Study On The Vessel Traffic Flow Characteristics And Modeling Method In The Meandering River

In recent years,with the vigorous development of the modernization of China’s water transportation industry,the role of water transportation in the comprehensive three-dimensional transportation system has become increasingly prominent,which has made a great contribution to the social and economic development.The middle reaches of the Yangtze River flow through the plain area,with complex channel plane shape,violent riverbed evolution and extremely unstable navigation channel;Different from the upstream and downstream reaches of the main channel of the Yangtze River,the middle reaches are affected by the joint operation of the Three Gorges,Gezhouba and other hubs.Among them,the Xiajingjiang River section is meandering and has complicated water flow conditions.It has been known as the "Nine Curved Ileum" since ancient times,and it is a key river section for the safety supervision of ships in the main channel of the Yangtze River and the improvement of the passing capacity.Navigation conditions are important factors affecting the characteristics and modeling methods of inland river ship traffic flow.Revealing the characteristics of inland river ship traffic flow under meandering rivers is of great significance for water traffic safety supervision and navigation risk assessment.According to the above research background,this paper carries out the statistics and analysis of ship traffic flow characteristics in meandering rivers,constructs the ship traffic flow simulation model,and verifies the accuracy of the model;According to the fractal theory,the meandering degree of the river in the study area is defined by using the fractal box dimension;From the micro and macro aspects,this paper selects the ship domain as the micro characteristics of ships and the distribution process of ship traffic flow as the macro characteristics,and deeply discusses the characteristics and modeling methods of ship traffic flow in meandering rivers.The main research results of this paper are as follows:(1)Research on ship data preprocessing and Simulation in meandering riverAccording to the plane characteristics of the river in the study area,the fractal box dimension of the study river is calculated by fractal theory to describe the meandering degree of the river;The historical AIS data are preprocessed to obtain the distribution law of main ship attributes such as ship type,size,speed and time distance between ships.The ship simulation model of meandering river is constructed based on Monte Carlo method.Finally,the actual data and simulation data are compared to prove the effectiveness of the model,which can provide data expansion for subsequent research.(2)Analysis on ship domain and carrying capacity of meandering riverBased on the historical AIS data,the ship dynamic domain boundary is fitted by mathematical statistics,and the ship dynamic domain model of meandering river is constructed.The effects of ship size,river water level and box dimension on the characteristics of inland river ship domain are discussed respectively.Based on the ship domain size obtained by the model,the carrying capacity and navigation saturation of rivers with different meandering degrees are further calculated.(3)Distribution analysis of ship traffic flow in meandering riversBased on the Greenshields linear model,by analyzing the agglomeration and dissipation process of ship traffic flow when ships enter and leave the meandering river,the influence model of traffic wave in meandering river is constructed,and the parameters such as the maximum queue length,queue time and the number of ships affected when ships enter and leave the meandering river are calculated quantitatively.Considering the actual situation,the speed density relationship of ships in the actual scene of the research water area is also analyzed.Combined with the ship domain model,the queuing situation of ships in the actual scene is obtained.The research results of this paper show that the plane shape of natural rivers is one of the important factors affecting the characteristics of ship traffic flow.Rivers with larger box dimension have smaller long axis length in the domain of ships,weaker river carrying capacity and lower navigation efficiency,which are more likely to cause serious ship congestion and greater risk of ship navigation.