【作者】 王秀英；

【导师】 李义天；

【作者基本信息】 武汉大学 ， 水力学及河流动力学， 2006， 博士

【摘要】 欧美国家航道治理的经验教训表明,强制性的整治并不能从根本上改变河床固有的演变特性,对河流的自然属性干预过大必然会带来更为严重的问题。充分考虑水沙条件与河床演变规律,利用河流自身特点,通过较少的工程措施,引导其向有利于通航条件改善的方向发展是更为科学的航道整治思路。这就要求作为浅滩整治工程基础的参数设计能够反映河段演变特性、浅滩冲淤规律及航道条件要求,并方便使用。而且水库下游河床处于非平衡调整过程中,浅滩演变规律会发生一定变化,航道条件也会随之出现许多新问题,部分河段甚至可能恶化。因此,水库下游非平衡条件下的整治参数更需要以能够准确反映工程作用的方法为基础,结合水库修建前后的差异分析确定。保证航道整治工程符合河床演变的一般规律,同时又能解决具体河段的特殊问题一直是整治参数确定的重点和要求。然而,目前枯水浅滩航道整治设计参数与河床演变规律之间关系的研究多是针对具体整治河段展开,综合性研究成果进展较为缓慢。虽然参数确定方法逐渐发展,但各方法之间的相互关系及其理论基础仍然不够完善,以至于不同方法确定的结果相差较大,更有些复杂河段无法应用。本文对航道整治设计理论及参数确定方法进行了系统分析和改进,综合考虑河床演变规律与航道整治工程作用,以浅滩碍航淤积量为结点,将产生淤积的水沙过程、河床冲淤、浅滩演变与消除碍航影响的通航设计水位、整治参数、整治建筑物联系到一起,力图概化影响因子,选取典型变量改进参数确定方法,使其能够反映水沙特性、浅滩类型、演变规律及航道等级。如此即便在水库下游非平衡条件下,通过合理选择变量值,仍能够适用,进而保证了水库修建前后工程设计的一致性。研究特色在于将河流动力学及河床演变研究成果与航道工程理论相结合,从基本概念层面完善整治参数理论体系,探讨各确定方法的理论支持与不足;通过分析不同类型浅滩演变规律及参数确定影响因素,提出整治工程保证率概念,并与能够反映浅滩碍航特性及航道等级的碍航淤积量、有效冲刷时间共同引入整治线宽度确定方法,给出了不同类型浅滩整治线宽度确定公式和河流动力学统一公式。论文结合长江中下游航道整治实例,分析了应用中存在的问题,采用改进公式进行试算,取得了较好效果,对进一步开展理论研究和工程技术运用研究都具有重要参考价值。全文主要讨论了以下几个方面的问题:(1)通过分析水沙条件及河床冲淤变化与航道整治工程设计的关系阐明航道整治设计理论有待健全和完善,提出以河床演变基本规律为指导,体现具体河段浅滩碍航特性的航道设计、整治参数确定方法是水沙条件变化前后航道整治发展的必然要求。(2)归纳总结了平衡状态下河流水沙输移、河床冲淤变化的一般特性,在此基础上对比分析了非平衡条件下水沙变化情况及其下游河道在输沙、河床冲淤等方面的响应;从航道治理角度分析浅滩类型及其演变规律,并总结了水库下游浅滩演变特点,以便于提取反映浅滩碍航特性的变量,为进一步航道整治设计提供理论支持。(3)对现有确定设计最低通航水位的方法进行了总结,重点分析了综合历时曲线法和保证率频率法在保证率取法、计算差值比较及数学表述等方面的区别,获得了取得一致性结论的途径。采用综合历时曲线法校核计算长江中下游重点水文站设计水位,并与保证率频率法计算结果进行了比较,分析结果表明各水文站设计水位在过去二十年内有明显的升降变化。将原有设计水位的概念延伸至非平衡河流河床冲淤变化过程中,提出了以水库调度和下游河段一维数学模型计算为基础的建库后设计水位变化线确定方法,以三峡水库蓄水后下游河段为例,分析了不同蓄水阶段设计水位的主要影响因素、影响过程及变化程度,计算了各站不同时段设计水位,构成非平衡河流设计水位变化线。保证率概念在设计水位确定中使用,实际上它可以贯穿整个航道整治工程设计,包括整治线布置、整治水位、整治线宽度。依据一定保证率确定工程所针对的条件,可起到简化水沙过程,反应工程对河床改变程度的作用。(4)以总体河势控制为前提,分析航道整治参数的基本问题;从航道整治工程特点出发,将其基本概念与河流动力学概念进行区分;总结整治参数影响因素及整治工程分类;与以往认识不同,指出整治线布置是整治水位、整治线宽度确定的基础,航道等级相同时,不同整治线布置方案对应不同碍航淤积量、浅滩冲刷时段,进而有不同整治水位和整治线宽度。总结分析了不同类型浅滩整治线布置原则,引进环流消失理论获得整治线型理论公式用以确定过渡段长度,在长江中游河段取得较好效果。(5)对现有沙质河床枯水整治水位确定方法进行了总结,分析各种方法的适用条件、可对比性;以长江中下游整治工程经验为基础,指出已有方法确定整治水位中存在的不足,依据整治参数影响因素总结了较为适用的方法;分析非平衡条件下整治水位确定方法,提出了在水位变化过程中利用水库下泄流量分级特点,采取两极整治策略,随着河床冲淤发展确定整治水位变化线的方法。(6)在系统分析现有整治线宽度确定方法的基础上,将其归纳为三种模式,剖析了各自的理论支持,针对顺直河段、分汊河段、弯曲河段浅滩整治前后断面冲淤关系,将浅滩演变特征量:碍航淤积量、有效冲刷时间、整治保证率引入整治线宽度确定公式,提出了分别适用于守护型和调整型不同河段的整治线宽度河流动力学方法计算公式,并以碾子湾水道、陆溪口水道及武桥水道为例确定整治线宽度;将非平衡条件下碍航淤积量分解为水沙波动引起和河床单向冲淤引起两部分,根据非平衡河床发展阶段分别确定,从而获得整治线宽度变化线,依据一定保证率,综合确定整治线宽度。(7)以守护型和调整型航道整治工程为标准对主要航道整治建筑物进行了分类讨论,分析了建筑物布置方法、结构形式、主要作用。更多还原

【Abstract】 Occidental experiences in navigable channel improvement history show that compulsive regularization can not change the inherent evolution characteristic of river bed fundamentally. Excessive interference in river natural attribute will bring serious problems inevitably. The more scientific means of channel regulation is that with to consider flow & sediment process and river bed evolution rules, building few projects assisted river characteristic with guiding it to improve navigable conditions.So it is necessary for regulation parameters calculation, as the basic of shoal regulation project, to reflect river evolution characteristic, scour and aggradations rule of shoal and navigable channel grade, and to use expediently. Furthermore, the river bed downstream dam is in a disequilibrium process to adapt variance of flow & sediment. Shoal evolution rules will have some changes and bring navigation conditions more new problems. Even some reaches are going to be worst. Therefore, the disequilibrium conditions downstream dams request the means of calculating regulation parameters more strictly.The key points of determining channel regulation parameters are to be assured that regulation works conform to the common rules, and at the same time to solve special problems of the reach. But now many researches on the relationship between the regulation design parameters of shoal in dry season and river