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General failure criteria for saltrock
302A 896105 General failure criteria for saltrock Hambley, D F; Fordham, C J; Senseny, P E Rock Mechanics as a Guide for Efficient Utilization of Natural Resources: Proc 30th U.S. Symposium, Morgaatown, 19-22 June 1989 P91-98. Publ Rotterdam." A ,4 Balkema, 1989 Brittle failure can occur in underground structures in salt rocks as a result of high stress and strain rates induced by excavation. Four failure criteria, extended Mohr-Coulomb, extended Drucker-Prager, Lade, and Kim et al, are discussed and their ability to predict brittle behaviour in salt rocks examined using data sets from Germany and the USA. 896106 Structural characterisation of the intact rock on large dams foundation Foyo Marcos, A; Tomillo, C; Cerda Ramos, J Proc Symposium on Rock Mechanics and Power Plants, Madrid, 12-16 September 1988 VI, P463-466. Publ Rotterdam." ,4 A Balkema, 1988 Granite samples from 3 dam sites in Spain were analysed petrographically before and after uniaxial compression testing. Results show 3 different types of behaviour, and a relation between orientation of pre-existing planar anisotropy and fracture surfaces caused by uniaxial testing. 896107 Soil cracking and vertical movements-hydric regime relationship. Two case histories in Argentina Trevisan, S J Proc 6th International Conference on Expansive Soils, New Delhi, 1-4 December 1987 P343-347. Publ Rotterdam." ,4 A Balkema, 1988 The active clay soil was basically illitic. Cracking occurring one summer was studied. Surface cracks of maximum width 30ram, length l-5m were seen. Three cracks remaining after the onset of rain were examined and the three dimensional crack patterns evaluated. Mean crack depth was about lm. Vertical movement of 2 footings was also studied. Maximum movement was about 20ram, less than half that expected on the basis of laboratory tests. Footing movement could be directly related to climatic pattern.
Time dependent behaviour See also: 896004, 896180 896108 Elasto-viscoplastic constitutive models for clays Oka, F; Adachi, T; Mimura, M Proc International Conference on Rheoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P12-28. Publ London: Elsevier, 1988 Constitutive models have been developed for both normally and overconsolidated clays. For normally consolidated clay, a new material function and internal variable have been introduced into the viscoplastic flow rule to produce a model able to describe the time dependent behaviour of clays such as strain-rate effect and creep phenomena. The model's performance is verified using undrained triaxial compressian and creep tests. For overconsolidated clays an elasto-viscoplastic constitutive model based on the non-associated flow rule and Perzyna's type viscoplastic theory has been developed.
896109 Creep-inclusive non-associative Cam-Clay plasticity model Kavazanjian, E; Hsii-Sheng Hsieh Proc International Conference on Rbeoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P29-43. Publ London. Elsevier, 1988 A non-associative dual yield surface elasto-plastic constitutive model for time-dependent behaviour of soft clay has been developed within the framework of modified Cam-Clay plasticity theory. The derived equations conform to a previously developed unified phenomenological model. The constitutive equations are implemented in a large strain finite element consolidation program with void ratio dependent permeability. Numerical analysis of I-D compression shows the model has improved predictive capacity over the single yield surface Cam-Clay model, and can reproduce a variety of important features of time-dependent behaviour of soft clays. 896110 Some observations on the creep behaviour of a silty clay O'Reilly, M P; Brown, S F; Austin, G Proc International Conference on Rbeoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P44-58. Publ London: Elsevier, 1988 Undrained creep tests were performed on reconstituted Keuper marl to study the mechanisms involved in creep. The experiments were carried out in a constant stress creep loading rig which allowed deadweight loading and automatically corrected vertical load so that a constant deviator stress was applied. Results are presented showing the relationships between stress level, time, pore pressure development and accumulation of shear strain. 896111 Application of rheoiogical properties of coal measure rocks to overburden stress determination Truong, D; Nguyen, V U Proc 2nd International Symposium on Field Measurements in Geomec&mics, Kobe, 6-9 April 1987 V1, P203-213. Publ Rotterdam: A ,4 Balkema, 1988 Experiments were undertaken to define the rheologic constants of various rock types amenable to strain relaxation. Timedependent models of rocks, uniaxial rheology, multiaxial rheology and determination of stress tensor are first reviewed. The experiments consisted of loading under axial and triaxial stress for a specified time and unloading instantaneously. Deformation was monitored. Results for a coarse grained sandstone are presented, showing the potential for in situ stress determination from measurements of relaxation strains on freshly retrieved rock cores. 896112 Fast landslide risk of an unstable clay slope (In French) Biarez, J; Boucek, B; Pardo-Parga, D Proc 5th International Symposium on Landslides, Lansmute, 10-15 July 1988 V2, Pl107-1110. Publ Rotterdam." A ,4 Balkema, 1988 Laboratory creep tests, isolated from dynamic and thermal effects, were carried out and showed that secondary creep can take place on a perfectly formed shear surface. In situ observations and theory support the observations. Although the stress interval of the secondary creep is very low, its existence is important, and it must be taken into account in assessing fast landslide risk.
