河湾改造水流变化研究.pdfVIP

III 摘 要 我国人口众多，人均土地占有量少，在使用土地资源时做到充分利用是可持续发展 的必然要求。水工工程中的裁弯取直工程，不仅是一项防洪工程，同时又是一项 “土地 再生”工程。裁弯取直，顾名思义，即以直线的形式将曲线形河道的进口和出口连接起 来，形成直线河道。原本被弯道包围的不可利用土地裸露出来，可以用作耕地，亦可以 作为城镇住房用地，这对于惜土如金的山区，是一笔莫大的财富。 在实际工程中，由于地形、地貌、地质等条件的限制，有些工程不能做到完全的取 直，于是出现了 “裁弯取弯”的工程形式，变大弯为小弯。因为弯曲河道中的水流较直 线河道复杂的多，所以如何选取改造后的河湾曲率半径成为了一项重要课题，本文依托 镇坪县南江河改造实体工程，就河湾改造后的水流变化状况进行了初步的研究。 首先，本文通过河工模型定床试验，观察了河弯改造前后水流的变化情况，初步验 证了工程的可行性，并通过对试验实测的水流流速和水位数据进行对比分析，比较了三 种不同曲率半径的河湾改造方案的优缺点，结合理论分析从中选出最佳方案。 其次，本文通过河工模型动床试验考察预选方案的不足，发现预选方案弯道冲刷淤 积现象明显，所以又通过补充试验，分析预选方案存在的不利水流因素，并针对预选方 案的不足，选择有的效措施加以治理，并结合理论分析验证了改善措施的可行性。 关键词：弯道水流，裁弯取直，预选方案，措施，治理 I Abstract The amount of land per capita is less than the world average but the Population is the largest in China. It is an inevitable requirement to take full advantage of land resources for sustainable development. Hydraulic engineering in cutting the bends project, not only is a flood control project, but it is also a project for land regeneration. Straightening, by definition, is to connect the inlet and outlet of a curved river in the form of a straight line to form a straight line river. Non-use land originally surrounded by the river has exposed and can be used as arable land, also can be used as land for urban housing, which will be a sum of great wealth to local government who cherish the dust like a mountain of gold. In the actual project, some of the works can not be completely straightened due to the limitations of the topography, geological conditions, so there is a new form of engineering to change big bend into small corner. Because the flow of water in the corners is more complex than the straight line river’s, how to select the bend radius of curvature becomes an important topic. The paper, relying on the