三峡变动回水区末端推移质输移带分布特性试验研究
发布时间：2018-08-30 17:45
【摘要】：三峡水库变动回水末端段河床主要组成物质为卵砾石,重庆主城河段是典型的山区河流弯曲河段,在主城范围内有5个连续弯道。河床质主要是卵石夹砂,河床边界稳定。其碍航特征表现为弯、浅、险。水流、泥沙的共同作用对河床演变的影响较大,卵石滩险的形成机理比较复杂。长江上游泥沙淤积主要是卵石推移质在起作用,卵石推移质的输移带在消落期可能造成碍航。所以在三峡变动回水区末端段的航道治理关键技术中卵石推移质输移带的宽度和位置的变化显得尤其重要。本文通过建立1:70的正态物理河工模型辅以数学模型对三峡变动回水区末端段各典型流量下的水流形态,推移质输移强度,推移质输移带位置和宽度等特性进行试验研究。得出变动回水区末端段各典型滩段的流场,推移质输移带位置的变化,区分动沙输移带和淤积输移带的不同强度的推移质输移方式。对结果进行大量的统计分析,建立了各滩段推移质的不同输移方式在各级流量下输移带强弱分布与流速、水深、比降的变化特性。最后统一成推移质输移带强弱分布与水流强度指标水流功率无量纲数*W的变化关系。试验结果:三峡变动回水区末端段各滩险典型流量下的水流流态分析,推移质输移带在各滩险的分布特性。输移带上*W的变化特性总结为动沙输移带的水流功率普遍比淤积输移带的*W值大,可以判断动沙输移强度要大于淤积输移强度,在枯水期和中水期,输移带*W明显要比无输移带*W值大。洪水期开始,水面比降下降,输移带*W平均值减小。各输移带*W值到大洪水期变化区域稳定。结论:动沙输移带的*W值较淤积输移带的*W值偏大,说明推移质动沙输移带是最强输移方式,淤积输移次之。中水期输移带的*W平均值大约是枯水期*W平均值的2-2.5倍左右,由此可见,在消落期可能出现推移质输移强度减弱造成碍航。洪水期开始,由于水面比降减小的原因,输移带的*W值减小,输移强度减弱,表明在三峡变动回水区末端会出现蓄水期、汛期淤积,汛末消落期冲刷的推移质输沙特性。对于三峡变动回水区末端段推移质的分布特性进行了总结,区分了不同的推移质输移强度,对流态进行了数值模拟,分析了推移质输移带强弱分布与水流强度指标的变化关系。在一定程度上,进一步推动了何种水流强度指标更适用于在三峡变动回水区表示泥沙输移强度的变化。
[Abstract]:The main composition of the river bed in the end of the variable backwater of the three Gorges Reservoir is gravel. The main city of Chongqing is a typical mountain river bend, and there are five continuous bends within the main city. Bed quality is mainly gravel sand, the riverbed boundary is stable. Its obstacle to navigation is characterized by bend, shallowness and danger. The interaction of flow and sediment has a great influence on the evolution of river bed, and the formation mechanism of pebble beach is complex. The sediment deposition in the upper reaches of the Yangtze River is mainly caused by pebble bedload, and the transport zone of pebble bed load may hinder navigation during the falling period. So it is very important to change the width and position of pebble bed load transport zone in the key technology of channel management in the end of the three Gorges variable backwater area. In this paper, the normal physical river engineering model of 1:70 is established, and the characteristics of flow pattern, bed load transport intensity, position and width of bed load transport zone at the end of the three Gorges variable backwater area are studied by means of mathematical model. The flow field and the change of bed load transport zone location in each typical beach section in the end of the variable backwater area are obtained, and the bed load transport modes with different intensity are distinguished between the moving sediment transport zone and the silting transport zone. A great deal of statistical analysis was carried out on the results, and the variation characteristics of the intensity and the velocity, the water depth and the specific drop of the transport zone were established for different transport modes of bed load at different levels of discharge. Finally, the relationship between the intensity distribution of bed load transport zone and the dimensionless power of water flow is unified. The experimental results show that the distribution of bed load transport zone in each beach danger is analyzed under the typical flow at the end of the three Gorges variable backwater area. The variation characteristics of W in the transport belt are summarized as follows: the flow power in the moving sediment transport zone is generally higher than the W value in the silt transport zone, which can be used to judge that the moving sediment transport intensity is greater than the silt transport intensity, and in the dry and middle water periods, The W value of the transport zone is obviously higher than that of the non-transport zone. At the beginning of flood period, the water surface specific drop decreases and the mean value of W in the transport zone decreases. The variation region of W value of each transport belt is stable to the flood period. Conclusion: the W value of the moving sediment transport zone is higher than that of the silt transport zone, which indicates that the bed load moving sediment transport zone is the strongest transport mode, and the silt transport is the second. The average value of W in the transport zone in mid-water period is about 2-2.5 times of that in dry season, so it can be seen that the weakening of bed load transport intensity may result in hindrance to navigation during the period of decline. At the beginning of flood period, due to the decrease of water surface specific drop, the W value of the transport belt decreases and the transport intensity weakens, which indicates that the bed load transport and sediment transport characteristics will occur at the end of the three Gorges variable backwater area during the storage period, the deposition in the flood season and the erosion at the end of the flood period. The characteristics of bed load distribution at the end of the three Gorges variable backwater area are summarized, different bed load transport intensity is distinguished, the convection state is numerically simulated, and the relationship between the intensity distribution of bed load transport zone and the flow intensity index is analyzed. To a certain extent, which water intensity index is more suitable for the variation of sediment transport intensity in the three Gorges variable backwater area.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV142.2
