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Consideration on soil response to the rotations of principal stress directions
357A 906278 Rocsan: a multipurpose geomechanics instrument Preston, C J; Webster, A C; Cotter, J; Kaasalainen, J; Frantzos, D; Tammemagi, H; Codrington, J B Proc 15th Canadian Rock Mechanics Symposium, Rock Engineering for Underground Excavations, 3-4 October 1988 P243-248. Publ Toronto: University of Toronto, 1988 ROCSAN instrumentation has been developed for blast monitoring. Initially,techniques using water filled boreholes were used to determine peak pressures and borehole timing from a blast and examine dynamic rock properties. Based on this, a system using hydraulic sensors to measure static and dynamic changes in borehole diameter, and computerised data collection was developed. Field evaluation of the instrumentation is presented. Further developments to improve sensitivity and accuracy and to allow measurement of stress changes are planned. 906279 Multichannei data acquisition and analysis system to monitor rockburst for assessing underground strata stability at Kolar gold fields Murty, G S; Subbaramu, K R; Shringarputale, S B Proc International Symposium on Underground Engineering, New Delhi, 14-17 April 1988 V1, P343-350. Publ Rotterdam." A A Balkema, 1988 Mining at deep levels at Kolar gold fields in India has led to rockbursts which pose severe safety problems and thus affect production. Current development in acoustic emission research and in multi-channel data acquisition and analysis methods has enabled precise location of the sources of the rockbursts. Further research has been directed towards understanding the phenomenon of rockbursts. The set-up of instruments and the results of the established rockburst monitoring system are presented.
Analysis Techniques and Design Methods See: 906212
906281 Description of flow of sand using state parameters Poorooshasb, H B Comput Geotech V8, N3, 1989, P195-218 The original concept of Critical State is extended to include the influence of the third invariant of the stress deviator tensor. The Poulos and Castro Steady State of Flow concept is examined and found to be substantially equivalent. The term Ultimate State is proposed as more appropriate. The framework of a unified state parameter approach to describing constitutive behaviour of granular materials is discussed. Within this framework, curvature of the yield and state boundary surfaces and laws of similarity under the so called l-g testing conditions are studied. 906282 Generalized plasticity and modelling of soil behaviour. Theme/feature paper Pastor, M; Zienkiewicz, O C; Chan, A H C int J Num Anal Meth Geomech V14, N3, April 1990, P151190 The generalised theory of plasticity, in which yield and plastic potential surfaces need not be explicitly defined, is outlined. Simple yet effective models for clays and sands under monotonic and cyclic loading are developed. Three dimensional behaviour and rotation of principal stress axis and the multimechanism constitutive model are examined. The hierarchical structure of the general model limits the number of parameters required for its calibration for a given material to those necessary for the problem under investigation. Currently used models are discussed. 59refs. 906283 Mohr diagram for three-dimensional reciprocal stretch vs rotation Treagus, S H J Struct Geol V12, N3, 1990, P383-395 Mohr diagrams for stretch are a useful alternative to the conventional Mohr diagram for 2 and 3 dimensional strain problems. Examples are presented of how polar graphs of stretch or reciprocal stretch against rotation can be used in strain analysis. The strain ellipsoid can be represented by a three circle reciprocal stretch diagram which represents the symmetric 3D stress tensor. The 3D deformation tensors may also be represented. The case of simple shear is illustrated.
See also: 906061, 906099, 906116, 906133, 906161
9O6284 Second phase of the community project COSA (comparison of rock-mechanics computer COdes for SAlt) (In French) Come, B Rev Fr Geotech NS1, 1990, P31-40
906280 Considerations on soil response to the rotations of principal stress directions Pietruszczak, S; Krucinski, S Comput Geotech I/8, N2, 1989, P89.110
The second stage of the COSA project, part of an EEC project concerning radioactive waste disposal in salt rock, is described. 12 attempts to predict behaviour for isothermal free convergence and around a heated probe are compared. The major conclusion is that improvements in the rheologicai model for salt are more essential than those in the computer codes themselves.
