Fractality of Grain Composition of Debris Flows

  • Institute of Mountain Hazards and Environment, CAS & Ministry of Water Conservancy, Chengdu 610041, China

Received date: 2004-10-28

  Revised date: 2005-02-18

  Online published: 2005-05-25

Supported by

National Natural Science Foundation of China, No.40101001; National Science Foundation for Outstanding Youth, No.40025103


Debris flow is in essence the process of mass transportation controlled by its constitution that can be characterized by a wide-ranged distribution of grain size. Soil samples of debris flows of various densities have been collected from different regions and gullies. Analysis of grain composition, particularly for debris flow of high density, ρs > 2 g/cm3, reveals that the cumulative curve can be fitted by exponential function with exponent varying with regions and gullies. More importantly, the exponent falls into a narrow-valued domain and hence provides an index signing the activity of debris flows. Furthermore, fractality turns out to exist in grain composition and porosity; and fractal dimension has been derived from cumulative curves in a certain range of size, a range that defines the upper limit of grains constituting the matrix of debris flow. In analogy to concentration in fluidization of granular materials, fractal structure of porosity has proved to take a crucial part in initiation of debris flows.

Cite this article

LI Yong, CHEN Xiaoqing, HU Kaiheng, HE Shufen . Fractality of Grain Composition of Debris Flows[J]. Acta Geographica Sinica, 2005 , 60(3) : 495 -502 . DOI: 10.11821/xb200503016


[1] Batrouni G G, Dippel S, Samson L. Stochastic model for the motion of a particle on an inclined rough plane and the onset of viscous friction. Physical Review, 1996, E53(6): 6496-6503.

[2] Bagnold R A. Experiments on a gravity-free dispersion of large solid spheres in a Newtonian fluid under shear. Royal Soc. London Proc., Ser. A, 1954, 225: 49-63.

[3] Bagnold R A. The flow of cohesionless grains in fluids. Royal Soc. London Proc., Ser. A, 1956, 249: 235-297.

[4] Campbell C S. Self-lubrication for long run-out landslides. J. Geol., 1989, 97: 653-665.

[5] Cleary P W, Campbell C S. Self-lubrication for long runout landslides: examination by computer simulation. Journal of Geophysical Research, 1993, 98(B12): 21911-21924.

[6] Fei Xiangjun, Shu Anping. Movement Mechanism and Disaster Control for Debris Flows. Beijing: Tsinghua University Press, 2004. 41-48.
[费祥俊, 舒安平. 泥石流运动机理与灾害防治. 北京: 清华大学出版社, 2004. 41-48.]

[7] Hunt A G, Gee G W. Application of critical path analysis to fractal porous media: comparison with examples from the Hanford site. Advances in Water Researches, 2002, 25: 129-146.

[8] Hampton M A. Buoyancy of debris flows. Journal of Sedimentary Petrology, 1979, 49(3): 753-758.

[9] Arya L M, Paris J F. A physicempirical model to predict the soil moisture characteristic from particle size distribution and bulk density data. Soil Sci. Soc. Am. J., 1981. 45: 1023-1080.

[10] Gevirtzman H, Roberts P V. Pore scale spatial analysis of two immiscible fluids in porous media. Water Resources Research, 1991, 27(4): 1167-1173.

[11] Hunt A G. Continuum percolation theory for pressure-saturation characteristics of fractal soils: extension to non-equilibrium. Advances in Water Researches, 2004, 27: 245-257.

[12] Hunt A G. Percolation transport in fractal porous media. Chaos, Solitons and Fractals, 2004, 19: 309-325.

[13] Katz A J, Thompson A H. Fractal sandstone pores: implications for conductivity and pore formation. Phys. Rev. Lett. 1985, 54(12): 1325-1328.

[14] Rieu M, Sposito G. Fractal fragmentation, soil porosity, and water properties: I. theory. Soil Sci. Soc. Am. J., 1991, 55: 1231.

[15] Savage S B. Gravity flow of cohesionless granular materials in chutes and channels. J. Fluid Mech., 1979, 92(1): 53-96.