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拦砂坝泄流孔断面优化设计及其实验研究
Alternative TitleOptimal design of draining hole and its experiment research
Language中文
王小军
Thesis Advisor陈晓清
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Keyword山洪泥石流 拦砂坝 实体重力坝 泄流孔 排泄孔
Other Abstract

坝身带泄流孔的重力式拦砂坝是泥石流防治工程中最常用的工程形式之一,但对于泄流孔的细部设计并没有相关规范规定,多参照类似的工程或根据工程师的经验设计而成。本文首先通过野外调查和文献查阅,总结已有工程中泄流孔设计多存在断面设计不合理而导致堵塞的问题,并提出了以排泄功能为主平衡泥石流峰值流量的泄流孔优化方案,通过数值模拟实验和水槽模型实验,研究了断面形态对优化后的泄流孔排泄性能的影响,同时分析了排泄孔内流速的分布规律,得出以下结论:1. 野外调查发现,泄流孔多存在断面设计不合理而导致堵塞的问题,主要表现在孔径过小,70%以上的拦砂坝泄流孔孔径小于80cm,由此而导致的堵塞概率为56.25%,从而导致坝前泥沙淤积速度过快,坝前库容使用寿命过短。2. 提出了以增大泄流孔断面尺寸,以平衡泥石流洪峰流量的以排泄功能为主的泄流孔优化方案,定义此类泄流孔为排泄孔。排泄孔主要利用有压出流原理,增大排泄孔的出流量,并分析了影响排泄性能的影响因素。通过数值模拟实验对比了同样水力断面条件的排泄孔与泄流孔的排泄能力,得出排泄孔的排泄能力更优;且排泄孔尺寸大,不容易被堵塞。3. 通过数值模拟实验和水槽模型实验,研究断面形态对排泄孔排泄能力的影响。对于矩形、正方形、圆形、椭圆形和U形等横断面形态,具有合理宽深比矩形的排泄能力最优,具体表现在对洪水(γ=1000kg/m3)和稀性泥石流(γ=1400kg/m3),窄深型的矩形排泄能力最优,而对于过渡性流体(γ=1700kg/m3)和粘性流体(γ=2000kg/m3),正方形断面的排泄能力最优。其次,直线型纵断面和曲线形纵断面对排泄效果影响不大,在实际工程应用中以直线型最佳;纵断面坡度越大,排泄流量越大;断面面积增大的喇叭口断面比进水口面积相等的等截面排泄能力更好。4. 排泄孔内流速分布较复杂,横向上多呈抛物线型分布,沿程变化则呈现进口段波动性增大、中部平稳变化及出口增大的规律,其中,最大流 5. 速出现在排泄孔出口处。其次,根据流速沿程变化规律可将排泄孔分为进口扰动段、急剧增大段、平稳变化段及出口增大段等区域。出口断面的平均流速与坝前泥深呈现良好的线性关系,线性系数受排泄孔断面条件、来流条件等影响。通过进一步研究,该思路可以在工程设计中,为排泄孔的抗磨蚀设计提供依据,即可通过控制排泄孔与溢流口之间的相对距离来控制排泄孔内的最大流速。 

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Check dams with draining holes is a kind of most popular structure measures used in debris flow mitigation, but design criteria about the draining hole is not clear. Many was designed according to the experience of engineers and similar structures. In this thesis, field investigation was carried on to find out the problems existing in nowadays engineering. Based on the investigation, optimal plan was proposed and further research on the draining capability of the optimized draining hole was carried and analyzed the influence of cross section type to draining capability and velocity distribution in draining hole. some conclusions can be reached as following:1) according to field investigation, irrational design of draining hole caused most of the clogging in draining hole and thus induced other problems. 70% of the draining hole diameter were designed smaller than 80cm and the clogging rate of such holes is 56.25% .2) an optimal strategy was proposed, that is, increase the cross section area to balance the peak discharge. This enlarged draining holes use pressure discharge to improve the draining capability. Firstly, the draining capacity of the traditional draining hole and the enlarged one with same cross sectional area were compared according to numerical simulation, the results showed that the enlarged draining hole share better draining capacity and lower possibility of clogging. 3) according to numerical simulation and hydraulic model tests, draining hole with different transverse sectional and longitudinal profile type presented different draining capacity. among rectangle, square, circle, oval and U-shape type, rectangle with rational width-depth ratio has the draining capability. In detail, for floods(γ=1000kg/m3) and low viscous flow(γ=1400kg/m3), rectangle cross-sectional draining hole was better than others while for transitional flow(γ=1700kg/m3) and high viscous flow, square cross section show better performance. For longitudinal profile, linear profile and curve profile share the same influence to draining effect. from the perspective of economic benefit and convenience of construction, linear profile should be a better choice. As the increase of slope, the drainage capacity increases and variable section shows better capacity to uniform section type. 4) Velocity distribution in draining hole is complicated. General, transverse distribution is a parabola, that is, velocity in the middle is higher than bilateral. analyses demonstrated that longitudinal distribution along the draining hole presented to be waved increase in the entrance of draining hole, steady change in the middle part and sharply increase in the outflow part. The maximal velocity value appears at the outflow cross-section. based on the distribution characteristic, four districts can be divided in the draining hole as entrance disturbed section, sharply increase section, steady variation section and outflow increase section, respectively.5) Comparing the curve of outflow velocity with curve of depth, they share the similar variation trend. According to statistic analyses, there is a good linear relationship between the maximal velocity and depth. the linear coefficients related with the cross-section type of draining hole and condition of incoming flow. It provides a way for anti-erosion design to estimate the maximal velocity by control the distance of draining hole position. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18990
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
王小军. 拦砂坝泄流孔断面优化设计及其实验研究[D]. 北京. 中国科学院大学,2016.
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