薄壁堰自由出流的试验研究

发布时间：2018-06-18 18:55

本文选题：薄壁堰 + 自由出流　；参考：《西华大学》2017年硕士论文

【摘要】：洪水灾害是世界上最严重的自然灾害之一,其往往分布在人口稠密、农业垦殖度高、江河湖泊集中、降雨充沛的地方,如北半球暖温带、亚热带。中国、孟加拉国是世界上洪水灾害发生最频繁的地区,美国、日本、印度和欧洲的洪水灾害也较严重。我国幅员辽阔,地形复杂,季风气候显著,是世界上水灾频发且影响范围较广泛的国家之一。全国约有35%的耕地、40%的人口和70%的工农业生产经常受到江河洪水的威胁,并且因洪水灾害所造成的财产损失居各种灾害之首。从洪涝灾害的发生机制来看,洪水灾害具有明显的季节性、区域性和可重复性。我国的洪水灾害一般发生在4-9月。在2016年7月发生的洪灾中,全国有26省(区、市)1192县遭受洪涝灾害,农作物受灾面积2942千公顷,受灾人口3282万人,紧急转移148万人,因灾死亡186人、失踪45人,倒塌房屋5.6万间,直接经济损失约506亿元。从受灾区域来看,城市受灾情况最为严重,造成的直接经济损失最大。因此,城市河道防洪是当前我国非常重要的课题。在现在的城市河道防洪系统中,洪水流量的计算尤为重要,而堰是作为重要的流量测定水工建筑物,对此,本文针对目前计算公式中所存在的问题,探讨薄壁堰在流量测定中的作用,重点对薄壁堰自由出流进行研究。基于动量定理,从上游水头与临界水头,雷诺数与上游水头、流量以及流量系数这几个因素的综合评价分析,采用最小二乘法和图解法,并通过方差分析得到了新自由出流计算公式。该研究结果适用性强,流量系数计算比目前计算公式更准确,更能适应当前极端气候下得薄壁堰自由出流计算。
[Abstract]:Flood disaster is one of the most serious natural disasters in the world, which is often distributed in places with dense population, high degree of agricultural reclamation, concentrated rivers and lakes and abundant rainfall, such as warm temperate zone in the northern hemisphere and subtropical zone. China and Bangladesh have the most frequent floods in the world, as are the United States, Japan, India and Europe. Our country is one of the countries with large territory, complicated topography and remarkable monsoon climate. About 35% of the cultivated land in China, 40% of the population and 70% of industrial and agricultural production are often threatened by river floods, and the property losses caused by flood disasters rank first among all kinds of disasters. According to the occurrence mechanism of flood disaster, flood disaster has obvious seasonal, regional and repeatability. The flood disaster in China generally occurred in April and September. In the floods that occurred in July 2016, 26 provinces (districts, cities and counties) were affected by floods. The crops affected an area of 2,942 thousand hectares, 32.82 million people were affected, 1.48 million people were urgently transferred, 186 people were killed and 45 people were missing as a result of the disaster. Collapse of 56000 houses, direct economic losses of about 50.6 billion yuan. From the disaster area, urban disaster is the most serious, resulting in the largest direct economic losses. Therefore, urban river flood control is a very important subject in our country. In the present urban river flood control system, the calculation of flood discharge is particularly important, and the Weir is used as an important flow measurement hydraulic structure. In view of this, this paper aims at the problems existing in the present calculation formula. The function of thin-walled Weir in flow measurement is discussed, and the free discharge of thin-walled Weir is studied. Based on momentum theorem, the least square method and graphic method are used to evaluate and analyze the factors of upstream water head and critical head, Reynolds number and upstream water head, flow rate and flow coefficient. The new formula of free discharge is obtained by variance analysis. The results of this study are more suitable for the calculation of free discharge of thin-walled Weir in extreme climate than the current formula.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV131.6

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