山区河流河床形态与水沙变化下的水位响应机理研究

发布时间：2018-04-23 18:48

本文选题：河床形态 + 泥沙补给　；参考：《工程科学与技术》2017年05期

【摘要】：山区流域暴雨山洪、滑坡、泥石流等灾害频发,大量泥沙以不同方式进入河道,河床形态在极短时间内迅速调整。在宽窄相间河段水流输沙能力差异较大,展宽段常因挟沙能力的降低而淤高河床,致使水位陡增,引发洪水灾害。为探讨山区河流宽窄相间河段与泥沙补给变化下的水位变化致灾机理,以室内物理模型系列试验结果为依据,分析不同流量定床清水时河床形态参数与各水力参数的变化关系,以及泥沙补给变化对河床形态及水流参数的影响。试验表明:上游泥沙补给量及河床形态是影响水流流态、水位变化的重要因素;定床清水条件下,河宽与比降的局部急剧调整影响水流参数变化,水流对河床变化的响应具有滞后性;当上游有泥沙补给时,水深变化较清水来流明显;随着来沙量的增大,大量泥沙淤堵河道且呈现溯源淤积的趋势,并淤高河床;在淤积段顶端,水流发生水跃现象,水位陡增,甚至出现漫滩致灾。由此可见,上游来沙及水流挟沙能力的降低将引起河床不同程度的落淤,造成河床形态改变,特别是在宽窄相间河段泥沙易落淤,水位增幅较大,为洪灾泛滥区,应作为水沙灾害的重点防治区域。
[Abstract]:Torrential torrential rain landslide debris flow and other disasters occur frequently in mountain basin. A large amount of sediment enters the river channel in different ways and the river bed shape is adjusted rapidly in a very short time. There is a great difference in sediment transport capacity between wide and narrow reach. The widening section often silts up the river bed because of the decrease of sediment carrying capacity, which results in a sudden increase of water level and causes flood disaster. In order to probe into the mechanism of water level change in mountainous rivers under the change of sediment supply and width, the variation relationship between river bed shape parameters and hydraulic parameters is analyzed according to the results of laboratory physical model series tests. And the influence of sediment recharge on the river bed shape and flow parameters. The results show that the upstream sediment supply and the river bed form are the important factors affecting the water flow and water level change, and the local sharp adjustment of the river width and specific drop affects the variation of the flow parameters under the condition of fixed bed clear water. The response of water flow to river bed change is lag; when there is sediment recharge upstream, the change of water depth is more obvious than that of clear water flow; with the increase of incoming sediment amount, a large amount of sediment silts the channel and shows a trend of tracing source siltation, and silting up the river bed. At the top of the silt section, the water jump, the water level increases sharply, and even the floodplain causes disaster. Thus, it can be seen that the decrease of upstream sediment and sediment carrying capacity of water flow will lead to the deposition of the river bed to varying degrees, which will result in the change of the river bed shape, especially in the broad-narrow reach where the sediment is liable to silt, and the water level increases greatly, which is the flood flood area. It should be regarded as the key area of prevention and control of water and sediment disasters.
【作者单位】：四川大学水力学与山区河流开发保护国家重点实验室水利水电学院;
【基金】：国家自然科学基金资助项目(51579163;51639007) 国家重点研发计划资助项目(2016YFC0402302)
【分类号】：P333.4;TV147

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