~r 1989 Pergamon Press pic. Reproduction not permitted
Time dependent behaviour See also: 896004, 896180 896108 Elasto-viscoplastic constitutive models for clays Oka, F; Adachi, T; Mimura, M Proc International Conference on Rheoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P12-28. Publ London: Elsevier, 1988 Constitutive models have been developed for both normally and overconsolidated clays. For normally consolidated clay, a new material function and internal variable have been introduced into the viscoplastic flow rule to produce a model able to describe the time dependent behaviour of clays such as strain-rate effect and creep phenomena. The model's performance is verified using undrained triaxial compressian and creep tests. For overconsolidated clays an elasto-viscoplastic constitutive model based on the non-associated flow rule and Perzyna's type viscoplastic theory has been developed.
896109 Creep-inclusive non-associative Cam-Clay plasticity model Kavazanjian, E; Hsii-Sheng Hsieh Proc International Conference on Rbeoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P29-43. Publ London. Elsevier, 1988 A non-associative dual yield surface elasto-plastic constitutive model for time-dependent behaviour of soft clay has been developed within the framework of modified Cam-Clay plasticity theory. The derived equations conform to a previously developed unified phenomenological model. The constitutive equations are implemented in a large strain finite element consolidation program with void ratio dependent permeability. Numerical analysis of I-D compression shows the model has improved predictive capacity over the single yield surface Cam-Clay model, and can reproduce a variety of important features of time-dependent behaviour of soft clays. 896110 Some observations on the creep behaviour of a silty clay O'Reilly, M P; Brown, S F; Austin, G Proc International Conference on Rbeoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P44-58. Publ London: Elsevier, 1988 Undrained creep tests were performed on reconstituted Keuper marl to study the mechanisms involved in creep. The experiments were carried out in a constant stress creep loading rig which allowed deadweight loading and automatically corrected vertical load so that a constant deviator stress was applied. Results are presented showing the relationships between stress level, time, pore pressure development and accumulation of shear strain. 896111 Application of rheoiogical properties of coal measure rocks to overburden stress determination Truong, D; Nguyen, V U Proc 2nd International Symposium on Field Measurements in Geomec&mics, Kobe, 6-9 April 1987 V1, P203-213. Publ Rotterdam: A ,4 Balkema, 1988 Experiments were undertaken to define the rheologic constants of various rock types amenable to strain relaxation. Timedependent models of rocks, uniaxial rheology, multiaxial rheology and determination of stress tensor are first reviewed. The experiments consisted of loading under axial and triaxial stress for a specified time and unloading instantaneously. Deformation was monitored. Results for a coarse grained sandstone are presented, showing the potential for in situ stress determination from measurements of relaxation strains on freshly retrieved rock cores. 896112 Fast landslide risk of an unstable clay slope (In French) Biarez, J; Boucek, B; Pardo-Parga, D Proc 5th International Symposium on Landslides, Lansmute, 10-15 July 1988 V2, Pl107-1110. Publ Rotterdam." A ,4 Balkema, 1988 Laboratory creep tests, isolated from dynamic and thermal effects, were carried out and showed that secondary creep can take place on a perfectly formed shear surface. In situ observations and theory support the observations. Although the stress interval of the secondary creep is very low, its existence is important, and it must be taken into account in assessing fast landslide risk.
~r 1989 Pergamon Press pic. Reproduction not permitted