| Inland waterway improvement projects generally include dredging projects,reef blasting projects,bank protection projects,bridge demolition,and river crossing pipeline reconstruction projects,navigation mark projects,ancillary facilities projects,and environmental protection projects.Waterway regulation is an engineering measure to adjust and control water flow by regulating buildings,stabilize river regime,and improve navigational conditions of waterways.This paper relies on the rectification project of navigation obstacles in the navigation channel of the Hechuan Section of Qujiang River,using a two-dimensional mathematical model of plane flow to conduct research,analyze the evolution of the river bed based on measured data,and select and verify a mathematical model.According to the channel water flow characteristics and the experimental construction conditions of the scheme,simulations are carried out for multiple remediation layout schemes.The flow conditions of the beach section before and after the scheme and the changing pattern of riverbed scour are analyzed,and on this basis,remediation schemes are proposed and compared and optimized.The main conclusions are as follows:(1)The measured water level,velocity distribution and buoy flow direction of the engineering river reach verify that the calculated results are in good agreement with the measured data,indicating that the plane two-dimensional mathematical model used in the study can correctly simulate the flow of actual rivers and can be used for channel regulation Study of program effects.(2)Based on the analysis of various inflow operating condition combinations of Qujiang,Jialingjiang,and Fujiang Rivers,combined with the Caojie and Fuliutan hub dispatching operation schemes,the one-dimensional numerical model was used to calculate the lowest navigable water at Qujiang Estuary.Reconstructed water levels of Danxikou,Lijiaxi,Qingcaoba,and Matouchang were calculated using two-dimensional digital simulation.(3)Through analysis,the project uses 4 indicators such as flow velocity,lateral flow velocity,navigation resistance,and ship thrust resistance ratio to evaluate the water flow effect after channel regulation.(4)The main reason why Danxikou obstructs navigation is that it is located at the top of the bend and the cross flow is large.In addition,the left bank slope span collapse formed after the left shore beach,silting channel.The left shore beach is cut by the current,forming the left branch,the whole beach potential is unstable,the current scattered,endangering the navigation safety.The regulation measures of bank revetment fixing slope and spur dike sealing inlet are adopted.Numerical simulation shows that the flow velocity and cross flow at the front of revetment decrease,which is beneficial to the stability of revetment.By comparing the velocity,flow pattern,navigation resistance and push-drag ratio before and after the project implementation,the regulation scheme has little influence on navigation conditions.(5)Lijiatan,Qingcaoba and wharf beaches obstructed navigation due to insufficient water depth in the trough area,and obstruction of navigation in shallow areas.The engineering measures adopted in Scheme 1 are dredging considering the depth of silt preparation,and Scheme 2 adopts dredging engineering and adopts dam construction to maintain the effect of channel regulation.Mathematical calculations show that the program has no obvious adverse effects on the navigational conditions.Option 2 In the low water level period,due to the water blocking and spurting effects of Dingshun Dam,there are undesirable flow patterns near Dingshun Dam,and the flow velocity of the channel is increased,which has a certain adverse effect on the navigation conditions.Therefore,Option 1 is recommended. |
