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E determination of salt behaviour under stress
344A 916103 Internal variable model for the creep of rocksalt Aubertin, M; Gill, D E; Ladanyi, B Rock Mech Rock Engng V24, N2, April-June 1991, P81-97
916107 Long term settlements of tall buildings on sand Vargas, M; Leme de Moraes, J T Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 VI, P765-768. Publ Rotterdam. A A Balkema. 1989
The creep rate of rock salt and other ductile crystalline materials can be described by a power law relation with the active stress, the difference between total deviatoric applied stress and an internal stress. The origin and nature of this internal stress are discussed. It is shown that it can serve as a state variable in the constitutive relation, representing microstructural evolution under the action of competing hardening and recovery mechanisms. A method is presented to determine the value of the internal stress analytically from steady state creep data, which gives results in good agreement with earlier measurements.
Many buildings around Sao Paulo are founded on a loose to dense clayey sand deposit, the lower horizon of the Sao Paulo tertiary geological basin. A method to evaluate settlements of structures on these deposits is discussed with reference to immediate settlement records of some tall buildings. Observation of long term behaviour indicates secondary compression of these deposits takes place. Theoretical analysis suggests initial semi-elastic deformation followed by viscous compression of the sand layer.
916104 Effect of strain rate on rock strength. Technical note Lajtai, E Z; Duncan, E J S; Carter, B J Rock Meeh Rock Engng V24, N2, April-June 1991, P99-109
916108 Viscoplasticity and finite elements for landslide analysis Vulliet, L; Desai, C S Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 1/2, P801-806. Publ Rotterdam: A A Balkema, 1989
Tests on two different rock types, a brittle limestone (Tyndallstone) and a ductile salt rock (Lanigan potash), are described. In dynamic and static fatigue tests on the limestone, a small strength increase was found with increasing strain or stressing rate. Different stress corrosion parameters were found for the dynamic and static tests, which was unexpected. Dynamic fatigue tests on the ductile rock showed a strong strain rate effect. A general strength criterion including effects of strain rate as well as confining pressure is necessary to describe the strength of Lanigan potash.
An advanced elasto-viscoplastic material model is presented, which incorporates the hierarchical plasticity model of Desai et al within the viscoplastic framework of Perzyna. A finite element model, a modification of that of Desai and Zhang (1987) is derived and the algorithm given in detail. Behaviour in isotropic and triaxial compression is analysed and plastic and viscoplastic solutions compared. The model is finally applied to the La Frasse landslide and its appropriateness for describing slowly moving soil masses is evident.
Surface properties 916105 Post-subsidence deformations of loess soils Petrukhin, V A; Rabinovich, I G Soil Mech Found Engng V27, N4, July-Aug 1990, P164-167 Long term time dependent deformation of loess soils has been observed in compression tests, under foundations, and under self weight. It is connected with consolidation, creep, and desalination of the soil. Curves have been plotted and a hyperbolic function developed which describes observed behaviour well. An extrapolation procedure has been developed which allows prediction of post subsidence deformation rates from compression tests and test pit trials at times much shorter than those to reach the steady state.
916106 A/E determination of salt behaviour under stress Mottahead, P; Vance, J B Proc 4th Conference on Acoustic Emission/Microseismic Activity in Geological Structures and Materials, Pennsylvania, 22-24 October 1985 P465-474. Publ Clausthal-Zellerfeld." Trans Tech Publications, 1989 High frequency acoustic emission under controlled laboratory conditions and in underground potash mines has been studied to improve understanding of the behaviour of salt rock under stress. Rock monitor data have been used to demonstrate correlation between high frequency AE count and closure, with increased count associated with increasing creep rate. The Kaiser effect has been demonstrated both in the laboratory and the field. Rock monitors can be used to provide advance warning of rock failure.
916109 Determination of asperity design parameters for constitutive models of rock discontinuities. Applications brief Plesha, M E; Hutson, R W; Dowding, C H Int J Nnm Anal Meth Geomech V15, N4, April 1991, P289294 The mechanical behaviour of joints is influenced by dilatancy and damage to the contact surfaces. Constitutive laws considering these phenomena have been developed, but new material parameters governing asperity damage are required. A summary of an investigation of joint asperity degradation (Hutson and Dowding, 1990) is presented and the implications for application within constitutive models discussed. 916110 Euclidean and fractal models for the description of rock surface roughness Power, W L; Tullis, T E J Geophys Res 1/96, NB1, Jan 1991, P415-424 Topography of rock surfaces is important in geology and rock engineering. It is generally non-stationary and approximately self-similar. Characterisation by Euclidean geometry is inappropriate in many cases and common statistical parameters are difficult to apply, and so fractal geometry is used. Selfsimilar and self-affine fractal surfaces are discussed. The divider and spectral methods to determine best fit fractat model from surface data are described. Data are presented which show topography of many natural rock surfaces is approximately self-similar over a 6.5 order of magnitude wide wavelength band of 10 microns to 40m. Self-affine behaviour may be exhibited within smaller wavelength bands.
