【摘要】：近年來我國對山區(qū)河流水力資源的開發(fā)利用力度越來越大,因此對山區(qū)河流水沙特征的研究也顯得越加重要。當(dāng)在河流中建造水庫等擋水建筑物后,下游的水流泥沙條件發(fā)生了改變,床面會遭受清水沖刷而導(dǎo)致河床粗化現(xiàn)象。對沖刷粗化現(xiàn)象的研究是研究河床演變和解決各種水電樞紐下游工程問題的關(guān)鍵。本文首先對卵石床面的特性進行了分析。卵石床面常見于山區(qū)河流中,它相較于沙質(zhì)床面和卵石夾沙床面有著不同的特性。文章具體分析了卵石床面中卵石運動的非恒定性、粗化層的特征及其形成原因、粗化現(xiàn)象的不同類型以及河流沿程細(xì)化現(xiàn)象等。為了詳細(xì)研究上述現(xiàn)象,本文進一步設(shè)計了清水沖刷卵石床面的水槽物理試驗。試驗選用粒徑范圍3-50mm的連續(xù)級配卵礫石作為試驗沙,在長17m、寬0.58m、深0.5m的水槽中進行了三組不同流量的清水沖刷試驗,測算了床面沖刷深度和粗化層級配,對卵石床面在清水沖刷作用下的變化進行了分析。此外,本文從起動流速出發(fā),定義了一個臨界最大起動粒徑,并據(jù)此提出了一個針對卵石床面的粗化層級配預(yù)報方法,該方法計算相對較為簡易。將該方法與試驗結(jié)果及其他實測資料進行驗證,結(jié)果精確度較高。
[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.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV147;TV149

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本文編號：2235993