bed evaluation rules aim at certain local reach. So there is lack of comprehensive results. Though the methods of determining regulation parameters develop gradually, their pertinences and rationales are still unconsummated. As a result, the outcomes of different methods are six to one. Even they are unable to apply in some complex sections.This paper analyzes the channel regulation theory and improves the determination methods of the channel regulation and design parameters. Considering river bed evolution rules and functions of regulation projects, the researches in this paper try to connect the flow & sediment process, the changes of riverbed, shoal evolution, which are the reasons to cause aggradations, with the design water level, regulation parameters, regulating structure, which can eliminate sediment on shoal. The influence factors can be simplified so that the typical variables are introduced into the method of regulation parameters calculation. So the improvement method can reflect the characteristic of flow & sediment, shoal type, evaluation rules and navigation grade. Even if the regulated reach was under the disequilibrium condition downstream dams, the method still would be suitable by choosing reasonable variable values.Main work in this paper can be divided into four parts: firstly, finding the linkage between the results of the river dynamics & river bed evolution research and the channel regulation theory in order to consummate the theory system of regulation parameters from the basic concepts; secondly, discussing the theory support and the insufficiency of each determination method; thirdly, proposing the guarantee rate concept of regulation works through analyzing evolution rules of different type of shoal and the influence factors of parameters determination, and putting the guarantee rate, channel obstructive quantity and effective scouring time, which can reflect shoal characteristic and channel navigation grade, into the method to computer the regulation parameters; fourthly, establishing the regulation width formula for different type shoal and the rivers dynamics unified formula. Most work is with the background of the middle and lower reaches of the Yangtze River, and application of the new method shows that the rebuilding formula could be applied to calculate the regulation width of complex reaches. Some key issues are shown as following.(1) The relationship among Flow & sediment process, riverbed evaluation and regulation works design indicates that the revision and supplement to the design theory is needed. It is necessary for the development of channel regulation that the methods to compute the design parameter and the regulation parameters should be able to reflect the channel obstructed characteristic and river evaluation rules.(2) The general characteristics of flow & sediment transport and river bed evaluation under the equilibrium condition are clarified. As contrast, the changes of flow & sediment process and river bed evaluation are analyzed under the disequilibrium condition. From the angle of convenience use in channel regulation, shoal types and their evolution rules are analyzed. In those foundations, shoal evaluation specialties downstream dams are summarized. It is useful to propose the variables into formula improvement.