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Study on hydro-environmental properties of rubble weir constructed of coarse rokcs

粗石砌筑的碎石堰水环境特性研究

基本信息

批准号：
12650513
负责人：
MICHIOKU Kohji
金额：
$ 2.3万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650513/
关键词：
Rubble mound weir Porous structure subsurface flow flow resistance discharge curve Image processing Particle tracking velocimetry Rapidly varied flow 堰越流捨石安定性再曝気開水路流水面変動

项目摘要

A "rubble mound weir" was proposed as a river discharge control system. The weir is expected to be a nature-friendly structure for controlling flow discharge in a way that it allows streamwise movement of aquatic animals. In order to make a suitable design of the structure, its hydrodynamics and hydro environmental properties were examined by performing laboratory experiments and a theoretical analysis. First, a laboratory experiment was carried out in order to find functional dependency of discharge on parameters such as water depth, weir's porosity, rubbles size, etc.. The weir model constructed of pebbles was installed in an open channel, where weir's dimension and grain diameter were varied. A one-dimensional flow analysis was performed to obtain a solution for water surface profile inside the weir. Flow resistance in the weir was evaluated from an experimental formula for turbulent porous media flow. The solution leads to a functional relationship between discharge and upstream wa … More ter depth. A theoretical discharge-curve was obtained through the analysis as functions of Reynolds number, porosity, specific grain size, weir's aspect ratio, dimensionless water depth, etc.. The solution was well correlated with the experimental data under wide range of flow conditions. Second, local flow structure around the weir was experimentally examined by applying a particle image velocimetry, PIV, which provides information of time and space scales of the flow fields. Because habitats of aquatic lives are very much influenced by time-dependent flow structure, it is very important from an environmental point of view to take time- and space- scales of flow motions into consideration in determining the weir's dimension. Third, a multi-variables analysis was applied to pick up various scales of energy-contain eddies ; some of them are responsible in collapsing the weir, some play important roles in gas transfer between the air-water interface, the others affects activities of aquatic animals, and so on. Fourth, dynamic stability of the structure was investigated by measuring pressure fluctuation inside the weir's porous body. The critical condition for failure or collapse of the structure was given from local flow force that takes the maximum value at the downstream side of the weir top surface. Integrating results from the present research project, one can make structural design of the rubble mound weir from both of hydrodynamic and hydro-environmental points of view. The rubble mound weir is expected to be a river structure that better preserves ecological system than conventional metal or concrete weirs. Less

提出了一种“碎石堆堰”作为河流流量控制系统。该堰预计将是一个自然友好的结构，用于控制流量排放的方式，它允许水生动物顺流运动。通过室内试验和理论分析，研究了该结构的水动力特性和水环境特性，为该结构的合理设计提供依据。首先，进行了一个实验室实验，以找到函数依赖性的流量参数，如水深，堰的孔隙度，碎石尺寸等。在明渠中设置卵石堰体模型，堰体尺寸和粒径均发生变化。进行了一维水流分析，以获得堰内水面线的解。根据多孔介质湍流流动的经验公式计算了堰内的流动阻力。该解导出了流量与上游水流量之间的函数关系 ...更多信息深度。通过对雷诺数、孔隙率、比粒径、堰宽比、无因次水深等因素的分析，得到了理论流量曲线。在较宽的流动条件下，该解与实验数据有较好的相关性。第二，采用粒子图像测速技术（PIV）对堰板周围的局部流场结构进行了实验研究，该技术提供了流场的时间和空间尺度信息。由于水生生物的栖息地很大程度上受随时间变化的水流结构的影响，从环境的角度来看，在确定堰的尺寸时考虑水流运动的时间和空间尺度是非常重要的。第三，应用多变量分析来拾取不同尺度的含能涡，其中一些是负责在崩溃的堰，一些起着重要的作用，在气-水界面之间的气体传输，其他的影响活动的水生动物，等等。第四，结构的动力稳定性进行了研究，通过测量内的压力波动的堰的多孔体。根据堰顶面下游侧局部水流力最大值，给出了结构破坏或倒塌的临界条件。综合本研究成果，可从水动力及水环境两方面进行抛石堰的结构设计。与传统的金属或混凝土堰相比，碎石堆堰有望成为一种更好地保护生态系统的河流结构。少