- Email: [email protected]
Sub-horizontal discontinuities of large extension in the basaltic lava-flows nucleus of the Parana basin (Brazil)
GEOMECHANICS ABSTRACTS
906004 Nucleation and growth of retrograde shear zones: an example from the Needle Mountains, Colorado, U.S.A. Gibson, R G J Struct Geol 1/12, N3, 1990, P339-350
General 906001 Normalized hehaviour and its application for soft clay Xu, S M; Chen, Y; Huang, K M Proc International Conference on Engineering Problems of Regional Soils, Belting, 11-15 August 1988 P493-496. Publ Beijing: International Academic Publishers, 1989 A unified normalization factor for use in Konders hyperbolic relation is developed to normalize the stress strain relations of soil samples with different overconsolidation ratios. It is derived from analysis of previous work on soft clays. Laboratory tests on two groups of remoulded clay samples are used in its validation. Application in finite element analysis of a plate loading tests demonstrates improvements in terms of simplicity of use when compared to the Duncan-Chang model.
Geology Tectonic processes and structural geology 906002 Joint origin as a predictive tool for estimation of geotechnical properties Rawnsley, K D; Hencher, S R; Lumsden, A C Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P91-96. Publ Rotterdam: A A Balkema, 1990 Extrapolation of inferred geotechnical properties from limited exposures to rock mass scale can be done with greater confidence if the procedures involved in joint formation are well understood. Joint formation within the network is examined on the level of single joint planes, joint sets, and joint system. Field examples are used to help interpret joint networks in terms of stress conditions during propagation. Influence of history of formation on orientation, persistence, spacing and morphology is demonstrated. 906003 Sub-horizontal discontinuities of large extension in the basaltic lava-flows nucleus of the Parana basin (Brazil) Souze, N N; Campos, J 0 Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P97-100. Publ Rotterdam: A A Balkema, 1990 Construction of large power plants in southern Brazil has allowed characterisation of structural geology of the basaltic lava flows of the Serra Geral Formation. Extensive cuts and many thousands of metres of rock core were examined. Subhorizontal discontinuities were found at all depths examined. The origins of these joints, which influence the permeability, shear strength, deformability, and natural stress relief, are discussed.
Processes associated with the formation of retrograde shear zones in basement gneisses exposed in the Needle Mountains are described. Earliest formed features are well preserved as there is only minor displacement. Fabrics observed at meso and micro scales suggest that the shear zones developed via initial fracturing and cataclasis, fluid intrusion into the dilatant zones caused hydration of existing mineral assemblages, and that phyllonites subsequently developed from these phyllosilicate-rich, reaction softened lithologies. 906005 Experimental calcite fabrics in a synthetic .weaker aggregate by coaxial and non-coaxial deformation Borradaile, G J; McArthur, J J Struct Geol V12, N3, 1990, P351-363 Calcite grain aggregates supported in a matrix of Portland cement, such that almost unrestrained rigid body rotation and alignment of grains is possible, were tested in triaxial compression and transpressive and pure shear at room temperature. Grain rotation was accompanied by twinning of calcite. Effects of pore pressure and deformation mode on deformation mechanisms and development of preferred orientations were examined. Results are discussed in terms of inferring deformational history of natural calcite rocks 9060O6 Experimental mullions at single and double interfaces Sokoutis, D J Struct Geol V12, N3, 1990, P365-373 When originally planar contacts between rocks of different theological properties are strained, lobe and cusp structures (mullions in 3D) are formed. This process has been simulated using model materials in a squeeze box apparatus. The tendency for the development of mullions with a dominant wavelength in non-Newtonian fluids with an effective viscosity contrast of less than 0.1, as has been suggested for geological materials,is examined. Previous work and theoretical aspects are also discussed. 9060O7 Finite difference modelling of sandbox analogues, compaction and detachment free deformation Waltham, D J Struct Geol 1/12, N3, 1990, P375-381 Finite difference modelling of hangingwail deformation above a fault is shown to give results in close agreement with sandbox analogue models of extensional faults. These results are used to provide further information on the dynamics involved and zones of faulting. The controlling equations are then
© 1990 Pergamon Press pic. Reproduction not permitted 323A
906004 Nucleation and growth of retrograde shear zones: an example from the Needle Mountains, Colorado, U.S.A. Gibson, R G J Struct Geol 1/12, N3, 1990, P339-350
General 906001 Normalized hehaviour and its application for soft clay Xu, S M; Chen, Y; Huang, K M Proc International Conference on Engineering Problems of Regional Soils, Belting, 11-15 August 1988 P493-496. Publ Beijing: International Academic Publishers, 1989 A unified normalization factor for use in Konders hyperbolic relation is developed to normalize the stress strain relations of soil samples with different overconsolidation ratios. It is derived from analysis of previous work on soft clays. Laboratory tests on two groups of remoulded clay samples are used in its validation. Application in finite element analysis of a plate loading tests demonstrates improvements in terms of simplicity of use when compared to the Duncan-Chang model.
