.6000 M Deep-sea Mining Lifting Pipeline Drag Characteristics

Manganese nodules on deep sea under 4000-6000m have huge exploitation value. People generally recognize the hydraulic lifting mining system for manganese nodules is the most practical system up to now. It consists of lifting pipe subsystem, surface vessel and collector. The lifting pipe subsystem is important part of the deep seabed mining system, which influences transportation of nodules, mining efficiency and system security.On the base of force situation of the lifting system in the deep seabed mining, in this paper, draging properties have been analyzed in a variety of operating conditions for the lifting system. The main contents are:(1) For a variety of operating cases of the system, loads acting on the lifting system , and the boundary conditions have been analyzed and a mechanical model for the lifting system has been established.(2) Based on the Morison equation, a method for calculating the hydrodynamic forces acting on an inclined pipe has been provided, and a selecting method of Drag coefficient has been illustrated.(3) In the paper, in the basic idea of FEM has been introduced and a geometrically nonlinear model for finite pipe-beam elements of a stepped lifting pipe has been founded; and stiffness matrixs of element and the whole system have been derivated.(4) The characteristics of drag have been numerically solved with a variety of operating conditions , and then compared,and the range of collector's work and force have been given.(5) In this paper, an experiment has been made to simulate the system of lifting pipe.The method and result of simulation for the lifting system in this paper would be helpful for the further research and development of the deep sea mining technology.