从蒋家沟泥石流阵流看泥石流堆积

Surges and Deposits of Debris Flow in Jiangjia Gully

野外观测和实验证明,泥石流的堆积是经过无数随机的"元堆积"叠加形成的。"元堆积"保留了泥石流的活动特征。根据云南东川蒋家沟泥石流阵流资料和阵流的数值模拟,发现堆积厚度与阵流的深度和速度,在统计上是一致的,说明了堆积与运动之间的系统性联系。这种联系为泥石流活动的系统性和泥石流灾害的评估提供了新的线索。

Debris flow has been observed to start its deposition at the front of the surge, with consequent piling up in ways of randomness. The original deposition suggests a relationship to the initiation of the surge; the stopped surge in the semblance of flowing allows one to take up flowing surges to explore the deposition. In this paper, observations of debris-flow surges in Jiangjia Gully are amassed to make clear the statistical properties. Deposition thickness assumes distribution similar to that of the flow depth, in form of power law, with effect of finite size. On the other hand, numerical simulation of surge provides a micro-picture of deposition, showing that there is a statistical commonality in velocity, flow depth, and deposition thickness, especially, the coincidence of the most probable depth with the most probable velocity. Furthermore, statistics of data from a single simulation surge is the same as the statistics on surges composing an event of debris flow. In other words, a surge in an occurrence plays the role of a point in a surge, suggesting that surge is the composition unit of debris flow. This maybe opens our eyes to the systematic behavior of debris flow.