宽级配泥沙分形特性及其输移规律试验研究

为了探寻宽级配泥沙粒度分形特性及其输移规律,通过水槽冲刷试验,分析了床沙和推移质的分形特征,并对不同床沙、不同流速条件下的泥沙粒度分维值进行了定量的计算和对比。结果表明:不论床沙还是推移质的级配都具有良好的统计自相似性,具有分形特征;级配是否连续对于粒度分维值的变化存在显著影响,床沙粗化后粒度分维值变小,且随着冲刷流速的增大,非连续级配时粒度分维值逐渐变小,而连续级配时粒度分维值逐渐变大。推移质粒度分维值与其所对应的中值粒径存在显著的负相关性。

Fractal Characteristics and Transport Law of Widely Graded Sediment Based on Fractal Theory

To explore the grain-size fractal characteristics and transport law of widely-graded sediment,we conducted erosion test in a flume to analyze the fractal characteristics of bed material and bed load.Besides,we performed quantitative calculation and comparison of the granularity fractal dimensions of sediment in different bed materials and different flow velocities.Results showed that: the grain-size distribution in both bed material and bed load were of obvious statistical self-similarity,which meant that fractal characteristics existed.We also found that the variation of granularity fractal dimension was closely related to the sediment gradation.The value of granularity fractal dimension would decrease in the presence of stable roughened bed material.Furthermore,with the increase of flow velocity,the granularity fractal dimension would increase for continuous grading bed material,while decrease for discontinuous grading bed material.The value of granularity fractal dimension of bed load had an obvious negative correlation with its corresponding median diameter.