(3) In the paper, a description of the methods of calculating design lowest navigable water level is given. The differences between guaranteed rate method and guaranteed rate–frequency method on the fundamental concept of guaranteed rate and the calculated result are carried out. According to the theoretical expression forms of the two methods, the new ways to get uniform results are proposed. This paper calculates the design water levels of some hydrometric stations in the middle and lower reach of the Yangtze River by the guaranteed rate method and compares them with the results of the guaranteed rate–frequency method. Those results show that the design water levels have changed in the past twenty years. With extending the concept of design water level from the equilibrium river into the disequilibrium river, the design water level line method is proposed on the basis of the flood routing through reservoir and one dimension numerical model downstream dams. As an example, the design water level change line is figured out downstream of the TGP (Three George Project) and the reasons are analyzed.The concept of guaranteed rate is used in the design water level, but in fact, it runs through the whole process of regulation works design, including regulation line, regulation water level and regulation widths. Flow & sediment process can be simplified by choosing some guaranteed rate, which indicates the interaction between regulation works and river bed. (4) With river control as precondition, the paper analyzes the basic problems on channel regulation parameters. Starting from the specialties of regulation works, we differentiate its concept from river dynamics and outline the factors effecting on regulation parameters and the types of regulation works. Different from absent knowledge, it is elucidated that the design of regulation line is the basis of regulation width and regulation water level and that different design has different channel obstructive quantity and shoal scour time, so that there is dissimilar regulation width and corresponding water level. We discuss the design principle on different shoal type, and establish a regulation line formula to decide the length of the transitional reach, which is well used in the middle reach of the Yangtze River, by introduce the circumfluence disappearing theory.(5) Summing–up the existed methods of regulation water level in the send–bed river, their applicability and comparability are analyzed. With the regulation works in the middle and lower reaches of the Yangtze River, the shortcomings of each regulation water level method are showed clearly and the more applied methods are point out. Though analyzing the characteristics of regulation water level calculation methods downstream dams, this paper brings forward the method that is according to the flow character downstream dams, choosing two grade regulation charges with high guaranteed rate and picturing the corresponding regulation water level curve changing with river bed.(6) The existing methods of regulation width can be divided into three modes. With analyzing respective theory basis and contraposing the section’s scour and deposition pre– and post–regulation in the straight river reaches, meandering river reaches and bifurcated river reaches, shoal evolution characteristic variables, which are channel obstructive quantity, shoal scour time and regulation guaranteed rate, are introduced into regulation width formula so that a new river dynamics unified formula is established. And it can be used in various guarding regulation works or adjusting regulation works. The regulation widths of the Nianziwan waterway, the Luxikou waterway and the Wuqiao waterway are respectively calculated by using the unified formula. If we divided channel obstructive quantity into two parts, caused by undulation of flow & sediment process and caused by reservoir, that regulation width formula can be used still downstream dams by accounting deposition and choosing some guaranteed rate.(7) According to different fundamentals of guarding regulation works and adjusting regulation works, several familiar regulating structures can be divided into two groups. This paper analyses their respective layout, structural styles and main actions.更多还原