消力池尾部结构对消能特性及泥沙淤积影响的试验研究

发布时间：2018-05-03 02:26

本文选题：底流消能 + 尾部结构　；参考：《河北工程大学》2017年硕士论文

【摘要】：消能设计是水工建筑物设计重要工作之一,良好的消能设施通过消减消力池内水流的动能,一方面防止下游河床受到冲刷,另一方面还能保护水工建筑物的稳定安全。平原地区的水闸等泄水建筑物,河床及岸坡抗冲刷能力较弱,这些水闸消能方式往往都采用底流式消能,消力池结构多为向下挖深式,通过斜坡段与水平底板相连接。而此种消力池的运行过程中,一般产生折坡水跃或者顺坡水跃,合理控制水跃长度和水跃消能效率是该类工程设计工作的重中之重。近年来,许多建于上世纪七、八十年代的泄水建筑物逐渐显露出各种问题,核心问题主要在消能结构上,消力池结构设计的核心主要是斜坡连接段、底板深度、消力池长度等,而这些结构的计算经验已经足够成熟。除此之外,消力池尾部结构、内部辅助消能工等对水流形态、紊动强度、冲淤效果具有重要的影响,因此,本文以消能效率和冲砂能力为目标,开展消力池尾部结构对消能特性及泥沙淤积影响的试验研究,具有一定的理论及实用价值。消力池的消能效果及泥沙冲淤受多重因素的影响,正交试验设计(Orthogonal experimental design)是研究多因素多水平的一种设计方法,它是根据正交性从全面试验中挑选出部分有代表性的点进行试验,这些有代表性的点具备了"均匀分散,齐整可比"的特点,正交试验设计是分析因式设计的主要方法,是一种高效率、快速、经济的实验设计方法。本文基于国内外学者对消力池水力特性及消能试验研究的基础,通过理论分析,确定了研究重点为尾坎结构变化对消力池的消能和冲砂效果的影响,以正交试验设计方法,通过建立水工消力池模型,在不改变消力池整体结构尺寸的基础上,反复调整尾槛坡度以及尾槛折坡位置,同时,将流量作为一个因素参与到正交设计中,以消能率和冲砂率为试验指标,确定正交表L9(34)。试验完成后,将数据整理到正交表内,经过正交试验极差分析和方差分析两种方法,最终得出流量、尾槛坡度、尾槛折坡位置三个因素对于消能率和冲砂率的影响趋势和影响程度大小。经分析得出结论:当流量越小、尾槛折坡点位置离尾槛越近、尾槛坡度越小时,消能率越大;流量越大、尾坎坡度越大、尾坎折坡位置距离尾坎越远时,消力池内淤积泥沙越少,排沙率越高。
[Abstract]:Energy dissipation design is one of the most important tasks in the design of hydraulic structures. By reducing the kinetic energy of the flow in the stilling pool, a good energy dissipation facility can prevent the downstream riverbed from being scoured, on the other hand, it can protect the stability and safety of the hydraulic structures. The floodgates in plain area have the weak scour resistance of the sluice and the river bed and bank slope. The energy dissipation methods of these sluices often adopt the bottom flow energy dissipation. The structure of the stilling pool is mostly the type of deep digging down, which is connected with the horizontal bottom plate through the slope section. In the operation process of this kind of stilling pool, the hydraulic jump is usually produced, and the reasonable control of the length of hydraulic jump and the efficiency of water jump energy dissipation are the most important in the design work of this kind of engineering. In recent years, many drainage structures built in the 1970s and 1980s have gradually revealed various problems. The core problems are mainly energy dissipation structures. The core of the design of the stilling pool structure is the slope connection section, the depth of the bottom plate, the length of the stilling pool, and so on. The calculation experience of these structures is mature enough. In addition, the tail structure of the stilling pool and the internal auxiliary energy dissipator have important effects on the flow pattern, turbulence intensity and scour and siltation effect. Therefore, the energy dissipation efficiency and the sand washing ability are the objectives of this paper. It is of great theoretical and practical value to study the effect of the tail structure of the stilling tank on the energy dissipation characteristics and sediment deposition. The energy dissipation effect of the stilling tank and the sediment scouring and silting are affected by many factors. Orthogonal experimental design is a design method to study the multi-factor and multi-level. It selects some representative points from the overall test according to the orthogonality. These representative points have the characteristics of "uniform dispersion, uniform comparison". Orthogonal test design is the main method of factor design, and it is a high efficiency, fast and economical experimental design method. In this paper, based on the theoretical analysis of the hydrodynamic characteristics and energy dissipation test of the stilling pool, the emphasis of the research is the influence of the structural change of the tail bar on the energy dissipation and sand washing effect of the stilling pool. The orthogonal experimental design method is used in this paper. Through the establishment of hydraulic stilling pool model and without changing the overall structure size of stilling pool, the slope of tail-sill and the position of tail-sill slope are adjusted repeatedly, and the flow rate is taken as a factor to participate in the orthogonal design. Taking the energy dissipation rate and sand washing rate as the test index, the orthogonal table L _ (9) ~ (34) was determined. After the completion of the experiment, the data are arranged into the orthogonal table, and the flow rate and the slope of the tail-sill are obtained by means of the orthogonal test range analysis and the analysis of variance. The influence of three factors on the energy dissipation rate and the sand scouring rate is analyzed. It is concluded that when the flow rate is smaller, the position of the slope point is closer to the end sill, the smaller the slope of the tail-sill, the greater the energy dissipation rate, and the greater the flow rate, the greater the slope of the tail-ridge, the farther the position of the caudal slope is from the tail-sill. The less silt in the stilling pool, the higher the sediment discharge rate.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV653

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