Gradation of coarse grained soil and fractal geometry character of particle breakage

The applicability of soil cumulative mass particle-size distribution for coarse grained soil was verified, and the change rule of fractal dimension was analyzed in the situation of different particle sizes and scale methods. The connection between scale gradation and original gradation was also established through fractal dimension. Relative breakage rate was calculated according to the triaxial tests with different parent rocks, gradations and particle shapes. The correlation between fractal dimension and relative breakage rate was also discussed. The results show that fractal dimension can quantitatively describe original gradation and scale gradations. There exist great differences between fractal dimension curves of particle size with different scale methods, and all of them deviate from original gradation's, the smaller scale size is, the bigger the deviation is. In the four scale methods, an excellent linear relationship between fractal dimension and the logarithm values of particle size has been found. The bigger the pressure is, the larger the broken fractal dimension and relative breakage rate is. The relative breakage rate decreases with the increase of fractal dimension before test. The broken fractal dimension and relative breakage rate displays a power functional relation under the condition of different parent rocks, gradations and particle shapes. Therefore, relative breakage rate of different pressure can be estimated through fractal dimension and fitting parameters. © 2015, Central South University of Technology. All right reserved.