Fractal Structure of Granularity Distribution of Regional Soils in China

The granularity characteristics of loess, laterite and expansive soil in China are studied according to the fractal geometry. It is found that there is a linear relationship between the accumulative granularity content and the grain size in log-log plot, and it’s slope b can be used to calculate the relative fractal dimension D by the equation D = 3 - b. Results show that the D of regional soils changes from 2 to 3, and the D of laterite is the largest and loess is the lowest. Further, the D may be taken as the series-parameter, which describes the soil system as a self-organization one. The higher the value of D, the greater the degree of the self-organization, correspondingly, the evolution of the soil is in the higher stage. Correlations between fractal dimension and sorting or grading, pore-size distribution, microstruc-ture characteristics are discussed respectively. It is concluded that the fractal dimension is a better index for the description of granularity characteristics and the classification of cohesive soils.