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Deterioration of mechanical properties of neogene sedimentary soft rocks
214A isotropic, deviatoric, axisymmetric linear, and constant volume. In the last case, induced anisotropy can lead to liquefaction even in dense samples. Most of these effects can be explained using a strain softening elastoplastic material model. 924069 Griggs deformation apparatus set up at Lille lngrin, J; Doukhan. J C Terra Nova I/3, N6, 1991, P603-606 Solid medium apparatus has been extensively used to study rocks under very high confining pressure, but problems with the classical apparatus include sample deformation during initial pressurisation/heating and poor precision in stress measurement. A new generation of improved equipment is now available. The set-up at the University of Lille is illustrated. Results are presented from tests on T-oriented Yule Marble specimens. Yield strength can be measured with reasonable precision (10MPa) and values as low as 50MPa can be detected. The equipment described is particularly suitable for work on small specimens.
wave velocities, but strength was less influenced. The effects were more noticeable under tensile conditions than under uniaxial compression. Theoretical models of microcracked media are seen not to be adequate to represent the behaviour of materials containing thermally induced microcracks. 924073 Triaxial empirical failure criterion for rocks - a contribution to safety calculations Tauber, F Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P351-354. Publ Rotterdam: A A Balkema, 1991 An empirical failure criterion has been developed for isotropic rock using published data on triaxial failure strength. It is expressed in invariant coordinates in the stress space, using all the components of the stress tensor. A distance measure, the distance between a stress state and the failure envelope, is used to fit the failure envelope to the data points and to provide a means of describing the safety of the stress state in a rock mass.
924070 Deterioration of mechanical properties of neogene sedimentary soft rocks Mimuro, T; Yamauchi, M; Watanabe, K; Denda, A Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI. P299-302. Publ Rotterdam: A A Balkema. 1991 The effect of environmental exposure and swelling due to stress relief have been examined for two Neogene mudstones from Japan. Weathering was simulated by wet/dry cycling. Stress relief swelling was studied using consolidated drained triaxial tests and consolidated rebounded drained triaxial tests. Weathering decreased the peak shear strength but had little effect on residual strength. Swelling had no noticeable influence on peak or residual strength or deformability. 924071 Scale effects in the determination of mechanical properties of joints and rock masses Cuhna, A P Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P311-318. Publ Rotterdam: A A Balkema, 1991 The inherent heterogeneity and discontinuous nature of rock masses result in measured properties being influenced by specimen size. This scale effect is examined. Sampling bias, disturbance, testing technique, and sample geometry must be considered. The Representative Elemental Volume (REV) may differ for different properties in the same rock mass or the same property in different rock masses. Scale effects in determining shear behaviour of a joint set or the deformability of a rock mass and the influence of the cross dimension in shear behaviour of joint sets are discussed with reference to engineering projects. 924072 Mechanical beha~our of an artificially microeracked marble Rotonda, T Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P345-350. Publ Rotterdam: A A Balkema, 1991 Strength, deformability and dynamic properties under uniaxial and triaxial conditions were determined on specimens of homogeneous, isotropic Carrera marble which had been precracked to varying degrees by slow heating. Low levels of microcracking markedly affected static deformability and
924074 Equivalent continuous medium modelling of highly jointed isotropic rock masses (In French) Thimus, J F; Sine, B; Bahedi, M L; Vouille, G Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P355-359. Publ Rotterdam: A A Balkema, 1991 Triaxial test specimens were made using a mixture of cement/sand/lime with plastic films introduced to simulate joints. Tests were carried out to failure and the effects on the mechanical properties of the different surface densities of simulated joints examined. Circular arch tests were used to confirm these results. The inferences from the mechanical testing are compared to constitutive behaviour indicated by finite element analysis with a strain softening stress strain relation. 924075 Engineering failure criterion for rockfill Yudhbir; Balasubramaniam, A S; Lee, Y H Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P375-380. Publ Rotterdam: A A Balkema, 1991 On the basis of triaxial test data on a variety of rockfill materials, an empirical failure criterion has been developed. It has two parameters, one constant for all the materials and the other, a measure of equivalent structural strength of rockfill, related to particle breakage index defined at confining pressure of I MPa. A classification of rockfill is proposed on the basis of the variable parameter and particle crushing index. The variation of friction angle with normal stress is predicted and compared to other published results. 924076 Hydromechanical and seismic properties of fractures Myer, L R Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P397-404. Publ Rotterdam: A A Balkema, 1991 Stress strain behaviour, flow properties, and P wave amplitude spectra were examined for a single fracture in granite as functions of normal stress. Some measurements were made after different numbers of loading cycles. Results indicate that the values of the parameters measured are significantly influenced by the geometry of the void structure of the fracture and can be explained in terms of linear elastic deformation of the
© 1992 Pergamon Press Ltd. Reproduction not permitted
wave velocities, but strength was less influenced. The effects were more noticeable under tensile conditions than under uniaxial compression. Theoretical models of microcracked media are seen not to be adequate to represent the behaviour of materials containing thermally induced microcracks. 924073 Triaxial empirical failure criterion for rocks - a contribution to safety calculations Tauber, F Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P351-354. Publ Rotterdam: A A Balkema, 1991 An empirical failure criterion has been developed for isotropic rock using published data on triaxial failure strength. It is expressed in invariant coordinates in the stress space, using all the components of the stress tensor. A distance measure, the distance between a stress state and the failure envelope, is used to fit the failure envelope to the data points and to provide a means of describing the safety of the stress state in a rock mass.
