山区河流航道整治线宽度的确定及稳定性分析

发布时间：2018-09-01 06:56

【摘要】：整治线宽度是浅滩整治工程设计中的重要参数，它决定了整治河段的断面形态，直接影响到整治工程的质量和工程量。枢纽的兴建拦截了上游大量来沙，加之对径流过程的调节，改变了枢纽下游河流的水沙条件，破坏了枢纽下游河流的平衡状态，触发其再造床过程，给枢纽下游河流功能的发挥带来了一定的影响。在长期的低含沙水流作用下，河床将发生不同程度的冲刷下切或河岸展宽以及河型转化等现象，从而影响河道的水流条件，进而影响到航运、防洪、取水和生态等多方面的人类活动。因此，只有在对河流水沙输移规律及其河床演变特性深入了解的基础上，才能进一步完善适用于枢纽坝下不同浅滩、不同冲淤规律的航道整治线宽度公式，规划治理出朝良性循环方向发展的优良航道。本文主要针对枢纽坝下浅滩河段整治的特点，采用理论分析结合数值模拟等方法，取得了以下成果：（1）简单分析了枢纽运行之后，水沙条件及河床演变规律的改变与航道整治设计之间的关系，回顾了航道整治线宽度确定方法、水流挟沙力、河道阻力规律、泥沙输移规律及泥沙数学模型的研究现状，突出了整治线宽度的确定方法是解决水沙条件变化后枢纽坝下河段浅段整治的关键所在。（2）考虑到来水来沙条件中泥沙粒径的影响，引入中值粒径，结合平滩河宽、平均水深、平均流速以及河床比降等因素提出了坝下河段航道整治线宽度确定的改进方法，并采用国内外多条河流的野外实测资料，确定了该整治线宽度公式的参数，，验证了其精度高于流量-比降公式及水力学公式。（3）以白石窑枢纽坝下河段的航道整治工程为依据，采用本文推导的整治线宽度公式确定了该研究河段的整治参数。在此基础上拟定了整治方案，建立了枢纽坝下河段平面二维水沙数学模型，对工程前后航道的稳定性进行了对比分析，结果表明研究河段枯水期水位降落明显，流速略有增加，有利于减少泥沙淤积，维持挖槽稳定。（4）采用少水年、中水年及丰水年三个典型年的水沙资料对此河段的泥沙冲淤变化规律进行研究，结果表明该河段总体输沙能力有限，枢纽坝下~观音岩河段冲刷较为严重，观音岩以下河段受飞来峡水库回水影响，流速减缓，输沙能力减弱，河床以淤积为主，且呈累积性淤积态势。最后，通过数学模型与物理模型试验结果的对比分析，发现各浅滩的淤积量、浅滩长度及最小航宽相差不大，进一步说明了本文提出的整治线宽度改进方法具有较好的可行性，能为工程提供参考。
[Abstract]:The width of the regulation line is an important parameter in the design of the shoal regulation project. It determines the section shape of the regulation river reach and directly affects the quality and quantity of the regulation project. The construction of the hub intercepts a large amount of upstream sediment, in addition to the regulation of the runoff process, which changes the water and sediment conditions of the downstream rivers, destroys the balance of the downstream rivers, and triggers the process of reconstructing the bed. It has brought certain influence to the function of downstream river. Under the action of low sediment flow for a long time, the river bed will be scoured and cut, river bank widened and river type transformed in varying degrees, thus affecting the flow conditions of the river, and then affecting the navigation, flood control, etc. Water and ecology and other aspects of human activities. Therefore, only on the basis of deep understanding of the water and sediment transport law and the evolution characteristics of river bed, can we further improve the width formula of channel regulation line suitable for different shoals and different erosion and siltation laws under the dam. Planning to govern the direction of benign cycle development of the good waterway. In this paper, according to the characteristics of the regulation of the shoal reach under the hub dam, theoretical analysis combined with numerical simulation is used to obtain the following results: (1) after the operation of the hub, The relationship between the change of water and sediment conditions and the evolution law of river bed and the design of channel regulation is reviewed. The current research status of channel regulation line width determination method, flow sediment carrying capacity, channel resistance law, sediment transport law and sediment mathematical model are reviewed. The method of determining the width of the regulation line is the key to the regulation of the shallow reach under the dam after the change of the water and sediment conditions. (2) considering the influence of the sediment particle size in the condition of incoming water and sediment, the median particle size is introduced, combined with the width of the Pingtan River. An improved method for determining the width of channel regulation line under the dam is put forward by the factors of average water depth, average velocity and river bed ratio drop, and the parameters of the regulation line width formula are determined by using the field measured data of many rivers at home and abroad. The accuracy is higher than the flow-ratio drop formula and the hydraulic formula. (3) based on the waterway regulation project under the Baishiyao Dam, the regulation parameters of the studied reach are determined by using the regulation line width formula derived in this paper. On the basis of this, the regulation scheme is drawn up, a two-dimensional mathematical model of water and sediment is established, and the stability of the channel before and after the project is compared and analyzed. The results show that the water level of the river reaches drops obviously and the velocity of velocity increases slightly during the dry period of the river reach. It is beneficial to reduce sediment deposition and maintain the stability of dredging channel. (4) using the water and sediment data of three typical years of less water year, middle water year and high water year to study the regularity of sediment scouring and silting in this reach. The results show that the overall sediment transport capacity of the reach is limited, and the erosion of the section under the hinge dam to the Guanyin Yan reach is more serious. The flow velocity of the section below Guanyin Rock is affected by the backwater of Feilaixia Reservoir, and the sediment transport capacity is weakened, and the river bed is mainly silted. And the accumulative siltation trend. Finally, by comparing and analyzing the results of mathematical model and physical model test, it is found that the siltation amount, shoal length and minimum navigation width of each shoal have little difference, which further shows that the improved method of improving the width of regulation line proposed in this paper has good feasibility. It can provide reference for engineering.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U617

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