October 1985 P3-13. Publ Clausthal-Zellerfeld: Trans Tech Publications. 1989 Triaxial compression tests were carried out on samples of Berea (clean, well sorted, friable) and Deadwood (well indurated, clean, orthoquartzite) sandstones with sawcut joints at 35 deg to the specimen axis. AE was measured during testing to failure by stick slip or stable sliding, then during reloading to failure or 60% of yield point. Deadwood sandstone (stick slip) showed moderate stress memory on reload to failure,more marked Kaiser effect when cycled to 60% of yield point. Berea sandstone (stable sliding) showed strong acoustic stress memory in both cases.
912061 Shear behaviour of physical models of rock joints under constant normal stiffness conditions Ohnishi, Y; Dharmaratne, P G R
Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P267-273. Publ Rotterdam: A A Balkema, 1990 Direct shear tests under conditions of constant normal stress and constant normal stiffness were carried out on a series of identical pairs of artificial joints of different roughness, which had been cast in cement mortar. Shear strength characteristics of the joints were significantly influenced by normal stiffness. Increases in normal stress followed the shear strength envelope of the joint.
912062 Shear strength of modelled filled rock joints Papaliangas, T; Lumsden, A C; Hencher, S R; Manolopoulou, S Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P275-283. Publ Rotterdam: A A Balkema, 1990
Artifcial joints were cast with two roughness profiles and tested in direct shear with infill of PFA, marble dust, and kaolin. Shear strength decreased with increasing fill thickness. With kaolin, strength was 50% of that of the clean joint for a fill thickness/joint roughness amplitude (f/a) as low as 0.1, then continued to decrease at a slower rate with increasing f. Rate of decrease of strength and strength decrease were lower for the frictional infill. Minimum shear strength was approached as f/a values reached 1.0 and 1.5 respectively for soft and frictional infill.
9 ! 2063 Effect of infiil thickness on shear behaviour of rock joints Phien-wej, N; Shrestha, U B; Rantucci, G Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P289-294. Publ Rotterdam: A A Balkema, 1990
Direct shear tests were carried out on simulated saw tooth rock joints containing dry bentonite infiil. Shear strength was influenced by joint roughness, normal load, and infill thickness. Effects of the first two factors were more pronounced when infill thickness/asperity amplitude (t/a) was small. Shear strength reduced to that of the fill material in all cases when t/a was around 2. Joint shear strength could be described as an exponential function of t/a.
~~ 1991 Pergamon Press pie. Reproduction not permitted
912057 Experimental investigation of the elastic modulus of a fractal system - a model of fractured rocks Chelidze, T L; Spetzler, H; Getting, I C; Avaliani, Z A Pure Appl Geophys VI34, NI. Aug 1990, P31-43 The elastic properties of a physical model representing a damaged rock matrix were studied using a square plastic lattice containing approximately 10000 bonds and under tensile loading. Random breaking of the bonds was used to simulate the degree of damage. The elastic modulus obtained is in agreement with that from percolation theory. The scale effect was studied using progressively smaller samples cut from the original large lattice. Results are pertinent to elastic properties of fault zones.
9 ! 2058 Shear strength of uni-sized gravels under triaxial compression Moroto, N; Ishii, T Soils Found V30, N2, June 1990, P23-32 Drained triaxial tests were carried out on two rounded natural gravels and six angular crushed gravels at confining pressure 196 kPa. Corrected Rowe's friction angle was closely related to minimum void ratio. The relation of strength components due to dilatancy and interlocking against Marsal's breakage factor is different for rounded and angular gravels. Dilatancy rate at failure is uniquely expressed by Moroto's parameter. Shear strength is directly related to failure probability of the grains. Results indicate geotechnical and geometrical parameters of gravels must be assessed for predicting their mechanical performance.
9 i 2059 Deformation and recrystallization mechanisms in naturally deformed sillimanites Lambregts, P J; van Roermund, H L M Tectonophysics V179, N3/4, July 1990, P371-378 Prismatic sillimanite of unit length 0.3-2.5mm, obtained from a garnet migmatite, was deformed at 750 deg C under confining pressure 6bar. Optical microscopy showed sharp, deformation-induced subgrain boundaries and minor recrystallisation. Transmission electron microscopy showed free dislocations, dislocation loops, planar defects and tiltwalls. The microstructure indicates recrystallisation occurred by a rotation mechanism, with single crystals becoming polycrystals by progressive development of internal high angle boundaries. Grain boundary migration follows recrystallisation.
912060 Kaiser effect and frictional deformation Dunning, J D; Leaird, J D; Miller, M E
Proc 4th Conference on Acoustic Emission[?'licroseismic Activity in Geological Structures and Materials, Pennsylvania, 22-24 October 1985 P3-13. Publ Clausthal-Zellerfeld: Trans Tech Publications. 1989 Triaxial compression tests were carried out on samples of Berea (clean, well sorted, friable) and Deadwood (well indurated, clean, orthoquartzite) sandstones with sawcut joints at 35 deg to the specimen axis. AE was measured during testing to failure by stick slip or stable sliding, then during reloading to failure or 60% of yield point. Deadwood sandstone (stick slip) showed moderate stress memory on reload to failure,more marked Kaiser effect when cycled to 60% of yield point. Berea sandstone (stable sliding) showed strong acoustic stress memory in both cases.
912061 Shear behaviour of physical models of rock joints under constant normal stiffness conditions Ohnishi, Y; Dharmaratne, P G R
Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P267-273. Publ Rotterdam: A A Balkema, 1990 Direct shear tests under conditions of constant normal stress and constant normal stiffness were carried out on a series of identical pairs of artificial joints of different roughness, which had been cast in cement mortar. Shear strength characteristics of the joints were significantly influenced by normal stiffness. Increases in normal stress followed the shear strength envelope of the joint.
912062 Shear strength of modelled filled rock joints Papaliangas, T; Lumsden, A C; Hencher, S R; Manolopoulou, S Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P275-283. Publ Rotterdam: A A Balkema, 1990
Artifcial joints were cast with two roughness profiles and tested in direct shear with infill of PFA, marble dust, and kaolin. Shear strength decreased with increasing fill thickness. With kaolin, strength was 50% of that of the clean joint for a fill thickness/joint roughness amplitude (f/a) as low as 0.1, then continued to decrease at a slower rate with increasing f. Rate of decrease of strength and strength decrease were lower for the frictional infill. Minimum shear strength was approached as f/a values reached 1.0 and 1.5 respectively for soft and frictional infill.
9 ! 2063 Effect of infiil thickness on shear behaviour of rock joints Phien-wej, N; Shrestha, U B; Rantucci, G Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P289-294. Publ Rotterdam: A A Balkema, 1990
Direct shear tests were carried out on simulated saw tooth rock joints containing dry bentonite infiil. Shear strength was influenced by joint roughness, normal load, and infill thickness. Effects of the first two factors were more pronounced when infill thickness/asperity amplitude (t/a) was small. Shear strength reduced to that of the fill material in all cases when t/a was around 2. Joint shear strength could be described as an exponential function of t/a.
~~ 1991 Pergamon Press pie. Reproduction not permitted