Predicting the soil freezing characteristic curve of the expansive soil with double porosity accounting for hydraulic effects

Based on the similarity between the drying-wetting process and freezing-thawing process in the soil, a physically based equation predicting the soil freezing characteristic curve (SFCC) can be formulated combining the generalized Clapeyron equation. In this paper, by introducing the weighing factors in two scales of pore sizes, the physically based equation for single-porosity soil is extended for double-porosity soil, with the ability in well characterizing the bimodality of the SFCC. A systematic approach formulating the SFCC of the expansive soil is presented accounting for the pore size distribution and its evolution in two scenarios of the hydraulic conditions. Good agreements can be found between model predictions and experimental data for both scenarios. The effects of hydraulic condition on the pore structure of an expansive soil, as well as the consequences of the evolved pore structure on the SFCC, are emphasized and quantified. In addition, the framework presented herein demonstrates how an initially bimodal SFCC evolves into a unimodal shape along hydration and provides the theoretical SFCCs at different levels of saturation, which contributes to modelling the water-heat transfer in the freezing process of the unsaturated expansive soil.

Automated summary

Based on the similarity between the drying-wetting process and freezing-thawing process in the soil, a physically based equation predicting the soil freezing characteristic curve (SFCC) is formulated. The equation is extended for double-porosity soil, with the ability to characterize the bimodality of the SFCC. A systematic approach is presented to account for the effects of pore size distribution and hydraulic conditions on the SFCC. Good agreements are found between model predictions and experimental data.