Work input analysis for soils with double porosity and application to the hydromechanical modeling of unsaturated expansive clays

Jian Li, Zhen Yu Yin, Yujun Cui, Pierre Yves Hicher

Research output: Journal article publicationJournal articleAcademic researchpeer-review

29 Citations (Scopus)


A mechanical approach for unsaturated expansive soils considering double porosity has been developed based on the porous media theory. In this approach, the adsorbed and the capillary water, as well as the micropores and macropores, are two distinct phases. An interaggregate stress considered as the work-conjugate of the macrostructural strain increment has been defined. Both physicochemical and capillary effects of the pore water have been introduced at the macroscopic level. Other work-conjugate variables relevant for the constitutive modeling of double-porosity unsaturated media have also been identified, consisting of the modified suction as conjugate of the increment of the macrostructural degree of saturation and the microstructural effective stress as conjugate of the microstructural volumetric strain increment. A hydromechanical model for unsaturated expansive clays taking into account the interaction between the micro- and the macrostructures in expansive clays can thus be built. Based on the bounding surface concept, an anisotropic loading – collapse yield surface has been introduced to reproduce the three-dimensional mechanical behavior. To analyze the model capabilities, two series of laboratory tests consisting of multiple wetting and drying cycle tests on Boom clay and triaxial tests on Zaoyang (ZY) expansive clay were simulated. The comparisons between numerical and experimental results show that the model can reproduce with reasonable accuracy the mechanical behavior and the water retention characteristic of unsaturated expansive clays.

Original languageEnglish
Pages (from-to)173-187
Number of pages15
JournalCanadian Geotechnical Journal
Issue number2
Publication statusPublished - 1 Jan 2017
Externally publishedYes


  • Anisotropy
  • Capillary hysteresis
  • Constitutive relation
  • Double porosity
  • Unsaturated expansive clay
  • Work-conjugate variables

ASJC Scopus subject areas

  • Civil and Structural Engineering

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