An anisotropic elastic-viscoplastic model for soft clays

Zhenyu Yin, C.S. Chang, M. Karstunen, P.-Y. Hicher

Research output: Journal article publicationJournal articleAcademic researchpeer-review

249 Citations (Scopus)


Experimental evidences have shown deficiencies of the existing overstress and creep models for viscous behaviour of natural soft clay. The purpose of this paper is to develop a modelling method for viscous behaviour of soft clays without these deficiencies. A new anisotropic elastic-viscoplastic model is extended from overstress theory of Perzyna. A scaling function based on the experimental results of constant strain-rate oedometer tests is adopted, which allows viscoplastic strain-rate occurring whether the stress state is inside or outside of the yielding surface. The inherent and induced anisotropy is modelled using the formulations of yield surface with kinematic hardening and rotation (S-CLAY1). The parameter determination is straightforward and no additional experimental test is needed, compared to the Modified Cam Clay model. Parameters determined from two types of tests (i.e., the constant strain-rate oedometer test and the 24 h standard oedometer test) are examined. Experimental verifications are carried out using the constant strain-rate and creep tests on St. Herblain clay. All comparisons between predicted and measured results demonstrate that the proposed model can successfully reproduce the anisotropic and viscous behaviours of natural soft clays under different loading conditions. © 2009 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)665-677
Number of pages13
JournalInternational Journal of Solids and Structures
Issue number5
Publication statusPublished - 1 Mar 2010
Externally publishedYes


  • Anisotropy
  • Clays
  • Constitutive models
  • Creep
  • Strain-rate
  • Viscoplasticity

ASJC Scopus subject areas

  • Modelling and Simulation
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics


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