Correction Functions for Soil-Water Characteristics Curves Extending the Principles of Thermodynamics

The soil-water characteristics curve (SWCC) that is typically measured from laboratory tests is fit using mathematical models that are based on capillary law and used along with the saturated soil properties for predicting the hydro-mechanical behavior of unsaturated soils. Such SWCC models are valid for coarse-grained soils. However, the same models are also extended for modeling the SWCC of fine-grained soils over suction range from 0 to 106 kPa with a correction function. Due to this reason, SWCC models with correction functions have limitations in rigorous analyses of complex thermo-hydro-mechanical-chemo (THMC) behaviors of unsaturated soils, especially in the high suction range. In the present study, correction function is proposed for modeling the SWCC behavior using two widely models based on a theoretical framework extending the principles of thermodynamics. The relationships between the traditional and the proposed correction functions are discussed. Finally, comparisons are provided between the proposed and the traditional correction functions on the SWCC behavior to highlight their differences. In addition, the effects of temperature and salinity on the SWCC with correction functions are also summarized. The proposed correction function is a valuable tool for rigorous analyses and reliable prediction of the complex THMC behaviors of unsaturated soils.