中文摘要：

土—水特征曲线是非饱和土力学研究的重要曲线,其拟合参数对于分析非饱和土的各种性质具有重要意义。基于滤纸法试验,测定了庆阳非饱和黄土土—水特征。以Gardner模型为基础,采用计算机语言MATLAB中的Lsqcurvefit、Nlinfit、Fminunc函数对试验结果进行拟合,同时对基质吸力与土体微观平面孔隙率及体积含水率间关系进行综合研究,结果表明：Nlinfit函数拟合效果较好,参数相近,曲线整体形状符合土水特征曲线（SWCC）的特征,且Nlinfit函数拟合的SWCC误差小于10%,具有较好的精度和稳定性。

英文摘要：

Soil water characteristic curve is an important curve in the study of unsaturated soil mechanics. And its simulation parameter has the great significance in the analysis of the properties of unsaturated soil. The paper tested soil water characteristic curve of unsaturated soil in Qingyang based on filter paper test. Based on Gardner model, test results were fitted through computer language MATLAB（lsqcurvefit function, nlinfit function, and fminunc function）.At the same time, the relationship among matric suction, soil microcosmic surface porosity and bulk water content was comprehensively conducted. The results showed that nlinfit function was with fine imitative effect and close parameters.And the overall shape of this curve fitted SWCC characteristic. Error of nlinfit function fitting SWCC was less than10%, and it had great accuracy and stability.