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902250 Elnstoplastic-viscoplastic bounding surface model for isotropic cohesive soils Kaliakin, V N Proc International Conference on Rheoiogy and Soil Mechanics, Coventry, 12-16 Sept 1988 P147-163. Publ London: Elsevier, 1988

A generalised 3-D constitutive model, based on the concept of the bounding surface in stress space, has been developed within the framework of coupled elastoplasticity-viscoplastic- ity and critical state soil mechanics. Formulation for isotropic cohesive soils, development of the specific form of the bound- ing surface, the hardening function, and response under undrained conditions are presented. Identification and deter- mination of the required parameters are described. The model is verified by comparison with published data from triaxial tests on undisturbed silty clay.

902254 Non linear incremental constitutive equation: application to sands Doanh, T; Di Benedetto, H; Golcheh, Y; Kharchafi, M Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P255-274. Publ Rotterdam: A A Balkema. 1989

A nonlinear incremental constitutive relation, based on labo- ratory test results, which is precise enough to represent com- plex Ioadings, is presented. The theoretical aspects of the model are described. The identification of the constitutive parameters from conventional and true triaxial tests is illus- trated. The ability of the model to predict behaviour in hollow cylinder tests and true triaxial tests, and its computer imple- mentation are discussed.

902251 Micromechanical approach to constitutive modelling for granular soils based on slip mechanism Chang, C S Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P183-200. Publ Rotterdam: A A Balkema. 1989

A model for granular soils is presented which treats the medium as a random packing of particles intersected by a large number of potential sliding planes (mobilized planes). The overall behaviour is obtained from the deformation on each mobilized plane. The model is calibrated using results of hollow cylinder and true triaxial tests on Hostun and Reid Bedford sands. The micromechanical model, with considera- tion of material anisotropy, can represent many important fea- tures of soil behaviour under a variety of stress paths.

902255 Modelling the stress/strain behaviour of sand using a multi- surface kinematic model Griffith, D V; Prevost, J H Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P275-291. Publ Rotterdam: A A Balkema, 1989

Data from true triaxial and hollow cylinder tests have been used to calibrate a multi-surface kinematic model. Predictions for both monotonic and cyclic loading tests are generally good, but some deficiencies are identified. Methods of parame- ter identification are described and the data provided for cali- bration assessed. Improvements to the model in the areas of shakedown during cyclic loading, prediction of failure loads, and circular stress paths are discussed.

902252 Use of hypoelasticity to model the behavior of sands Collins, S A; Bachus, R C Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P201-236. Publ Rotterdam: A A Balkema, 1989

Hypoelasticity (Truesdell, 1955), where the stress rate depends on the state of stress and rate of deformation, is briefly reviewed. The theory is used to describe the constitutive beha- viour of sands. The advantages and disadvantages of this approach are discussed. Excellent results are obtained for pre- diction of behaviour of sands along complex load paths and at relatively high confining pressures. A method to model strain softening and cyclic and load/unload effects is presented.

902256 Prediction of deformation behaviors of sands by the subloading surface model Hashiguchi, K; Imamura, T; Ueno, M Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P293-306. Publ Rotterdam: A A Balkema, 1989

The subloading surface model, which can overcome shortcom- ings of classical theory and describe plastic deformation in the subyield state, is presented. The constitutive equations, with parameters from drained hollow cylinder and true triaxial tests, are used to predict behaviour of sands. Refinements to the model to improve its predictive capacity are discussed.

902253 Incrementally non-linear constitutive relation and its predictions Darve, F; Dendani, H Proc International Workshop on Constitutive Equations for Granular Non-Cohesive Soils, Cleveland, 22-24 July 1987 P237-254. Publ Rotterdam: A A Balkema, 1989

The assumptions of an incrementally nonlinear constitutive model for soils are presented and discussed, and the differ- ences between such models and conventional elastoplastic the- ories are examined. The model is calibrated for Hostun and Reid Bedford sands. The influence of interpolation rules on predictions for a deviatoric circular stress path is illustrated. The structure of the constitutive relation is important to the quality of the predictions in this case.

902257 Plastic constitutive relation for slumping loess Dong, S Y; Liu, Z D Proe International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P220-223. Publ Beijing: International Academic Publishers, 1989

Triaxial consolidation slaking tests at constant stress ratio were used to determine the stress-strain-moisture content behaviour of a collapsible loess soil. Based on these results and plasticity theory, a constitutive relation representing the col- lapsibility of loess is proposed. Initial and hardening collapse yield surfaces are illustrated. The model gives predictions in good agreement with observed laboratory behaviour.

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