Research On Creep Consolidation Behavior And Constitutive Model Of Soft Soil

The soft soil has a notable time's effect,which is codetermined by console-dation characteristic and creep characteristic.If we don't take no account of cree-p characteristic in the foundation deformation analysis in practical engineering we'll neglect the latent risk of the foundation stability.So understanding fully the behavior and mechanism of the coupling effect of creep and consolidation have theoretical significance in describing correctly the engineering behavior of struc-tural soft soil and have practical significance in analyzing and estimating correc-tly the foundation deformation and stability of the various big,huge engineering and forcasting ground settlement geologic hazard with the urbanization.Basing upon the research trends of the home and abroad and the demands of practical engineering, summarizing the predecessors' researches,the thesis stud-ied on tests and analyzed on the theory of coupled character of consolidation a-nd creep of the representative soft soil in Yingkou,Xiamen,Wuhan area.The means of indoor test about consolidation and creep of the soft soil was discuss-ed;the rule of deformation about the coupled character of consolidation and cre-ep of the representative soft soil in above area was summed up;the empirical f-ormula about deformation of consoledation and creep of the representative soft soil in above area was fited out;elastic-viscous model about consolidation and c-reep of the soft soil was established according with the deformation rules; furth-ermore the creep modle based on disturbed state concept was discussed prelimi-nary.Taking one with another,the principal works and conclusions of this thesis can be summarized as follow:1.Based on the predecessors' research results, the theories of consolidation and creep of soft soil is systematically discussed.2.The coupled character of consolidation and creep may be studied by the improved three dimension compression instruments.When the stress level is lo-wer,attenuation creep arise,the creep finally inclines to a certain stable value wi-th the time increasing in the relative curve of strain and time.When the stress l-evel is higher, non-attenuation creep is able to happen,The more the stress level is high,the more obvious the displacement of creep.3.In the three dimention creep consolidation tests ,when the stress level is low the isochronousre curves of the stress-strain of samples are one cluster of broken line or right line approximately and the deformation of soil mass is nonlinear;When the stress level arise the isochronousre curves of the stress-strain of samples approach to strain axis and the creep deformation is more obvious.4.By means of research to the porepressure together with time's relationship curves of these tests of three-strain compressing consolidation-creep,we can see that the rule is inclining to be steady on the partial stress action of each grad-e.With the stress level increasing,the pore-pressure is also increasing.This illustr-ates that creep deformation may cause pore-pressure rising below the term of c-onsolidated-undrained.The changes of creep deformation and pore-pressure posse-ss have the sameness rule.In terms of mechanism, they are aroused by the slug-gish effect that the adjacent pellets come into being in the soil mass medium.5.Uniting the test data of consolidation-creep,the fitting has been carried out to test's curves of consolidation-creep by the means of the application mathematical statistics and the empirical formula of every test curve has been obtained.6.Based on test results and Singh-Mitchell creep equation,an empirical creep model considering undrained condition is proposed. Furthermore a sensu lato Kelvin calculating model that accord with the deformation rules has been proposed.Based on disturbed state concept the disturbed state model has been discussed preliminarily and it is also proposed that the method of determination of parameters.7.Through calculating a engineering example,the conclusion show that:impro-ved creep-consolidation constitutive model of soft soil can reflect deformation of foundation more better and the calculating results are close to the practical sta-tus...