Geometrical Correlation Research On Dynamic Behavior Of Deep Sea Mining Hose Operation Process

The deep sea mining system faces a lot of challenges besides the complex working environment.The geometric characteristics of the system structure and its changes greatly affect the safety and reliability of the system.The mine lifting hose,as the link connecting the relay cabin and the mine collector,is used mainly to transport the mineral resources collected by the mine collector to the relay cabin.The existing state of polymetallic nodules determines that the deep sea mining system will face the following problems during operation: the dynamic stability of the system would be influenced by the extremely large length-diameter ratio and ultra-long geometric characteristics of the lifting hard pipe,and the dynamic response would change along with the length and configuration of the conveying hose in the operation scope.These dynamic response changes caused by the geometric characteristics of the system structure and their changes bring new problems to the system reliability evaluation.Therefore,it is necessary to carry out a more comprehensive and fundamental research on the correlation between geometric characteristics and dynamic behavior of deep sea mining system,which could provide information to confirm the geometric design elements of the system structure and assess the system structure after the change of its geometric characteristics.When the collector works on the seabed,the length of the hose determines its operating range.The geometric space configuration formed at different positions in the operation process is the premise for the safe transportation of ore slurry to the relay compartment.Well-designed geometric space configuration and reasonable operating range are the guarantee of the safety and stability of the mining system.The research object of this paper is a 100-meter-long conveying hose at a depth of 1,000 water.Based on the finite element method,a fluid-solid coupling dynamic model of fixed hoses at both ends under the co-action of internal and external current is established,and the general dynamic characteristics of the single arch configuration hose at different geometric positions are studied.The main research results are as follows.The analysis of the hose modal at different geometric position shows:(1)With the collector getting away from the cabin,the natural frequency of the ore collector increases slowly.The wider the operation range is,the larger the bending curvature radius of the operating hose,and the greater its natural frequency.(2)With the collector getting away from the cabin,the amplitude of the collector decreases slowly.The closer the collector get to the cabin,the greater the amplitude.(3)During the operation process,the vibration modes of hoses in different geometric positions are basically the same,and the vibration modes of conveying hoses have nothing to do with the operation scope of the ore collector.The analysis of transient dynamics of the hose at different geometric position shows:(1)With the collector getting away from the cabin,the bending curvature radius of the operating hose increases,and the vibration displacement of the hose increases.Therefore,for the sake of the safety and stability of the system,the operating range should be strictly controlled to prevent the hose from touching the seabed.(2)When the outflow changes in the forward and reverse directions,the stress and strain changes can be ignored,but the vibration displacement of the hose would be influenced,especially in the Y-direction displacement.(3)When the direction of ocean current forms an angle with the surface of the hose,the lifting hose vibrates violently,and the stress and strain states change obviously,which would affect the system security.In the design of the mine lifting system,the influence of the direction of ocean current cannot be ignored.