Determination of the effective stress parameter in unsaturated soils: an analytical formulation based on the soil water retention properties

Modeling the hydro-mechanical behavior of unsaturated soils is of crucial importance for many geotechnical engineering projects which span from the evaluation of the earth dams to the risk analysis of rainfall induced landslides. To better understand the hydro-mechanical behavior of unsaturated soils, the most accurate and practical formulas for the stress measures of such media are required. The determination of the stress measures such as the effective stress has, thus, faced much attention in the recent decades. In this regard, the effective stress parameter is a key parameter for which many empirical equations have been introduced in the literature. In this study, an analytical formulation for the effective stress parameter has been introduced. The proposed approach employs the principles of thermodynamics to formulate the effective stress parameter based on the soil water retention properties. Last but not the least, it accounts for the contribution of the capillary forces which has, commonly, been overlooked in the previous studies.

Keywords:

Unsaturated Soils , Thermodynamics , Soil Water Retention Curve , Effective Stress Parameter