Predicating soil-water characteristic curves of soils with different initial void ratios based on a pedotransfer function

A pedotransfer function (PTF), which is a nonlinear regression equation, is proposed for predicting the parameter n of the van Genuchten (VG) model. Considering the regressive relationship between the parameter α of the VG model and the initial void ratio e₀, the soil-water characteristic curves (SWCCs) of soil specimens with different initial void ratios can be accurately predicted. The fitting parameters (i.e., a, b and A, B) of the regression equations corresponding to the parameters n and α can be calibrated using the test data obtained from three sets of conventional SWCC tests. The test data in each reference available are divided into two parts. One part is used for the calibration of the fitting parameters (i.e., a, b and A, B), and the other part is employed for the verification of the predicted SWCCs based on PTFs. The results show that the SWCCs, which are predicted by using the proposed nonlinear regression equation (PTF) concerning the parameter n of the VG model, have good agreement with the test data in the references. Only one predictive variable (i.e., initial void ratio, e₀) is needed in the proposed PTF. This PTF is suitable for both rigid and deformable soils.