Geology Tectonic processes and structural geology 906002 Joint origin as a predictive tool for estimation of geotechnical properties Rawnsley, K D; Hencher, S R; Lumsden, A C Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P91-96. Publ Rotterdam: A A Balkema, 1990 Extrapolation of inferred geotechnical properties from limited exposures to rock mass scale can be done with greater confidence if the procedures involved in joint formation are well understood. Joint formation within the network is examined on the level of single joint planes, joint sets, and joint system. Field examples are used to help interpret joint networks in terms of stress conditions during propagation. Influence of history of formation on orientation, persistence, spacing and morphology is demonstrated. 906003 Sub-horizontal discontinuities of large extension in the basaltic lava-flows nucleus of the Parana basin (Brazil) Souze, N N; Campos, J 0 Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P97-100. Publ Rotterdam: A A Balkema, 1990 Construction of large power plants in southern Brazil has allowed characterisation of structural geology of the basaltic lava flows of the Serra Geral Formation. Extensive cuts and many thousands of metres of rock core were examined. Subhorizontal discontinuities were found at all depths examined. The origins of these joints, which influence the permeability, shear strength, deformability, and natural stress relief, are discussed.
Processes associated with the formation of retrograde shear zones in basement gneisses exposed in the Needle Mountains are described. Earliest formed features are well preserved as there is only minor displacement. Fabrics observed at meso and micro scales suggest that the shear zones developed via initial fracturing and cataclasis, fluid intrusion into the dilatant zones caused hydration of existing mineral assemblages, and that phyllonites subsequently developed from these phyllosilicate-rich, reaction softened lithologies. 906005 Experimental calcite fabrics in a synthetic .weaker aggregate by coaxial and non-coaxial deformation Borradaile, G J; McArthur, J J Struct Geol V12, N3, 1990, P351-363 Calcite grain aggregates supported in a matrix of Portland cement, such that almost unrestrained rigid body rotation and alignment of grains is possible, were tested in triaxial compression and transpressive and pure shear at room temperature. Grain rotation was accompanied by twinning of calcite. Effects of pore pressure and deformation mode on deformation mechanisms and development of preferred orientations were examined. Results are discussed in terms of inferring deformational history of natural calcite rocks 9060O6 Experimental mullions at single and double interfaces Sokoutis, D J Struct Geol V12, N3, 1990, P365-373 When originally planar contacts between rocks of different theological properties are strained, lobe and cusp structures (mullions in 3D) are formed. This process has been simulated using model materials in a squeeze box apparatus. The tendency for the development of mullions with a dominant wavelength in non-Newtonian fluids with an effective viscosity contrast of less than 0.1, as has been suggested for geological materials,is examined. Previous work and theoretical aspects are also discussed. 9060O7 Finite difference modelling of sandbox analogues, compaction and detachment free deformation Waltham, D J Struct Geol 1/12, N3, 1990, P375-381 Finite difference modelling of hangingwail deformation above a fault is shown to give results in close agreement with sandbox analogue models of extensional faults. These results are used to provide further information on the dynamics involved and zones of faulting. The controlling equations are then
© 1990 Pergamon Press pic. Reproduction not permitted 323A