Stress analysis
Various plasticity formulations are evaluated as to their ability to describe the influence of rotation of the principal stress axes. The classical framework of plasticity is seen to have shortcomings in this respect, and a mathematical framework is introduced which employs a continuum model of internal fabric. A phenomenological law results which qualitatively describes clay anisotropy. The mathematical form of the governing equations allows modelling of the sensitivity of soil response to principal stress rotation.
9O6285 Anisotropy of dilation, 3-D stress state and Talobre friction cone
Brosch, F J Rock Mech Rock Engng V23, N2, April-June 1990, P113-121
The friction cone method is a useful graphical technique for analysing rock mass stability. Its application requires knowledge of dilation angle,which may be anisotropic, in which case
© 1990 Pergamon Press pie. Reproduction not permitted
Analysis Techniques and Design Methods See: 906212
906281 Description of flow of sand using state parameters Poorooshasb, H B Comput Geotech V8, N3, 1989, P195-218 The original concept of Critical State is extended to include the influence of the third invariant of the stress deviator tensor. The Poulos and Castro Steady State of Flow concept is examined and found to be substantially equivalent. The term Ultimate State is proposed as more appropriate. The framework of a unified state parameter approach to describing constitutive behaviour of granular materials is discussed. Within this framework, curvature of the yield and state boundary surfaces and laws of similarity under the so called l-g testing conditions are studied. 906282 Generalized plasticity and modelling of soil behaviour. Theme/feature paper Pastor, M; Zienkiewicz, O C; Chan, A H C int J Num Anal Meth Geomech V14, N3, April 1990, P151190 The generalised theory of plasticity, in which yield and plastic potential surfaces need not be explicitly defined, is outlined. Simple yet effective models for clays and sands under monotonic and cyclic loading are developed. Three dimensional behaviour and rotation of principal stress axis and the multimechanism constitutive model are examined. The hierarchical structure of the general model limits the number of parameters required for its calibration for a given material to those necessary for the problem under investigation. Currently used models are discussed. 59refs. 906283 Mohr diagram for three-dimensional reciprocal stretch vs rotation Treagus, S H J Struct Geol V12, N3, 1990, P383-395 Mohr diagrams for stretch are a useful alternative to the conventional Mohr diagram for 2 and 3 dimensional strain problems. Examples are presented of how polar graphs of stretch or reciprocal stretch against rotation can be used in strain analysis. The strain ellipsoid can be represented by a three circle reciprocal stretch diagram which represents the symmetric 3D stress tensor. The 3D deformation tensors may also be represented. The case of simple shear is illustrated.
See also: 906061, 906099, 906116, 906133, 906161
9O6284 Second phase of the community project COSA (comparison of rock-mechanics computer COdes for SAlt) (In French) Come, B Rev Fr Geotech NS1, 1990, P31-40
906280 Considerations on soil response to the rotations of principal stress directions Pietruszczak, S; Krucinski, S Comput Geotech I/8, N2, 1989, P89.110
The second stage of the COSA project, part of an EEC project concerning radioactive waste disposal in salt rock, is described. 12 attempts to predict behaviour for isothermal free convergence and around a heated probe are compared. The major conclusion is that improvements in the rheologicai model for salt are more essential than those in the computer codes themselves.
Stress analysis
Various plasticity formulations are evaluated as to their ability to describe the influence of rotation of the principal stress axes. The classical framework of plasticity is seen to have shortcomings in this respect, and a mathematical framework is introduced which employs a continuum model of internal fabric. A phenomenological law results which qualitatively describes clay anisotropy. The mathematical form of the governing equations allows modelling of the sensitivity of soil response to principal stress rotation.
9O6285 Anisotropy of dilation, 3-D stress state and Talobre friction cone
Brosch, F J Rock Mech Rock Engng V23, N2, April-June 1990, P113-121
The friction cone method is a useful graphical technique for analysing rock mass stability. Its application requires knowledge of dilation angle,which may be anisotropic, in which case
© 1990 Pergamon Press pie. Reproduction not permitted