Relationship between grain composition and debris flow characteristics: a case study of the Jiangjia Gully in China
Relationship between grain composition and debris flow characteristics: a case study of the Jiangjia Gully in China
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DOI：
10.1007/s10346-014-0475-z
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发表时间：
2015-02
期刊：
影响因子：
6.7
通讯作者：
Yong Li;Jingjing Liu;F. Su;Jiang Xie;Bao-Jian Wang
中科院分区：
文献类型：
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作者：
Yong Li;Jingjing Liu;F. Su;Jiang Xie;Bao-Jian Wang
蒋家沟泥石流发生频繁，平均每年发生10次，且表现出多种多样的性质。结果表明，泥石流物质满足P（D）=CD−μexp（−D/Dc）的通用粒度分布，且参数μ和D与泥石流的密度、流速和流量等动力学性质密切相关。μ小意味着孔隙度小，流动中可能存在高的超孔隙压力，反映了高的流动性和运输能力，而Dc大意味着颗粒成分范围广，因此颗粒浓度高。泥石流总是达到一定的运动性和密度状态，μ和Dc可以很好地描述这种状态，并且这些参数对泥石流涌浪的波动具有幂律约束。单位宽度流量的上限估计为Qu = 1.25Dc1.12。GSD参数的变化也描述了泥石流与河床沉积物之间的物质交换。当颗粒成分存在显著差异时，会发生强烈的切割或沉积。由于GSD具有普遍的适用性，因此JJG模型的计算结果也可应用于其它条件下潜在泥石流的特性和洪峰流量的评价。
Debris flow occurs frequently (ten events on average per year) and displays a great variety of properties in the Jiangjia Gully (JJG) in southwest China. We find that the material of debris flow satisfies a universal grain size distribution (GSD) ofP(D) =CD−μexp(−D/Dc), and the parametersμandDcare closely related to the dynamical properties such as flow density, velocity, and discharge. A smallμimplies a small porosity and possible high excess pore pressure in flow, reflecting high mobility and capacity of transportation, and a largeDcmeans a wide range of grain composition and hence a high grain concentration. A debris flow always achieves a state of certain mobility and density that can be well described byμandDc, and the parameters impose power law constraints on the fluctuations of debris flow surges. An upper limit of unit-width discharge is estimated asQu= 1.25Dc1.12. Variation of GSD parameters also describes material exchanges between debris flow and streambed sediment. Intense incision or deposition occurs when remarkable difference of grain composition exists. As the GSD is satisfied universally, the results derived from JJG are expected to be applicable for evaluating the properties and peak discharge of a potential debris flow in other conditions.