The Study On Stability And Protection Technology Of Spur Dike In The Middle Reach Of The Yangtze River

The spur dike is a common regulation measure used in channel improvement. It will be rise to serious consequence if its design is improper. Because the flood damaged phenomenon is common, and the factors of effecting water destruction are very complicated in the middle reach of the Yangtze River, so it is extremely necessary that the protective measures and structure pattern of spur dikes are investigated deeply.This thesis first summed up the design experiences of the spur dikes in our country. According to prototype projects and actual situation, the reasonable experimental schemes were designed. For the organic and the stone spur dikes, flow turbulent intensity, stress distribution on the bottom and movable bed erosion nearby spur dike were analyzed through the method of drawing out the contour of them, the relationships of them were studied. The position and scope of the scoured pit were investigated and predicted with the aid of flow turbulent intensity and stress distribution. The stability of spur dike was discussed in detail with fuzzy mathematics. In view of the phenomenon that loose rock spur dikes were damaged, the experimental results showed that the nod spur dike, the fan spur dike as well as the circular arc spur dike are of the different characteristics. According to experimental results of the string stone protective measure, the threshold velocity of the rubble stone of spur dike is increased obviously. The nod spur dike with the string stone was used as the optimal structure pattern of spur dikes in the middle reach of the Yangtze River. Finally, the flow field around spur dike was simulated with the developed numerical model.