Fractal dimension and physical characteristics of clay-sand mixtures
Wei Yujie, Wu Xinliang, Pi Jiangping, Cai Chongfa, Ding Shuwen
(Soil and Water Research Center at Huazhong Agricultural University, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) in Ministry of Agriculture, 430070, Wuhan, China)
Abstract：To understand the anti-erodibility and slope stability mechanisms of clay-sand mixtures, we prepared artificial soils with different particle size distributions by mixing clayey soil and engineering sand in different mass ratios. The effect of soil particle size composition on soil fractal dimension and physical characteristics was discussed by analyzing the structure and physical-mechanical parameters of these artificial soils. Results were as follows: 1) artificial soil particle composition could be characterized by particle fractal dimension D and D increased as the sand content decreased and the silt-clay content increased; 2) with the increase of fractal dimension D, bulk density increased first and then decreased, whereas the total porosity showed an opposite trend, while capillary porosity increased and non-capillary porosity decreased; when D was 2.75, the dry bulk density reached the maximum value of 1.74g/cm3, but the total porosity, saturation moisture content and capillary moisture content were at the minimum values of 34.52%，19.83% and 17.19%, separately; 3) as particle fractal dimension D increased, internal friction angle and cohesion of saturated soils displayed a downward parabola and an exponential increase respectively, but the angle of repose changed following an upward quadratic parabola trend, and the angle of repose in air was larger than that in water and the difference between them decreased with the increase of D. It was concluded that: particle size composition was the main factor influencing soil structure; shear strength under saturation increased with soil compactness; and the angle of repose was mainly affected by the uniformity and diameter of soil particles.
2013, Vol. 11 
