Abstract: Soil-water characteristic curves（SWCCs）are one of the basic parameters in unsaturated soil mechanics, which is usually used to estimate the properties of unsaturated soils. However, the measurement of SWCC is time-consuming and laborious. In order to solve this problem, we used the one-point SWCC measurement and parameters of particle size distribution to estimate the three parameters of Van Genuchten equation for sandy soils. Parameters of the Van Genuchten model were correlated with the basic properties of 43 (No.1−43) types of sandy soils. Then we obtained two equations to estimate the three parameters. The values of the three parameters were calculated by the two equations and one-point SWCC measurement. The results show that the parameter av can be expressed as an exponential function of the combined parameter (P1 000/P500), and mv can be expressed as an exponential function of 1/nv. Sensitivity analysis shows that the one-point SWCC measurement locating in the range of 1 kPa and 10 kPa gave the most reliable estimated results. The proposed method was evaluated using a total of 4 (No.44−47) types of sandy soils. It shows that the proposed method has a good performance in estimating SWCC.

Key words: soil-water characteristic curves, Van Genuchten model, sandy soil, sensitivity analysis