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New methods of measuring fracture toughness on rock cores
125A 844020 Three-dimensional hydraulic fracture propagation in the prescoce of stress variations Palmer, I D; Carroll, H B
Soc Pet Eugr J V23, N6, Dec 1983, P870-878 Two computer models FL1 and FL2 for hydraulic fracture expansion in blanket sands bounded by higher, but equal, minimum in situ stresses, are presented. 844021 New methods of measuring fracture toughness on rock cores Ouchterlony, F; Sun Zongqi
Swedish Detonic Research Fouadation report DS 1983:10, 8 Dec 1983, 24P In the evaluation of fracture toughness from core based specimen types, specimens with chevron notches, the short rod and a bend specimen show the greatest promise. They have the potential for providing accurate fracture toughness predictions for rock with minimal specimen preparation and testing efforts, even for very small cores.
Avail: The Foundation, Box 32058, S-126 11 Stockholm, Sweden Strength characteristics 844O22 Undrained onisotropy and principal stress rotation in saturated sand Symes, M J P R; Gens, A; Hight, D W
Geoteclmique V34, N1, March 1984, Pll-27 Undrained hollow cylinder tests were carried out on samples of saturated sand in order to investigate: (1) the initial anisotropy of strength and stiffness of the material, and (2) the effects of both monotonic and cyclic rotation of the major and minor principal stress directions during shear. The concept of a State Boundary Surface was used to interpret results. The over-riding importance of initial anisotropy in determining the response of the sand to rotations in the principal stress directions is demonstrated. Pore pressures are shown to be generated by principal stress rotation and their accumulation during cyclic principal stress rotation can lead to failure. 844023 Shearing resistance of saturated clays. Technical note Allam, M M; Sridharan, A
Geoteclmique V34, NI, March 1984, Pl19-122 The note attempts to identify which model for the particle configuration in saturated clays explains the shear strength behaviour. The models considered are a 'contact model' - the particles are randomly oriented with at least one edge-face contact with its nearest neighbour and a 'parallel plate model' - particles are oriented parallel to each other with no inter-particle contact. It is concluded that edge-face linkages are inevitable and these linkages explain the non-viscous behaviour of the system at water contents below the liquid limit. 844024 Developments in cone penetration testing - the friction
p|ezocone Swain, C W Ground Eugug VI7, N2, March 1984, P26-27 The simple cone penetrometer, introduced approximately 50 years ago, has been largely superseded by the friction cone. More recently, piezocones incorporating pore pressure measurement have been introduced. The latest development is a friction piezocone which can simultaneously measure cone end resistance, local side friction and pore water pressure generated
during penetration. . ~-844O25 Force penetration curve corrections in the CBR test Marsh, A H Highway £ugr V30, N2, Feb 1983, P2-7 The forms of force penetration curves obtained in the BS1377 laboratory determination of the California Bearing Ratio have been examined from reported test data and just under half have been found to depart from the desired convex upwards shape. Six basic categories of force penetration curves are described and the detailed application of corrections to each is discussed within the framework of the standard test method's requirements. 844026 Membrane penetration effects in triaxiai testing Baldi, G; Nova, R
J Geotech Engag Die ASCE VIIO, NGT3, March 1984, P403-420 Membrane penetration effects in drained and undrained tests are discussed. A qualitative analysis is performed to find which factors influence the membrane penetration and, at least approximately, to what extent. It is shown that apparent volumetric strain due merely to membrane penetration decreases linearly with increasing sample diameter. The factor of major influence is the grain size but the confining pressure, rigidity and thickness of membrane play a non-negligible role. A method to correct the measured values of pore pressure in undrained tests is proposed. It is shown that the correction factor depends on the volumetric stiffness of the sample which is not a constant but depends markedly on the state of stress. Auth. 844027 Lateral stress measurements during m t i c and cyclic direct simple shear testing Dyvik, R; Zimmie, T F
Norw Geotech last Publ N149, 1983, 8P Presents lateral stress results for three fine-grained soils (clays) during the consolidation stage and the static or cyclic portion of a consolidated, constant volume direct simple shear test. Calibrated wire reinforced membranes were used in the shear device to measure the lateral stresses. The lateral stress measurements during shear were used to establish the Mohr's circle state of stress. The change in lateral stress ratio, the orientation of the failure planes, and the stress paths were also determined during the shear phase of the tests. 844028 Failure of natural clays by shear zones in triaxial tests (In French) Davre, F
Rev Fr Geotech N24, Aug 1983, 1'27-38 The development of shear zones during the failure of North American structured clays is analysed as a bifurcation of the mode of strains, induced by the constitutive behaviour of the material. The localized conditions of strain in the non-linear incremental constitutive law allows the prediction, for a given loading path, of the stress strain state at which the shear band begins to appear and the local orientation of this shear band. Some examples of the application of theoretical results to a natural clay are presented and compared with experimental data.
