Local Scour Experiments And Protection Of Spur Dike On The Lancang River

The spur dike is a kind of important engineering measures in river regulation andprotection project, which is widely used in the channel improvement engineering ofmany domestic and overseas rivers. But as time passes, the spur dike is often destroyedby the influencing factors of dynamic force, structure, human activities,maintenancemanagement. In recent years, the corruption problem about the spur dike is researchedquantificationally and some results have achieved but not mature. The flume experimentmethod is used in the research by most of the scholars, but the consequences have theshortage of insufficient applicability and extensibility. Besides this, the Lancang river asone of most important water channels between yunnan and southwest China andsoutheast Asia for developing the border trade, the research about local scour on whichis more little. Therefore, through studies, the article can not only help us to understandthe destruction mechanism of the spur dike on the lancang river, but also offer supportfor waterway regulation on mountainous rivers, and also is beneficial to China shippingdevelopment.This paper research the local scour mechanism and protection problems of the spurdike on the lancang river through the methods of flume model experiment and plane2Dflow numerical simulation. main research contents are as follows:1) Based on the prototype information of the manting waterway on lancang river,combined with the laboratory condition, the horizontal scale of the model is intended tobe1:100, then, flume generalized model is established.2) Through the fixed bed model test, the paper study the surface patterns and thechange of flow field under the action of the spur dike in the pentrough, and focuse onthe analysis of the flow field and the change of the backflow length near the spur dikewhich is under the condition of different angles and different tail water depth.3) The two-dimensional flow mathematic model is used to simulate and verify theflow structure near the spur dike. and through multigroup calculation of the mathematicalmodel and comprehensive comparison, representative typical working conditions isselected for the further tests of the physical model.4) Through the local scour experiment of the spur dike, this article preliminarilydiscusses the scour mechanism and the formation process of the scoured pit near thespur dike. By means of analysing the relationship between maximum scour depth andflow conditions, scale of the spur dike, sediment gradation and so on, the maximal scour depth formula of groyne head is derived through the methods of dimension analysis andmultiple regression. Then the formula was revised and verified by calculating themeasured data of the prototypical datas, the results show that the calculated value is inaccordance with the measured.5) The paper summarizes the form of spur dike damaged by flood on the mountainstream and analyses the cause of the damage by flood from three aspects of the impetusof water flow and sediment, the structure of the spur dike and human factors. andthen,according the characteristics of the local damage of the groyne head, protectivemeasures are put forward from the respects of the structure of the spur dike, the dammaterial, flow condition and so on.