A constitutive model describing the combined process of simultaneous consolidation and creep is used to evaluate the practical significance of time effects on interpretation of test results and also on settlements in field. The constitutive model includes elastic strains, visco-plastic strains, a yield stress and a hardening law and is generally formulated in three dimensions. The model is compared to other models and to traditional models of separated processes of consolidation and creep. When a soil is assumed to consolidate and creep simultaneously the combined process depends on the strain rate or stress rate in the test. The results from conventional incremental consolidation tests have been evaluated based on this constitutive model, where the effect of rate has been considered. Focus is on preconsolidation stress, consolidation coefficient and interpretation of creep. Finally the model has been applied to settlement calculations on sites where soil is sensitive to creep and practical significance of rate dependency has been evaluated and related to various types of soil.
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