Study On The Flow Characteristics Of Different Structural Types Of Spur Dikes And Their Influence On The Diffusion Of Pollutants In The Surrounding Water Body

Spur dikes are commonly used dams in the Yangtze River,which can effectively increase the height of the water surface line of the channel,reduce the flow velocity of the channel,and the erosion of the water flow to the shore,thus playing a role in protecting the channel.In actual projects,most of the spur dikes are trapezoidal cross-section riprap spur dikes.In the existing data,there are few studies on the effect of changing the profile of the spur dike on the water and sediment characteristics of the channel.In addition,pollution in the Yangtze River Channel is serious.In recent years,attention has been paid to water pollutants in the channel.In order to protect the ecology of the channel,research on the impact of remediation of buildings on the diffusion and interception of pollutants is particularly important.Therefore,it is of great significance to study the flow characteristics of different structural types of spur dikes and their influence on the diffusion and interception of pollutants in the channel.The research object of this paper is the most common ordinary entity spur dike in waterway regulation and the new type of spur dike proposed by the research team and obtained national patent.The results obtained are useful for selecting the dam body curve and gap size and better exerting the role of the spur dike in waterway regulation.Certain reference value.On the basis of much research results,this paper has produced two sets of ordinary solid spur dikes with different cross-sections and four sets of new pervious spur dikes with different gap sizes.Through combining the methods of constant flow fixed bed physical model test and theoretical analysis,the paper studies the water surface line,surface flow field near the spur dike and the influence on the diffusion of pollutants in the channel under the conditions of different control flow rates,different profile forms,different gap sizes and different pollutant placement positions,and obtain the flow characteristics of the spur dike under different conditions and its influence on the diffusion of pollutants in the channel.The main research results are as follows:(1)The new spur dike is superior to ordinary spur dikes in improving the water depth of the upstream and downstream,increasing the water depth of the narrow section and reducing the flow velocity of the channel;And the new pervious spur dike with a certain gap size can more effectively reduce the water surface line gradient and alleviate the narrowing Section water flow velocity.(2)The concentration of pollutants in the spur dam and the head of the spur dam has the biggest change.The spur dike has more impact on the diffusion of heavy metal pollutants from the right bank(the opposite bank of the spur dike)than the left bank(the spur dike bank);And the closer to the spur dike,the greater the impact of the point.The effect of intercepting pollutants in front of the new solid spur dike is better than that of the ordinary solid spur dike,but the effect of the new pervious spur dike has declined.(3)The spur dike will change the diffusion path of the oil spilled on the surface of the channel,thereby spreading the oil to the narrow section and increasing the spreading area of the oil spill.The new permeable spur dike can effectively reduce the spreading area of the oil spilling through the spur dike.Compared with the ordinary physical spur dike,the new spur dike is better than the ordinary solid spur dike in terms of improving the channel and intercepting pollutants,And increasing a certain gap size will more effectively reduce the water surface line gradient of the channel,protect the channel and improve the water quality.effect.An optimal gap size is obtained by comparison,so that the new permeable spur dike has the best effect in all aspects.