FRACTAL ANALYSIS OF THE ROUGHNESS AND SIZE DISTRIBUTION OF GRANULAR-MATERIALS

The roughness, i.e. general shape and surface irregularity, of particu late soil is an important characteristic that affects the mass behavio r of the soil. Characterization of roughness has typically been limite d to visual comparison of particles to standard charts, although other more quantitative methods such as Fourier analysis have also been use d. Particle size distribution is another important mass-behavioral cha racteristic of granular soils, and similar to roughness, is defined wi thin limited boundaries. Fractal geometry can be applied to irregular or fragmented patterns such as roughness and grain size distribution t o provide quantifying and unique numerical values. This paper presents an evaluation of the applicability of fractal dimensioning techniques to the quantification of both physical particle roughness and grain s ize distribution of granular soil. The divider and the area-perimeter fractal dimensioning techniques are used to quantify roughness of plan ar profiles of individual sand grains. The characterization of the siz e distribution of granular material using fractal geometry is evaluate d through Korcak's fragmentation theory. As shown herein, both the div ider and the area-perimeter fractal dimensioning techniques are useful in characterizing soil particle roughness, and the results confirm th e importance of differentiating between textural and structural aspect s of roughness. Fractal geometry can also be used to quantify the size distribution of granular soils with relatively well-graded size distr ibutions. (C) 1997 Elsevier Science B.V.