关于溃坝问题水动力特性的实验研究

发布时间：2018-04-01 02:25

本文选题：溃坝实验　切入点：水位　出处：《浙江大学》2017年硕士论文

【摘要】：溃坝通常指蓄水库围堰突然坍塌进而在水库下游形成溃决洪水造成人类生命、生态环境和生产经济巨大损失的灾害性事件。溃坝问题的研究并不局限于内陆区域,在海岸工程方面也存在十分重要的研究意义。研究溃坝水流的演变过程有利于理解海啸与涌潮的水动力传播特性,从而为海岸带防灾减灾策略的制定提供科学依据。本文采用物理模型试验研究了溃坝波的水动力特性。实验中,将多种设备连接至计算机并辅以相关软件,通过观察高速相机记录的图像,解决了高采集频率下的波高仪、流速仪和高速相机的时间同步问题。同实验条件下多次的实验结果表明本研究的实验具有足够的重复性和可靠性,满足研究分析要求。对室内实验而言,闸门开启速度是影响溃坝波水动力特性的重要因素。相对于距离闸门较远的位置而言,闸门开启速度对距离闸门较近位置的水位和流速的影响更大。而随着时间的推移,这种影响逐渐减小。在此基础上,本研究进行了一系列的闸门快速开启的溃坝实验,包括下游初始干床和湿床两种情况,研究了下游初始水深、上下游水头差、上游水箱长度等因素对溃坝波水位和流速的影响。干床与湿床情况下的溃坝波水位和流速存在显著不同。上下游水头差相同时,湿床情况下的正向波前速度明显小于干床情况的。此外,下游观测点的最大水位和流速主要受上下游水头差的影响,而水位和流速较大值的持续时间则主要由上游水箱长度决定。考虑到闸门处是一个非常特殊且重要的位置,本文利用高速相机记录的图像,得到了闸门处的水位随时间的变化。在对比了实验结果与既有理论结果的基础上,给出了各理论解的适用范围。总体而言,对于下游/上游初始水深比小于0.138的情况,Lin等的理论解与实验结果的吻合度较高。本文利用物理模型实验,较为系统地研究了溃坝波的水动力特性。将实验结果与理论结果进行对比,归纳分析了理论解的适用性。与此同时,本研究的溃坝实验数据可以为数值模型提供精准可靠的验证资料,为进一步研究溃坝波特性打下了良好的基础。
[Abstract]:Dam break usually refers to the catastrophic event that the reservoir cofferdam collapses suddenly and then forms a burst flood in the lower reaches of the reservoir, which results in great loss of human life, ecological environment and production economy. The study of dam break is not limited to the inland area. It is also of great significance in coastal engineering to study the evolution of dam-break flow, which is helpful to understand the hydrodynamic propagation characteristics of tsunamis and tidal bore. In this paper, the hydrodynamic characteristics of dam-break wave are studied by physical model test. In the experiment, many kinds of equipments are connected to computer and related software is used. By observing the images recorded by high speed camera, the wave altimeter with high acquisition frequency is solved. The time synchronization of the velocity meter and the high speed camera. The experimental results under the same experimental conditions show that the experiment in this paper has enough repeatability and reliability to meet the requirements of the research and analysis. The opening speed of the gate is an important factor affecting the hydrodynamic characteristics of the dam-break wave. Compared with the location far away from the gate, the opening speed of the gate has a greater effect on the water level and velocity of the gate near the gate. On the basis of this, a series of dam-break experiments were carried out, including the initial dry bed and wet bed, and the initial water depth of downstream and the difference of upstream and downstream water head were studied. The influence of the length of upstream water tank on the water level and velocity of dam-break wave is significant difference between dry bed and wet bed. When the water head difference between upstream and downstream is the same, The forward wave front velocity in wet bed is obviously lower than that in dry bed. In addition, the maximum water level and velocity of downstream observation point are mainly affected by the upstream and downstream water head difference. However, the duration of the larger water level and velocity is mainly determined by the length of the upstream water tank. Considering that the gate is a very special and important position, the images recorded by the high-speed camera are used in this paper. The variation of the water level at the gate with time is obtained. On the basis of comparing the experimental results with the existing theoretical results, the applicable range of the theoretical solutions is given. For the case where the initial water depth ratio of downstream / upstream is less than 0.138, the theoretical solution of Lin et al is in good agreement with the experimental results. The hydrodynamic characteristics of dam-break wave are studied systematically. The applicability of the theoretical solution is summarized and analyzed by comparing the experimental results with the theoretical results. The experimental data can provide accurate and reliable verification data for the numerical model and lay a good foundation for further study of dam-break wave characteristics.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV122.4;TV131.6

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