924070 Deterioration of mechanical properties of neogene sedimentary soft rocks Mimuro, T; Yamauchi, M; Watanabe, K; Denda, A Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI. P299-302. Publ Rotterdam: A A Balkema. 1991 The effect of environmental exposure and swelling due to stress relief have been examined for two Neogene mudstones from Japan. Weathering was simulated by wet/dry cycling. Stress relief swelling was studied using consolidated drained triaxial tests and consolidated rebounded drained triaxial tests. Weathering decreased the peak shear strength but had little effect on residual strength. Swelling had no noticeable influence on peak or residual strength or deformability. 924071 Scale effects in the determination of mechanical properties of joints and rock masses Cuhna, A P Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P311-318. Publ Rotterdam: A A Balkema, 1991 The inherent heterogeneity and discontinuous nature of rock masses result in measured properties being influenced by specimen size. This scale effect is examined. Sampling bias, disturbance, testing technique, and sample geometry must be considered. The Representative Elemental Volume (REV) may differ for different properties in the same rock mass or the same property in different rock masses. Scale effects in determining shear behaviour of a joint set or the deformability of a rock mass and the influence of the cross dimension in shear behaviour of joint sets are discussed with reference to engineering projects. 924072 Mechanical beha~our of an artificially microeracked marble Rotonda, T Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P345-350. Publ Rotterdam: A A Balkema, 1991 Strength, deformability and dynamic properties under uniaxial and triaxial conditions were determined on specimens of homogeneous, isotropic Carrera marble which had been precracked to varying degrees by slow heating. Low levels of microcracking markedly affected static deformability and
924074 Equivalent continuous medium modelling of highly jointed isotropic rock masses (In French) Thimus, J F; Sine, B; Bahedi, M L; Vouille, G Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P355-359. Publ Rotterdam: A A Balkema, 1991 Triaxial test specimens were made using a mixture of cement/sand/lime with plastic films introduced to simulate joints. Tests were carried out to failure and the effects on the mechanical properties of the different surface densities of simulated joints examined. Circular arch tests were used to confirm these results. The inferences from the mechanical testing are compared to constitutive behaviour indicated by finite element analysis with a strain softening stress strain relation. 924075 Engineering failure criterion for rockfill Yudhbir; Balasubramaniam, A S; Lee, Y H Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 VI, P375-380. Publ Rotterdam: A A Balkema, 1991 On the basis of triaxial test data on a variety of rockfill materials, an empirical failure criterion has been developed. It has two parameters, one constant for all the materials and the other, a measure of equivalent structural strength of rockfill, related to particle breakage index defined at confining pressure of I MPa. A classification of rockfill is proposed on the basis of the variable parameter and particle crushing index. The variation of friction angle with normal stress is predicted and compared to other published results. 924076 Hydromechanical and seismic properties of fractures Myer, L R Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P397-404. Publ Rotterdam: A A Balkema, 1991 Stress strain behaviour, flow properties, and P wave amplitude spectra were examined for a single fracture in granite as functions of normal stress. Some measurements were made after different numbers of loading cycles. Results indicate that the values of the parameters measured are significantly influenced by the geometry of the void structure of the fracture and can be explained in terms of linear elastic deformation of the
© 1992 Pergamon Press Ltd. Reproduction not permitted