Fractal characteristics and fitting analysis of soil-water characteristic curves

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.