© 1991 Pergamon Press plc. Reproduction not permitted
916107 Long term settlements of tall buildings on sand Vargas, M; Leme de Moraes, J T Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 VI, P765-768. Publ Rotterdam. A A Balkema. 1989
The creep rate of rock salt and other ductile crystalline materials can be described by a power law relation with the active stress, the difference between total deviatoric applied stress and an internal stress. The origin and nature of this internal stress are discussed. It is shown that it can serve as a state variable in the constitutive relation, representing microstructural evolution under the action of competing hardening and recovery mechanisms. A method is presented to determine the value of the internal stress analytically from steady state creep data, which gives results in good agreement with earlier measurements.
Many buildings around Sao Paulo are founded on a loose to dense clayey sand deposit, the lower horizon of the Sao Paulo tertiary geological basin. A method to evaluate settlements of structures on these deposits is discussed with reference to immediate settlement records of some tall buildings. Observation of long term behaviour indicates secondary compression of these deposits takes place. Theoretical analysis suggests initial semi-elastic deformation followed by viscous compression of the sand layer.
916104 Effect of strain rate on rock strength. Technical note Lajtai, E Z; Duncan, E J S; Carter, B J Rock Meeh Rock Engng V24, N2, April-June 1991, P99-109
916108 Viscoplasticity and finite elements for landslide analysis Vulliet, L; Desai, C S Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 1/2, P801-806. Publ Rotterdam: A A Balkema, 1989
Tests on two different rock types, a brittle limestone (Tyndallstone) and a ductile salt rock (Lanigan potash), are described. In dynamic and static fatigue tests on the limestone, a small strength increase was found with increasing strain or stressing rate. Different stress corrosion parameters were found for the dynamic and static tests, which was unexpected. Dynamic fatigue tests on the ductile rock showed a strong strain rate effect. A general strength criterion including effects of strain rate as well as confining pressure is necessary to describe the strength of Lanigan potash.
An advanced elasto-viscoplastic material model is presented, which incorporates the hierarchical plasticity model of Desai et al within the viscoplastic framework of Perzyna. A finite element model, a modification of that of Desai and Zhang (1987) is derived and the algorithm given in detail. Behaviour in isotropic and triaxial compression is analysed and plastic and viscoplastic solutions compared. The model is finally applied to the La Frasse landslide and its appropriateness for describing slowly moving soil masses is evident.
Surface properties 916105 Post-subsidence deformations of loess soils Petrukhin, V A; Rabinovich, I G Soil Mech Found Engng V27, N4, July-Aug 1990, P164-167 Long term time dependent deformation of loess soils has been observed in compression tests, under foundations, and under self weight. It is connected with consolidation, creep, and desalination of the soil. Curves have been plotted and a hyperbolic function developed which describes observed behaviour well. An extrapolation procedure has been developed which allows prediction of post subsidence deformation rates from compression tests and test pit trials at times much shorter than those to reach the steady state.
916106 A/E determination of salt behaviour under stress Mottahead, P; Vance, J B Proc 4th Conference on Acoustic Emission/Microseismic Activity in Geological Structures and Materials, Pennsylvania, 22-24 October 1985 P465-474. Publ Clausthal-Zellerfeld." Trans Tech Publications, 1989 High frequency acoustic emission under controlled laboratory conditions and in underground potash mines has been studied to improve understanding of the behaviour of salt rock under stress. Rock monitor data have been used to demonstrate correlation between high frequency AE count and closure, with increased count associated with increasing creep rate. The Kaiser effect has been demonstrated both in the laboratory and the field. Rock monitors can be used to provide advance warning of rock failure.
916109 Determination of asperity design parameters for constitutive models of rock discontinuities. Applications brief Plesha, M E; Hutson, R W; Dowding, C H Int J Nnm Anal Meth Geomech V15, N4, April 1991, P289294 The mechanical behaviour of joints is influenced by dilatancy and damage to the contact surfaces. Constitutive laws considering these phenomena have been developed, but new material parameters governing asperity damage are required. A summary of an investigation of joint asperity degradation (Hutson and Dowding, 1990) is presented and the implications for application within constitutive models discussed. 916110 Euclidean and fractal models for the description of rock surface roughness Power, W L; Tullis, T E J Geophys Res 1/96, NB1, Jan 1991, P415-424 Topography of rock surfaces is important in geology and rock engineering. It is generally non-stationary and approximately self-similar. Characterisation by Euclidean geometry is inappropriate in many cases and common statistical parameters are difficult to apply, and so fractal geometry is used. Selfsimilar and self-affine fractal surfaces are discussed. The divider and spectral methods to determine best fit fractat model from surface data are described. Data are presented which show topography of many natural rock surfaces is approximately self-similar over a 6.5 order of magnitude wide wavelength band of 10 microns to 40m. Self-affine behaviour may be exhibited within smaller wavelength bands.
© 1991 Pergamon Press plc. Reproduction not permitted