Study On Deformation Characteristics And Elastoplastic Constitutive Model Of Remolded Soft Clay

In recent years,Chinese internal and external economies has been developed,and some coastal areas have begun to build large numbers of high-speed transportation facilities,such as the underground railways in the cities,and the high-speed railways that cross the intercity or province,etc.These projects not only rely on the technological innovation of the transportation facilities itself,but also rely on the in-depth study and breakthrough of the basic characteristics of the underlying foundation of soft clay,especially the deformation characteristics and stress-strain characteristics of the saturated soft clay.In this paper,the static triaxial test of remolded soft clay in Jiaojiang District of Taizhou was carried out to analyze the basic deformation characteristics of remolded samples: rheology,elastoplasticity and dilatancy.The following work was mainly done:(1)The research results of creep models of predecessor soft clays are collated,the creep properties of soft clays are analyzed,and the mathematical method of decomposing fractional derivative is used to construct a new type of component model.This model can not only describe traditional components.The model does not exhibit nonlinearities and can describe accelerated creep.The established creep model was fitted and verified by previous triaxial shear creep test.(2)In strict accordance with the rules of soil test,the triaxial shearing drainage test of normal consolidated remolded soft clay and the triaxial shearing drainage test of overconsolidated soft clay in Jiaojiang district of Taizhou were carried out,and the stress and strain of the reshaped specimen was obtained;an indoor compression experiment was conducted and the curve was obtained,and the compression index and rebound index were calculated.(3)Analysing the elasto-plastic characteristics of soft clay deformation,according to the assumptions whether or not the internal variable are related to the stress path and the orthogonal flow rules,two soft clay constitutive models were established respectively,and the MATLAB numerical calculation software was used to obtain the Compared with the theoretical results of the triaxial shear drainage test results of soft clay and the same parameters of the related classical tests,the rationality of the two types of models is initially verified,and it is found that the latter is superior to the former.(4)Based on the yield surface constructed under the assumption that the hardening parameter is independent of the stress path,combined with the hardening parameters that have been proposed by previous researchers and independent of the stress path,a constitutive equation suitable for remodeling overconsolidated soft clay was constructed and passed through classical tests.Compared with the results,preliminary verification of its reasonableness.