Research On The Towing Safety Of Inland Towing System

With the rapid development of inland navigation and Yangtze river golden waterway construction in China,the inland towing business has increased year by year.Inland towing operation is generally carried out by highly experienced mariners or pilots who operate the inland towing system composed of towing ships,towed large ship,immersed tube tunnel element or other floating bodies through the inland waterways,which is a difficult task and has high operation safety requirements.Currently,the characteristics of inland towing operation has caused widespread concern in related units and communities.On one hand,complicated navigation environment and heavy traffic of inland waterways have increased the towing safety requirements and danger coefficients.On the other hand,the maneuverability of an inland towing system is susceptible to wind,current or shallow water effect because of the medium or low speed of the system and other characteristics of towing system navigating in inland area.Therefore,it is necessary to research the towing safety of inland towing system under the influence of wind,current and shallow water effect systematically.Main contents of this thesis are as follows:At the beginning,on the basis of analyzing research progress on the prediction of ship maneuverability,the 3-DOF equations of ship maneuvering motion considering shallow water effect is established by applying ship maneuverability theory which can be used to simulate the inland towing system motion.With the established 3-DOF equations of ship maneuvering motion,the maneuvering motion model for the inland towing system is established which takes the influence of wind,current and shallow water effect in to consideration.Computer simulations of forward sailing and turning test of the inland towing system are carried out.The factors which affect the inland towing system maneuverability are analyzed by applying the inland towing system maneuvering motion model.These factors include the length of towline,main engine rotational speed,wind,current and shallow water effect.The results of this study can provide guidance on inland towing operation.Considering the medium and low speed characteristics of the towing system navigating in inland area,wind-induced and current-induced inland towing system drift mathematical models are established.The accuracy and validity of the models are verified by applying the full scale tests under multiple conditions.Taking the towing project of Honggu Tunnel in Nanchang as an example,the safety limitations of towing the immersed tube tunnel element under the influence of wind and current is analyzed by applying the wind-induced and current-induced ship drift mathematical models.The proposed models can provide theoretical guidance for other inland towing project.Based on ship maneuverability theory,the ship maneuvering motion model of inland towing system and the wind-induced and current-induced ship drift mathematical models are established by applying mathematical modeling method,full scale tests and computer simulation.The towing safety of inland towing system is put forward and analyzed qualitatively and quantitatively.Through the present study,it provides a new way to research the towing safety in inland area.