Study of Fitting Soil-water Characteristic Curves for Compacted Loess by MATLAB

Three functions in MATLAB,i.e.lsqcurvefit,nlinfit and fminunc,were used to find a convenient and accurate way to fit soil-water charactieristic curve(SWCC)of compacted loess,by using van Genuchten model and Gardner model separately.The fitting data of volumetric water content and matrix suction were obtained by one dimensional infiltration test of compacted loess.The analysis on fitting effects shows that the fitting result of Gardner model by fminunc function is the best among the methods used in this study.Finally,the data from a parallel test were used to verify the fitting formulae.The errors between calculated and measured data are less than 10%,which further verifies that Gardner model fitting SWCC of compacted loess by using fminunc of MATLAB is convenient,stable and accurate.