Potential constitutive equation of unsaturated double-porosity media and its application

To analyze the multi-physical field and multi-phase coupling effects in complex geotechnical engineering, it is necessary to construct a general constitutive theoretical framework for unsaturated double-porosity media. First, double-porosity media was regarded as the nested superposition of two single-porosity media, and an energy conservation equation for unsaturated double-porosity media was derived from classical mixture theory based on the internal relations between strain and pore deformation of each component. Then, the general potential constitutive equations were established under small strain condition for unsaturated double-porosity media on the basis of the mechanical behaviors of conjugate quantity pair. As an application of the general potential constitutive equation, the potential function was adopted as a quadratic polynomial of strains, and it was supposed that each conjugate quantity was independent of each other. Thus, an isotropic linear elastic model of unsaturated double-porosity media was established, and model parameters were determined by experimental data. When unsaturated double-porosity media was degenerated into saturated double-porosity or unsaturated single-porosity media, the proposed model was degenerated into corresponding existing model. The general potential constitutive equation obtained in this paper can provide guidance for the specific modeling of unsaturated double-porosity media, and the linear elastic constitutive model can be used to formulate corresponding consolidation governing equation. Copyright ©2021 Journal of Harbin Institute of Technology.All rights reserved.