Capturing the transition from diffuse to localised failure in constitutive modelling of partially saturated soils

Dat G. Phan, Giang D. Nguyen, Ha H. Bui, Terry Bennett

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)


Localised failures in the form of shear band induce localised deformation and saturation within partially saturated soils. Inelastic responses mainly take place inside the shear band, while the zone outside it usually undergoes unloading processes with much smaller changes in deformation and saturation, as observed in several triaxial tests. The interaction between responses inside and outside shear bands governs the macro behaviour under effects of the hydromechanical coupling. This mechanism, along with properties of shear band (inclination, thickness) and the specimen size, are usually missing in existing classical models based on homogenous assumption. They are incorporated into our approach to correctly capture the post-localisation behaviour of partially saturated soils. In our proposed approach, enrichment terms for kinematics are used in the thermodynamics-based formulation to account for strong variations of hydromechanical responses (stress-strain, suction-saturation) outside and inside the shear band. The proposed formulation results in a size-dependent constitutive structure capable of describing the transition of behaviour from homogeneous to localised stages. The promising features of the proposed formulation are illustrated using data from drained triaxial tests.

Original languageEnglish
Article number103783
Number of pages26
JournalInternational Journal of Plasticity
Publication statusPublished - Dec 2023


  • Bifurcation
  • Constitutive modelling
  • Hydro-mechanical coupling
  • Localisation
  • Localisation band
  • Partially saturated soils
  • Size-dependent
  • Thermodynamics

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