In unsaturated soils with high saturation

gas phase is disconnected

and the occluded gas pressure may change and affect the soil behavior. The properties of unsaturated soils with high saturation are first discussed; and then a constitutive model is developed within an existing constitutive framework of unsaturated soils by using the principle of generalized effective stress. This model takes into account the effect of gas diffusion

with a hardening law accounting for the effect of occluded gas pressure change. To validate the new model

the modeling results are compared with the experimental results available in the literature and the simulated results of existing models. It is shown that this model performs better than existing models

especially for the unsaturated soils at high saturation.