Soc Pet Eugr J V23, N6, Dec 1983, P870-878 Two computer models FL1 and FL2 for hydraulic fracture expansion in blanket sands bounded by higher, but equal, minimum in situ stresses, are presented. 844021 New methods of measuring fracture toughness on rock cores Ouchterlony, F; Sun Zongqi
Swedish Detonic Research Fouadation report DS 1983:10, 8 Dec 1983, 24P In the evaluation of fracture toughness from core based specimen types, specimens with chevron notches, the short rod and a bend specimen show the greatest promise. They have the potential for providing accurate fracture toughness predictions for rock with minimal specimen preparation and testing efforts, even for very small cores.
Avail: The Foundation, Box 32058, S-126 11 Stockholm, Sweden Strength characteristics 844O22 Undrained onisotropy and principal stress rotation in saturated sand Symes, M J P R; Gens, A; Hight, D W
Geoteclmique V34, N1, March 1984, Pll-27 Undrained hollow cylinder tests were carried out on samples of saturated sand in order to investigate: (1) the initial anisotropy of strength and stiffness of the material, and (2) the effects of both monotonic and cyclic rotation of the major and minor principal stress directions during shear. The concept of a State Boundary Surface was used to interpret results. The over-riding importance of initial anisotropy in determining the response of the sand to rotations in the principal stress directions is demonstrated. Pore pressures are shown to be generated by principal stress rotation and their accumulation during cyclic principal stress rotation can lead to failure. 844023 Shearing resistance of saturated clays. Technical note Allam, M M; Sridharan, A
Geoteclmique V34, NI, March 1984, Pl19-122 The note attempts to identify which model for the particle configuration in saturated clays explains the shear strength behaviour. The models considered are a 'contact model' - the particles are randomly oriented with at least one edge-face contact with its nearest neighbour and a 'parallel plate model' - particles are oriented parallel to each other with no inter-particle contact. It is concluded that edge-face linkages are inevitable and these linkages explain the non-viscous behaviour of the system at water contents below the liquid limit. 844024 Developments in cone penetration testing - the friction
p|ezocone Swain, C W Ground Eugug VI7, N2, March 1984, P26-27 The simple cone penetrometer, introduced approximately 50 years ago, has been largely superseded by the friction cone. More recently, piezocones incorporating pore pressure measurement have been introduced. The latest development is a friction piezocone which can simultaneously measure cone end resistance, local side friction and pore water pressure generated
during penetration. . ~-844O25 Force penetration curve corrections in the CBR test Marsh, A H Highway £ugr V30, N2, Feb 1983, P2-7 The forms of force penetration curves obtained in the BS1377 laboratory determination of the California Bearing Ratio have been examined from reported test data and just under half have been found to depart from the desired convex upwards shape. Six basic categories of force penetration curves are described and the detailed application of corrections to each is discussed within the framework of the standard test method's requirements. 844026 Membrane penetration effects in triaxiai testing Baldi, G; Nova, R
J Geotech Engag Die ASCE VIIO, NGT3, March 1984, P403-420 Membrane penetration effects in drained and undrained tests are discussed. A qualitative analysis is performed to find which factors influence the membrane penetration and, at least approximately, to what extent. It is shown that apparent volumetric strain due merely to membrane penetration decreases linearly with increasing sample diameter. The factor of major influence is the grain size but the confining pressure, rigidity and thickness of membrane play a non-negligible role. A method to correct the measured values of pore pressure in undrained tests is proposed. It is shown that the correction factor depends on the volumetric stiffness of the sample which is not a constant but depends markedly on the state of stress. Auth. 844027 Lateral stress measurements during m t i c and cyclic direct simple shear testing Dyvik, R; Zimmie, T F
Norw Geotech last Publ N149, 1983, 8P Presents lateral stress results for three fine-grained soils (clays) during the consolidation stage and the static or cyclic portion of a consolidated, constant volume direct simple shear test. Calibrated wire reinforced membranes were used in the shear device to measure the lateral stresses. The lateral stress measurements during shear were used to establish the Mohr's circle state of stress. The change in lateral stress ratio, the orientation of the failure planes, and the stress paths were also determined during the shear phase of the tests. 844028 Failure of natural clays by shear zones in triaxial tests (In French) Davre, F
Rev Fr Geotech N24, Aug 1983, 1'27-38 The development of shear zones during the failure of North American structured clays is analysed as a bifurcation of the mode of strains, induced by the constitutive behaviour of the material. The localized conditions of strain in the non-linear incremental constitutive law allows the prediction, for a given loading path, of the stress strain state at which the shear band begins to appear and the local orientation of this shear band. Some examples of the application of theoretical results to a natural clay are presented and compared with experimental data.