Simulation Study On Regulation Of Sandy And Curved River Channel

The riverbeds of plain rivers are mainly sandy,and the movement of sediments is frequent and the evolution is complex and diverse,which is the main research object of channel regulation.And the curved channel is the more common river type in plain rivers.Due to the complicated structure of the water flow in the bend,disorganized the flow state and the obvious sediment erosion.The influencing factors of the obstacle shoal are many.So that the remediation is difficult.Therefore,it is of great practical significance and application value to analyze the riverbed evolution rule and the experimental research of the channel regulation project for the obstacle navigation characteristics of the curved river sandy shoal.According to the “13th Five-Year Plan” of Guangdong Province,in order to develop the water transport industry and promote the economic development of the coastal areas,the Dongjiang Penangtan to Hengli Channel will be upgraded from the V-class channel to the Grade III,with the focus on rectifying the curved section of the Shaliyuan in the shallow section.The remediation of the shoal is of great significance to the whole line of the channel.Based on the project,this paper analyzes and studies the relevant data of the river section and the formula calculation,and combines the mathematical model with the physical model to research the water and sediment characteristics,the evolution of the riverbed and the cause of the shoal and the cause of the shoal.On this result,the remediation plan for the river section is proposed.The Shaliyuan section consists of two reverse curves.The upper curve has a small bending radius,and has shallow depth of water and fast water flow during the dry season.The lower curve is excessively widened which causes the water dispersion.Under the design flow rate,according to the Class III waterway standard,the water depth in the channel is seriously insufficient,and there has a strong sweeping water in the bend,which results in a poor state of flow.The research section has undergone many remediation,such as spur dikes along the coast.However,due to the large amount of sand mining activities,the riverbed has been cut down year by year,which makes some spur dikes ineffective.The hydrodynamic axis has a large swing under different flow discharge,which leads to poor navigation conditions in the whole river section.In order to achieve the requirements of the bundled water and fixed beach during the dry season,and to better adapt to the guiding function required for the riverbed undercut,the smaller rectification line width and the lower remediation water level were selected through calculation and analysis.Remediation principles and measures which include dredging as the main method,remediation and dredging combined were proposed.However,the remediation of curved shoals should pay attention to not only the water depth during the dry season should meet the requirements,but also the flow velocity and flow regime change after remediation.Through flume model test,mathematical model calculation and physical model test to verify the actual river channel,which shows that the excavation of single-section trough is greatly affected by discharge at medium and low flow rates,which aggravates the deterioration of water flow conditions in the curved waterway.The lateral flow velocity is increased,which is not conducive to the safe driving of the ship.The compound cross section of trenching has a significant effect on reducing the flow rate and adjusting the flow state.However,with the increase of discharge,the influence of different types of trenching section on the water flow condition is gradually weakened.Therefore,the remediation of the shoal of the curved section of Shaliyuan should be carried out to excavate the compound cross section type of trough.According to the measured hydrological sediment data of the river section and the recent river topographic map,the mathematical model and the physical model are respectively established,and the scheme test is carried out after water line along the road,section flow velocity and flow direction verification result of the model meet the specification accuracy requirements.The mathematical model with flexible calculation and convenient is used to screening scheme,and the physical model is verified and adjusted.The comparison results show that the simulation results are roughly similar,but the physical model test results are closer to the actual situation.Finally,a moving bed test was carried out to illustrate the problem of sedimentation and siltation after remediation.And based on the recommended scheme of fixed bed test,the scheme was optimized and the final plan was proposed.The results show.After the implementation of the final plan,the navigation channel is basically stable.The water depth of the river section meets the design requirements,and the navigation flow conditions are good,reaching the requirements of the Class III channel,which can provide reference for the same type of waterway improvement project.