天然河道不连续宽级配床沙特性及形成条件探讨

选取我国有代表性的几个河段对不连续宽级配床沙特性及形成条件进行了初步探讨,为不连续宽级配床沙运动规律研究提供了基础。认为不连续宽级配床沙特性为:泥沙粒径范围很宽,某一粒径范围泥沙较少甚至缺失,床沙粒径重量百分数具有明显的双峰分布特征。不连续宽级配床沙形成的一般条件为:河床床沙本身具有一定的不均匀性,河床有一定的覆盖层厚度,上游具有补给性的来沙条件,河段水流速度具有一定的变化幅度。

Characteristics and Formation Conditions of Discontinuous Widely-Graded Sediment in Natural River Course

With three typical natural river courses in China as case study,we preliminarily discussed the characteristics and formation conditions of discontinuous widely-graded sediment,providing basis for researching discontinuous widely-graded bed load transport.It’s believed that the characteristics of discontinuous widely-graded sediment are as follows:the sediment particle size varies in a wide range;sediment of a certain size is in a small amount or even in absence;and the weight percent of bed sediment exhibits a clear bimodal distribution.The formation of discontinuous widely-graded sediment is based on three conditions:non-uniform bed sediments and thick riverbed cover,sediment supplies from the upstream,and varying flow velocity in the river course.