Model for predicting evolution of microstructural void ratio in compacted clayey soils

The hydromechanical behavior of compacted clayey soils is significantly influenced by its microstructure. The microstructural void ratio is a key parameter that is strongly associated with the microstructural state. The objective of this study is to provide a practical and reliable estimation approach for predicting the evolution of the microstructural void ratio of compacted clays soils subjected to wetting and drying paths. In this paper, the microstructural evolution of 12 clayey soils were investigated quantitatively using the mercury intrusion porosimetry (MIP) results. Based on this study, a comprehensive criterion has been developed for identifying different pore populations of compacted clayey soils for interpreting the MIP results. The “as-compacted state line” (ACSL) was proposed to estimate the initial microstructural void ratio of clayey soils at the as-compacted state. A incremental linear constitutive model was proposed for correlating the microstructural void ratio to the “microstructural average skeleton stress” in compacted clayey soils following monotonic wetting and drying paths. The developed approach is validated by providing comparisons between the predicted and interpreted microstructural void ratios for all the examined soils. The proposed approach can be extended in constitutive modelling of the hydromechanical behavior of compacted clayey soils by incorporating explicitly the microstructural information.