卵石床面冲刷特性与试验研究

发布时间：2018-09-11 07:17

【摘要】：近年来我国对山区河流水力资源的开发利用力度越来越大,因此对山区河流水沙特征的研究也显得越加重要。当在河流中建造水库等挡水建筑物后,下游的水流泥沙条件发生了改变,床面会遭受清水冲刷而导致河床粗化现象。对冲刷粗化现象的研究是研究河床演变和解决各种水电枢纽下游工程问题的关键。本文首先对卵石床面的特性进行了分析。卵石床面常见于山区河流中,它相较于沙质床面和卵石夹沙床面有着不同的特性。文章具体分析了卵石床面中卵石运动的非恒定性、粗化层的特征及其形成原因、粗化现象的不同类型以及河流沿程细化现象等。为了详细研究上述现象,本文进一步设计了清水冲刷卵石床面的水槽物理试验。试验选用粒径范围3-50mm的连续级配卵砾石作为试验沙,在长17m、宽0.58m、深0.5m的水槽中进行了三组不同流量的清水冲刷试验,测算了床面冲刷深度和粗化层级配,对卵石床面在清水冲刷作用下的变化进行了分析。此外,本文从起动流速出发,定义了一个临界最大起动粒径,并据此提出了一个针对卵石床面的粗化层级配预报方法,该方法计算相对较为简易。将该方法与试验结果及其他实测资料进行验证,结果精确度较高。
[Abstract]:In recent years, the development and utilization of hydraulic resources in mountain rivers have become more and more intensive, so the study on the characteristics of water and sediment in mountain rivers is becoming more and more important. When the reservoir and other water retaining structures are built in the river, the downstream flow and sediment conditions have changed, and the bed surface will be washed away by clear water, which will lead to the river bed coarsening. The study of scour coarsening is the key to study the river bed evolution and solve the downstream engineering problems of various hydropower hubs. In this paper, the characteristics of the pebble bed are analyzed. Pebble bed surface is common in mountain rivers, which has different characteristics compared with sandy bed surface and gravel sand bed surface. This paper analyzes concretely the unsteady movement of pebble in the cobble bed, the characteristics of coarsening layer and its forming reasons, the different types of coarsening phenomenon and the phenomenon of river thinning along the course, etc. In order to study the above phenomena in detail, a flume physical test was designed to wash the pebble bed with clear water. The continuous gradation gravel with 3-50mm particle size was selected as test sand. Three groups of clean water scour tests were carried out in a flume of 17m in length, 0.58m in width and 0.5m in depth. The scour depth of bed surface and the gradation of coarse gradation were calculated. The change of pebble bed surface under the action of clean water was analyzed. In addition, starting from the starting velocity, a critical maximum starting particle size is defined, and a prediction method of coarsening gradation for the cobble bed is proposed, which is relatively simple to calculate. The method is verified with the experimental results and other measured data, and the accuracy of the results is high.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV147;TV149

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