Research On Optimization Tugboat Configuration In The Natural Navigation Area And Backwater Zone In The Upper Yangtze River

Since the 19 th National Congress of the Communist Party of China,with the indepth promotion of the strategy of strengthening transportation,inland waterway shipping has been greatly developed,and the proportion of waterway transportation in the comprehensive transportation system has continuously increased.In the upper reaches of the Yangtze River,since the completion of the Three Gorges Reservoir,there has been a distinct three-level pattern of reservoir area,backwater area,and natural navigation section.The natural navigation section and backwater area above Changshou Yangjiaobao have significant water level fluctuations,rapid water flow velocity,and poor channel conditions,with distinct accident prone characteristics.At the same time,it is easy to encounter dangerous situations in the river basin caused by insufficient ship power,blocking traffic,and affecting the order of water traffic.The tugboat deployed at this leg is the most important force to participate in accident rescue and solve the dangerous situation at the hanging beach.Reasonable and effective deployment of tugboats at this leg plays a very important role in ensuring navigation safety,maintaining navigation order,and promoting the orderly development of inland waterway transportation.For this reason,this paper aims to solve the problem of tugboat configuration in the natural sections and backwater areas of the upper reaches of the Yangtze River,and constructs a tugboat optimal configuration network for the research waters.Considering the overall structure of the waterway,this thesis solves the problem of tugboat optimal configuration in the sections.This thesis mainly conducts research work from the following aspects:Firstly,a field survey was conducted on the navigation environment and accident profiles over the years in the natural leg and backwater areas of the upper reaches of the Yangtze River,as well as statistical analysis of relevant data.The basic process and requirements for tugs participating in towing assistance and rescue in the natural leg and backwater areas of the upper reaches of the Yangtze River were clarified,and the basic environment for studying the configuration of tugs in the water area was analyzed in depth.Secondly,a tugboat optimal configuration network is constructed based on tugboat nodes and waterway nodes.Mux Viz and Network X are used to visually analyze the tugboat optimal configuration network,and node location attributes,as well as passage capacity attributes of waterway nodes,and power attributes of tugboat nodes are given,making the network more practical.A cascading failure model of the network is established,and the tugboat handling coefficient and waterway handling coefficient that affect the change of node load capacity during the cascading failure process are defined.Based on TOPSIS analysis method,network vulnerability is analyzed and evaluated from three comprehensive network indicators: structural entropy,connectivity robustness,and efficiency.Finally,by inputting the initial load and capacity of nodes,three attack strategies are designed: random attack,attack based on degree distribution,and attack based on accident(danger)weight order.The process of node failure in the entire tugboat optimized configuration network under different attack states is simulated.By comparing the overall vulnerability change trend of the network,the network vulnerability change under different processing coefficients is analyzed.Starting from the tugboat node alone,it explores the vulnerability changes of the network after the tugboat node is attacked,analyzes and compares the vulnerability impact of each tugboat node on the network,and proposes a specific tugboat deployment plan based on this.