桃源枢纽坝下汇流区推移质运动特性试验研究

Experimental study on bed load movement characteristics in the downstream confluence area of Taoyuan junction

为分析桃源枢纽坝下汇流区推移质运动特性,采用整体定床物理模型开展了定床水流和定床输沙试验,观测各级流量下水流要素和输沙带分布。对比分析发现,随来流汇流比的不同,汇流区水动力条件复杂多变,但汇流区泥沙淤积体范围总是与主流带分布密切相关。推移质泥沙沿主流带输移,泥沙淤积体多见于输沙带边线处、流线转折较大处以及河床局部背水面下凹处。中枯水期因下泄水流流速较大,且沿程流速迅速降低,坝下推移质泥沙为短距离泥沙输移;洪水期因河段流速整体较大,为长距离泥沙输移。

In order to analyze the bed load movement characteristics in the confluence area under the Taoyuan junction,the fixed bed flow and sediment transport experiments were carried out by using the integral fixed bed physical model to observe the distribution of water flow elements and sand transport belts under different flow rates.It is found that the hydrodynamic conditions in the confluence area are complex and changeable with the different confluence ratio,however,the range of sediment deposition in the confluence area is always closely related to the distribution of the main flow area.The bed load sediment is transported along the main stream,and the sedimentation bodies are mostly found at the boundary line of the transport belt,the turning point of the streamline and the concave under the local back surface of the riverbed.In the middle and low water period,the sediment transport under the dam is short distance because the discharge flow velocity is large and the flow velocity decreases rapidly along the river.In the flood period,the sediment transport is long distance because the river velocity is large.