Dynamics of a Pipe System for Hardrock Fracturing in Deep- Ocean Floor

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A new advanced mining pipe system for deep-ocean crust mining in ocean floor depths up to 2,500 meters is proposed and to be evaluated by numerical simulation. The mining system consists of a slowly continuous moving ship which maneuvers a deep ocean pipe with a mining vibrator or ocean-floor vehicle to fracture or crush the crust minerals. The development of this system, which has been identified by the industry as one of the most crucial, involves the analysis and control of the transient behavior of the pipe bottom end caused by the ship's oscillatory and maneuvering motion, hydrodynamic loading due to ocean waves and current, mining vibrator excitations, and dynamic interaction of fractured mineral and water mixture flows with oscillating pipe motion. The transient response of the pipe system consists of nonlinear large coupled bending-axial-torsional deformation of the pipe. A three- dimensional model of the complete pipe system based upon the discrete element method (DEM) is to be developed in order to analyze the nonlinear dynamics of this coupled pipe system due to the harsh operating and environmental loads encountered in a mining operation.