Temperature-dependent water retention curve model for both adsorption and capillarity

A temperature-dependent water retention curve (WRC) model is necessary in numerous geotechnical engineering cases such as the disposal and storage of nuclear waste, buried high-voltage cables, heat dissipation embankments and geothermal structures. A series of pioneering models attempting to consider the mechanisms of temperature effect have been proposed. Nevertheless, it should be noted that very limited research can be found in the literature to consider temperature effects on both capillarity and adsorption. Thus, a temperature-dependent WRC model for both adsorption and capillarity is developed in this study. An adsorption equation is first proposed by integrating Kelvin equation, Clausius-Clapeyron equation and the adsorption enthalpy equation. Then, the proposed adsorption equation and an existing capillary equation are incorporated into Peters-Durner-Iden (PDI) model to establish the temperature-dependent WRC model. Sixteen series of non-isothermal WRC data are employed to illustrate the application and performances of the proposed model. The proposed WRC model provides good agreement between the predicted and measured temperature-dependent WRCs. Moreover, the main differences between different types of soils are temperature effects on adsorption. The value of parameter alpha gradually increases from sandy soils to bentonite, representing an increasingly strong soil-water interaction and increasingly significant temperature effects on adsorption. By comparing with three existing models, the proposed model is found as the most suitable for describing the observed data.