稀性泥石流的平均运动速度研究

Study on Mean Velocity of Thin Viscous Debris Flows

泥石流的运动速度是泥石流动力学研究中最重要的参数。稀性泥石流是常见也是危害较大的泥石流类型,准确而简洁地计算稀性泥石流的运动速度非常重要。现有的稀性泥石流平均速度经验公式,在使用上和适用地区上还存在一些问题。本文通过分析一系列稀性泥石流观测资料中的体积浓度与稀性泥石流的运动速度和阻力特征的关系,得出了一个新的计算稀性泥石流平均运动速度的经验公式,该公式能适应各种类型的泥石流沟,适用于一般急流的稀性泥石流;对于缓流稀性泥石流,计算值与观测值相比偏大,但很接近;不适用于缓慢稀性泥石流。本文提出的经验公式,使用简洁,计算稳定,与其他方法计算的稀性泥石流平均运动速度很接近。该速度计算经验公式也适用于稀性泥石流堆积扇上游沟道,但对于堆积扇上的速度,计算值偏大,且越往堆积扇的下游,偏差越大。

Thin viscous debris flows are common and dangerous, and their mean velocities are the most important one of their dynamic parameters. It is very important to be able to simply and accurately calculate the mean velocity of thin viscous debris flows. There are still some problems in application of the empirical formulas currently available for the mean velocity of thin viscous debris flows. Based on analysis of the relation of the volume concentration vesus velocity and resistance of the thin viscous debris flows from a series of field observation data, an empirical formula has been proposed to calculate the mean velocity of the thin viscous debris flows. The empirical formula is applicable to various types of flow gullies, and general rapid thin viscous debris flows; but not slow ones because the calculated velocities are larger than the observed ones. The formula is simple and stable in practical calculation, and its results are very close to those obtained with other methods. It is also applicable to the thin viscous debris flow upstream the piled fan; but the calculated velocity of the piled fan is larger than the real one; the further down stream the piled fan is the location, the larger the velocity difference is.