为了建立一种参数有明确物理意义的土-水特征曲线拟合方法,基于分形理论,给出了一种直接通过土-水特征曲线实测数据求解分维数的计算方法,建议了一种土-水特征曲线拟合分析的分形模型。为验证所建议拟合方法的合理性,采用液压千斤顶制作了7个不同干密度黏性土试样,利用压力板仪测量了土-水特征曲线。基于土-水特征曲线实测值计算了分维数,在此基础之上对土-水特征曲线实测数据进行分析拟合。结果表明:分维数计算及拟合分析时,7个试样相关系数都集中在0.97~0.99之间,从而证明了土-水特征曲线具有良好的分形特性,建议的拟合方法效果较好。此外,研究发现,分维数、进气值随干密度几乎呈线性增加,据此建议了一种不同压实度下的土-水特征曲线预测方法,其预测结果与实测值吻合较好。
In order to establish a fitting approach for soil-water characteristic curves (SWCC) with clear physical meanings, a method is presented to directly calculate the fractal dimensions through the SWCC data based on the fractal theory, and a fractal model of SWCC is proposed. To verify the proposed fitting method, seven clay samples with different dry densities are prepared using hydraulic jacks, and the soil-water characteristic curves are measured by using the pressure plate apparatus. Based on the experimental results of SWCC, the fractal dimensions are calculated. On this basis, fitting analysis of the SWCC data is performed by using the presented method. The results show that, all the correlation coefficients of the seven samples range from 0.97 to 0.99, which indicates good fractal characteristics of SWCC as well as good fitting performance of the proposed method. In addition, it is found that the fractal dimensions and the air entry values increase almost linearly with the dry density. On this basis, a prediction method of SWCC at different compaction degrees is also proposed and tested. The prediction results are in good agreement with the measured values.