Research On Hydraulic Properties Of Submerged Dikes For Enriching The Regulation Measures Of Reservior Rapids

Yangtze River as the largest waterway traffic roads,is an important link between the southwest and central China,East China's three major economic zones,to maintain its stability and security of ship sailing channel is a matter of national focus.Yangtze river between two of the Three Gorges-Gezhouba dam is an important part of the Yangtze river main channel,between river flow regime disorders,river regime steep,fast-flowing,shallow set many rapids,dangerous,anxious features,it is not conducive to the development of navigation and waterway transport ships.Seen from the current research,the traditional Reservoir rapids Regulation means not satisfactory,therefore,this paper presents a " submerged dams to slow" approach to emergency shoal reservoir,for rich means of waterway regulation between the two dams,improve the efficiency of the water transportation,etc.It is of great significance.In this paper,Smagorinsky subgrid turbulence model and generalized flume experiment are used to analysis the hydraulic characeristics of Submerged Dikes.Research on single submerged dam,submerged dikes factors of slow flow zone width behind dam,get the following main conclusions:(1)Area of sustained flow is formed on the back of dams due to the water was blocked by the dikes.The size of the area of sustained flow is closed related by the shape of the dam and flow characteristics.(2)Based on a lot of sigle-dam flume experiments and Three-Dimensional Numerical Simulation,found that the submergence degree and the narrow beam reat of submerged dikes are the main Influencing factors of the width of sustained flow area.On the contrary,the influence of Froude number(Fr)is not obvious.The velocity decrease rate is affected by the submergence degree and Froude number(Fr),rather than the narrow beam reat.The relation between the width of sustained flow area and submergence degree could be negative exponent relationship.There was a positive linear relationship between the width of sustained flow area and the narrow beam rate.The velocity decrease rate increases with water flow intensity,but decreases with the submergence degree.The relationship among submergence degree,the narrow beam and the width of sustained flow area are initially established.(3)This paper summarizes the relationship between the overflow ratio and the narrow beam rate by the method of single factor analysis.Finally,the relationship between the overflow ratio and the narrow beam rate has been obtained.(4)The width of sustained flow area was not changed with the number of and the distance of the submerged dam which severely affected the velocity decrease rate after making an analysis of the test.The results showed that water flow state is the most stable when the distance between the dikes was 3-5 times dam length.(5)The difference between upstream and downstream water surface is decreased when the number of dikes is lager than 2.The minimum difference between upstream and downstream water surface when the distance between the dikes was 3-5 times dam length.