Ship Route Optimization And 3D Simulation Of Navigation Environment In The Fluctuant Backwater Area Of Three Gorges Reservoir

According to the operating rules of Three Gorges Reservoir, water level would be degraded to 145m before flood season, while it would reach 175m before dry season, which was generally called fluctuating backwater. The channel influenced by fluctuating backwater was named fluctuating backwater area. From the operation of Three Gorges Reservoir in recent years and hydrological characteristics of fluctuating backwater area, water area from Chongqing Lidu Yangtze River Bridge,547.8km of upper reaches of the Yangtze River, to Bai Shatuo of Jiangjin section of Yangtze River,704.0km of upper reaches of the Yangtze River was called fluctuating backwater area.The impoundment in the Three Gorges Reservoir made the water area wide and deep, which improved its navigation condition apparently, whereas the area of fluctuant backwater in the Three Gorges Reservoir was still characterized by the natural navigation route of mountain area and the navigation environment was complex, therefore, the unreformed channel should be optimized. Besides, with a lot of channel bends, crossing-river bridges, shelves and shoals, maritime accidents frequently occurred in this area and navigational aids or methods should be improved.The flow condition was proved to be one of the crucial factors for sailing safety by the result of analysis and evaluation of navigation environment of this area. In this paper, based on numerically simulated flow field during the period of falling stage, the character of navigation-obstructing flow in the typical channel was analyzed and the navigation path under the complicated water flow was optimized with artificial intelligence and three-dimensional virtual navigation system with the fusion of numerical water flow information was established under the virtual reality technology. The main research contents were listed as follows:(1)Through the temporal and spatial statistics of maritime accident in the area of fluctuant backwater and extraction of the key factor influencing sailing safety, navigation flow condition was regarded as one of crucial factors influencing sailing safety. (2)Because of the irregular inland river coastline, two-dimensional flow model under orthogonal curvilinear coordinate system was established and verified.(3) The verified flow mathematical model was used to simulate numerically flow field in the typical channel around bridge, bending channel and branch river estuary.(4) On flow numerical simulation basis, artificial intelligence optimization was comprehensively applied to optimize inland river navigation path and control navigation path of ship crossing river.(5) Three-dimensional navigation environment simulation model was constructed with the three-dimensional modeling and simulation technology. Based on that, three-dimensional virtual navigation system with the fusion of numerical water flow information was established under the interaction of flow numerical simulation and 3D simulation system.The innovation points in this paper were listed as followed:(1) Navigation environment risk estimation index system in the area of fluctuant backwater of the Three Gorges Reservoir was proposed based on the analysis of temporal and spatial statistics of maritime accident and accident-causing theory. Navigation environment risk assessment model was established through information entropy theory and unascertained theory. Besides, the key factors influencing traffic safety in this area were extracted.(2) Fitness function according with optimized goal of navigation path was designed with comprehensive application of flow numerical simulation technique and Artificial Intelligence Algorithms. Vessel crossing river were affected by different water pressures, therefore, velocity distribution function of channel section was constructed and control function of navigation path optimization was designed and optimal control of navigation path of ship crossing river was proposed.(3) Three-dimensional virtual navigation system with the fusion of numerical water flow information was constructed for flow condition of navigation intuitively.The optimizing navigation route and three-dimensional navigation environment fused with numerical water flow information provided pilot and shipping management department with decisive reference. The optimized navigation channel help confirm the best crossing river point. Besides, pilot can judge main and slow flow as well as avoid shoals intuitionally through three-dimensional virtual navigation system with the fusion of numerical water flow information. The research provided a good technical support for rapid, safe and economic sailing the area of fluctuant backwater of Three Gorge Reservoir and stimulates the prosperity of Marine Shipping Industry in Three Gorge Reservoir.