Climate and Environmental Change

Fractality of grain composition of debris flows

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

Received date: 2004-11-24

  Revised date: 2005-02-06

  Online published: 2005-09-25

Supported by

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


Debris flows in essence are the process of mass transportation controlled by the constitution featured by a wide-ranged distribution of grain size. Debris-flow samples of different densities collected from different regions and gullies reveal that cumulative curve of grain composition, in particular for debris flows of high density, ρs >2 g/cm3, can be fitted well by exponential function with exponents varying with regions and gullies. Debris flows fall into a narrow-valued domain of the exponent, as evidenced by Jiangjiagou Gully (JJG) with high occurrence frequency of debris flows. Furthermore, fractality of grain composition and porosity have been derived from cumulative curves in a certain size range, a range that determines the upper limit of grains constituting the matrix of debris flows. One can conclude that fractal structure of porosity plays crucial roles in soil fluidization that initiates debris flows, and debris flows occur at some range of fractal dimension, in coincidence with field observations.

Cite this article

LI Yong, CHEN Xiaoqing, HU Kaiheng, HE Shufen . Fractality of grain composition of debris flows[J]. Journal of Geographical Sciences, 2005 , 15(3) : 353 -359 . DOI: 10.1360/gs050309


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

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

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

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

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

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

[7] Fei Xiangjun, Shu Anping, 2004. Movement Mechanism and Disaster Control for Debris Flow. Beijing: Tsinghua University Press, 41-48. (in Chinese)

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

[9] Hampton M A, 1979. Buoyancy of debris flows. Journal of Sedimentary Petrology, 49(3): 753-0758.

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

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

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

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

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

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