清水冲刷下非均匀卵石床面粗化过程及分选模式

Sorting of non-uniform bedload in clear water scouring

在一定的水流条件下,滚动是卵石河床上推移质的主要运动形式,由于不同粒径颗粒的移动距离不同,床面泥沙将发生分选输移,最终形成以不动粗颗粒为主体的粗化稳定结构。本文主要研究清水冲刷条件下非均匀卵石床面粗化过程及分选模式。通过引入滚动力学模型,运用数值计算方法计算了不同情况下滚动颗粒的运动轨迹,构建了非均匀卵石床面经清水冲刷后的级配计算模式,并通过一个实际算例计算出了不同时刻不同河床段经冲刷后的级配变化过程以及冲刷稳定后的级配曲线。本文的理论成果适用于卵石的滚动运动,为研究卵石河床的分选过程提供了一种理论计算方法。

Generally, rolling is the primary form of bedload movement on pebble riverbeds under certain flow conditions. Due to different moving distances of the particles with different sizes on a bed surface, sorted sediment transport will occur, forming a stable structure with coarse particles as the main body of the bed. This work focused on a study of the coarsening process of non-uniform pebble beds during clear water scouring and the sorting modes that were stably formed after scouring. Based on a roiling mechanics model, tracking of the rolling particle movement under different conditions was numerically calculated; a gradation calculation model of stable non-uniform pebble beds washed by clear water was developed. This model was used in a practical example to calculate variations in bedload gradation and gradation curves at different time for different river sections. The theoretical results presented in this paper are applicable to rolling movement of pebbles and provide a theoretical method for further studies of pebble bed sorting.