Abstract: Due to the complexity of the pore size distribution (PSD), the variation pattern of the pore structure for clay during the drying process is not clear, which leads to an inaccurate calculation of the soil-water characteristic curve (SWCC) based on the pore distribution model. To address this issue, a study was conducted to quantitatively analyze the PSD of remodeled clay with the single or double pore structure during the drying process based on the shrinkage test and mercury intrusion porosimetry test. The results revealed that there were translational and scaling transformations of the PSDs during the drying process. The t-distribution and double t-distribution functions were proposed to describe the PSDs of clay. The degrees of freedom, the peaks and the pore diameters corresponding to the PSD peaks were extracted as characteristic parameters to characterize the variation of PSDs. Good linear relationships between the characteristic parameters and the void ratio of remodeled clay were observed. Based on these findings, the relationship of water content-void ratio-pore size distribution was further established, and a framework for calculating the SWCC of remolded clay considering the variation of pore structure was proposed. Finally, the accuracy of the proposed calculation method was verified by comparing with the experimentally measured SWCC.

Key words: clay, unsaturated soil, pore size distribution, mercury intrusion porosimetry test, soil-water characteristic curve, drying- shrinkage test