地理学报 ›› 2005, Vol. 60 ›› Issue (3): 495-502.doi: 10.11821/xb200503016

• 泥沙研究 • 上一篇    下一篇

泥石流颗粒组成的分形特征

李泳, 陈晓清, 胡凯衡, 何淑芬   

  1. 中国科学院、水利部成都山地灾害与环境研究所, 成都 610041
  • 收稿日期:2004-10-28 修回日期:2005-02-18 出版日期:2005-05-25 发布日期:2010-09-09
  • 作者简介:李泳 (1967-), 男, 副研, 当前的主要兴趣在泥石流的系统动力学方面。E-mail: ylie@imde.ac.cn
  • 基金资助:

    国家自然科学基金项目 (40101001); 国家杰出青年科学基金项目 (40025103)

Fractality of Grain Composition of Debris Flows

LI Yong, CHEN Xiaoqing, HU Kaiheng, HE Shufen   

  1. Institute of Mountain Hazards and Environment, CAS & Ministry of Water Conservancy, Chengdu 610041, China
  • Received:2004-10-28 Revised:2005-02-18 Online:2005-05-25 Published:2010-09-09
  • Supported by:

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

摘要:

泥石流是主动的流域物质输移形式, 土体的颗粒组成决定了泥石流的活动。不同地区、不同流域、不同密度的泥石流样本分析表明, 高密度 (ρs > 2 g/cm3) 泥石流的颗粒分布曲线总体上具有指数形式, 指数呈现出显著的区域性差异。泥石流多发生在一定的指数区间;颗粒组成具有良好的分形特征, 不同密度泥石流颗粒的分形区间不同, 这个区间可以认为是形成泥石流结构的颗粒区间, 从而也确定了泥石流基质的颗粒界限;颗粒的分维随密度变化, 密度越大 (大颗粒含量越多), 分维越大。颗粒的分形结构也是颗粒孔隙的分形结构, 它决定了土体的液化, 因而也决定了泥石流所表现的特征。

关键词: 泥石流, 颗粒分布, 分形

Abstract:

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.

Key words: debris flow, grain composition, fractality