中文摘要：

在重力作用下，泥沙沿输送管道横截面的分布呈现上层稀疏下层浓密的特点。据此可将整个流动简化为具有不同平均速度和平均浓度的两层流动。以中沙在直径为150mm管道上的实测流动为例，用迭代方法确定了两层流动的分界面位置，结果表明两层流动模型能够刻画泥沙在管道巾流动的主要特征和内部结构。

英文摘要：

Under the action of gravity, the cross sectional distribution of sediment in the conveying pipelines shows that the sediment in the upper part of the pipelines is thin while the sediment in the lower part is dense and thick. As a result, the whole flow can be reduced to two levels of flow with different mean velocity and mean concentra tion. Taking the measured flow of medium sand in Ф150 mm pipelines as an example, the location of the interface between the two levels of flow is determined with the iteration method. The results show that the two-level flow model can depict the major features and internal structure of sediment flow in the pipelines.