Evaluation Of Safe Navigation For North-extended Approach Channel In Yueqing Bay

With the acceleration of the urbanization process in Wenzhou,the shortage of cargo capacity such as bulk groceries and oil products has become increasingly prominent.For this problem,it is planned to build a 100,000 DWT bulk cargo terminal and a 50,000 DWT oil tanker terminal with approach channel and turning basin in the north Yueqing bay.Under the influence of natural factors such as wind,wave and current,yaw,collision and capsizing may happen in sailing,and ships may deviate from the turning basin area and affect the navigation in nearby channel.In order to ensure the navigation safety,it is necessary to carry out an evaluation in the planning and design process.By theoretical analysis and numerical simulation,this paper evaluated the navigation safety of the proposed approach channel and turning basin in north Yueqing bay.The conclusions are as follows:(1)The hydrologic and meteorological data in the area of the proposed project are measured and collected.According to the data,the effect on ships caused by tide,current,wave and wind was analyze.It is considered ships could navigate safely in the normal weather conditions,which made little impact.(2)The design dimensions of channel and turning basin for design ships types was demonstrated by Chinese design codes.The results showed that the design value was reasonable and meet the safety navigation requirements of the design ship types.(3)In the simulation part,tidal current characteristics before and after dredging project were numerically simulated based on the latest bathymetry data and structured mesh.And a comparison with observed data was made,which proved the credibility of the simulated results.(4)Mathematical models of approach channel and turning basin were developed with 5 conditions combined with wind,wave and current,which based on the simulated tidal current data of the finished channel.In these models,approach and turning motion status of full-load 100,000 DWT bulk cargo ship and full-load 50,000 DWT oil tanker were numerically simulated.The numerical simulated results showed that in the condition combined with wind,wave and current,both the track width and the yawing angle of design ship types reached the maximum,so steering attention should be paid.The design dimension of turning basin was reasonable for 50,000 DTW oil tanker,which could turn by itself at the low speed.However,the design dimension appeared to be smaller for 100,000 DWT bulk cargo ship,which needed assistance of tug for the safe navigation.(5)Navigation status in a narrow section of approach channel for two ships meeting each other in opposite direction was studied.A full-load and a ballast 100,000 DWT ship could safely meet in the narrow channel.The distance of ships was more than twice the ship's width,which meant that the channel navigation route was safe and reasonable.