Transverse Circulation Flow And Regulation Of Fujiang Channel

The braided river of Fujiangsha is the main hinder and shallow channel which located in 12.5m deep water channel of Yangtze River from Nanjing to Liuhe estuary. It is very important to develop the Yangtze River golden waterway for mastering the inlets in hydrodynamics and sediment transport including distributary sand. The south branch of Fujiangsha is a typical curve, so the lateral velocity of transverse sediment transport plays a decisive role. Therefore, this paper studies the transverse circulation and sediment transport, and then established new circulation flow formula and inlet sediment transport formula, which has an important guiding significance to enrich the theory of river dynamics, better reveal Fujiangsha inlet diversion mechanism of sand, and grasp the deep water channel regulation strategy.Aiming at the problems of Engelund bend circulation velocity formula in the treatment of boundary conditions, we fixed the lateral slip velocity at the bottom of bed; put forward new turbulent Prandtl transverse stress form, and applicate them into the bottom boundary conditions to get the improved transverse circulation velocity formula. We validated the improved circulation velocity formula by the measured data, and compared it with the Engelund formula and other formulas, analysis the deviation degree between the calculated values and measured values. Results show that, the improved formula is better than the other formulas, and at the same time means that new lateral turbulent shear force form is reasonable.The transverse has an obvious influence circulation on fluvial sediment diversion ratio, consider the circulation transport items, we got the new inlet sediment diversion ratio formula, which improves the accuracy of the formula for the calculation. According to the existing data of Fujiang River, calculate the diversion of the braided river sediment diversion using the new formula. The improved formula of sediment diversion ratio coincided better than the original formula on validation with the measured data.Using the improved circulation velocity formula, calculated the inlet in suspended load transverse transport of sediment and the inlet in bedload transverse transport of sediment. The result is that if the south channel of Fujiangsha to be built the one way channel with the depth of 12.5 m and width of about 200m, the transverse transport of sediment will be 296.2million in the convex side bar excavation area one year.For the further step, analysis the regulation scheme A and B for north channel of Fujiangsha. Calculating the hydrodynamic and sediment diversion ratio of scheme A, B in order to analyze inlet in remediation of velocity, flow and sediment concentration changes, through the calculation and analysis for the remediation program were selected, plan B is better. Due to the large amount of transverse transport of sediment, the dredging engineering amount is large, so the south channel of Fujiangsha will be difficult to maintain the normal navigation. Therefore, it is not recommended for remediation of Funan branch, but maintained the Deepwater Harbor now.