A plasticity constitutive model for unsaturated, anisotropic, nonexpansive soils

Panagiotis Sitarenios, Michael Kavvadas

Research output: Contribution to journalArticle

1 Citation (Scopus)


The paper describes and evaluates an incremental plasticity constitutive model for unsaturated, anisotropic, nonexpansive soils (CMUA). It is based on the modified Cam-Clay (MCC) model for saturated soils and enhances it by introducing anisotropy (via rotation of the MCC yield surface) and an unsaturated compressibility framework describing a double dependence of compressibility on suction and on the degree of saturation of macroporosity. As the anisotropic and unsaturated features can be activated independently, the model is downwards compatible with the MCC model. The CMUA model can simulate effectively: the dependence of compressibility on the level of developed anisotropy, uniqueness of critical state independent of the initial anisotropy, an evolving compressibility during constant suction compression, and a maximum of collapse. The model uses Bishop's average skeleton stress as its first constitutive variable, favouring its numerical implementation in commercial numerical analysis codes (eg, finite element codes) and a unified treatment of saturated and unsaturated material states.

Original languageEnglish
Pages (from-to)435-454
Number of pages20
JournalInternational Journal for Numerical and Analytical Methods in Geomechanics
Issue number4
Early online date16 Dec 2019
Publication statusPublished - 1 Mar 2020


  • Bishop stress
  • constitutive model
  • critical state plasticity
  • soil anisotropy
  • unsaturated soils

ASJC Scopus subject areas

  • Computational Mechanics
  • Materials Science(all)
  • Geotechnical Engineering and Engineering Geology
  • Mechanics of Materials

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