Influence of fine sediment on the fluidity of debris flows
Influence of fine sediment on the fluidity of debris flows
复制标题
细粒泥沙对泥石流流动性的影响
DOI：
10.1007/s11629-013-2522-y
复制
发表时间：
2013
影响因子：
2.5
通讯作者：
Haruo Nishimoto
中科院分区：
文献类型：
--
作者：
N. Hotta;Takahiro Kaneko;T. Iwata;Haruo Nishimoto
摘要泥石流是一种具有反级配、颗粒分离和细颗粒液化等内在特征的颗粒类型。细颗粒泥沙液化对泥石流的流动性有一定的影响，但细颗粒泥沙在泥石流中的行为和影响还没有得到充分的研究。本研究利用水槽实验，探讨细颗粒泥沙对实验室泥石流流动性的影响，实验室泥石流由不同粒径的颗粒组成。从实验中，最大的泥沙浓度和流深观察到的泥石流与细泥沙混合，表明增加流动阻力。通过将实验值代入泥石流本构方程，将实验摩擦系数与理论摩擦系数进行了比较。理论摩擦系数是从两个模型与不同的细沉积物处理：假设所有的细沉积物是固体颗粒或颗粒组成的流体相，涉及孔隙水液化。从摩擦系数的比较，一个完全液化状态检测到的细颗粒混合物。当细颗粒泥沙的混合比和粒径不同时，其他情况下被认为是处于部分液化的过渡状态。这些结果表明，泥石流中细颗粒泥沙的液化不仅受粒径等几何条件的影响，而且受水流条件的影响。
Debris flows include a great diversity of grain sizes with inherent features such as inverse grading, particle size segregation, and liquefaction of fine sediment. The liquefaction of fine sediment affects the fluidity of debris flows, although the behavior and influence of fine sediment in debris flows have not been examined sufficiently. This study used flume tests to detect the effect of fine sediment on the fluidity of laboratory debris flows consisting of particles with various diameters. From the experiments, the greatest sediment concentration and flow depth were observed in the debris flows mixed with fine sediment indicating increased flow resistance. The experimental friction coefficient was then compared with the theoretical friction coefficient derived by substituting the experimental values into the constitutive equations for debris flow. The theoretical friction coefficient was obtained from two models with different fine-sediment treatments: assuming that all of the fine sediments were solid particles or that the particles consisted of a fluid phase involving pore water liquefaction. From the comparison of the friction coefficients, a fully liquefaction state was detected for the fine particle mixture. When the mixing ratio and particle size of the fine sediment were different, some other cases were considered to be in a partially liquefied transition state. These results imply that the liquefaction of fine sediment in debris flows was induced not only by the geometric conditions such as particle sizes, but also by the flow conditions.