A thermodynamics-based formulation for coupled hydro-mechanical behaviour of unsaturated soils

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

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther


The nonlinear behaviour of unsaturated soils is governed by the fully coupled hydro-mechanical phenomenon due to the irrecoverable movement of particles and fluids. It is usually accounted for in constitutive modeling using separate evolution rules for plastic deformation and saturation, linked with two yield conditions for stress and suction. In this paper, a new generic thermodynamics-based approach is developed to provide a more rigorous way to capture these underlying mechanisms. A special form of dissipation potential leading to strong inter-dependence of mechanical and hydraulic internal variables is used for the derivation of a single yield surface. A specific critical state model using a small number of identifiable parameters is derived from the proposed formulation. Its capabilities in predicting the drained and undrained experimental results are investigated to highlight the applicability of our approach.

Original languageEnglish
Title of host publicationChallenges and Innovations in Geomechanics - Proceedings of the 16th International Conference of IACMAG - Volume 1
EditorsMarco Barla, Alice Di Donna, Donatella Sterpi
Number of pages8
ISBN (Print)9783030645137
Publication statusPublished - 2021
EventInternational Conference of the International Association for Computer Methods and Advances in Geomechanics 2021 - Turin, Italy
Duration: 5 May 20218 May 2021
Conference number: 16th
https://link.springer.com/book/10.1007/978-3-030-64518-2 (Proceedings)
https://www.issmge.org/events/16th-international-conference-of-the-international-association-for-computer-methods-and-advances-in-geomechanics-iacmag (Website)

Publication series

NameLecture Notes in Civil Engineering
ISSN (Print)2366-2557
ISSN (Electronic)2366-2565


ConferenceInternational Conference of the International Association for Computer Methods and Advances in Geomechanics 2021
Abbreviated titleIACMAG 2021
Internet address


  • Constitutive modelling
  • Coupled hydro-mechanical
  • Thermodynamics
  • Unsaturated soils

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