Microstructurally Related Model for Predicting Behavior of Unsaturated Soils with Double Porosity in Triaxial Space

11 Microstructure can have an important impact on the hydraulic and mechanical 12 behaviour of unsaturated soil and so it is necessary for it to be considered in constitutive 13 models to enable accurate predictions of soil behaviour. This paper focuses on 14 constitutive modelling of soils exhibiting a dual-porosity structure. Based on the 15 assumption that macro and micropores contained in the double porosity structure have 16 different influences on the mechanical and hydraulic behaviour, the effective degree of 17 saturation was selected as a microstructural index. This microstructural index was 18 implemented within a Bishop’s effective stress based approach and the Glasgow 19 Coupled Model and the Modified Camclay Model were adopted as the basic framework 20 for the development of a constitutive model. Typical samples of low-expansive, non- 21 expansive and collapsible soils with dual porosity were selected to validate the model’s 22 performance, with the model found to perform well when compared with experimental 23 data in terms of isotropic compression, triaxial shear and wetting tests.