本文编号：2213808
[Abstract]:The main composition of the river bed in the end of the variable backwater of the three Gorges Reservoir is gravel. The main city of Chongqing is a typical mountain river bend, and there are five continuous bends within the main city. Bed quality is mainly gravel sand, the riverbed boundary is stable. Its obstacle to navigation is characterized by bend, shallowness and danger. The interaction of flow and sediment has a great influence on the evolution of river bed, and the formation mechanism of pebble beach is complex. The sediment deposition in the upper reaches of the Yangtze River is mainly caused by pebble bedload, and the transport zone of pebble bed load may hinder navigation during the falling period. So it is very important to change the width and position of pebble bed load transport zone in the key technology of channel management in the end of the three Gorges variable backwater area. In this paper, the normal physical river engineering model of 1:70 is established, and the characteristics of flow pattern, bed load transport intensity, position and width of bed load transport zone at the end of the three Gorges variable backwater area are studied by means of mathematical model. The flow field and the change of bed load transport zone location in each typical beach section in the end of the variable backwater area are obtained, and the bed load transport modes with different intensity are distinguished between the moving sediment transport zone and the silting transport zone. A great deal of statistical analysis was carried out on the results, and the variation characteristics of the intensity and the velocity, the water depth and the specific drop of the transport zone were established for different transport modes of bed load at different levels of discharge. Finally, the relationship between the intensity distribution of bed load transport zone and the dimensionless power of water flow is unified. The experimental results show that the distribution of bed load transport zone in each beach danger is analyzed under the typical flow at the end of the three Gorges variable backwater area. The variation characteristics of W in the transport belt are summarized as follows: the flow power in the moving sediment transport zone is generally higher than the W value in the silt transport zone, which can be used to judge that the moving sediment transport intensity is greater than the silt transport intensity, and in the dry and middle water periods, The W value of the transport zone is obviously higher than that of the non-transport zone. At the beginning of flood period, the water surface specific drop decreases and the mean value of W in the transport zone decreases. The variation region of W value of each transport belt is stable to the flood period. Conclusion: the W value of the moving sediment transport zone is higher than that of the silt transport zone, which indicates that the bed load moving sediment transport zone is the strongest transport mode, and the silt transport is the second. The average value of W in the transport zone in mid-water period is about 2-2.5 times of that in dry season, so it can be seen that the weakening of bed load transport intensity may result in hindrance to navigation during the period of decline. At the beginning of flood period, due to the decrease of water surface specific drop, the W value of the transport belt decreases and the transport intensity weakens, which indicates that the bed load transport and sediment transport characteristics will occur at the end of the three Gorges variable backwater area during the storage period, the deposition in the flood season and the erosion at the end of the flood period. The characteristics of bed load distribution at the end of the three Gorges variable backwater area are summarized, different bed load transport intensity is distinguished, the convection state is numerically simulated, and the relationship between the intensity distribution of bed load transport zone and the flow intensity index is analyzed. To a certain extent, which water intensity index is more suitable for the variation of sediment transport intensity in the three Gorges variable backwater area.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV142.2
【参考文献】
相关期刊论文 前2条
1 杨克君;黄尔;刘艺平;;全动床复式河槽水流阻力特性的试验研究[J];四川大学学报(工程科学版);2007年06期
2 窦国仁;;全沙模型相似律及设计实例[J];水利水运科技情报;1977年03期
相关会议论文 前1条
1 刘德春;陈新益;;三峡入库推移质输沙特性变化及其原因[A];中国水力发电工程学会水文泥沙专业委员会第四届学术讨论会论文集[C];2003年
相关硕士学位论文 前1条
1 胡小庆;金沙江大雪滩群航道整治技术研究[D];重庆交通大学;2010年
，本文编号：2213808
本文链接：https://www.wllwen.com/kejilunwen/shuiwenshuili/2213808.html
